The car could produce 1800kg of downforce at 200mph in high downforce mode
The car could do 0-400 in 12s in low downforce mode maybe
It's not impossible but it's a stretch. The car is probably less slippery than the Chiron, but it may be much shorter, and have a smaller cross area.

Maybe is high downforce mode like you said, but the acceleration times still sound flawed. 200-400km/h in 7.6 seconds while for example the GT that did 300mph in 1 mile did 200-400km/h in around 8 seconds flat. I know the transmission difference, but the GT has >1000hp more has less downforce and is geared for top speed. I don't see how Bolide could be quicker from 200-400km/h.

Bugatti's claim of 0-400 km/h in 12 sec is laughable. The UGR Lambo that did 0-259 mph in approx 13 sec with far less downforce had 3000+ hp. I rest my case...

I mean that didn't have much traction for a lets say <2.5 sec 0-60
The best car to compare it with is this GT

Ok let's use the Ford GT shall we which had at least 2500hp given the dyno maxed out at 2035bhp. Low downforce, about 1500kg(stripped out) 200-300 km/h 3.5 sec(slower than the Evija and Bugatti, apparently) 300-400 km/h 5 sec so that's, according to Bugatti, slower?? FFS i've heard enough shit for one day lol

I think they shouldn't have said the acceleration estimates especially after what happened with SSC
They should have just said 0-100 and 0-200 km/h or maybe 0-300 km/h and left others to tests that they do(like a 0-400-0 km/h or perhaps a 0-300-0 mph run if it really can hit 300 mph)

Problem is Bugatti are such wankers that they won't allow any independent testing of their cars so all we've got is their simulations which IMO are full of shit. Maybe Bugatti and SSC can become partners lol

I wish they did
All of the hypercar makers I mean

The Bolide has a cdA of 1.31 in high downforce mode and a cdA of 0.54 in low downforce mode, which is less than the Tuatara, less than the Jesko Absolut and FAR less than your Ford GT dragster. And given the massive amounts of moveable aero parts that could actually be possible. Drag coefficient is key at top speeds. Furthermore, this Bugatti weighs 300kg less than the Ford GT as well. And Bugatti's latest claimed numbers on the Chiron were perfectly on par with reality. So why would they lie? Not to mention that the 919 Evo was capable of doing 150-250kph in 2.2 seconds, with a worse power to weight ratio! Compared to those two, the Ford GT is a kit car.

Oh lord, just stop being a soyboy Speedking. Bugatti's claims for the Chiron were UNDERestimating the real world numbers.

If those numbers are unrealistic to you just because a kit car with a parachute offers worse times, you probably question the 919 Evo as well? Because that one does 150-250kph in 2.2 seconds either, faster than the Ford GT, with a worse power to weight ratio (allegedly).

A Bugatti Bolide with lower downforce than a Tuatara or Jesko Absolut bahahaha. You're clearly a buffoon.

Or you just don't understand the word:
A D J U S T A B L E

Somebody who doesn't understand that downforce isn't the same thing as a drag coefficient should be careful about calling me a "buffoon".

Bugatti hasn't lied in the the past. In fact, they underestimated the Chiron numbers. Why would they now? And how so?

For me it makes perfect sense. The roofline is extremely low, so even with a drag coefficient of above 0.3 in low downforce mode, it STILL has a cdA just 3% above the Jesko Absolut because of the smaller frontal area. Wouldn't even surprise me if you completely disassembled the spoilers and flaps, you would get a cd in the low 0.2s, the whole bodywork is streamed through. One channel even goes all the way from the front splitter THROUGH THE DOOR to one of the radiators. The inflatable "golf balls" on the roof, the adjustable spoiler, front, diffusor etc. leave a massive playroom for aerodynamics that aren't possible in FIA racing due to rules.

"should be careful about calling me a "buffoon". that coming from someone who referred to me as a "soyboy" so don't you be taking the moral high ground. Back to facts Bugatti claim the Bolide has 1240kg(dry weight) so what is the kerb weight with fuel? In addition they say the downforce is 800kg at front wing and 1800kg at rear wing at 200mph. What is the downforce at 250 or 300mph? Does the "adjustability" reduce the downforce by half above 200mph, highly unlikely and Bugatti don't reveal any details re that so claiming a particular figure would be speculative. Anyway i could go on but given Bugatti are such elite fcuks and won't allow anyone to independently test their cars so they can claim what they like but it doesn't mean it's true and i'm not gullible like so many others to swallow their claims :)

My "soyboy" wasn't about morality at all, just about knowledge, which you seem to lack...

You STILL don't get it, do you? The wing, front splitter, diffusor, intakes AND roof are adjustable and the whole car consists of holes. You have the 2.6 tons of downforce at 200mph only in downforce mode. In high speed mode - where the acceleration figures belong to - you DO NOT HAVE those amounts of downforce. As for your question about the adjustability, another prime example: JUST the air brake on the Veyron (you know, where the spoiler goes vertical) suddenly increases the cd value from 0.36 to over 0.7! Nuff said?

Furthermore the roof is insanely low, the car isn't even 1m high, decreasing the surface area massively. That's why it doesn't even need a cd of below 0.3 to still reach a cdA of 0.54 in high speed mode. Its roof is 22cm below the Jesko or Chiron.

"Claiming a particular figure would be speculative"

Sure, because Bugatti doesn't have fluid mechanics simulations. In contrast to SSC or Koenigsegg, the cd values Bugatti puts out always fitted the theoretical mathematic values for calculating top speed (wind + rolling resistance). They did on the Veyron and the Chiron, why wouldn't it now?

"given Bugatti are such elite ****s"

And that's where all objectivity is flushed down the toilet. And how do they claim what they like? During the Veyron record runs, Guinness was present. During the Chiron runs, the German TÜV was present. Both are enough to verify the speed is real. Furthermore, in contrast to SSC their videos didn't leave any questions either. As for trying to prove a back wind, the Chiron SS had a ~10kph cross wind blocked by the trees around the track. And Ehra Lessien is DEAD flat.

And while we are at Ehra Lessien:
You do realize that it isn't Bugatti's but VW's test track? And you also realize that there are a SHITLOAD of prototypes that other manufacturers aren't supposed to see? Not to mention Pahrump (SSC and Agera RS records) actually has multiple advantages from thinner air to a double-downhill sections going both directions to leave the possibility of actually cheating.

I don't think its that easy. To have active aero wing, splitter, diffusor and claim that you now have two cars - one as good as LMP1 prototype on track and the other that goes 500 kph.

It implies that McLaren were idiots when they built the Speedtail. They could have just make the aero bits movable on Senna and they would have 400 kph car.

I just can't convince myself looking at that picture that its a 500 kph car. Or, especially, that it can do that and stay with LMP1 on Nurburgring. Maybe I am just too jaded and cyclical about this as I am about most things...

"My "soyboy" wasn't about morality at all, just about knowledge, which you seem to lack.." Get off your fcuking high horse, you're not that smart and it was a derogatory comment regardless of how you want to defend yourself. You can crap on with as many figures as you like but that doesn't prove anything. All it does is suggest that certain things are possible in theory but that doesn't mean it's going to have the overall effect in reality. I, at no point claimed that the Bugatti didn't do 304 mph i just said that it would need closer to 1800hp to attain that speed and nothing you can say will disprove that, get it?

"Maybe I am just too jaded and cyclical about this as I am about most things"... No you're being a realist and Bugatti are full of shit, regardless of what BTICronox says...

"Get off your fcuking high horse, you're not that smart"

You're talking to an actual engineer, but k. Who cares.

"I, at no point claimed that the Bugatti didn't do 304 mph i just said that it would need closer to 1800hp to attain that speed and nothing you can say will disprove that, get it?"

If it would be a NORMAL Chiron, that would be true. But it isn't. The Chiron SS300+ would need a cd value of ~0.33 to reach that speed with the advertised 1600hp. The regular Chiron has 0.35. Shall I calculate it for you? If that's sooo far off reality for you, there's nothing I can do for you.

"No you're being a realist and Bugatti are full of shit"

So you say, yet you haven't countered with evidence even ONCE. I gave my hints towards proving Bugatti's claims in my latest comments, to which you didn't give a proper answer. Which probably means that you simply can't.

"You're talking to an actual engineer, but k. Who cares." precisely, having a degree does not make your opinion incontrovertibly correct. You can cite as many theoretical calculations as you like but they are just that , theoretical, therefore unproven.

Anyone who doesn't allow their cars to be independently tested is elitist and more often than not has something to hide. Furthermore, making outlandish theoretical claims that a 1850hp car with at least 1450kg(which includes fuel and driver) can accelerate from 200-400 km/h in 7.6 sec with significant downforce is laughable. I have a drag racing background with real experience and will never be that gullible...

That's at least a valid answer I can work with...

"It implies that McLaren were idiots when they built the Speedtail."

No, McLaren just is on the brink of bankruptcy while Bugatti is "sponsored" by the billions VW has to offer. Also, the Senna still has to be street legal and moveable aero parts are Furthermore, as you said, "it's not that easy" - the Bolide is a COMPLETELY different car to the Chiron. Onto that later.

"Or, especially, that it can do that and stay with LMP1 on Nurburgring"

Even Bugatti says it "only" does 2.8g lateral including the slick tires. A 919 Evo does over 5g. However, this accelerates A LOT harder than regulated LMP1 cars to compensate for that. Now describing the Bolide itself in a seperate comment (too long)... I'll give you my thoughts on why I think the specs are actually senseful.

B O L I D E A E R O D Y N A M I C S

I understand your doubts, but take a deep look towards the aerodynamics. Nearly the whole car is streamed through. The interior cabin, which is the most problematic part in terms of streaming area (no place for air to go but around it), is tiny compared to the Chiron.

The roof is 22cm (!) lower than the Chiron, massively decreasing the frontal area. If the frontal area is reduced by the same percentage (22%), that would mean that even with the exact same cd value, it would need far less power. If that would apply to the Bolide vs the Chiron SS, it would just need ~1300hp to reach the same 490kph (304mph). The Bolide is also 3cm narrower than the Chiron and has cameras instead of side mirrors. Furthermore, it's even lower to the ground, further decreasing drag through the tires underneath the chassis.

The frontal area is nearly completely open and guides the air through the car. Even two of the REAR intakes start in the front and are guided through the door (!) to get to the radiator.

In high speed mode, there are "bubbles" in a typical golf ball shape that rise to prevent the air tearing off the roof and creating unwanted low pressure areas. The low roofline also basically guarantees that the air won't tear off until it reaches the spoiler.

The flaps built into the diffusor, front and spoiler are variable completely and are responsible for most of the downforce simultaneously. Because of the crash behaviour (especially front), flaps of this size are basically impossible to get street legal.

The "rims" are turbofans and efficient in terms of aerodynamics as well. Estimated, they reduce drag on such big rims by ~4% alone!

That's it for now.

"having a degree does not make your opinion incontrovertibly correct."

That's correct, but I at least give arguments towards the topic instead of simply calling it "bullshit" and the manufacturer "elitist ****s".

"You can cite as many theoretical calculations as you like but they are just that , theoretical, therefore unproven."

And you can call it bullshit all you want. Until you've actually proven them wrong, we have to accept the given specs and analyse how and why they could be correct... or if you think they're wrong, go into detail and analyse it just like I did.

"Anyone who doesn't allow their cars to be independently tested is elitist[...]"

I don't even know what you're talking about. Old Top Gear got one, Grip did, various owners have put it above 230mph, PP Performance even "Stage 1"'d a Veyron. You can even talk to Bugatti as a customer and give your car a go at Ehra Lessien if you like. I know, I live nearby.

"[...] and more often than not has something to hide"

Except Bugatti's specs in the last 15 years were underestimated. They claim a 13.5s 0-300kph in the Chiron, it did it in 13.1s already. Just an example.

"theoretical claims that a 1850hp car with at least 1450kg(which includes fuel and driver)[...]"

Let's check that... It has 1240kg of dry weight. The Chiron engine needs ~15 liters of oil, which makes 13.5kg, and 40 liters of water. The driver normed in the German "Leergewicht" is 70kg. And even 100 liters of E85 (full to the brim, Chiron fuel tank) are "only" 78kg extra. That makes a total of ~1360kg including the driver and empty tank and 1440kg including the driver and a full to the brim fuel tank. "At least", yea :P

"[...]can accelerate from 200-400 km/h in 7.6 sec with significant downforce is laughable"

That's your problem. You think that the car always has this amount of downforce. It doesn't, see my comment about aerodynamics above. Furthermore, it has a tiny frontal area.

" I have a drag racing background with real experience"

And on what cars? Surely not something that basically has the height of the average F1 car in an enclosed cage and consists of holes everywhere. And comparing it to a Ford GT dragster with a horribly inconsistent gearbox, parachute on the back (horrible cd value), increased weight due to the tuned engine and cage and no known hp number is the cherry on top.

The whole problem revolves around you not believing the car can achieve such a low drag coefficient. If what Bugatti said is true about the cdA in high speed mode, their numbers about the acceleration are probably accurate as well. If the car can NOT achieve such a low cdA, the acceleration numbers will fall apart, simple as that. The horses and weight are just part of the whole.

Have a nice day.

The car has a dry weight of 1250kg, then with fluids it doesn't have to have all of the fuel in it. Just enough to do the run, like a few liters.
If we assume the weight with driver is 1400kg.
the kinetic energy difference between 400kph and 200kph is 6.48MJ.
Over 7.6s that = 1160PS per second needed if this car was accelerating in a vacuum.
If we assume the car has a top speed of say, 530kph.
Then that infers that the car needs 1825hp to overcome the 530kph air resistance. and we can calculate how much hp is being lost to air resistance at 400kph. 1825(400/530)^3 = 785PS. Remaining hp to accelerate the car 1040PS.
While at 200kph, the car has a power loss of 1825(200/530)^3 = 98PS.
Remaining hp to accelerate car at 200kph = 1727PS.

Of course there are drive train losses, which I suspect could be less the conventional 15% if they used straight cut gears, or racing components. The math says it might be possible, but that's assuming the car CAN do 530kph.

I find it a little awkward that VW group which is popularly known to give BS conservative HP and performance numbers would be so aggressive with these theoretical figures.

"The math says it might be possible, but that's assuming the car CAN do 530kph."

The Bolide according to Bugatti has a cdA of 0.54 in high speed mode and 1850 metric hp. Giving it the exact same situation the Chiron SS had, the Bolide would actually be capable of doing ~560kph (346mph), as unreal as it sounds.

If this car can really do 500 kph and Nurburgring 5:25 this is the first and only car of this kind, because nothing is even close to having both of those capabilities at the same time, including Formula 1, LMP1 top fuel dragsters and Thrust SSC world land speed record car.

I am not sure aerodynamics are as simple as you are desribing. Even if most of the aero surfaces of this car ar movable, they still can't disappear. If the air is turbolent it will still hit them and generate drag. And even if ari flow is smooth, there will still be some sharp edges sticking out in the air flow which will generate more drag than their miniscule surface area might suggest.

In other words, a rear wing side plate might have almost zero frontal area, but it will generate nonzero drag, same for the "disabled" movable wing surface itself. It doesn't exactly disappear, it will still catch some buffering air.

Bolide has low roof, but about the wheel arches? They are effectively front wing too. Can they disappear also?

The car just doesn't look smooth. I know that looks don't really equate to wind tunnel results but I just think its a major major stretch to think that car which goes 5:25 ar Nurburgring can have all of that aero effectively disappear thanks to some servo motors moving some winglets here and there, so that it now becomes a 500 kph streamliner.

Capable of 560 km/h?

Formula 1 and LMP1 are limited to rules, the 919 Evo afterwards was limited by budget, which is why they only changed minor things and derestricted the car. Top Fuel dragsters could go MUCH faster than 500kph, they do that in 400 meters. And the Thrust SSC is a rocket on wheels...

No, please don't get me wrong, aerodynamics are everything BUT simple, the thing is though that the Bolide, in contrast to any other Bugatti or generally hypercar for that matter, is like a swiss cheese. The intakes for the intercoolers start up front and the side, the air goes through the radiator and after that straight through the very open rear end that no other car has like this.

Of course the wheel arches can't disappear, however, the bodywork above is (pretty obviously from a side view) way more aerodynamically shaped than on the Chiron, and they said something about air being guided around the wheel arches as well. Forgot about that one.

Of course it is hardly believable, but I think part of the (simulated!) Nordschleife time is the absurd acceleration of this car. In most longer stretches this thing would greatly surpass the 919 Evo's straight line speed to compensate for the worse grip. And the long straights at LeMans would greatly play into the Bolide's hands, since it simply has a shitload more power than LMP1 cars.

Still would love to see what this car is actually capable of nonetheless. Hopefully, this won't become a pure museum piece and will be tested. Until then, I'll just believe Bugatti for the simple fact that they haven't lied about specs for the last 15 years. Call me naive :P

I know, sounds like bogus looking at it. But taking Bugatti's specs, that's the outcome.

Power to overcome wind and rolling resistance:
P = cdA * rho/2 * v^3
P = m * g * f(roll) * v
P (total) = [ P (wind) + P (roll) ] * 1,36 * 1,1 (in horsepower)

The cdA according to Bugatti is 0.54, the rolling resistance of slicks like this on asphalt is probably ~0.02, the car weighs 1400kg including a driver and fuel (pretty much useless, since wind is 98% of the resistance at that speed), rho at the Chiron SS300+ run was 1.205kg/m^3, and P total is 1850hp. 1.36 is the conversion to kW and 1.1 is the internal resistances (friction).

If you bring em all in and convert it to v, you'll get the 560kph i'm talking about, in meters per second value of course.

Funny enough, suddenly the "20 seconds to 500kph" value makes sense again, the Agera RS needed something like 26 seconds to 400kph and had a top speed of 446kph, which isn't as far off as the 0-400 would suggest.

But that all will only happen if the Bolide can actually achieve such a low cdA. Not afraid of the lack of power in this monstrous engine xD

"I just think its a major major stretch to think that car which goes 5:25 ar Nurburgring can have all of that aero effectively disappear thanks to some servo motors moving some winglets here and there, so that it now becomes a 500 kph streamliner."

Not only is it inconceivable but even if they halved the drag above 200mph through their adjustable wizardry you would need way more than 1850hp to reach 560 km/h at which point a catastrophic crash would be a very real scenario. Honestly it's getting totally idiotic. BTW a top fuel dragster with 11,000hp can do 340mph in 4.4 sec however they do have close to 2500 kg of downforce at that speed to enable them to put the power to the ground and prevent them from flying lol

"even if they halved the drag above 200mph through their adjustable wizardry you would need way more than 1850hp to reach 560 km/h"

With that statement, you've clearly stated that you don't give a shit about math. I gave you EVERYTHING to prove exactly that. The exact same formula btw works with the Chiron SS reaching 490kph with the advertised 1600hp and a cd of ~0.33 ;)

There's a difference between maths, theory and reality. When someone goes to the trouble of actually testing all the various configurations including confirming power levels and produces your claims then i'll believe it. In the meantime take a chill pill coz your ego isn't dealing well with being challenged. It's not that important :)

Some collection of random crap spawed by some random arian missionary, sent to educate us by some random german cars forum. We should all be grateful to germans who take their time to explain how they can defy physics laws, just by being germans. Where is cosimo?

1: "The roof is 22cm (!) lower than the Chiron, massively decreasing the frontal area. If the frontal area is reduced by the same percentage (22%)"

bolide's height is 1m, so 1.22 to 1 is not a 22% decrease.

2: "The cdA according to Bugatti is 0.54"

it is extremely unlikely that bolide's cda is less than 0.6, unless you entirely replace the chassis. frontal area might be slightly less than 2m^2, but as it is 2m wide and 1 meter high, it is basically impossible that it is less than 1.8m^2, since the rear engine openings stick up at probably 0.95-0.9m. if you remove all spoilers, wings, etc one maybe gets a cd=0.37, if lucky enough. There are still plenty of huge cooling holes, vents and the whole rear is completely not designed to have a low cd.

3: "P = m * g * f(roll) * v
the rolling resistance of slicks like this on asphalt is probably ~0.02,"

power to overcome rolling resistance is linear in speed? ahahahaha
pathetic, just like any german institution who gave you any sort of degree, should you ever earned one.

"With that statement, you've clearly stated that you don't give a shit about math. I gave you EVERYTHING to prove exactly that. The exact same formula btw works with the Chiron SS reaching 490kph with the advertised 1600hp and a cd of ~0.33 ;)"

you proved a jack shìt: your "computation" assumes both a cda of 0.54, which is laughable at best AND a negligible rolling resistance, which is a mix of incompetence and meth-level dope.

not to have your arse kicked, go back trolling rennsport.

"Where is cosimo?"

Probably too busy insulting others. Or it's your second account, who knows? At least you sound like him.

By comparison, 1.22m to 1m is a 22% INcrease though. And that's how I calculated, not vice versa. Should've been more clear about that.

"it is basically impossible that it is less than 1.8m^2"

Uhm... the Koenigsegg Jesko Absolut has 1.88qm while having a roof 21cm higher as well and actually being WIDER than the Bolide. The frontal area could as well be around 1.7qm. We don't know yet.

"since the rear engine openings stick up at probably 0.95-0.9m"

No... just, nope. Look at the pictures again please. I actually took a side view picture and counted the pixels, and compared the very top of the roof to the side intakes. The side intake's very top is at ~77-78cm height. But we're nitpicking now.

Then, prove me wrong. Should be easy for you. That's the formula, deal with it. The "m" could increase because of downforce, or even decrease because of uplift, but otherwise it's set. Not to mention that it doesn't even matter because it's responsible for (far) less than 5% of the top speed at that level. I only see one pathetic here...

"your "computation" assumes both a cda of 0.54, which is laughable at best"

It's what Bugatti states for the Bolide. And everything they gave us so far mathematically perfectly fit reality for the past 15 years. Deal with it.

"AND a negligible rolling resistance"

Calculate it for yourself or shut the **** up. Rolling resistance at over 500kph is meaningless in comparison to wind resistance. Even a retard like you should understand.

Next time, come up with some evidence, you're embarassing yourself...

"In the meantime take a chill pill coz your ego isn't dealing well with being challenged"

Oh, don't you care about my ego. I'm fine :)

So whoever disagrees with a German or goes up against a 911/VW fanboy is considered an insult ? and last, all fingers are pointed at cosimo ? LOL

I think you need to take that chill pill ASAP!

"Some collection of random crap spawed by some random arian missionary, sent to educate us by some random german cars forum. We should all be grateful to germans who take their time to explain how they can defy physics laws, just by being germans."

"pathetic, just like any german institution who gave you any sort of degree, should you ever earned one."

"you proved a jack shìt: your "computation" assumes both a cda of 0.54, which is laughable at best AND a negligible rolling resistance, which is a mix of incompetence and meth-level dope."

"not to have your arse kicked, go back trolling rennsport"

Sure, that's not insulting at all... and such argument, wow! insert doge meme

insert doge meme

You don't have to take things way too seriously.

It's the interweb after all, anyone can chime in and aim at you with whatever they have. This dick contest thing will never end, it just keeps on coming back again and again.

Try the Bahamas as your country.

I don't personally feel attacked by it though. It's just the "oh lord" moment that keeps me going somehow. And yes, I know I'm digging way too deep :P

""power to overcome rolling resistance is linear in speed? ahahahaha"
Then, prove me wrong. Should be easy for you. That's the formula, deal with it."

yes, i will do my best to deal with it, sweetheart, how lovely. Let's see...
what i should deal with, specifically:

"the rolling resistance of slicks like this on asphalt is probably ~0.02"

here you actually claim rolling resistance is constant, which says a lot about your mastering of these subjects. For sake of the interested reader, let's assume you really meant rolling coefficient instead.

Vehicle Dynamics: Theory and Application--Di Reza N. Jazar. Springer
pag. 76 fig. 1.56
https://books.google.it/books?id=5fokDwAAQBAJ&pg=PA68&lpg=PA68&dq=%22fourth+degree%22+speed+rolling+resistance&source=bl&ots=B9DKEmLq0a&sig=ACfU3U2GHYRE9Rno-w72yQDTYSnP5LosKQ&hl=it&sa=X&ved=2ahUKEwij5P-csefsAhUEzqQKHWgZBKoQ6AEwFnoECA0QAg#v=onepage&q=%22fourth%20degree%22%20speed%20rolling%20resistance&f=false

that's a quadratic fitting to experimental data rolling coeff measurements in function of speed.
The fitting is good up to the tyre's "critical speed", at which point, the experimental explodes and probably is no longer even polynomial.

How is that as "proof"? You talk about mathematics, proofs, etc but you can't compute percentages, you don't understand the difference between force and a coefficient, you approximate a likely exponential graph with a constant and tell me to "deal with it".

germancarforum...no?

"here you actually claim rolling resistance is constant, which says a lot about your mastering of these subjects. For sake of the interested reader, let's assume you really meant rolling coefficient instead."

That's your problem? A formality? Yes I do mean the coefficient, I did from the beginning, should've been clear from within the formula... But I apologize for forgetting a single word after basically writing multiple essays in a language that isn't even my mother tongue :D

About it being a constant, onto that later in this comment.

"pag. 76 fig. 1.56"

You realize that this graph ignores tire pressure completely? Scroll down to Figure 1.59, where the author unfortunately switches to motorcycle tires for whatever reason, nonetheless it's important for both types of tires, as seen in equation (1.118). Thanks for the source anyway, that's something to work with at least. I actually did an experiment and calculated the needed power for both, my calculation before and the one from the book including the quadratic factor by using said equation (1.118) and (1.120) respectively.

I don't know the pressure of the slicks mounted on the Bolide, the Chiron had ~3.2 bar. Taking that factor, the rolling resistance at 560kph was actually LOWER than my calculation before, at just 42kW compared to 48kW using the "simple" equation. I compensated for that by taking the higher value beforehand. And yes, when you don't change the speed by assuming the approximate top speed value before, "ur" becomes (!) a constant. Who cares about 550 or 560kph? That's a difference of less than 2% for "ur" compared to the up to 100% depending on tire pressure - and that only being a percentage OF the percentages following!

Also did a second calculation, and even at Formula 1 pressure (doubt that, the tires have to withstand the extremely high speeds, less deformation needed, Bugatti talks about just 2.8g lateral, F1 does 6g), it just barely reached 80kW. The engine produces 1360kW. At 560kph, the rolling resistance for 3.2 bar is ~3.2% of the whole resistance including wind, and even at F1 pressure it's still just 6.2%. But "can't compute percentages", I guess.

I included rolling resistance into the 560kph calculation despite saying "negligible" from the beginning btw. Even gave the Bolide some extra weight through downforce despite "high speed config" AND gave the slicks a higher "K" to strengthen YOUR argument despite the source saying the exact opposite, that a slick tire has LOWER friction. And yes, in terms of top speed, especially with such a leap, a one digit percentage is nearly negligible for my taste, because an increase in power by another 100kW (136hp more!) to completely compensate for the rolling resistance would mean an increase of a mere 13kph thanks to the wind resistance. But here we are, arguing about a few kW when talking about speeds north of 500kph...

So... deal with it? ;)

You could've also calculated for yourself, instead of shitting on me. Would've increased the value of this conversation, you know. But that would've shown you that your figure 1.56 doesn't show real world results and your argumentative base would've fallen apart before even writing the comment.

I don't give a crap about the German car forum, neither do I see what it has to do with this discussion. But you seem to have fun bringing in redundancy into a conversation.

Hope that's helpful, have a nice day.

they're already dead bro calm down you dont need to outsmart them by that much of a margin

"You realize that this graph ignores tire pressure completely?"

so what? you asked for a proof of coefficient of rolling resistance Crr not being constant, you already forgot? and there you have it. In that graph there is an experimental Crr with tyre pressure of about 2.5 bar which is far from being constant and regardless the tyre pressure it will never be constant, nor linear or even quadratic in speed.

"Taking that factor, the rolling resistance at 560kph was actually LOWER than my calculation before, at just 42kW compared to 48kW using the "simple" equation. I compensated for that by taking the higher value beforehand. And yes, when you don't change the speed by assuming the approximate top speed value before, "ur" becomes (!) a constant"

i do not understand what you are saying, nor do i understand what's the "simple" formula and your blabbing about mu_r being constant. You are lacking basic knowledge of the subject and do not comprehend science/enigineering college textbooks.

What that textbook is trying to tell you is, at first approximation, there are
two scenarios: 1. you want to model Crr below tyre's critical speed, or 2. at any speed. In the first case, apparently, if you regress measured Crr only on one predictor (velocity^2) and the constant term, you get some reasonable model:
mu_0=0.015 and mu_1=7e-6, according to the author. If one wishes to model Crr even above critical speed, you need at least a fourth degree term (velocity^4) in your model: see example 59 in the link i provided you. The reason being that above tyre's critical speed Crr explodes, as anyone clearly sees from fig. 1.56.

As for computations, if you are obsessed about pluggin in tyre pressure somewhere, you can use the formula written a couple of pages later, which expresses Crr=mu_r in function of velocity (v_x), tyre's pressure (p) and load (F_z).
I am not a fan of using a formula i do not know the origin of, and i would rather use the v^4 linear regression model, but that is what you want.
Plug in v_x=500km/h=139m/s (so that we can also make fun of Chiron ss300 real power), p=300kpa=3bar, F_z=3500 newton (1.4 tons /4) you get Crr=0.07.

Such a Crr at 500km/h yields 34kw needed to overcome rolling resistance per each wheel. Since rumor has it that bugatti cars have 4 wheels, this amounts to 135kw=182hp for the car, which is more than 10% of the aerodynamic drag.

HOWEVER, there are two huge caveats:

the load i considered is just the weight of the car+driver, which is hugely underestimated at 500km/h. Even without any wings, spoiler etc, just because of air deflection against front shield and chassis (newton's second law) and some venturi under the car, the load could be several thousands newtons higher than 3500. This resulting in a large increase of Crr.

there is no tyre which has critical speed higher than 500km/h. Y rated tyres, such as chiron 300's, have a max speed of 300km/h. Say that the Bugatti's bespoken version is slightly higher than that. That implies that at 500km/h any tyre is head and shoulders above its critical speed, therefore
the v^2 model used in the computation is no longer effective, and the v^4 one would yield a better fit. Do i need to tell you what happens to Crr if we use v^4 model instead of v^2 for v=500km/h ?

All in all, Chiron ss300 needed at least something like 1800hp to reach 500km/h (i.e. the power claimed for bolide...go figure...lol) and Bolide's 560 km/h with 1800hp is as realistic as the earth bursting in a supernova tomorrow, ahahah. Oh never mind, you are german, physics just applies to the rest of the world

He just got outsmarted back. Does this happen when Einsteins fight?

Could you calculate the theoretical max speed of the McLaren Senna because it appears to be slower than a 570S in testing?

The Senna has 800kg of downforce at 155mph however it also has adjustable front winglets 40deg and the rear wing can move up to 30deg from its horizontal position. It's a bit hard to know what the downforce is at 200mph but it pretty much starts to hit the wall at approx 170mph and progressively slows approaching its top speed of 204mph on a Florida airport runway compared to the 570S speed of 206mph. According to dyno tests the 570S has approx 600 crank hp whereas we know the Senna has at least 830hp or more. They both have the same gear ratios.

the wing is the reason the top speed is lower. now apparently, the theoretical top speed is 215mph, but I kinda doubt that

If I recall correctly the senna tops out at around 800kg downforce because the active aero will reduce the angle of attack at higher speeds to prevent the suspension from breaking

Ok that would make sense and in addition i'm guessing that it would also place an excessively high load on the street tyres which wouldn't be ideal. The thing that amazes me is how much affect the drag has on the Senna's top speed when compared to the 570S for example which has approx 230 less hp but low downforce. The claim is that the rear wing alone generates 500kg of the total downforce. This is primarily why i have doubts with the simulated figures claiming the Bolide will be capable of going well over 500 km/h. I'm not saying it's impossible but i do claim that the acceleration figures from 200-500 km/h in 15 sec is simply bullshit.

In the end, the only way we'll know for sure is Bugatti trying it out. Although there will be "fraud" news about the engine's power then, surely :P

Well obviously engine hp is finite and the more power one extracts the greater the heat and excessive heat is the enemy of longevity in any ICE. I can't see Bugatti pushing the power level much beyond 1850hp because traction also becomes a challenge. Anyway time will tell and i look forward to seeing how close they get to their claims assuming it happens?

"You are lacking basic knowledge of the subject and do not comprehend science/enigineering college textbooks."

Kind of a reach, isn't it? Most "car guys" here don't even know what's the "basic" stuff we're talking about. But sure, if you feel better by insulting others, keep going.

I simply forgot to type in a "4" in front of the calculation. However, the more I calculate with your formula, the less believable is the outcome, as the rest of the comment will state.

"i do not understand what you are saying, nor do i understand what's the "simple" formula and your blabbing about mu_r being constant."

Every single publication I went for stated mu_r as what is mu_0 in your publication, including high speeds. Simple as that. Even "Engineering Explained" - a mechanical engineer with a Youtube channel - uses my way for calculating top speed. Guess he's just one of the "dumb Youtubers" and should burn his degree immediately, because he didn't use a calculation that I by now could only find in your single publication and nowhere else, including my own old publications used for learning. Neither do the calculations state where the constants (numbers) actually come from. Neither does it consider tire width, tire mixture, nor my own "huge caveat" that I'll address in the last section.

Just for fun, I calculated the needed power for the old Veyron by using your own formula. The power to overcome wind resistance for the old Veyron to go 407kph using the known data, which is a cd of 0.36, an A of 2.07, is ~650kW (882hp). The rolling resistance according to your formula on all four tires accumulated would be 143kW (195hp), even not including your "huge caveat"! So in total it would need 1077hp just to reach 407kph. And that doesn't even include internal losses. The Veyron only has 1000hp BEFORE internal losses! I'm sorry, but your formula just doesn't fit. However, mine does, giving a power to overcome rolling resistance of 33kW (45hp), leaving space for 8% in internal losses. If I would include those into your calculation, that would mean the Veyron would've even needed 1160hp.

Well, except Bugatti lied for the past 20 years consecutively, which is the base of your argument to begin with... too bad they never got caught and people in real life are achieving the exact same accelerations as "press cars".

"The reason being that above tyre's critical speed Crr explodes, as anyone clearly sees from fig. 1.56. [...] Say that the Bugatti's bespoken version is slightly higher than that. That implies that at 500km/h any tyre is head and shoulders above its critical speed, therefore the v^2 model used in the computation is no longer effective, and the v^4 one would yield a better fit. Do i need to tell you what happens to Crr if we use v^4 model instead of v^2 for v=500km/h ?"

Then why didn't you do it despite your own publication stating so? Afraid that the demanded power that you'll get would exceed the horsepower the car has, even without considering wind resistance? Hard to calculate against reality, isn't it? :P

"Such a Crr at 500km/h yields 34kw needed to overcome rolling resistance per each wheel. Since rumor has it that bugatti cars have 4 wheels, this amounts to 135kw=182hp for the car, which is more than 10% of the aerodynamic drag. [...] All in all, Chiron ss300 needed at least something like 1800hp to reach 500km/h"

First of all, why are you mixing up the Chiron SS with the Bolide? This whole argument didn't have a structure from the beginning. If I take your Crr for the Chiron SS, it would've even needed 241kW (327hp) just to overcome rolling resistance at 490kph. Too bad the whole rest of calculation doesn't fit then AGAIN! Neither does it for the Agera RS (cdA lower than the base Agera... lol!), neither for the McLaren F1, neither the Hennessey Venom GT. Guess they all just lie...

Secondly, why didn't you calculate including your beloved fourth potency of the "critical speed"? Why are you ignoring your own warnings? Smell sus?

"just because of air deflection against front shield and chassis (newton's second law) and some venturi under the car"

Why don't you just call it downforce? Because everything that increases the load on the tires would be downforce. Btw Bugatti states that the Chiron SS has the same amount of downforce as it has uplift. Who knows... possibility is there definitely.

My own "huge caveat"

You know what bothers me most about the whole passage of the book and the equation all the time? Assuming that the tire wouldn't deform differently at higher speeds. The best visible example would be dragster tires at warm up.

The centrifugal force of well over 4000g inside the tire at such speeds makes every cubic cm of air inside there press against the tire from the inside, furthermore (and most importantly) the centrifugal force of the tire itself does, greatly decreasing the tread shuffle and deformation, and therefore, rolling resistance as well, independently of the increase through speed. According to Google, the average tire has a density of 1.8g per cubic cm. At said 4000g, every cubic cm "flies" to the outside with 7.2kg. The tread shuffle of a single Chiron's front tire easily exceeds 200cm^2. Assuming the tire to be 1cm thick, that would be above 1.4 tons of force "straightening" itself back against the normal force of the vehicle - until the shuffle becomes small enough again.

"Your" book just doesn't even consider this, because it doesn't matter for the average car, or especially efficient but slow EVs which is the worldwide topic now, for which those books are written. There's a reason why those graphs barely even exceed 180kph.

But I guess I'm just "lacking basic knowledge".

Fact stands by itself. Using my "simple" formula, the needed power, cdA and weights for every car that did a top speed record in the past 30 years, perfectly fit the math, while they are completely off in yours.

Case closed for me. Farewell.

I remind you that the whole discussion started because, while lurking around this site,
i read your posts trying to enlighten us about the claim that bolide is capable of 560km/h with only 1800hp. Checking your computation it appeared that you were plugging in the bolide’s tyre Crr at 0 km/h and pretending that to give you a plausible rolling resistance at 560km/h.

Then i wrote my first post pointing that you did not know what you were talking about
claiming that Crr is constant in speed. You replied to prove my statement, and that would have been easy for me. Indeed, that was easy: linked to a reference showing a graph derived experimentally of Crr in function of speed. Even a 2 years old baby can see the graph is not constant. Are you claiming this reference is the only one showing Crr is not constant?

Next you brought up some formula you found in that textbook, used it improperly to get
wrong numbers, and then claimed that “my” formula makes no sense because it shows bolide cannot reach 560km/h. ahahah You are a constant non sequitur.
I never intended to use any formulas, just brought up the one in the text which you claimed to have used. You keep forgetting: you went nuts because in the graph there was not "pressure" dependance and you went around searching for one such formula. I just plugged numbers in the formula with pressure you claimed to have used.

The rolling resistance according to your formula on all four tires accumulated would be 143kW (195hp), even not including your "huge caveat”!

Crr of a Veyron tyre is 0.0508 @ 407km/h according to the textbook formula
using 5000 N load, 3 bar pressure tyres. This gives 28.7kw rolling resistance at 407 km/h per tyre or 114.8kw=154hp.

Power absorbed by drag is 651kw=873hp @407km/h, cda=0.74. Therefore the sum is
1027hp. What is it wrong with it? Do you know for sure that tyres pressure was 3 bar and not 3.3 or what the air pressure was, or that when you activate the high-speed procedure, the engine will not push some 50hp more? Seems a pretty reasonable model to me.

I'm sorry, but your formula just doesn't fit. However, mine does, giving a power to overcome rolling resistance of 33kW (45hp)

bùllshìt: even the model that predicts 0 rolling resistance fits, when it accounts for a percentage within the error margin.

Well, except Bugatti lied for the past 20 years consecutively, which is the base of your argument to begin with...

No my son, it is not the assumption of my argument, it is rather the thesis...

http://letmegooglethat.com/?q=thesis+hypothesis

nothing unusual for germans lying for 20 years, volkswagen experientia docet.

First of all, why are you mixing up the Chiron SS with the Bolide? This whole argument didn't have a structure from the beginning.

because the same argument shows chiron 300 could not reach 500km/h with only 16**hp.

Secondly, why didn't you calculate including your beloved fourth potency of the "critical speed"? Why are you ignoring your own warnings? Smell sus?

Because i do not know the tyres' critical speed. Do you know it? please let me know.

You know what bothers me most about the whole passage of the book and the equation all the time? ...

AHAHAHAHA. Before it was the pressure that bothered you the most. Few lectures with random numbers/formulas out of your rear later, it is the centrifugal force. why do you even fùcking care, since Crr is constant in speed ahahah.

For non arian cars, mathematical modelling of rolling resistance is an extremely complicated task,
they have been trying to study it for a century now, because it has important applications. People end up just regressing experimental data with some plausible regressors, like speed, or using FEM approximations to solutions of analytical models. Just for german cars the correct model is Crr=constant, ahahahahaha.
Go figure these arian missionaries....

I said farewell, but well... why not, kinda in the mood now. I'll concentrate on the most important bits and let out the conspiracy blah...

"then claimed that “my” formula makes no sense because it shows bolide cannot reach 560km/h"

No, I claimed that your formula doesn't work because the Veyron, which ALREADY DID 407kph, would've needed 150hp more than advertised to fit your formula. Simple as that. You just took a different K for your calculation, but let me remind you that we're talking about a sporty compound at 265mm and 365mm width.

"Therefore the sum is 1027hp. What is it wrong with it?"

Hmm, maybe the fact that the Veyron only has 1000hp in total and you didn't even include internal losses and still are above that? Customer Veyrons, which have shown identical acceleration numbers to the top speed test car, have been dyno'd often enough btw.

According to your formula, the Agera RS would've needed a lot more power than Koenigsegg states as well for their run. So would've the Hennessey Venom GT. The XP3 McLaren F1 did 370kph at Nardo with below 600hp, completely impossible using your method.

Every single top speed test from ANY manufacturer proves that using your formula, the car would've needed more power even without losses than the manufacturer even claims. No matter how you twist it, your result is far off reality, especially subtracting the wind resistance and just facing the "rest" power.

But of course, they all must lie, because manone says so :'D

"because the same argument shows chiron 300 could not reach 500km/h with only 1600hp."

Indeed, it only did 490 ;)
Not to mention its cdA is a lot higher than the claimed Bolide ones.

"Because i do not know the tyres' critical speed"

Horrible excuse. Let me quote you:

"Y rated tyres, such as chiron 300's, have a max speed of 300km/h. Say that the Bugatti's bespoken version is slightly higher than that. That implies that at 500km/h any tyre is head and shoulders above its critical speed"

"Before it was the pressure that bothered you the most [...] why do you even fùcking care, since Crr is constant in speed"

Because I constantly rethink a topic, instead of simply going by the book like you without asking if the formula applies to the dimensions the experiment is about.

Do we really need to go on? Have a nice day ^^

"Hmm, maybe the fact that the Veyron only has 1000hp in total and you didn't even include internal losses and still are above that? Customer Veyrons, which have shown identical acceleration numbers to the top speed test car, have been dyno'd often enough btw."

German car manufacuters are well known to constantly deliver engines with 10% more power than advertised. Here they just need that output in the max speed mode, not even in ordinary use. That would be less cheating than with porsche turbo s, golfs, bmws etc. Therefore the estimate of 1027hp, not knowing tyres pressure, and air temperature is not contraddictory at all with bugatti's 407 km/h claim.

You claim the textbook rolling resistance formula is wrong because it can't explain
why these other cars reached their top speed with their claimed power, thus they would all be lying, and this is a contraddiction. Classical "proof by contraddiction" lol. Instead, constant rolling resistance is a good fitting model.
Let's just pick the first mentioned car, just for the heck of it: Agera rs.

According to your formula, the Agera RS would've needed a lot more power than Koenigsegg states as well for their run.

let's see: textbook formula (p=3.2 bar, F=3750 N, v=124m/s) yields 134hp rolling resistance+934hp drag resistance (cd=0.33, A=1.87, rho=1.21)
for a total of 1068hp. Koeniggsegg claims 1160hp @crank fuelled by gasoline and E85 "for even higher power levels". This, if anything, shows that the v^2 textbook formula is starting to underestimate rolling resistance at those speed, implying that probably tyres' critical speed was lower than 124 m/s.

Every single top speed test from ANY manufacturer proves that using your formula, the car would've needed more power even without losses than the manufacturer even claims. No matter how you twist it, your result is far off reality, especially subtracting the wind resistance and just facing the "rest" power.

Wow, really? I missed that. Basically, this is as real as 120-20%=100 or Crr is constant. Only in germany you can get this truth.

** "Because i do not know the tyres' critical speed"
Horrible excuse. Let me quote you:
"Y rated tyres, such as chiron 300's, have a max speed of 300km/h. Say that the Bugatti's bespoken version is slightly higher than that. That implies that at 500km/h any tyre is head and shoulders above its critical speed" **

Let me reiterate, this: if k=f(x), in order to know k, you need x. In other words: don't ask me k, if you do not provide me x first. This is something you should have learned in 3rd degree elementary school in your country.

Because I constantly rethink a topic

ahahahah, and the conclusion is always the same: germans are better.

I'm enjoying the repartee between you guys but i just want to say one thing which will either back up or disprove the formulas and that is simply this. The cars must be independently dynoed prior to an official speed record attempt to ensure there's no bullshit hp claims by turning up the boost. That would make it incontrovertible :)

You know what bothers me most about the whole passage of the book and the equation all the time? Assuming that the tire wouldn't deform differently at higher speeds. The best visible example would be dragster tires at warm up.
....
Assuming the tire to be 1cm thick, that would be above 1.4 tons of force "straightening" itself back against the normal force of the vehicle - until the shuffle becomes small enough again.

Let me get this right: you saying that if you make a tyre spin fast enough,
the centrifugal force will countereffect the vertical tyre load so that the rolling resistance will be as if the load is 0?
So in the same ol' graph, measured Crr should tend to 0 as velocity tends to infinity. Is this what happens to cars in germany? Wow, interesting

But I guess I'm just "lacking basic knowledge".

have a better way to qualify somebody who cannot see from a graph if a function is constant or cannot compute percentages?

yeah. However, it would be trivial to make a special ECU mapping for getting an extra 10-15% power for a minute or so, which will not be tested while on the dyno.

Yeah you'd have to lockdown the car after the dyno run and make sure no one fiddled with the ECU prior to or during the run to make it unlikely that they didn't cheat. It would go a long way to making the record attempt more transparent.

i wonder if one can trigger a special ecu mode if you slam on the accelerator, i.e. having an accelerometer connected to the accelerator. I guess you can still measure highest power on a dyno without slamming on the accelerator.

Ha yeah that's why it would have to be independently done to make sure there weren't any shenanigans by SSC for example(given that they're cheating bastards) lol

"German car manufacuters are well known to constantly deliver engines with 10% more power than advertised."

Bland statement without substance. The Veyron was dyno'd often enough and has shown that it only delivers ~850hp on regular fuel (ignition angle issue) and around 980-1020hp on premium fuel. (RON98)... again, without the losses of all wheel drive, three differentials and a massive dual clutch gearbox.

"let's see: textbook formula (p=3.2 bar, F=3750 N, v=124m/s) yields 134hp rolling resistance+934hp drag resistance (cd=0.33, A=1.87, rho=1.21)
for a total of 1068hp. Koeniggsegg claims 1160hp @crank fuelled by gasoline and E85 "for even higher power levels". This, if anything, shows that the v^2 textbook formula is starting to underestimate rolling resistance at those speed, implying that probably tyres' critical speed was lower than 124 m/s."

Ouch... you realize that only the BASE Agera has a cd of 0.33? And that only in the aero setting? The Agera RS's bodywork and engine have way more in common with the One:1, which has a cd of 0.45 in aero setting already! If you're lucky, the Agera RS has a cd of 0.39, rather shy above 0.4 (too bad Koenigsegg doesn't provide one). Even the base Agera already had a cd of 0.37 when generating 300kg of downforce at 250kph... the Agera RS produces 485kg at the same speed, the One:1 610kg at 260kph and 830kg at simulated 440kph (aero setting for 440!). Oh btw, you missed adding that downforce onto the normal force in your calculation. Furthermore, both have more wind resistance than the base Agera due to the bigger cooling system thanks to the 200hp more they offer, even without the downforce issue. Try harder. For now, I've only seen that you can't read spec sheets...

And how about the McLaren F1 that did 387kph average in March 31st 1998 (rho > 1.25) at Ehra Lessien? The McLaren only produced 627hp, and 550hp are gone there for wind resistance already - again, BEFORE internal losses.

No matter how much I calculate to your favor, the numbers in total are always higher than the hp the cars offer. Even before losses.

"Let me get this right: you saying that if you make a tyre spin fast enough,
the centrifugal force will countereffect the vertical tyre load so that the rolling resistance will be as if the load is 0?"

Nope, never said that. I just said it will make the tread shuffle smaller and therefore reduce the rolling resistance until the force of the tread shuffle pushing outwards and the weight pushing back become equal. The smaller the tread shuffle, the less resistance.
And yes, I think that's the counter answer to the quadratic issue. Not even saying your formula is wrong, but simply putting in numbers into your formula always contradicts with the rest in this particular case. It just does not work here. In not a single example.

And what's all about that German / Arian talk? Pretty narrow minded if you ask me, all of these cars are international projects.

I think we can leave it at that.

Sorry, corrected the copy&paste mistake and now your answer's gone. Wasn't intended. Answering your questions from memory now -.-

First of all, about the 10% margin: Bugatti isn't AMG or M GmbH. And actually the stock M4 had less power than advertised e.g. at JP Performance's channel twice. Furthermore, we're not talking about "mid tier" sports cars here ^^

The McLaren F1 record was an official Guinness world record, so how would their speed be questionable? GPS recording is accurate for a long time now. And of course it's possible for an F1 to be faster than a 720S 160-200mph. The McLaren F1 has a cd of 0.31 and an A of just 1.68 (cdA lower than a Jesko Absolut), the F1 is tiny and therefore has a lot less wind resistance than the downforce oriented 720S. Furthermore it's a lot lighter than the 720S. Unfortunately, McLaren doesn't communicate cdA values on their newer cars for whatever reason, the 570S had 0.37 though (and is wider and higher than the F1 as well).

Hope I got everything covered :)

"The McLaren F1 record was an official Guinness world record, so how would their speed be questionable?" The question i have is was it a GPS electronic speedometer reading because i've tried to find something online to confirm that that was the case but was unable to do so. If it was GPS, then the next question is how accurate was it given that it was 1998? There would've been far fewer satellites compared to what's available now. These are valid questions :)

That's the run, you're welcome:
https://youtu.be/wYmIfDAQ9Y0
And thinking that even in 1938 they were able to measure the 432.7kph (exclamation mark on the ".7" here) of the Mercedes "Rekordwagen", I think we're fine with the accuracy of the McLaren :)

"And thinking that even in 1938 they were able to measure the 432.7kph (exclamation mark on the ".7" here) of the Mercedes "Rekordwagen"," that speed was measured over a flying kilometre so using the time/distance formula they got an accurate measurement. Apparently the body of the Merc had a drag coefficient of only 0.170 which is an extraordinary figure and was powered by a 5.6-liter V12 with 765 horsepower!! Perhaps i've underestimated the significance of drag coefficient?

"The Veyron was dyno'd often enough and has shown that it only delivers ~850hp on regular fuel (ignition angle issue) and around 980-1020hp on premium fuel." Not according to this dyno test 1076hp at the crank
https://www.motor1.com/news/399251/bugatti-veyron-dyno-run/

Thanks for the correction on the speed of the Merc, didn't really look into that one tbh xD
However, GPS devices were already pretty good in 1998.

Maybe you did, it's you who must know that :D
I mean, to quote CvK, he called the normal Jesko "not that one" when he got asked if that was the 300mph car (Shmee interview). On the other hand, the Absolut (almost same weight, identical power, far less drag) shall do 531kph. That's at least 50kph (31mph) more just by changing the aero.

I'll go through that in detail now. To quote your link:

"Royalty Exotics’ Veyron goes for three runs on the dyno and the best numbers it gets are 897 wheel horsepower (669 wheel kilowatts) and 909 lb-ft (1,232 Nm) of torque at the wheels. According to Dynojet, it’s safe to say that an all-wheel-drive car like the Veyron has approximately 20 percent mechanical losses"

First of all, those are bhp, in metric hp that's 909.8hp. Important later.

Can pretty much guarantee you the losses aren't THAT high. Dynojet probably translated the losses of "normal" cars onto that one, however the power loss isn't one in percentage, but in kW (friction). In real life, the percentual loss sinks with an increase in power. Just pulling out a simple example here: Capristo for example dyno'd a 599GTB and measured the whp and crank hp independently, result was 565whp and 614hp - that's just about 8% in losses. The AWD doesn't take away too much on top, maybe ~3%. And the Veyron has a lot more power, to add that onto the argument above.

Nonetheless, the wheel horsepower are the important ones in your linked case, because they are the only ones that actually move you. The wind resistance already takes up ~880hp (metric!) for going 407kph (depending on the exact rho that day, cd is 0.36, A is 2.07). That would leave just 29.8hp for the rolling resistance. Typical rolling resistance (assuming a coefficient of 0.015 - against manone's will :P) calculated with "my old method" would be 33hp. Very small deviation.

However if I use the calculation from manone's "Vehicle Dynamics" publication, the result would be 147hp (even pumped up the tires to 3.2 bar instead of 3 bar the Veyron typically uses). That's over 5x the amount of what would be left. So sorry, but nope, I'll stand by my statement :P

To end the whole topic, I just found something:
https://www.cbcity.de/hochstgeschwindigkeit-abgeregelt
Yes, it's in German, sorry, for that. But It shows a quadratic formula similar to the "vehicle dynamics" one as well for the rolling resistance ("Rollwiderstand"), however, the author describes the coefficient as a constant despite knowing the formula "to make it easier" for a simple top speed calculation. My assumption is that fr1 and fr4 must be ridiculously low so they won't make much of a difference OR just occur in very specific cases that aren't driving straight on asphalt. The solution to manone's and my "beef" must lie somewhere in there.

I think I'll leave it at that. Have a nice day, both of you :)

"Capristo for example dyno'd a 599GTB and measured the whp and crank hp independently, result was 565whp and 614hp - that's just about 8% in losses. The AWD doesn't take away too much on top, maybe ~3%."

This is an area that i have researched and let me tell you there's no chance in hell that there's only a 8% drivetrain loss. The general rule of thumb adopted by the vast majority of tuners and proven to be reasonably accurate on a load bearing Dynojet is FWD 10-12% RWD 12-14% and AWD 17-20%. Inertia hub dynos have less drivetrain losses approx 3% less than load bearing dynos due to no load ie. wheels are removed and axles are bolted to the dyno itself. So the end result is that the figures provided in that article are pretty close to reality :)
https://www.weistec.com/media-events-press/crankvswheelhp/

"The rules, however, are not absolute or 100% accurate."

Actually, AM&S magazine had a similar problem when they measured the 991 Turbo S. Porsche says 560hp, they measured shy above 600hp. After lots of research (together with Porsche, they were interested), they found out that there was a problem with new cars being measured on new dynos and afterwards calculating the losses by old norms that don't apply anymore because of intelligent engine management systems. As a result, the losses were calculated way too high inside the program. Wouldn't surprise me if Dynojets would have the same problem, since they are in the game for a long time as well.

Btw all that doesn't change the calculation either way, because I used the whp anyway and the drag torque from the dyno should be relatively low on a Veyron as well, because it weighs a lot and has massive tires and brakes to give counter-momentum. In general, lighter cars with small tires (e.g. Lotus Elise) show way bigger losses for whp over hp compared to a car that weighs twice as much and has massive compound (like the Ferrari I mentioned). But the whole dyno topic can be a bitch on its own, I'll rest my case here ^^

Will be my last one. This whole thing eats up waaay too much time xD

Keep having fun \m/

In an ideal world it would be revealing if we could get the W16 on an engine dyno and then using the same power parameters/tune run them on different dynos whether they be load or inertia eg. Dynojet vs Mustang vs Superflow vs Mainline etc with different drivetrain/transmission setups. That would give us the most accurate picture, obviously, but there's not really sufficient interest to motivate anyone to go to those lengths so there will always be arguments about what is real or not....c'est la vie...

Nailed it xD

**"German car manufacuters are well known to constantly deliver engines with 10% more power than advertised."

Bland statement without substance. **

is reality of enough substance to you, german?

https://www.motortrend.com/news/2019-porsche-911-carrera-s-dyno-test/

https://www.caranddriver.com/features/a27437648/2019-bmw-m5-dyno-horsepower/

https://jalopnik.com/dyno-test-reveals-the-2020-bmw-z4-has-a-lot-more-torque-1835649742

Ouch... you realize that only the BASE Agera has a cd of 0.33? And that only in the aero setting?

Poor idìot, do you think people do not know how to make a search on google?
https://www.koenigsegg.com/car/agera-r/#aerodynamics

"Cd. 0.33 to 0.37 with adaptable rear wings"

On the planet earth, the "Agera-r" name in the link would suggest that ... this is Agera r, not the base agera, and that agera rs in max speed configuration was not with full wings...

Even the base Agera already had a cd of 0.37 when generating 300kg of downforce at 250kph... the Agera RS produces 485kg at the same speed, the One:1 610kg at 260kph and 830kg at simulated 440kph (aero setting for 440!). Oh btw, you missed adding that downforce onto the normal force in your calculation.

let me copy and paste: On the planet earth, the "Agera-r" name in the link would suggest that ... this is Agera r, not the base agera, and that agera rs in max speed configuration was not with full wings...

And how about the McLaren F1 that did 387kph average in March 31st 1998 (rho > 1.25) at Ehra Lessien? The McLaren only produced 627hp, and 550hp are gone there for wind resistance already - again, BEFORE internal losses.

No. 387km/h was hit by prototype xp5 we do not know the power of. What was the temperature during the attempt? You know a jack shìt yet, you claim a formula on a graduate textbook is useless based on plugging in random numbers. You cannot multiply two numbers together, yet, if a formula shows german serial cheaters are lying on power, it must be wrong.

Xp3 prototye reached 371km/h at Nardò while "being perhaps 577hp" according to Mclaren.
Rolling resistance of xp3 at 371km/h is 63hp on road tyres according to what you claim to be a faulty formula, but xp3 had slicks, so maybe little less. Nardò temperature was close to 40C, always according to McLaren, which means 461hp drag resistance. Total: less than 524hp.
You are so stupìd, you are not even able to bring up examples which prove your claims. One more try then.

Nope, never said that. I just said it will make the tread shuffle smaller and therefore reduce the rolling resistance until the force of the tread shuffle pushing outwards and the weight pushing back become equal. The smaller the tread shuffle, the less resistance.

And when the "force of the tread shuffle pushing outwards and the weight pushing back become equal", what happens to the rolling resistance? Please do not be shy, say it bluntly. I want to laugh hard, please answer.

Not even saying your formula is wrong, but simply putting in numbers into your formula always contradicts with the rest in this particular case. It just does not work here. In not a single example.

Let's see you claimed 3 cars would show the formula on rolling resistance of the textbook "Vehicle Dynamics Theory and Application", by Reza N. Jazar, edited by Springer is useless. On the other hand, your formula with coefficient of rolling resistance constant is correct.

Car #1 you brought up:
Veyron 407kmh claimed 1000hp. Drag resistance=861hp @15C or 845hp @25C. Rolling resistance=145hp @3.2 bar tyres pressure. Total resistance could be 990hp @ 25C or 1006hp @15C. Plus drivetrain losses, easily offset by regular german cars power underestimation.

Car #2 you brought up. Agera rs 447km/h, 1341hp E85 configuration. Rolling resistance=135hp @3.2 bar. Drag resistance 965hp @15C. Total resistance =1100hp+drivetrain losses.

Car #3 you brought up. xp3 prototype McLaren F1 371kmh, 580ish hp. Rolling resistance<63hp. Drag resistance 461hp @40C. Total resistance<524hp + drivetrain losses.

So the 3 cars you pointed at proved the textbook's formula provides a decent model, if not underestimating in the case of Agera rs, as expected.
Is 3=0 in Germany? Do you use modulo 3 integers in germany for counting? loll

And what's all about that German / Arian talk?

Maybe you should provide an explaination about this shìt you have been spreading around the world for at least a century.

I said it would be my last one, but it's a lazy day and your hatred is just too funny not to answer :'D

"is reality of enough substance to you, german?"

No, because NONE of these cars actually is a Veyron. Neither would even the 1077hp by Speedking explain how your method would work, especially not since you ignore downforce and bend numbers to your liking.

"Poor idìot, do you think people do not know how to make a search on google?"

Obviously you can't. The Agera R shares its whole existence with the base Agera and is just modified to be able to run on E85. To quote your own link:

"As 95 octane fuel has less octane than ethanol E85, the power is reduced to 960hp with 1100Nm of torque due to the boost pressure and ignition timing being altered to match the fuel characteristics."

That's EXACTLY the numbers the base Agera has. What a surprise! The Agera RS however shares the base with the One:1, including almost all the aero except the back wing and one instead of two frontal flap pairs.

"prototype xp5 we do not know the power of"

It's not a turbo engine ffs, it won't suddenly increase the power by over 200hp out of nowhere, especially not with the rev limit just 700rpm above stock and a limited fuel injection.

"What was the temperature during the attempt?"

About 8-10°C, historical weather shows it was a pretty cold month. And with it comes increased wind resistance of course.

"if a formula shows german serial cheaters are lying on power"

Didn't know Koenigsegg or McLaren are German... you're not doing yourself a favour claiming fraud beforehand either, that's a Trump move.

"Rolling resistance of xp3 at 371km/h is 63hp on road tyres according to what you claim to be a faulty formula"

Actually it's 62kW, which is 84hp... and I even took the Chiron's tire pressure, however, the tire pressure for cars below 400kph never was communicated above 2.8 bar (e.g. Koengisegg CCX), in that case it would be even 95hp.

"Nardò temperature was close to 40C, always according to McLaren, which means 461hp drag resistance. Total: less than 524hp."

Actually 556hp then. Leaves 20hp for losses, even for me that's not enough ;)

But there's another HUGE problem you're completely forgetting about... Nardo being an oval and therefore g-force increasing the normal force (banked curve) AND lateral forces (bank is only designed for up to 240kph), both vastly increasing friction. Quoting the book:
https://issuu.com/themagazineshop/docs/mclaren_f1

"Even on Nardo's vast banking, at the speed the computer said it could do, the F1 would be cornering very hard indeed"

There's a reason why I didn't take Nardo as an example ;)

"You are so stupìd, you are not even able to bring up examples which prove your claims"

Yea, because Nardo was such a good example... oh dear. Veyron, Chiron SS300+, Agera RS, McLaren F1 Ehra Lessien. Should be enough already I thought. And yes, I'll come back to those in the end. Additionally, here's the Veyron SS as well:

Has 1200hp, a cd 0.35, A 2.1m^2, rho was 1.208kg/m^3 that day, weighs 1950kg without downforce. Wind resistance would be 1036hp then.
Rolling resistance would be 47hp with my formula, leaves 10.8% in losses. Rolling resistance would be 172hp with your formula, 8hp too much for losses at all.

"And when the "force of the tread shuffle pushing outwards and the weight pushing back become equal", what happens to the rolling resistance? Please do not be shy, say it bluntly."

You STILL don't get it, do you? When your tread shuffle gets smaller, the force gets smaller as well. However, that force does NOT apply to the tire contacting the asphalt, it ONLY applies to the tire stretching itself against the car's weight. Guess I'm just thinking too far right now and you don't get it...

"Veyron 407kmh [...] Rolling resistance=145hp @3.2 bar tyres pressure"

The Veyron has 3 bar pressure. Makes 158hp according to you. Total resistance higher than the claimed horses without even mentioning losses.

"easily offset by regular german cars power underestimation."

This is a hypercar, not a Golf. But what a cozy excuse it is, huh? :D

"Rolling resistance=135hp @3.2 bar" (Agera RS)

Koenigsegg never communicated 3.2 bar either, but who cares, took it anyway as well. You left out downforce. A One:1 does 830kg at top speed in aero setting (otherwise it wouldn't even reach 440kph), the Agera RS does 485kg at 250kph when the wing is up (One:1 610kg at 260kph), is it too much to assume at least 400kg for the Agera RS at top speed in aero setting? Then that would be 165hp, not 135hp.

"Drag resistance 965hp @15C" (Agera RS)

It was a bit warmer, and I included that. Anyway, as I said, the Agera RS shares its base with the One:1, which has 0.45, and on which Koenigsegg claims 440kph. The Agera RS just did a mere 7kph more. With a cd of 0.4, that would be 1170hp in wind resistance then, not 965hp - and 0.4 is a reach in your favour. The total would then make 1337hp - again, before losses. And I calculated to your favour!

Take a deep look at both. One:1:
https://www.koenigsegg.com/car/one1/
Agera RS:
https://www.koenigsegg.com/car/agera-rs/
And now compare it to the car you took:
https://www.koenigsegg.com/car/agera-r/
And the Agera:
https://www.koenigsegg.com/car/agera/

I hope you realize yourself that the Agera R doesn't have any frontal flaps, no side flap, a more closed off frontal bonnet and a far smaller spoiler. Not to mention the resistance through bigger cooling system not visible in the pictures. The only difference from the Agera R to the base Agera however is the rear wing, and both claim the exact same amount of downforce.

"Rolling resistance<63hp"

Sure it is... going round a corner at such a rate that they had to replace the tire because of security concerns :'D

"Let's see you claimed 3 cars would show the formula [...] by Reza N. Jazar [...] is useless"

No, I just said it wouldn't work in this case and thus added there must be more to it, simple as that.

"Maybe you should provide an explaination about this shìt you have been spreading around the world for at least a century."

I'm only 28 years old, and the Third Reich has fallen 75 years ago. Right now I only see one racist, and that's you.

Just take the L, before you'll get a heart attack :D

We're already turning in circles and you'll keep denying, so that's really the "farewell" for me now. Bye.

Hmm this has become quite the battle of wits and formulas. I just wish someone would do as i suggested earlier ie. dyno the cars then do the max speed runs to see how close all this theoretical science gets to reality but alas the makers of these hypercars are far too caught up in the pissing contest between themselves. Humans and their egos are so obscene lol

**"is reality of enough substance to you, german?"

No, because NONE of these cars actually is a Veyron.**

My claim was German car manufacuters are well known to constantly deliver engines with 10% more power than advertised and you replied Bland statement without substance. All of the cars i linked at are GERMAN, thus it is spot on relevant. Problems in understanding english?
Here we are discussing GERMAN reliability about their cars' specs. Being Bugatti german owned, it would be of absolutely no suprise if indeed veyron's prototypes and stock cars would push in excess of 1000hp.

**Neither would even the 1077hp by Speedking explain how your method would work, **

Problems in writing english?

especially not since you ignore downforce and bend numbers to your liking.

What's the downforce of Veyron at 400 km/h? didn't you previously mention
it was zero? Higher downforce would mean higher Crr at 400km/h and the formula would prove the amount of BS Bugatti is dumping is even greater.

I must have skipped these gems:
Ouch... you realize that only the BASE Agera has a cd of 0.33? And that only in the aero setting? The Agera RS's bodywork and engine have way more in common with the One:1, which has a cd of 0.45 in aero setting already! If you're lucky, the Agera RS has a cd of 0.39, rather shy above 0.4 (too bad Koenigsegg doesn't provide one). Even the base Agera already had a cd of 0.37 when generating 300kg of downforce at 250kph... the Agera RS produces 485kg at the same speed, the One:1 610kg at 260kph and 830kg at simulated 440kph (aero setting for 440!)

Besides the utter nonsense of calling agera R the base model, you seem to claim that Agers RS top speed attempt of 447km/h was made in its high downforce track setting, when, even Agera R had the possibility of changing its cd fro 0.37 to 0.33. So you claim that Koeniggsegg decided to put Agera RS in a huge competitive disadvantage in his speed attempt. It makes sense! and assuming this to be the case, then you claim the textbook formula is wrong... ahahah

It's not a turbo engine ffs, it won't suddenly increase the power by over 200hp out of nowhere, especially not with the rev limit just 700rpm above stock and a limited fuel injection.

there are 670hp variants of that engine. What if it was one of them in the prototype.

About 8-10°C, historical weather shows it was a pretty cold month. And with it comes increased wind resistance of course.

ahahah, usual out-of-your-ass bùllshìt. I asked for the "temperature during the attempt" not whether in that month you were historical cold at your home.

**Actually it's 62kW, which is 84hp... **

No, it is not. L=3000N, tyres' pressure=3.2 bars, yields precisely 63.7 hp. Are you still struggling with your 1.2-20%=1?

and I even took the Chiron's tire pressure, however, the tire pressure for cars below 400kph never was communicated above 2.8 bar (e.g. Koengisegg CCX), in that case it would be even 95hp.

again out-of-your-ass assumptions. 2.8 bars gives 71.8 hp and does not change a jota.

You STILL don't get it, do you? When your tread shuffle gets smaller, the force gets smaller as well. However, that force does NOT apply to the tire contacting the asphalt, it ONLY applies to the tire stretching itself against the car's weight. Guess I'm just thinking too far right now and you don't get it...

No, i do not get it! Please master, enlight me: answer to the simple question
WHAT HAPPENS TO THE ROLLING RESISTANCE WHEN THE TYRE'S LOAD IS TOTALLY COUNTERED BY THE TYRE'S CENTRIFUGAL FORCE.
Is this going to be bigger than Nevada's Koeniggsegg high downforce speed record? or 1.2-20%=1?

It was a bit warmer, and I included that. Anyway, as I said, the Agera RS shares its base with the One:1, which has 0.45, and on which Koenigsegg claims 440kph. The Agera RS just did a mere 7kph more. With a cd of 0.4, that would be 1170h

AGAIN, just out of your ass random numbers. you look at a cooling vent and fart out a cd out of it... you are exceedingly ridicolous.
Fact is that Koenigsegg has obviously set his agera rs with the lowest possible cd, which is in line with agera r. here is agera rs drag resistance @25C at various cds:
0.33-->934hp
0.35-->990hp
0.37-->1047hp
0.39-->1103hp
Being rolling resistance 135hp @3750N load, all of them underestimate the power koenigsegg claims=1300hp.
Once again you just provided a proof that the textbook formula actually underestimates Crr at speeds above 400km/h, which is highly expected, given all the measured Crr graphs around tyre's critical speed.

** manone: Let's see you claimed 3 cars would show the formula [...] by Reza N. Jazar [...] is useless"
No, I just said it wouldn't work in this case and thus added there must be more to it, simple as that.**

It is just in case of german cars (Bugatti, specifically) that the numbers do not match. In all the other cases, either the formula perfectly fits known data (e.g. mclaren f1 xp3) or UNDERESTIMATES the real coefficient of rolling resistance (e.g. agera rs).

I'm only 28 years old, and the Third Reich has fallen 75 years ago. Right now I only see one racist, and that's you.

This is the usual shìt germans dump when asked about their history. You guys never rationalized the 2 world wars you proudly started, just dismissed by a "wasn't even born at that time". The very same underlying subculture of classifying as "inferior" any non-german/non-arian entity is still hugely widespread nowadays and you are a prototypical example, if any. To the point dismissing physics formulas modelling our universe, as we know it, if they show Bugatti is lying.

Actually, AM&S magazine had a similar problem when they measured the 991 Turbo S. Porsche says 560hp, they measured shy above 600hp. After lots of research (together with Porsche, they were interested), they found out that there was a problem with new cars being measured on new dynos and afterwards calculating the losses by old norms that don't apply anymore because of intelligent engine management systems.

hahahaha. Not surprising, i must say. The german magazine, naively dynos a porsche and the numbers they get are higher than the usual 5% engine power tolerance. Porsche comes, say some ununderstandable buzz words, and the german magazine swiftly salute.

A question for you re the Huracan STO. Lamborghini claim that the Huracan STO has a 37% increase in airflow efficiency and 53% more downforce than the Performante. Do you think Lambo mean drag coefficient when referring to airflow efficiency because 37% seems unachievable. In addition to that one would think that if that was the case then the additional 53% downforce would have negligible effect on acceleration and top speed which at 310 km/h is considerably less than the Performante. Your thoughts?

**Hmm this has become quite the battle of wits and formulas. **

a long story short. Bugatti makes claims about the following data:
max speed, power, cd, frontal area, weight of their cars.

However, all these variables are physically related, so using known formulas one may check if data stated by bugatti make or do not make sense. One part of the resistance a car encounters at very high speed (400km/h and above) is "Rolling resistance". The 28 yo german guy says that using the coefficient of rolling resistance (denoted by Crr, strictly related to the rolling resitance) at speed=0, Bugatti's data are plausible.
I told him that a host of empirical experiments show that measured Crr is very much NOT constant in speed. e.g. a graph from the textbook i linked at reports Crr=0.012@0km/h, 0.02@100km/h, 0.03@150km/h and 0.05@200km/h.
Therefore, using Crr=0.012 @500km/h is not a sensible thing to do, even for a slick tyre. The higher the coefficient, the higher (linear relation) the rolling resistance, so you get a much lower rolling resistance than you actually have in reality.
The same book provides a formula for Crr in function of speed (quadratic relation), load and tyre pressure. From the measured Crr graph, we can easily predict that the model will underestimate Crr near and above Tyres' critical speeds. Yet, if we use that model, Bugattis need higher and much higher power to reach their respective claimed speeds. On the other hand, mclaren F1 prototype xp3 speed, power is spot on with max speed, and for agera rs the model very likely starts to underestimate the rolling resistance, as predicted, implying that adding an higher degree velocity term will improve the model fit at overcritical speeds. In turn, this results with and even higher rolling resistance for bugattis and the even higher power necessary to reach the advertised speeds.

increasing efficiency usually refers to get some "good" effect with little "bad" tradeoff. Here good effect i guess they mean high downforce, while the tradeoff usually is drag. Very roughly speaking, you can get high downforce with little drag increase if you use venturi's type of fluidodynamics channeling (usually underbody airflow with a crucial rear diffuser). Using wings, spoilers create downforce by Newton's second law, unlike Venturi's. And unlike venturi's you get a component of the force acting not "down" but "against" car motion. This is accounted by the Cd term in the drag resistance formula.

If they compute "airflow efficiency" as a simple ratio Eff=downforce/drag (i do not know), you can get a 37% increase of this ratio, i.e. Eff*1.37, by increasing downforce by 37%, while maintaining the same drag, or for instance multiplying the drag by 1/1.37=0.73 (i.e. decreasing the drag by 27%) while maintaining the same downforce. Or increasing downforce by 53% while increasing
drag by only 11%.

What prompted my question was that Lamborghini reportedly claim that the max speed of the Huracan STO is only 192 mph vs the Performante's 202 mph which is a significant difference. Assuming the gear ratios/final drive haven't changed?( based on acceleration figures 0-200km/h in 9 sec) then the 53% greater downforce must be far more prominent as a restrictor than the reduced drag reduction with the 37% greater airflow efficiency? Aerodynamics is not my forte that's why i left it up to the duelling formula theorists to chime in.

What prompted my question was that Lamborghini reportedly claim that the max speed of the Huracan STO is only 192 mph vs the Performante's 202 mph which is a significant difference. Assuming the gear ratios/final drive haven't changed?( based on acceleration figures 0-200km/h in 9 sec) then the 53% greater downforce must be far more prominent as a restrictor than the reduced drag reduction with the 37% greater airflow efficiency? Aerodynamics is not my forte that's why i left it up to the duelling formula theorists to chime in.

You won't be able to link the Lamborghini statement to the top speed. Perfomante has active aero, STO most likely has manually adjustable rear wing.
The Lamborghini statement certainly implied the advantage of the STO in high downforce mode. The top speed of both could be achieved with low drag/low downforce settings. In that case ratios may be different.
However, even in appearance, it can be assumed that a car with such a large rear wing won't have high top speed.

"it can be assumed that a car with such a large rear wing won't have high top speed." Yeah that was my thinking as well. One only needs to look at the Senna which even with approx 820hp hits the wall at 204mph and won't go any faster.

Thought I could've ended it here, but since you lay words in my mouth I never said ...

"What's the downforce of Veyron at 400 km/h? didn't you previously mention
it was zero?"

Nope, Chiron SS300+. And it wasn't me who claimed it, it's Andy Wallace who does, a British test driver for Bugatti.

"My claim was German car manufacuters are well known to constantly deliver engines with 10% more power than advertised"

Just have to look at JP Performance's dyno videos to see that claim's bullshit. He had more German cars that underperformed than ones that overperformed. It's dependent on the individual car, simple as that.

"Besides the utter nonsense of calling agera R the base model"

Exact same engine including all numbers, exact same cd and downforce numbers, exact same weight, just an optically slightly different wing and new materials to be ready for E85. Everything else is literally identical. ... yea sure, "utter nonsense". Not my fault you can't even read a spec sheet.

"So you claim that Koeniggsegg decided to put Agera RS in a huge competitive disadvantage in his speed attempt."

Never claimed that either. Koenigsegg claims a top speed of 440kph and 830kg of downforce at those 440kph for the One:1. In downforce setting, thanks to the cd of 0.5, the One:1 wouldn't even be able to reach 440kph at all, not even close (~1400hp needed to overcome wind resistance alone in Agera RS record conditions!), so the number has to be in top speed setting (~1260hp wind resistance). And except for a slightly different wing and one instead of two frontal flap pairs, the Agera RS is identical to the One:1.

Furthermore the Agera R is claimed to have a top speed of 440kph as well with over 200hp less than the One:1 or Agera RS and the Agera RS just did 7kph more than the One:1 claims to be capable of with the same amount of horses. That would result in a cd of approximately 0.43 for the Agera RS applying the same wind resistance power loss of the One:1 percentually (actually would be more, since less rolling resistance). Nuff said? By giving the Agera RS a cd of 0.4, I actually did you a favor :'D

"you look at a cooling vent and fart out a cd out of it"

Gonna ignore the spoilers? The frontal flaps? The side flaps? The hood? The engine specifications? Sorry, but that's just pure ignorance from your side. You must be really desperate at this point.

"here is agera rs drag resistance @25C at various cds:"

Taking your cd's from below, you assumed rho to be 1.16, however:
https://www.timeanddate.de/wetter/usa/pahrump/rueckblick?month=11&year=2017
It shows 22°C (maximum), not 25°C. And the rest of the data gives a calculative rho of 1.186 at the lowest possible point! So much about farting numbers.
"bUt eRmAhGerD, A gErMan sItE. DOnT tRuSt tHem"

"all of them underestimate the power koenigsegg claims=1300hp."

Koenigsegg states 1360hp, and that's what I worked with, because in contrast to you, I don't simply negotiate numbers :P

"It is just in case of german cars (Bugatti, specifically) that the numbers do not match. In all the other cases, either the formula perfectly fits known data (e.g. mclaren f1 xp3)"

Sure, by turning a blind eye and ignoring that Nardo's actually a curve! I wonder why you wrote such an essay, yet didn't even mention that one ;)

"or UNDERESTIMATES the real coefficient of rolling resistance (e.g. agera rs)."

... by applying the cd of one car onto a totally different car that has way more in common with a car that has a WAY higher cd than you'd like to hear :'D

"I asked for the "temperature during the attempt" not whether in that month you were historical cold at your home."

End of March showed 10°C in Ehra Lessien. Unlikely it will suddenly increase by 20°C, aye? Weather report doesn't get any more accurate, okay? It was 1998 ffs...

"No, it is not. L=3000N, tyres' pressure=3.2 bars, yields precisely 63.7 hp."

Let's agree to disagree. You probably take a lower "K" out of nowhere.

"No, i do not get it!"

Yea, thought so... the force does NOT work against the car, because the upper part of the tire goes against it simultaneously. Doesn't change the fact that centrifugal forces will stretch the tire.

"THE TYRE'S CENTRIFUGAL FORCE."

We're only talking about the tread shuffle. The centrifugal force just decreases the tread shuffle by "bending" the tire outwards, the decreased tread shuffle then decreases the centrifugal force working against the normal force, because there's less tire mass actually touching the ground. But I guess you're just helpless there...

"Problems in writing english?"

English is written in capital, always. And the sentence would sound a lot better if you took "problems writing in English?" or "problems in English writing?". Neither did my sentence contain a mistake. You just dissed yourself with that one...

"The german magazine, naively dynos a porsche and the numbers they get are higher than the usual 5% engine power tolerance. Porsche comes, say some ununderstandable buzz words, and the german magazine swiftly salute."

It took months of cooperative work. But got it, you're sour and therefore discredit everybody who's not on your side.

"This is the usual shìt germans dump when asked about their history"

What shall I do? Travel back in time? There are several countries nowadays that have a lot more racists than Germany currently has, including the USA. And now keep that bullcrap.

... why am I even here anymore? What an incredible waste of time... Don't you think we can do better things with our time? As said, we're already turning around in circles. Therefore this discussion stopped making sense.

Bye.

"What's the downforce of Veyron at 400 km/h? didn't you previously mention
it was zero?"

Nope, Chiron SS300+. And it wasn't me who claimed it, it's Andy Wallace who does, a British test driver for Bugatti.

Zero downforce? I have little doubt that the downforce is quite low but to claim that it has zero downforce has got to be bullshit. Problem is no one can factually dispute that unless they can get hold of the car and do independent tests :) BTW that would apply to the hp figure as well...

Just have to look at JP Performance's dyno videos to see that claim's bullshit. He had more German cars that underperformed than ones that overperformed. It's dependent on the individual car, simple as that.

i am afraid it is not as simple as that. there is a 5% tolerance on engine power, if it were true that
the number of underpowered units equals the number of overpowered units, then all german makers would go bankrupt as customers could file a class legal action against them and easily win. Moreover, a german trying to prove that physics do not apply to german cars by linking a german reference usually stinks fishy.

Furthermore the Agera R is claimed to have a top speed of 440kph as well with over 200hp less than the One:1 or Agera RS and the Agera RS just did 7kph more than the One:1 claims to be capable of with the same amount of horses. That would result in a cd of approximately 0.43 for the Agera RS applying the same wind resistance power loss of the One:1 percentually (actually would be more, since less rolling resistance). Nuff said? By giving the Agera RS a cd of 0.4, I actually did you a favor :’D

basically you are trying to derive agera rs cd on november the 4th 2017, from a speed attempt that never happened (one-1 @440km/h) of a car of unknown cd. Before trying to do that, i would suggest you to sort out how to compute a percentage and to understand the difference between a scalar and a vector.

Gonna ignore the spoilers? The frontal flaps? The side flaps? The hood? The engine specifications? Sorry, but that's just pure ignorance from your side. You must be really desperate at this point.

same recommendation, the learning curve involves percentages and basic linear algebra, or else you end up typing random numbers and words.

Taking your cd's from below, you assumed rho to be 1.16, however:
https://www.timeanddate.de/wetter/usa/pahrump/rueckblick?month=11&year=2017
It shows 22°C (maximum), not 25°C. And the rest of the data gives a calculative rho of 1.186 at the lowest possible point! So much about farting numbers.

No. i used rho=1.18 which is a good approximation for 25C. My computer sums numbers in such a way that 1+1=2, i do not know about yours in germany.

Koenigsegg states 1360hp, and that's what I worked with, because in contrast to you, I don't simply negotiate numbers :P

There is no computation requiring engine’s power. No surprise i could use the numbers you type as a random generator.

Sure, by turning a blind eye and ignoring that Nardo's actually a curve! I wonder why you wrote such an essay, yet didn't even mention that one ;)

ahahahah Nardo’ is a …. “curve” !?!? even a stright line is a “curve” for that matter…ahahah
I just realised that i have also skipped the fact that Nardò begins with N and that it is located in Italy…

End of March showed 10°C in Ehra Lessien. Unlikely it will suddenly increase by 20°C, aye? Weather report doesn't get any more accurate, okay? It was 1998 ffs…

again just puking random numbers. 10 degrees is farting.
If you do not have the weather report, you do not know air density, you do not do computations.
In Nardò, for xp3 we have all the data… you do computations. y=f(x). you have x? you can compute y. No x? no party. Does it make any sense to you?

Let's agree to disagree. You probably take a lower "K" out of nowhere.

No. we do not agree, at all. I reiterate that my computer is based upon 1+1=2 and not on another definition of sum. There is no second opinion. K=0.8 because, I quote:

“The parameter K is equal to 0.8 for radial tires, and is equal to 1.0 for non- radial tires. “

same usual non-arian textbook you hate...

By the way, i noticed that you went to check on a german textbook whether, the rolling res. formula involving speed was really existing ahahahah. And then you tell me you are not the classical arian ****, lol.

We're only talking about the tread shuffle. The centrifugal force just decreases the tread shuffle by "bending" the tire outwards, the decreased tread shuffle then decreases the centrifugal force working against the normal force, because there's less tire mass actually touching the ground. But I guess you're just helpless there...

bùllshìt. we were talking about rolling resistance and you brought this
rubbish up. Too easy to hide your hand after throwing a rock, son. Say what happens to ROLLING RESISTANCE when the centrifugal force equals tyre's otherwise load.

It took months of cooperative work. But got it, you're sour and therefore discredit everybody who's not on your side.

ahahaha you are a never-ending source of entertainment. You do not even realize that the words "Porsche", "german magazine", "cooperative" form a prototype of oxymoron. Not surprising, you are german.

**What shall I do? Travel back in time? **

you could do the first step: acknowledge that physics laws apply to german cars, as well.

Zero downforce? I have little doubt that the downforce is quite low but to claim that it has zero downforce has got to be bullshit. Problem is no one can factually dispute that unless they can get hold of the car and do independent tests :) BTW that would apply to the hp figure as well...

since you must have some downforce simply from the air flowing over the chassis, you should use some appendix generating a lifting force....

**then the 53% greater downforce must be far more prominent as a restrictor than the reduced drag reduction with the 37% greater airflow efficiency? **

as i wrote, if they use the ratio=downforce/drag as definition of "efficiency"
then, an increase of 37% of this ratio along with a 53% increase of downforce
imply the drag must increase by 11%. This might be the cause of max speed drop.

It has downforce, it just has the same amount of uplift as well. They're equalling out.

How can somebody write so much, yet say so little? :D

Took K = 0.8 as well, our rho difference came from freedom horses (bhp) vs metric hp.

Btw finally found the origin of the quadratic formula problem... it's the tire itself (like I thought about a dozen comments before). The quadratic losses through speed come from hysteresis losses. The approximation using "your" formula only works that way for H-rated and V-rated tires though. While H-rated tires have a u_rr of ~0.009 near standstill and ~0.016 at 200kph, a typical Y-rated tire has ~0.0115 near standstill and just ~0.013 at over 200kph, both tires being tested at the same tire pressure, temperature etc. And no, that doesn't have anything to do with the critical speed, the curvature in general just drastically lowers down. And it doesn't even end there. The Michelins on both Bugatti and Koenigsegg are just "Y-rated", because there simply doesn't exist a category higher, however Michelin has stated themselves that the tire has a far more withstanding inner profile (therefore less hysteresis losses). The typical Y-rated tire is officially capable of doing 300kph, the Michelins on the Koenigsegg are officially 400kph+ tires, the ones on the Chiron SS were even 500kph+ rated by Michelin after thorough testing.

But instead of finding the solution together with me, you saw yourself as flawless beforehand, kept ignoring Nardo's massive lateral forces, kept ignoring all specs round different Koenigsegg models, kept ignoring every fact that went against your opinion and seasoned your spout with insults. No surprise at this point. Koenigsegg now spouts random numbers as well, okay. And yea got it, we're all still members of the Third Reich :'D

You know, when I realize that something doesn't fit I try to find the solution instead of randomly accusing people of fraud.

Nonetheless, I hope you're secrectly happy being so sour. I for my part can finally rest the case now that this is cleared. Peace out :P

While H-rated tires have a u_rr of ~0.009 near standstill and ~0.016 at 200kph, a typical Y-rated tire has ~0.0115 near standstill and just ~0.013 at over 200kph, both tires being tested at the same tire pressure, temperature etc

do you have a reference for these numbers? not saying they are wrong, just asking for a reference. Anyhow, they are totally irrelevant for speeds in the order of 400-500km/h.

And no, that doesn't have anything to do with the critical speed, the curvature in general just drastically lowers down

The last statement is simply meaningless. Of course, 200 km/h has nothing to do with critical speed of a Y tyre, which is rated at 300km/h max speed. This might well be the first correct statement you posted so far.

On planet earth, one first observes the phenomenon, measuring the metrics he is interested in. To understand it, and try to predict it, one creates then a model, which is an equation relating the metrics involved.

The phenomenon is not exibited by the numbers you quoted about Y-rated tyres.
Here are some links to graphs of measured rolling resistance (or coefficient of rolling resistance) in function of speed.

https://freeimage.host/i/FVtnSV (dashed graph, taken from the usual textbook)

https://www.researchgate.net/publication/238179470_Full_Two-Dimensional_Model_for_Rolling_Resistance_II_Viscoelastic_Cylinders_on_Rigid_Ground
(fig. 14, resistance)

There are many others, which you will not believe as they are not arian certified sources. These are not Y rated tyres, but they provide a clear idea to what happen to tyres' Crr up to and above their critical speed.
The key word here is MEASURED: does this ring any bell to you?
They are not graphs from a model, this is the real thing, can you spell that?
In case you wonder about the physics behind the sharp increase of Crr at critical speed, never mind, that is simply far out of your brain's reach.

In the first graph the coefficient Crr is 2.5 times higher at critical speed than 0 speed and 6 times thereafter. In the second graph the resistance is like 7 times at critical speed than at 20% of critical speed and is in NO WAY LINEAR in speed. Let me remind you that you started the topic by stating that Crr @500km/h was roughly the same as @ 0 km/h, the difference being just a handful of kws in the resistance.
It is hard to claim that tyres' critical speed is irrelevant to speeds in the order of 400-500km/h. Any tyre michelin came up with is almost surely far above its critical speed at 500km/h.Thus those are the Crrs we should be looking at, plus the very likely added aerodynamic load.

But instead of finding the solution together with me you saw yourself as flawless beforehand, kept ignoring Nardo's massive lateral forces

solutions? solutions for not being able to read a graph? Tell me about Nardo's massive lateral forces and how much they affect a car speed. BTW, still wating to know about the rolling resistance when the centrifugal force equals in module the tyres' load. You brought this up in the attempt of gauging your intelligence, right? Then finish it up, why stopping in the middle. If possible, using meaningful english words.

Koenigsegg models, kept ignoring every fact that went against your opinion and seasoned your spout with insults. No surprise at this point. Koenigsegg now spouts random numbers as wel

humm, let's see. Where did koenigsegg advertised that Agera RS' cd was 0.43 in Nevada? I have just read this from some average german in an exercise of writing numbers out-of-his-àss on fastestlaps. Not exactly Koenigsegg, right?

"do you have a reference for these numbers?"

https://files.germany.ru/wwwthreads/files/2-28781433-hucho_aerodynamik1.pdf
Abb. 3.5. Original source by Michelin themselves. Furthermore, tires in 2005 were a lot smaller than nowadays, there's over a decade in development in between and we're talking about regular Y-rated tires here, not 450kph+ ones that have teflon and carbon fibre weaved inside the compound to hinder further deformation.

"solutions for not being able to read a graph?"

Again assuming things out of your imagination. I just said there must be more to it because of the exceeding outcome in kW, and I found it.

"is in NO WAY LINEAR in speed"

I wonder how you still haven't noticed that I agreed on that an eternity ago. However, the stronger a tire is, and the bigger it is, the lower the quadratic factor will be in comparison to the speed of the vehicle. Which is why you can't use your formula as the holy grail, because it doesn't consider that at all - like I mentioned before as well! Even Reza himself says it's only an approximation - for normal road cars, to add that.

For H-rated tires, your formula gives a reasonable approximation. For Y-rated tires, your formula doesn't fit at all! A u_rr of 0.011 (like Michelin measured) at 60kph would require a ~3.2 ton vehicle running on just 2 bar. Can we agree that's nonsense? On the other hand, that exact vehicle would have a u_rr of 0.023 at 180kph - according to the graph, it has 0.0125.

"In case you wonder about the physics behind the sharp increase of Crr at critical speed, never mind, that is simply far out of your brain's reach."

Circumferential waves (classical frequency problem). Isn't that a better explanation than insulting me again for no proper reason?

"Any tyre michelin came up with is almost surely far above its critical speed at 500km/h.Thus those are the Crrs we should be looking at, plus the very likely added aerodynamic load."

Reza says: "Above the critical speed, overheating happens and tire fails very soon", and Michelin said neither the Agera RS nor the Chiron SS run showed any signs of the tire failing soon - so I have to assume that your statement is simply wrong.

However, if you're so sure, then why do you still refuse to calculate with it? Just do it for the Chiron SS or Jesko Absolut when Koenigsegg finally does it.

"Tell me about Nardo's massive lateral forces and how much they affect a car speed."

Open up Reza's book and scroll down. You're welcome. Additionally, I recommend those two:
https://www.youtube.com/watch?v=OXnX5RFghsA
https://www.youtube.com/watch?v=G-2ob6kZPcc
Exactly the same car, with no power modifications, one is done at Papenburg, one in Nardo. Both could've gone faster than the indicated speed, however, the TR1000 does 340-370kph in ~15 seconds in Nardo, while it only needs ~10 seconds in Papenburg. No matter how one twists it, that's a massive difference. Conditions were nearly identical.

Koenigsegg couldn't reach the alleged top speed for the CCR (over 395kph) in Nardo either. Neither could the double-engine Audi TT of MTM.

"still wating to know about the rolling resistance when the centrifugal force equals in module the tyres' load"

Still don't get it? It doesn't, because the centrifugal force from the upper side of the tire equals out the vertical forces from the tire itself. The load onto the tire stays the same. Doesn't change the fact that centrifugal forces stretch a tire. I'm saying one thing, and you're assuming something completely different.

"Where did koenigsegg advertised that Agera RS' cd was 0.43 in Nevada?"

Where did they advertise that it had the same cd as an Agera (R), like you assumed out of your ass yourself? They are completely different iterations. Meanwhile, they actually have a car that is nearly identical and has a given cd of 0.45 and a top speed estimation just 7kph lower than what Koenigsegg actually did using the same horses as advertised on the other car. You assuming the Agera RS would have 0.33 was just laughable to say the least, I gladly give the "is simply far out of your brain's reach" back to you.

In the end, we both had our idiot moments. And we both were wrong at some point either. The only difference is that I have the courage to admit that while you get eaten up by your own hatred. Adieu! May you find peace eventually.