Estimate of THE 7:29 GT-Rs power based on Nurburgring straight sections

[swamp2]

Originally Posted by footie

swamp, Like Lucid, I tried to open the file but no go. Don't know for why.

Truly comical. Pages and pages of drivel and you never even looked at the results and numbers, only read the post. Classic. PM me your e-mail address and I am still happy to share the spreadsheets.

Originally Posted by footie

I believe my observations of the times are roughly correct, as I chose to use the Nissan's timer as it was in hundredth unlike the Vette timer. I also believe my observations of the distance the Vette was gaining to be correct, based on experience and good judgement.

The two I pointed out above are positively incorrect and not just by just a little bit.

Originally Posted by footie

Motortrend tested the ZR1, GTR, 599 and GT2

And the times for the 1/4mile runs showed the ZR1 to be 0.1s ahead of the 599, 0.2s ahead of the GT2 and 0.4s ahead of the GTR. Now if you were to look at the acceleration times by speed the ZR1 totally destroys the GTR, posting a time 1.1s ahead of the GTR to 100mph, but only 0.4s ahead by the 1/4mile. Call me stubborn but these figures don't sound unlike what is seen happening in the comparison video on the ring. I know we are talking about higher speeds but I think everyone else knows the point I am trying to make. Edmunds also tested both the ZR1 and GTR and posted dyno results, with the ZR1 (505hpwhp) and the GTR (406whp), is it possible that the GTR has a 24% drivetrain lose, personally I doubt it. I even doubt 20%.

As I can't open the file, can to provide some split times with speed and distance points for both cars so as I can get a feel for your data and see how it looks.

P.S.
I still disagree with the ZR1 exiting the corner quicker, based on watching the entire two videos and matching the two cars from corner to corner, if anything the GTR should be the one leaving that corner the sooner.

With the losses I used for the ZR1 I find CarTest predicts 502 rwhp (136 hp of loss, including tires). Not bad I'd say. One more point of consistency for the ZR1 simulation. It does sounds high at 21% but this 21% includes losses for all auxiliaries, all of the tranny and drivetrain and the tires. I still find it traping in simulation at 127 mph, a bit shy of the 130 result from Motortrend but still in the range of results reported by other magazines. When they all report differently one (obviously) can not match all of them.

As far as any other comparisons with the GT-R, dynoed or not, I simply say all bets are off. We are NOT talking about the GT-R tested by Motortrend, we are talking about the GT-R used to get the 7:29, and I think those cars are quite different. That is a big part of my point. Here is what I can offer though in this regard. If I was a betting man I'd be willing to place a very large wager that the GT-R that dynoed at 406 whp COULD NOT clock a 7:29, no way.

[footie]

There has been something that has bugged me since it was first stated on this forum, the new 997 Carrera S ring time of 7:50 in the hands of Horst, that is a full 15 seconds inside it's previous time Sport Auto got for a 997 Mk1 and the only real change is the gearbox and a slight increase in power which is slightly offset by being heavier than before.

Surely the 997S is as big a jump in faith as the GTR's time.

P.S.
Please forget the straight argument on the GTR for a minute and solely take the two laps in entirity, the one of the GTR and the 997 CarreraS with PDK.

[swamp2]

Originally Posted by footie

There has been something that has bugged me since it was first stated on this forum, the new 997 Carrera S ring time of 7:50 in the hands of Horst, that is a full 15 seconds inside it's previous time Sport Auto got for a 997 Mk1 and the only real change is the gearbox and a slight increase in power which is slightly offset by being heavier than before.

Surely the 997S is as big a jump in faith as the GTR's time.

P.S.
Please forget the straight argument on the GTR for a minute and solely take the two laps in entirity, the one of the GTR and the 997 CarreraS with PDK.

Sure, fine a bit OT but a bit on topic as well as to the potential benefits of a DC. A more apples to apples comparison is the new 2009 Carrera S with 6MT vs. the new 2009 Carrera S with PDK. Those times are 7:58 and 7:50 respectively. I think 8 seconds for a DC, say roughly 1 second per minute is reasonable. I guesstimated the difference, long ago when first talking about the M-DCT, as in the 5-10 second range (for the N'Ring). Bringing it back on topic, we will ask is this particular car a massive over performer? Based solely on a regression analysis, no, absolutely not. It comes in at 1.6 standard deviations better than the simple power to weight model predicts. This is a solid over performer but not enormously so. Heck the previous 2008 model 997S is already an over performer by about 0.6 standard deviations, and for a 997S that is really no surprise at all. The new car with the PDK, DI and other little tweaks makes it a better car and make it over perform by a greater margin. Again, no surprise at all.

As a reminder the 7:29 GT-R is 3.4 standard deviations better than the model. I know you don't fully appreciate the huge significance of this number, but again it is very loosely akin, in a statistical sense, of flipping 19 heads in a row (I realize I said 10 in a row last time but that was a really rough guess, this time I actually did the calculation....).

[footie]

Thanks for posting the data and instead of re-writing the whole thing I just copied the reply I PMed you with some minor additions.

When I look at the data purely on speed and believe that the GTR and ZR1 are reaching to same speeds then I would agree the data looks to show the ring car is producing way more than quoted. But when you look at it purely on distance, how long it takes from point A to point B the power figures don't add up to me the same way.

I mean, your under rated simulation for the GTR (I am assuming it's 550hp)isn't that far off what Motortrend got from their example. Your simulation car covered the 1/4mile in 11.8s @ 121mph, while Motortrend got 11.6s @ 118mph. Look at the 1000ft ~ 1320ft, the ZR1 with the wind factored in takes 1.8s to cover this distance, all the time accelerating from 114.9mph to 125.7mph, the GTR takes 1.9s for the same discipline and 111mph to 121mph. It's only lost 1mph during this distance but took an extra 0.1s to do it.

I still believe that the motortrend example and the one used in the 7:29 time are very similar in output. One thing I would like to add is I have seen different examples dynoing at 426hp which shows Nissan's consistency is no too good, that's a 5% variation. So it's very possible that if the Nissan does have a 21% transmission lose then a 426hp example would be producing 540hp at the crank.

See what I mean by the ring car being stock.

Next the regression figures. How far off is the GTR when you adjust the power output to 540hp? I know it's still at the upper scale and may well be the highest there but I would love to know how close it gets to cars like the CSL.

[swamp2]

Originally Posted by footie

When I look at the data purely on speed and believe that the GTR and ZR1 are reaching to same speeds then I would agree the data looks to show the ring car is producing way more than quoted. But when you look at it purely on distance, how long it takes from point A to point B the power figures don't add up to me the same way.

Good we are making some progress.

Originally Posted by footie

I mean, your under rated simulation for the GTR (I am assuming it's 550hp)isn't that far off what Motortrend got from their example. Your simulation car covered the 1/4mile in 11.8s @ 121mph, while Motortrend got 11.6s @ 118mph.

Let's stick to trap speed instead of times. Do recall that to give the GT-R the greatest benefit of the doubt I have simulated it as a RWD vehicle. This punishes it a bit in terms of its take off performance, low speed times to distance, even 1/4 time, etc. It does not do much at all to the trap speeds which are in general better predictions/matches with power. The difference in trap speeds for a 530 hp RWD GT-R and a 550 hp RWD GT-R (via CarTest) is only about 1.5 mph. So again my conclusion is that the Motortrend car certainly did not have the same power as the Ring ringer and did not have 550 hp.

Originally Posted by footie

Look at the 1000ft ~ 1320ft, the ZR1 with the wind factored in takes 1.8s to cover this distance, all the time accelerating from 114.9mph to 125.7mph, the GTR takes 1.9s for the same discipline and 111mph to 121mph. It's only lost 1mph during this distance but took an extra 0.1s to do it.

Not sure your point. The simulation and videos both show the GT-R as slightly behind the ZR1 with the head wind estimate, the numbers above are completely in line with this.

Originally Posted by footie

I still believe that the motortrend example and the one used in the 7:29 time are very similar in output. One thing I would like to add is I have seen different examples dynoing at 426hp which shows Nissan's consistency is no too good, that's a 5% variation. So it's very possible that if the Nissan does have a 21% transmission lose then a 426hp example would be producing 540hp at the crank.

See what I mean by the ring car being stock.

Well if you want to call a 480 hp car putting out 540 hp "stock" then I guess I can agree . Do recall that my bare minimum estimate in the OP was in fact 530 hp, but I am more confident with 550 hp.

Originally Posted by footie

Next the regression figures. How far off is the GTR when you adjust the power output to 540hp? I know it's still at the upper scale and may well be the highest there but I would love to know how close it gets to cars like the CSL.

540 hp yields 2.9 standard deviations of over performance, indeed still the largest amount of over performance. This is really a long way off the next best over achiever at "only" 2.0 sigma (standard deviations) the Pagani Zonda F Clubsport. However, it does also place it just inside the "magic" 3 sigma point, which is one that really causes the eyebrows to raise for a scientist. The CSL is way down at a much more believable 0.6 sigma and is not even in the top 15 over performers in the list.

The percentage likleihood for a 2 sigma vs. 3 sigma event is 0.5% vs. 0.003% (single side of the probability function, counting only such over achievers, not the equally unlikely under achievers). Two full orders of magnitude less likely. So about ten times, and then ten times again on top of that! Hope that also helps put "sigma" in perspective.

[footie]

Originally Posted by swamp2

Good we are making some progress.

As I said in my PM replies, the 530 vs 550hp isn't really a big issue to me. I always said there is enough evidence out there to say there are examples putting out close to either of the two figures to conclude that the ring car was one of those examples. The only thing I can be sure of and neither can anyone else outside of the test team is whether the suspension was stock or not.

Originally Posted by swamp2

Let's stick to trap speed instead of times. Do recall that to give the GT-R the greatest benefit of the doubt I have simulated it as a RWD vehicle. This punishes it a bit in terms of its take off performance, low speed times to distance, even 1/4 time, etc. It does not do much at all to the trap speeds which are in general better predictions/matches with power. The difference in trap speeds for a 530 hp RWD GT-R and a 550 hp RWD GT-R (via CarTest) is only about 1.5 mph. So again my conclusion is that the Motortrend car certainly did not have the same power as the Ring ringer and did not have 550 hp.

I know Bruce and you look at trap speed over the actual time achieved to reach a given point. My only point highlighting the time over the speed is because we don't know the speed of the GTR in the ring video, only the speed of the ZR1 which isn't exactly the same thing.

Originally Posted by footie

Look at the 1000ft ~ 1320ft, the ZR1 with the wind factored in takes 1.8s to cover this distance, all the time accelerating from 114.9mph to 125.7mph, the GTR takes 1.9s for the same discipline and 111mph to 121mph. It's only lost 1mph during this distance but took an extra 0.1s to do it.

Originally Posted by swamp2

Not sure your point. The simulation and videos both show the GT-R as slightly behind the ZR1 with the head wind estimate, the numbers above are completely in line with this.

OK, my point is like I said above, we don't know the speeds the GTR achieved on that straight, only the times when it reached them. That's why I kept repeating the relevance of when the ZR1 and GTR reached each point and how the gap kept increasing, proving that the GTR wasn't accelerating as quickly as the ZR1. It's just a shame your simulation didn't continue up in the speed/time/distance above the 1/4mile it stopped at. Only then would we be able to look for sure what kind of power each car was kicking out.

Originally Posted by swamp2

Well if you want to call a 480 hp car putting out 540 hp "stock" then I guess I can agree . Do recall that my bare minimum estimate in the OP was in fact 530 hp, but I am more confident with 550 hp.

We need to come away from the thinking of the GTR putting out 480hp. It's purely a figure Nissan chose to make the GTR look other worldly in performance terms. The same was true for the R32, R33, R34 and it looks like Nissan can't break the habit. Best think of the GTR as putting out between 520~540hp in stock form.

Originally Posted by swamp2

540 hp yields 2.9 standard deviations of over performance, indeed still the largest amount of over performance. This is really a long way off the next best over achiever at "only" 2.0 sigma (standard deviations) the Pagani Zonda F Clubsport. However, it does also place it just inside the "magic" 3 sigma point, which is one that really causes the eyebrows to raise for a scientist. The CSL is way down at a much more believable 0.6 sigma and is not even in the top 15 over performers in the list.

The percentage likleihood for a 2 sigma vs. 3 sigma event is 0.5% vs. 0.003% (single side of the probability function, counting only such over achievers, not the equally unlikely under achievers). Two full orders of magnitude less likely. So about ten times, and then ten times again on top of that! Hope that also helps put "sigma" in perspective.

Never will truly understand this part of the discussion. Maybe if I hadn't spent so much time playing with cars and spent more time in my books I would fully believe in it as a tool. But as we are in agreement it's a rough guide and shouldn't be regarded as what is and isn't possible then I think it OK.

[lucid]

Originally Posted by swamp2

I sent it to your personal email, not through PM on the forum.

I tried again with both my Mac and Windows machines and the zip file opens perfectly to reveal two spreadsheets with multiple pages each. I used the zip program built in to Windows as opposed to WinZip but it shouldn't matter.

OK, I checked out the spreadsheet you sent me. You indeed seem to have nailed the ZR1 simulation. Good work on that. So, I buy into the guts of the argument you have presented here with the slight reservation that the GTR might have indeed had some kind of a "net" tailwind on that section. Regardless, it does indeed seem safe to say that that specific car had 530+ hp. I would bet on that. The thing is we will never really know the answer though unless an insider leaks data/proof associated with that run...

I also looked at the lightning lap data. Too bad they didn't have the ZR1 in there, and that you had to use the ACR numbers to estimate the GTR's exit speed. But, knowing that the ZR1 exited the Ring corner at 109 mph, 107 seems like a reasonable estimate for the GTR since the lightning lap data show 113 for the ACR and 107 for the GTR. However, it's hard to know what the variation on those data are and all that, but still better than no basis for the estimate.

[swamp2]

Originally Posted by footie

As I said in my PM replies, the 530 vs 550hp isn't really a big issue to me. I always said there is enough evidence out there to say there are examples putting out close to either of the two figures to conclude that the ring car was one of those examples. The only thing I can be sure of and neither can anyone else outside of the test team is whether the suspension was stock or not.

Just a matter of opinion at this point. I think 530 is significant and dishonest in the first place, 550 just pushes this point even further.

Originally Posted by footie

I know Bruce and you look at trap speed over the actual time achieved to reach a given point. My only point highlighting the time over the speed is because we don't know the speed of the GTR in the ring video, only the speed of the ZR1 which isn't exactly the same thing.

More work could certainly be done with a parameter study to simulate a range of GT-R corner exit speeds. I did some work on that and enough to convince myself my choice was pretty close but this part of the effort needs more work increase the rigor.

Originally Posted by footie

OK, my point is like I said above, we don't know the speeds the GTR achieved on that straight, only the times when it reached them. That's why I kept repeating the relevance of when the ZR1 and GTR reached each point and how the gap kept increasing, proving that the GTR wasn't accelerating as quickly as the ZR1. It's just a shame your simulation didn't continue up in the speed/time/distance above the 1/4mile it stopped at. Only then would we be able to look for sure what kind of power each car was kicking out.

I have always pointed this out. Thr GT-R in real life, and in my simulations, with 550 hp is NOT as fast as the ZR1 in this section. Perhaps I falsely called this "neck and neck" in a previous post. Again the point is that 550 hp pretty reasonably simulates the amount by which the ZR1 stays ahead.

By the way, I did continue the simulations all the way to 174 mph (well past the 1/4 mi). It is just that CarTest in its standard report template provides much more tabular data for the 1/4 mi run. The rest comes from graphs. If there are any particular figures you want from these sims I can let you know what they are.

Originally Posted by footie

We need to come away from the thinking of the GTR putting out 480hp. It's purely a figure Nissan chose to make the GTR look other worldly in performance terms. The same was true for the R32, R33, R34 and it looks like Nissan can't break the habit. Best think of the GTR as putting out between 520~540hp in stock form.

I agree completely (especially with the part I made bold) and this is what is so dishonest about the whole thing. Nissan has done a great job with the DC tranny (less warranty problems...), the AWD system, the chassis, handling and ease of driving the car on limit. HOWEVER, these things do not make it the mythical UFO that so many believe it to be. It gets its speed, straights or track like everyone else, power to weight ratio. The last point is until we have seen much greater consistency in terms of its performance there is no reliable and accurate absolute power output figure. Some cars might be 480, some 520, some 550. So if you want to quote a range it needs to be pretty large.

[swamp2]

Originally Posted by lucid

OK, I checked out the spreadsheet you sent me. You indeed seem to have nailed the ZR1 simulation. Good work on that. So, I buy into the guts of the argument you have presented here with the slight reservation that the GTR might have indeed had some kind of a "net" tailwind on that section. Regardless, it does indeed seem safe to say that that specific car had 530+ hp. I would bet on that. The thing is we will never really know the answer though unless an insider leaks data/proof associated with that run...

It is one of those unfortunate situations where we will never the answer with 100% certainty.

Originally Posted by lucid

I also looked at the lightning lap data. Too bad they didn't have the ZR1 in there, and that you had to use the ACR numbers to estimate the GTR's exit speed. But, knowing that the ZR1 exited the Ring corner at 109 mph, 107 seems like a reasonable estimate for the GTR since the lightning lap data show 113 for the ACR and 107 for the GTR. However, it's hard to know what the variation on those data are and all that, but still better than no basis for the estimate.

It is indeed too bad they did not have the ZR1 in the lightning lap. Well even better would have simply been a speedo in the GT-R N'Ring lap. As I mentioned just above a parameter study on this variable would be good. I did some stuff informally there and enough to convince me the final estimate was pretty good but it is certainly not rigorous.

[footie]

Originally Posted by swamp2

Just a matter of opinion at this point. I think 530 is significant and dishonest in the first place, 550 just pushes this point even further.

I know it's dishonest but that is how big business works.

Originally Posted by swamp2

More work could certainly be done with a parameter study to simulate a range of GT-R corner exit speeds. I did some work on that and enough to convince myself my choice was pretty close but this part of the effort needs more work increase the rigor.

I think here is the one part of your simulation that I will have the biggest problem with. I have probably spent more time than most here, viewing both laps in their entirety and on just about every corner the GTR looks to be coming out on to the next straight the quicker of the two, though this is more pronounced in the slower corners.

Originally Posted by swamp2

I have always pointed this out. Thr GT-R in real life, and in my simulations, with 550 hp is NOT as fast as the ZR1 in this section. Perhaps I falsely called this "neck and neck" in a previous post. Again the point is that 550 hp pretty reasonably simulates the amount by which the ZR1 stays ahead.

By the way, I did continue the simulations all the way to 174 mph (well past the 1/4 mi). It is just that CarTest in its standard report template provides much more tabular data for the 1/4 mi run. The rest comes from graphs. If there are any particular figures you want from these sims I can let you know what they are.

If it's not too much trouble I would really love to seen the segments running from 100mph up to 174mph in which ever way it comes, hopefully with each car showing the distance required for each 10mph segment and at what time they were reached. It's here were your analyses lives or dies. It's in the detail as you like to call it.

Originally Posted by swamp2

I agree completely (especially with the part I made bold) and this is what is so dishonest about the whole thing. Nissan has done a great job with the DC tranny (less warranty problems...), the AWD system, the chassis, handling and ease of driving the car on limit. HOWEVER, these things do not make it the mythical UFO that so many believe it to be. It gets its speed, straights or track like everyone else, power to weight ratio. The last point is until we have seen much greater consistency in terms of its performance there is no reliable and accurate absolute power output figure. Some cars might be 480, some 520, some 550. So if you want to quote a range it needs to be pretty large.

Again I have to disagree with that opinion, on any track the handling is just as important as the actual speed down the straights, in fact I would reckon it to be more so and for very good reason. The corner sets the car up for the next straight bit, you actually spend less time flat open on the throttle than not. It's the thing which separates good cars from great cars, the CSL was a great car, the Megane R26R another even greater one, it's incredible lap time came from not having an impressive power to weight or an amazing straight line speed but the way it took the corners. For heaven-sake it's within 4 seconds of the M5 which boasts an extra 280hp, that's almost two and a third times more power. The GTR is of this type, it's clearly not as fast in the straights as the ZR1, in fact on the other straight bits the gap was even greater, so clearly it was more special in the corner. The GTR was designed to be quick on the Nurburgring, that's where it's trick suspension and awd system comes into play.

I doubt if it will be able to go much quicker, even with the changes Nissan will make for the V-Spec and maybe the same is true of the ZR1 in it's current form, maybe with a wing and splitter to create some decent downforce but as it is it may have shown it's trump card with this 7:22. The one which really should have done better is the Viper ACR and I expect it to come back with another magical lap.

On a final note, if you are still wondering about the GTR's hardware not being that almighty think for one second just how much weight that thing is throwing around, be it under braking or in a corner or changing direct. Compared to the others it's a miracle it can do what it does.

[lucid]

Swamp, did you share your simulation results with the folks on 6speed? Appearently, the guy who started that thread you referenced has been saying the same thing since 9/30, but he doesn't have the data and analysis to back it up very clearly.

Post 52 below:
http://www.6speedonline.com/forums/9...heating-4.html

I figured he wasn't you as I can't see you calling yourself "heavychevy".

[swamp2]

Originally Posted by lucid

Swamp, did you share your simulation results with the folks on 6speed? Appearently, the guy who started that thread you referenced has been saying the same thing since 9/30, but he doesn't have the data and analysis to back it up very clearly.

Post 52 below:
http://www.6speedonline.com/forums/9...heating-4.html

I figured he wasn't you as I can't see you calling yourself "heavychevy".

Yup, I got some inspiration for my analysis there and posted it for those guys to have a look as well. I am swamp2 over there also. Interestingly enough got a similar reply, some said, "looks about right" or "nice work" and others said the predictable, you can not simulate a car with physics nor use a youtube video...

[swamp2]

Originally Posted by footie

I know it's dishonest but that is how big business works.

Apparently only for some and more so for those making turbo charged sports cars. M vehicles perform quite consistently, track and strip in accordance with stated power and weight. Many others do as well. I would call it select manufacturers and models rather than an indictment on "big business".

Originally Posted by footie

If it's not too much trouble I would really love to seen the segments running from 100mph up to 174mph in which ever way it comes, hopefully with each car showing the distance required for each 10mph segment and at what time they were reached. It's here were your analyses lives or dies. It's in the detail as you like to call it.

I can offer two things. Set runs from speed X to speed Y providing the time required or graphs, which without the software are very tough to read accurately. You can see an example of such a graph on one of the sheets in one of the spreasheets I mailed you. For graphs I can provide distance vs. time, speed vs. time, speed vs. distance and acceleration vs. time. Unfortunately, I doubt you will find any of this tremendously useful.

Originally Posted by footie

Again I have to disagree with that opinion, on any track the handling is just as important as the actual speed down the straights, in fact I would reckon it to be more so and for very good reason. The corner sets the car up for the next straight bit, you actually spend less time flat open on the throttle than not. It's the thing which separates good cars from great cars, the CSL was a great car, the Megane R26R another even greater one, it's incredible lap time came from not having an impressive power to weight or an amazing straight line speed but the way it took the corners. For heaven-sake it's within 4 seconds of the M5 which boasts an extra 280hp, that's almost two and a third times more power. The GTR is of this type, it's clearly not as fast in the straights as the ZR1, in fact on the other straight bits the gap was even greater, so clearly it was more special in the corner. The GTR was designed to be quick on the Nurburgring, that's where it's trick suspension and awd system comes into play.

Look, I am not saying handling does not matter, it is just typically very much trumped by power to weight. Of course as the course gets shorter/slower/tighter this is less and less true. The other obvious problem is that it is quite hard to quantify "handling". You can use skidpad, slalom, etc. but as we have discussed these are not perfect metrics. Power to weight certainly varies more among sporty cars than does cornering speed as well. As to the the Renault it achieved that time with Toyo track tires. Using the handy regression analysis shows that car to only be an over performer by 1.6 standard deviations with the track tires. Do remember it is not just power, so all of your figures about 2 1/3 times more power are meaningless, both physically and with regards to the regression. It is power to weight that matters.

Originally Posted by footie

On a final note, if you are still wondering about the GTR's hardware not being that almighty think for one second just how much weight that thing is throwing around, be it under braking or in a corner or changing direct. Compared to the others it's a miracle it can do what it does.

Again, it does have a great chassis, suspension, AWD, transmission, software, etc. and it is indeed hard to get handling with so much weight. However, as I keep saying, it simply counters this huge lumbering mass (just a bit more mass than our M3s actually) with its enormous power!

Do recall many of the various testers complaining about a couple significant handling flaws in the GT-R as well as a big ride quality problem. Just pointing this out to reinforce the idea that it aint perfect and aint a UFO.

[footie]

Originally Posted by swamp2

Apparently only for some and more so for those making turbo charged sports cars. M vehicles perform quite consistently, track and strip in accordance with stated power and weight. Many others do as well. I would call it select manufacturers and models rather than an indictment on "big business".

I don't think it a turbo charged problem, only some manufacturers demand their cars exceed their quoted figures regardless of weather or altitude conditions.

One thing I did notice on regression figures was that the car which produced the next highest regression figures after the GTR was another turbo awd car, the Audi S3. In fact Audi are among the most consistent of all brand to stay close to the expected times though usually post slightly better than expected. On the other hand BMW, especially their more powerful models do decidedly worse, whether it's rwd being the problem which I doubt because of all the other similar example which don't suffer the same. No I reckon it might be their choice of sticking close to the 50/50 balance, it might only work right up to a certain power output and after this the balance may need to be shifted to more weight over the driven wheels. Sorry for getting off topic with this.

On the ZR1 vs GTR discussion, I must admit I looked at the graph but felt it was a waste of time, it's too inaccurate to get any decent meaning out of.

Originally Posted by swamp2

As to the the Renault it achieved that time with Toyo track tires. Using the handy regression analysis shows that car to only be an over performer by 1.6 standard deviations with the track tires. Do remember it is not just power, so all of your figures about 2 1/3 times more power are meaningless, both physically and with regards to the regression. It is power to weight that matters.

I have admit I have followed the R26R's development quite closely and must have missed the tyre choice, are you saying that these were r-compound rubber or proper track tyres. I find it hard to believe it's the latter.

If it's just r-compound rubber like what most are running like the RS4, M3 and M6 then I don't agree that r-compound rubber can make such a difference and as we have discussed this before with no agreement there is little point reopening that avenue.

[swamp2]

Originally Posted by footie

I don't think it a turbo charged problem, only some manufacturers demand their cars exceed their quoted figures regardless of weather or altitude conditions.

But turbos are so much better in dealing with both issues related to input air density fluctuations!

Originally Posted by footie

One thing I did notice on regression figures was that the car which produced the next highest regression figures after the GTR was another turbo awd car, the Audi S3. In fact Audi are among the most consistent of all brand to stay close to the expected times though usually post slightly better than expected. On the other hand BMW, especially their more powerful models do decidedly worse, whether it's rwd being the problem which I doubt because of all the other similar example which don't suffer the same. No I reckon it might be their choice of sticking close to the 50/50 balance, it might only work right up to a certain power output and after this the balance may need to be shifted to more weight over the driven wheels. Sorry for getting off topic with this.

Not sure about the S3. Of course I noticed this outlier as well. Could be under rated, could be great suspension and drive systems, could be tires, could have been favorable weather and track conditions. I really have no idea but these certainly could be contributing. My gut tells me that although an "S" model it just is not track specialized/hardcore enough to be 2 sigma below regression. This is more of an over peformer than the Donkervoort, the GT2, Zonda, Carrera GT, etc., etc. Without a great deal more investigation I would not want to make any call on the cause. Just the fact that you noticed this value and its significance shows the value of standard error calculations supplementing a regression analysis! Good job.

Originally Posted by footie

On the ZR1 vs GTR discussion, I must admit I looked at the graph but felt it was a waste of time, it's too inaccurate to get any decent meaning out of.

Perhaps the best way to say this is that the graph does not offer the precision required. This is not a case of "accuracy".

Originally Posted by footie

I have admit I have followed the R26R's development quite closely and must have missed the tyre choice, are you saying that these were r-compound rubber or proper track tyres. I find it hard to believe it's the latter.

If it's just r-compound rubber like what most are running like the RS4, M3 and M6 then I don't agree that r-compound rubber can make such a difference and as we have discussed this before with no agreement there is little point reopening that avenue.

"Toyo track tires", source.

Further research tell us they are Proxes R888, which according to Toyo is a D.O.T. approved competition tire. These are one step above a Michelin Pilot Sport Cup+, perhaps more on par with the Michelin Pilot Sport Cup.

[footie]

Originally Posted by swamp2

But turbos are so much better in dealing with both issues related to input air density fluctuations!

I bow to your better judgement on this. I honestly thought N/A engines had less variations in temperature and altitude but clearly I must be wrong in this opinion.

Originally Posted by swamp2

Not sure about the S3. Of course I noticed this outlier as well. Could be under rated, could be great suspension and drive systems, could be tires, could have been favorable weather and track conditions. I really have no idea but these certainly could be contributing. My gut tells me that although an "S" model it just is not track specialized/hardcore enough to be 2 sigma below regression. This is more of an over peformer than the Donkervoort, the GT2, Zonda, Carrera GT, etc., etc. Without a great deal more investigation I would not want to make any call on the cause. Just the fact that you noticed this value and its significance shows the value of standard error calculations supplementing a regression analysis! Good job.

The S3 is a car I know quite a bit about as I very nearly bought one for the wife instead of the GTI. I don't know if you could call it under rated, it's 0-100mph time is 13.6s and with it's PTW and an awd chassis to get it off the line properly it's not even as quick as a 335i with similar PTW. It awd system is Haldex, so it's primarily a front wheel driver and only brings up to 50% to the rear when things get difficult, so you can expect understeer when pushed too hard. It's got a 60%/40% weight balance so one would think their is no advantage there and yet it's the second highest regression of all the cars tested.

BTW the tyres used on an S3 are no better than Pilot Sport 2 but I actually believe they aren't even that good.

Maybe the system has it's flaws that can't figure all cars in the same way and might let the odd S3 and GTR through the net.

Originally Posted by swamp2

"Toyo track tires", source.

Further research tell us they are Proxes R888, which according to Toyo is a D.O.T. approved competition tire. These are one step above a Michelin Pilot Sport Cup+, perhaps more on par with the Michelin Pilot Sport Cup.

That's what I thought, the equivalent to the Cup tyre. Still an incredible result and in my opinion a result more memorable than that of the S3.

[!Xoible]

swamp you need a girlfriend, and if u do have one you 2 need to learn "sex" and practice that more often

HOLY FUCKING SHIT, some people man!!!!!!!!!!!!!!!!!

[footie]

And this comment from the man who has posted here almost 12000 times.

How it cooking hairy palms. (j/k)

[!Xoible]

Originally Posted by footie

And this comment from the man who has posted here almost 12000 times.

How it cooking hairy palms. (j/k)

my posts are half a fucking line! his are longer than anything i've ever read, ever!

[Dascamel]

[QUOTE=footie;3581126]I bow to your better judgement on this. I honestly thought N/A engines had less variations in temperature and altitude but clearly I must be wrong in this opinion.

QUOTE]

[Dascamel]

Modern day turbos can adjust for far more variables than a traditional N/A engine. The ECU can raise/lower boost as needed for ideal combustion and power under varying air pressure changes. Go race a 335i at 5000 ft and then again at sea level.

[bruce.augenstein@comcast.]

Originally Posted by footie

I bow to your better judgement on this. I honestly thought N/A engines had less variations in temperature and altitude but clearly I must be wrong in this opinion...

The SAE says that, at a given boost level, forced induction engines gain and lose more power due to ambient temperature and humidity than normally aspirated engines do, but they lose less due to altitude (which is obvious if you think about it*). However, turbo engines now do even better at altitude because they typically compensate for altitude (up to a point) by simply dialing up the boost accordingly.

They do this by dialing into an absolute pressure maximum, rather than a boost maximum. If a given car has a boost limit of 10.3 psi at sea level (thereby giving 25 psi absolute), it will typically bump the boost to 13 psi if you are at 12 psi ambient due to altitude or if you're in the funnel of a tornado - when admittedly max boost may not be the thing foremost in your mind.

Bruce

* The reason it's obvious is that, if you lose 3psi due to altitude in a max boost system (set at 10.3 for 25 total at sea level), you're losing proportionally less than if you started at 14.7 psi and lost 3.