Mystery Solved: Complete correlation between S55 Dyno's, Simulations, and Real World

[Stevens21234]

it's ok. swamp's insecurity surfaces whenever anyone credible questions him.

[e39>all]

Originally Posted by Stevens21234

it's ok. swamp's insecurity surfaces whenever anyone credible questions him.

I'm 99.99% sure swamp is whatever the opposite of insecure is...

[04RC51]

Originally Posted by Brosef

this thread is hopelessly bereft of data. where's Swamp??

He's holding his E92 tightly and whispering in its tailpipe that it's still king of the road, don't worry. All these threads are lies and it's still the HP king.

I wish the E9X folks would just turn the page already and move on. Holding on so dearly to yesteryears trying to rationalize all that money spent to build a car that everyone can buy off the floor now. They will always be great cars, no one is putting them down. You don't have to defend them so vigorously. The F8X is a beast and may possibly just be underrated. Get some therapy and cope fellas.

Or argue and look sad. Whatever works!

[Boss330]

Originally Posted by 04RC51

He's holding his E92 tightly and whispering in its tailpipe that it's still king of the road, don't worry. All these threads are lies and it's still the HP king.

I wish the E9X folks would just turn the page already and move on. Holding on so dearly to yesteryears trying to rationalize all that money spent to build a car that everyone can buy off the floor now. They will always be great cars, no one is putting them down. You don't have to defend them so vigorously. The F8X is a beast and may possibly just be underrated. Get some therapy and cope fellas.

Or argue and look sad. Whatever works!

That's such a gross misrepresentation of what swamp is saying that it's not even funny

He has repeatedly stated that the F8x throunces the E9x in all areas when it comes to performance. There is no debate on this. The F8x IS significantly faster than the E9x and swamp has repeatedly said so himself

He is trying to explain WHY it's so much faster, without the engine being underrated by BMW. He's actually not saying anything more radical than that the performance of the car matches what BMW claims.

It's actually quite interesting to see how many here is arguing for the conspiracy on BMW's part (in deceiving EU, US, and the rest of the worlds authorities, by knowingly stating a false HP/Tq number and misleading independent type approval institutions), than they are in believing that the performance numbers are actually achieveable within the scope of BMW factory HP/Tq numbers.

As swamp also have said, if we start seeing stock F8x's trapping consistently above 120MPH, then the underrating case seems more plausible. Regardless I/we should all be open to new data and evidence one way or the other. This is still early days for the F8x generation and new information will certainly become available as time goes...

[ASAP]

Originally Posted by Boss330

That's such a gross misrepresentation of what swamp is saying that it's not even funny

He has repeatedly stated that the F8x throunces the E9x in all areas when it comes to performance. There is no debate on this. The F8x IS significantly faster than the E9x and swamp has repeatedly said so himself

He is trying to explain WHY it's so much faster, without the engine being underrated by BMW. He's actually not saying anything more radical than that the performance of the car matches what BMW claims.

It's actually quite interesting to see how many here is arguing for the conspiracy on BMW's part (in deceiving EU, US, and the rest of the worlds authorities, by knowingly stating a false HP/Tq number and misleading independent type approval institutions), than they are in believing that the performance numbers are actually achieveable within the scope of BMW factory HP/Tq numbers.

As swamp also have said, if we start seeing stock F8x's trapping consistently above 120MPH, then the underrating case seems more plausible. Regardless I/we should all be open to new data and evidence one way or the other. This is still early days for the F8x generation and new information will certainly become available as time goes...

I think Swamp has provided a lot of useful mathematical data and calculations to learn theory from. Unfortunately, as someone has already stated real world and theory rarely are on par... my main gripe was that I've never come across a car of this weight and his supposed whp (365) numbers that could trap remotely what an M4 could.

[Black Gold]

Originally Posted by Boss330

That's such a gross misrepresentation of what swamp is saying that it's not even funny

He has repeatedly stated that the F8x throunces the E9x in all areas when it comes to performance. There is no debate on this. The F8x IS significantly faster than the E9x and swamp has repeatedly said so himself

He is trying to explain WHY it's so much faster, without the engine being underrated by BMW. He's actually not saying anything more radical than that the performance of the car matches what BMW claims.

It's actually quite interesting to see how many here is arguing for the conspiracy on BMW's part (in deceiving EU, US, and the rest of the worlds authorities, by knowingly stating a false HP/Tq number and misleading independent type approval institutions), than they are in believing that the performance numbers are actually achieveable within the scope of BMW factory HP/Tq numbers.

As swamp also have said, if we start seeing stock F8x's trapping consistently above 120MPH, then the underrating case seems more plausible. Regardless I/we should all be open to new data and evidence one way or the other. This is still early days for the F8x generation and new information will certainly become available as time goes...

the car making 400 whp does not mean it will trap over 120. the car needs more power for that, its 3600 lbs.

second of all, you said the same thing about "conspiracies" with the BMW claimed weight loss and it being impossible to not conform to TUV standards. guess what, there are no places where the m4 has come close to weighing 3300 lbs. so is that a conspiracy too?

seems like these companies don't necessarily have to be 100% accurate with their claims.

and again, BMW is not the only manufacturer who has FI engines that are underrated. Audi and Merc do too.

[solstice]

Agree on 120 mph being an unreasonable trap speed to show under rating of a 425 hp car weighing ~3700 lbs with driver. That would require about 500 hp at the crank with common formulas. The car has already been trapped above 120 mph and dynos back up far above 425 hp, honestly at this stage it seems mostly like desperately trying to find more and more unusual formulas to prove a theory mainly based on a belief in regulatory compliance instead of looking at the combined results of measured and calculated data.

I assume people know or google to find calculators but if not here are some short cuts if you want to plugin 3700 lbs and 120 mph trap speed:

http://www.prosystemsracing.com/calculate.html
http://www.wallaceracing.com/et-hp-mph.php
http://www.tciauto.com/tc/racing-calculators/
http://www.xcceleration.com/et.calculator.html
http://web-cars.com/math/accel2.pl

And again, FI cars and power plateaus are nothing new. I would think most people designing and using these calculators are FI owners due to their superior tunability..

[ASAP]

Originally Posted by solstice

Agree on 120 mph being an unreasonable trap speed to show under rating of a 425 hp car weighing ~3700 lbs with driver. That would require about 500 hp at the crank with common formulas. The car has already been trapped above 120 mph and dynos back up far above 425 hp, honestly at this stage it seems mostly like desperately trying to find more and more unusual formulas to prove a theory mainly based on a belief in regulatory compliance instead of looking at the combined results of measured and calculated data.

I assume people know or google to find calculators but if not here are some short cuts if you want to plugin 3700 lbs and 120 mph trap speed:

http://www.prosystemsracing.com/calculate.html
http://www.wallaceracing.com/et-hp-mph.php
http://www.tciauto.com/tc/racing-calculators/
http://www.xcceleration.com/et.calculator.html
http://web-cars.com/math/accel2.pl

And again, FI cars and power plateaus are nothing new. I would think most people designing and using these calculators are FI owners due to their superior tun ability..

I don't think one needs to look far... the C7 Corvette is rated at 460 HP and weighs at most 3300 lbs by all accounts that I've seen. The fastest trap that I have seen for it online was at Atco Raceway which is without a question one of the fastest tracks in the nation and the car trapped 119.6 there. For my old 3500 lb 335i to trap that identical trap at Capitol took 425 whp Dynojet on an equally DA friendly track. The car is under rated, no questions asked.

Update - By the calculators you just provided that would require 494 flywheel hp which happens to be awfully close to 425 whp x 1.15 (DT loss). LOL

[gthal]

Originally Posted by ASAP

I don't think one needs to look far... the C7 Corvette is rated at 460 HP and weighs at most 3300 lbs by all accounts that I've seen. The fastest trap that I have seen for it online was at Atco Raceway which is without a question one of the fastest tracks in the nation and the car trapped 119.6 there. For my old 3500 lb 335i to trap that identical trap at Capitol took 425 whp Dynojet on an equally DA friendly track. The car is under rated, no questions asked.

Update - By the calculators you just provided that would require 494 flywheel hp which happens to be awfully close to 425 whp x 1.15 (DT loss). LOL

A C7 Z51 is weighing in closer to 3,450lbs in real life. I believe the car you are referencing is a Z51 (assuming it is Snorman's car). Just clarifying as there have been few, if any, C7s actually weighing in less than 3,400lbs and they would likely need to be non-Z51 and base everything.

[ASAP]

Originally Posted by gthal

A C7 Z51 is weighing in closer to 3,450lbs in real life. I believe the car you are referencing is a Z51 (assuming it is Snorman's car). Just clarifying as there have been few, if any, C7s actually weighing in less than 3,400lbs and they would likely need to be non-Z51 and base everything.

I am going by manufacturer's/magazine claims online. A non Z51 C7 is claimed to be 3298.

[FogCityM3]

We all know where the insecurities really lie. And complete misinterpretation of comments is actually one of the less egregios transgressions (in comparison to competely making something up).

Originally Posted by Boss330

That's such a gross misrepresentation of what swamp is saying that it's not even funny

[Black Gold]

Originally Posted by FogCityM3

We all know where the insecurities really lie. And complete misinterpretation of comments is actually one of the less egregios transgressions (in comparison to competely making something up).

you, and a lot of other people (myself included), need to cut this stuff out.

its obvious you are biased towards the e9x as many here who own / will be owners of the f8x are biased towards that car (like me). there is a reason we all own the car we do.

so lets not act like you are some sort of non biased observer, and everyone else is biased except you

[gthal]

Originally Posted by FogCityM3

We all know where the insecurities really lie. And complete misinterpretation of comments is actually one of the less egregios transgressions (in comparison to competely making something up).

I don't understand the "insecurity" argument on either side of this debate. The car is much faster than the E9X regardless of whether the stated HP is underrated or not. How can there be insecurity when the real world result is well known and well accepted by everyone? This debate, for me anyway, is somewhat academic more than anything else.

The car traps 119-120+ and is faster than the E9X in pretty much every measurable way. Anything else is intellectual stimulation only... no insecurity needed

Originally Posted by KennyPowers

so lets not act like you are some sort of non biased observer, and everyone else is biased except you

True statement... there is no such thing as non-bias Some are less biased than others but no one is without bias... except me

[Boss330]

Originally Posted by ASAP

I think Swamp has provided a lot of useful mathematical data and calculations to learn theory from. Unfortunately, as someone has already stated real world and theory rarely are on par... my main gripe was that I've never come across a car of this weight and his supposed whp (365) numbers that could trap remotely what an M4 could.

Originally Posted by KennyPowers

the car making 400 whp does not mean it will trap over 120. the car needs more power for that, its 3600 lbs.

second of all, you said the same thing about "conspiracies" with the BMW claimed weight loss and it being impossible to not conform to TUV standards. guess what, there are no places where the m4 has come close to weighing 3300 lbs. so is that a conspiracy too?

seems like these companies don't necessarily have to be 100% accurate with their claims.

and again, BMW is not the only manufacturer who has FI engines that are underrated. Audi and Merc do too.

Originally Posted by solstice

Agree on 120 mph being an unreasonable trap speed to show under rating of a 425 hp car weighing ~3700 lbs with driver. That would require about 500 hp at the crank with common formulas. The car has already been trapped above 120 mph and dynos back up far above 425 hp, honestly at this stage it seems mostly like desperately trying to find more and more unusual formulas to prove a theory mainly based on a belief in regulatory compliance instead of looking at the combined results of measured and calculated data.

I assume people know or google to find calculators but if not here are some short cuts if you want to plugin 3700 lbs and 120 mph trap speed:

http://www.prosystemsracing.com/calculate.html
http://www.wallaceracing.com/et-hp-mph.php
http://www.tciauto.com/tc/racing-calculators/
http://www.xcceleration.com/et.calculator.html
http://web-cars.com/math/accel2.pl

And again, FI cars and power plateaus are nothing new. I would think most people designing and using these calculators are FI owners due to their superior tunability..

Originally Posted by ASAP

I don't think one needs to look far... the C7 Corvette is rated at 460 HP and weighs at most 3300 lbs by all accounts that I've seen. The fastest trap that I have seen for it online was at Atco Raceway which is without a question one of the fastest tracks in the nation and the car trapped 119.6 there. For my old 3500 lb 335i to trap that identical trap at Capitol took 425 whp Dynojet on an equally DA friendly track. The car is under rated, no questions asked.

Update - By the calculators you just provided that would require 494 flywheel hp which happens to be awfully close to 425 whp x 1.15 (DT loss). LOL

There is one factor most of you constantly seem to ignore/overlook/disregard in this debate, and that's the issue regarding average power in gear during acceleration.

No one has provided a rebuke on that, or provided facts to show that all the cars you use to compare with, also has the same/similar average power in gear during a 1/4 mile run.

Why is that point completely ignored (at least a dissection of the point would bring some substance to the claims of under rating)...

As have been pointed out ad nauseum, the S55 makes a average power of 425hp from 5500-7300rpm. I would like to see someone calculate the average power (in gear during a acceleration run) of those cars that are used as a comparison.


And even though FI isn't anything new, the plateau power curve is NOT something a FI engine has by design! A traditional turbo engine usually peaks quite early and the falls off towards the redline. This effect is something that BMW managed to minimize in the S63 (and more recently the S55) which often has been said is more rewarding to take to the redline than the Audi RS7 engine.

Look at the power curve of a car like the Focus ST 2014:

http://www.fordracingpartsdirect.com...-9603a-fst.htm

http://www.focusfanatics.com/forum/s...d.php?t=297467



Even the N63TU only manages to have a plateau of 500rpm, and there aren't that many turbo engines around with the plateau the S63 and S55 has (maybe the RS6/7 engine has a similar plateau?).

Engine builders haven't really gone for the plateau power curve as far as I know, they want max power as early as possible and doesn't really care about replicating a high rpm nature of their engines (as BMW M has had to do in order to be in line with high rpm M engines).


As regards the weight, that has also been verified by TÜV. But here there are substantial allowances for leaving equipment out of the tested vehicle (although I would also say that the difference of type approval weights and real world is on the large end of the scale...).

[Black Gold]

Originally Posted by Boss330

There is one factor most of you constantly seem to ignore/overlook/disregard in this debate, and that's the issue regarding average power in gear during acceleration.

No one has provided a rebuke on that, or provided facts to show that all the cars you use to compare with, also has the same/similar average power in gear during a 1/4 mile run.

Why is that point completely ignored (at least a dissection of the point would bring some substance to the claims of under rating)...

As have been pointed out ad nauseum, the S55 makes a average power of 425hp from 5500-7300rpm. I would like to see someone calculate the average power (in gear during a acceleration run) of those cars that are used as a comparison.


As regards the weight, that has also been verified by TÜV. But here there are substantial allowances for leaving equipment out of the tested vehicle (although I would also say that the difference of type approval weights and real world is on the large end of the scale...).

no one is disregarding that, are you serious? everyone who is posting is well aware of what average power is and how it works.

ill give you two examples.

c7 vette

-3350-3400 lbs
-400-415 whp
-trap speed 118

f8x m3

-3600 lbs
-365ish whp (according to you / swamp)
-trap speed 118

So, you are telling me that "average power" of an m3 with 365ish whp, compared to the c7 vette with the torque/power curve posted below (which is also relatively flat at higher RPM) which also weighs over 200 lbs less than the m3, will result in the same trap speed between the two cars? NO FREAKING WAY.

Assuming the c7 drops 2000 rpm per shift its still making almost 400whp average over that interval. In fact, it doesn't look much different than the m3 curve.

The m3 has to be making 400 whp for the results to make any sense. BUT, if you believe the 400whp dynos for the m3, things start to make sense. DCT gives it a small advantage which approximately neutralizes the vette weight advantage, resulting in the two cars having very similar acceleration numbers.

The car is making approximately 400 whp stock. Dynos show it, real world results show it, its real.

[swamp2]

Guys, if you recall I have completely REVERESED my thoughts in this matter.

That is why I wanted to be extremely thorough in such a reversal. I am completely swamped at work and preparing for a week out of town. I also have two toddlers... I appreciate some patience as some significant time is needed for a thorough reply and perhaps some additional simulation work. As I pointed out prior my work is incredibly misrepresented in the OP and there are some serious short comings in the various approaches in the OP. That should be painfully obvious to anyone familiar with physics based vehicle simulation.

Any absurd accusation that this has anything to do with what car I drive or any others genuinely involved in this debate is pure absurdity. Folks who own an M4 are just as likely to want to believe it makes more power than it does than those owning a prior generation car who might be upset that they don't have the latest greatest.

Although you might call the interest academic, I find it extremely interesting and a bit of a puzzle. If all you care about it real world performance, fine, don't participate in the discussion.

Again, appreciate some patience here.

[Boss330]

Originally Posted by KennyPowers

no one is disregarding that, are you serious? everyone who is posting is well aware of what average power is and how it works.

ill give you two examples.

c7 vette

-3350-3400 lbs
-400-415 whp
-trap speed 118

f8x m3

-3600 lbs
-365ish whp (according to you / swamp)
-trap speed 118

So, you are telling me that "average power" of an m3 with 365ish whp, compared to the c7 vette with the torque/power curve posted below (which is also relatively flat at higher RPM) which also weighs over 200 lbs less than the m3, will result in the same trap speed between the two cars? NO FREAKING WAY.

Assuming the c7 drops 2000 rpm per shift its still making almost 400whp average over that interval. In fact, it doesn't look much different than the m3 curve.

The m3 has to be making 400 whp for the results to make any sense. BUT, if you believe the 400whp dynos for the m3, things start to make sense. DCT gives it a small advantage which approximately neutralizes the vette weight advantage, resulting in the two cars having very similar acceleration numbers.

The car is making approximately 400 whp stock. Dynos show it, real world results show it, its real.

First of all, if you still believe that dyno's can be trusted and used for comparison then there is nothing more to say about that. There have been posted substantial evidence that shows a variation of as much as 15% between same brand and type dyno for the same vehicle.

Chassis dynos can, at best, be used to compare before and after gains of modifications (provided the same operator and conditions).

The C7 with sports exhaust make 460hp and this is the official dyno chart:



As you can see, the power curve looks very different from the S55 (as it should and must, and as it also did in the dyno graph you posted as well).

It makes 460hp @ 6000rpm and around 400hp @ 4500rpm (with a assumed 1500rpm drop for each gear)

The power delivery isn't completely linear between 4500-6000rpm, but let's for simplicitys sake assume it is:

400+460/2 = 430hp in average power between 4500-6000rpm

If the rpm drop is higher in each gear, average power drops accordingly and if it's less, average power rises accordingly.

Assuming the same 2000rpm drop as you did gives us roughly 350hp at 4000rpm:

350+460/2 = 405hp in average power between 4000-6000rpm

Makes sense that the F8x traps similar to what the C7 does if the C7 "only" has 405hp in average power but is a bit lighter than the 425hp average S55


-

EDIT (from bold parts in the quoted post):

How do you calculate a average whp of over 400 for the C7 from the dyno graph you posted???

It peaks at 408,56whp and drops to 310whp at 4000rpm. There is NO way I can get those two numbers equal a average whp number of 400... (a simple calculation assuming linear power delivery equals an average of 359,28whp)

The power curves are VASTLY different... Just take a closer look at the rpm range and HP readings from 5500-7300 on the S55 and from 4500-6500 on the C7

[FogCityM3]

LOL.. Your responses are proof positive of what my statement was saying

This thread is about the bhp produced and the power curve of the S55 and how that explains the trap speeds.

As far as “this needs to stop” actually, no this is about expressing opinions and in this thread about providing some suggestions for data logging in trying to discover the truth.

S65 vs S55, trap times, swamp being insecure, mine is bigger than yours, etc etc…were brought up by many “contributors” to this thread, those guys got called out by others and me and appropriately so.

Also, no I am not unbiased and it should be pretty clear that I’m pretty biased toward N/A engines, but again that has nothing to do with this thread, where I provided some information on my experience with datalogging and a couple of verification methods. It seems that the OP has taken some interest into my analysis and what I had to say.

I think that representing swamps analysis as some unbridled love for the S65 is a gross misrepresentation of what he has said, what his intent is, and what he has done on M3Post for years. He is an extremely valuable contributor, as are some others on this thread and I have learned a ton from them. Also if you know Swamp, as a person of science, he will be the first to admit that he was wrong if the evidence is overwhelming (he has a high burden of proof). I find it extremely problematic when someone who has something valueable to say (Boss, Swamp, Bruce) automatically gets "pooped on" if theres any hint of something "negative" about the S55 (swapms thread on the topic isn't really negative at all, its more about how performance is acheived by something that we don't view as obvious.)

Really guys, best to keep an open mind and learn from experts rather than getting all defensive. I know I’ve learned a ton from these guys and they have quite a bit to offer to the community.

Originally Posted by KennyPowers

you, and a lot of other people (myself included), need to cut this stuff out.

its obvious you are biased towards the e9x as many here who own / will be owners of the f8x are biased towards that car (like me). there is a reason we all own the car we do.

so lets not act like you are some sort of non biased observer, and everyone else is biased except you

Originally Posted by gthal

I don't understand the "insecurity" argument on either side of this debate. The car is much faster than the E9X regardless of whether the stated HP is underrated or not. How can there be insecurity when the real world result is well known and well accepted by everyone? This debate, for me anyway, is somewhat academic more than anything else.

The car traps 119-120+ and is faster than the E9X in pretty much every measurable way. Anything else is intellectual stimulation only... no insecurity needed



True statement... there is no such thing as non-bias Some are less biased than others but no one is without bias... except me

[P1 Motorcars]

Originally Posted by FogCityM3

My point is that it appears that some sort of minimum torque setting that can be overridden with certain tunes and influence the actual moment, otherwise it is a strict calculation. But on a stock car and with certain tunes the calculations appear to be directly affected by various parameters, unless something is overridden (based on my discussions with tuners and my own logging of dozens of parameters, where it can be clearly seen). It is my understanding the ECU looks for a minimum torque value that is calculated (or set so low in the table that it won't matter unless things are going wrong..I'll have to look back at my logs but I believe I get different miminum torque ratings based on environmental factors, showing that untuned, it is a calculated value from various parameters) or alternatively with different tunes, this calculation be overridden. I just know what I've gotten with stock tune, and two different tunes using actual moment with dozens of logs. The person who maintained the dyno DB also did some actual moment logging and seemed to work fine with stock cars, but not with all tuned cars. You can talk to the various tuners as to what they modify/don't modify. Also, when I put in better fuel, the timing targets are hit (vs timing pulled on 91) and there is a direct change in power as calculated by actual moment, even at equivalent temperature/ pressure. Also, I have observed that changes in mass airflow, altitude, atmospheric pressure, IATs vs ambients all influence power/actual moment produced. I have the benefit of road logging on flat roads at sea level, where it is very easy to control for environmental factors and established enough baselines to see how changes in various parameters influences power. So to me is shows that various inputs change the calculation, unless things in certain tables get overridden.

If actual moment can be calculated just from acceleration and all the other variables the ECU and BMW already know, then adding a torque table override doesn't make sense to me. From a design view, that doesn't make sense because A) it's not needed, and B) adds complexity. But you make a very good point that bone stock, Actual Moment may be good enough. We'll be more than happy to try it on our F8x when the BT tool software gets updated.

BTW, I started looking at Dash Dyno last night but didn't get a chance to finish. I love gadgets so we'll probably get one and give it a try.

Originally Posted by Boss330

It's actually quite interesting to see how many here is arguing for the conspiracy on BMW's part (in deceiving EU, US, and the rest of the worlds authorities, by knowingly stating a false HP/Tq number and misleading independent type approval institutions), than they are in believing that the performance numbers are actually achieveable within the scope of BMW factory HP/Tq numbers.

We've looked up EU regulations in the past and found them all public and free (unlike the SAE which you must pay for). Do you have any references to the actual EU regulations (by name/number) that regulate power reporting by auto manufacturers? We'll be happy to look them up and give our opinion of what we think they mean.

As swamp also have said, if we start seeing stock F8x's trapping consistently above 120MPH, then the underrating case seems more plausible. Regardless I/we should all be open to new data and evidence one way or the other. This is still early days for the F8x generation and new information will certainly become available as time goes...

This is interesting because just by the numbers, it's hard to make a case for 425 chp.

According to entries in Drag Times, M3Post and others, the E9x M3-DCT range from 108-112 MPH bone stock, and 113-118 MPH FBO. Weight with a 175 pound driver is approximately 3789 pounds (based on posted scale weights : 3614 + 175). Drag is 0.31, and frontal area is 23.4 sq/ft.

According to magazines and vBox results, the F8x M3/M4-DCT range from 117-119 MPH bone stock. Weight with 175 pound driver is approximately 3753 pounds (based on posted scale weights : 3578 + 175). Drag is 0.34, and frontal area on the M3 is 24.65 sq/ft.

According to those numbers, the F8x car weighs 36 pounds less, has worse drag and greater frontal area traps 8 MPH higher with only 11 more horsepower. I haven't followed the other threads, but curious how that gets explained.

Originally Posted by ASAP

I think Swamp has provided a lot of useful mathematical data and calculations to learn theory from. Unfortunately, as someone has already stated real world and theory rarely are on par... my main gripe was that I've never come across a car of this weight and his supposed whp (365) numbers that could trap remotely what an M4 could.

Our simulations ("theory") worked the very first time. We also have past experience with this and have a track record of getting this right. And we agree with you, a car can't trap 118-120 MPH on 425 chp and 3750 pounds.

Originally Posted by swamp2

Guys, if you recall I have completely REVERESED my thoughts in this matter.

That is why I wanted to be extremely thorough in such a reversal. I am completely swamped at work and preparing for a week out of town. I also have two toddlers... I appreciate some patience as some significant time is needed for a thorough reply and perhaps some additional simulation work. As I pointed out prior my work is incredibly misrepresented in the OP and there are some serious short comings in the various approaches in the OP. That should be painfully obvious to anyone familiar with physics based vehicle simulation.

It's not obvious where we went wrong or what input parameter to CarTest we used incorrectly. CarTest isn't difficult to use, but it is tedious and if you want your simulations to match real world results, then you have to do what we've done successfully on many previous occasions. We used BMW published data, actual car measurements, actual road conditions, actual weather conditions, actual wheel weights, actual tire pressures, and actual wheel horsepower. Our simulation produced the same results as the real world on the very first try and we don't think that's a coincidence. We documented every input parameter. If the flaws in this approach are so obvious and the shortcomings so glaring, then extra time and simulations wouldn't be required. Just give us a hint where we went wrong and why our simulations match real world and why real world matches the dyno's as well.

We understand you're busy and have toddlers and going on vacation. We hope you have a good vacation. When you get back, we welcome the technical discussion on technical merit alone. I know your thread is long and I didn't read all of it. I never saw you post any of your CarTest input parameters, while we posted all of ours. It's hard for anybody to verify your work for peer review without this information. So when you get back, we look forward to seeing all of your input data along with an explanation why those are the right values and ours are wrong. We already did this and look forward to what you did so we can review it as well.

[Boss330]

Originally Posted by P1 Motorcars

We've looked up EU regulations in the past and found them all public and free (unlike the SAE which you must pay for). Do you have any references to the actual EU regulations (by name/number) that regulate power reporting by auto manufacturers? We'll be happy to look them up and give our opinion of what we think they mean.



This is interesting because just by the numbers, it's hard to make a case for 425 chp.

According to entries in Drag Times, M3Post and others, the E9x M3-DCT range from 108-112 MPH bone stock, and 113-118 MPH FBO. Weight with a 175 pound driver is approximately 3789 pounds (based on posted scale weights : 3614 + 175). Drag is 0.31, and frontal area is 23.4 sq/ft.

According to magazines and vBox results, the F8x M3/M4-DCT range from 117-119 MPH bone stock. Weight with 175 pound driver is approximately 3753 pounds (based on posted scale weights : 3578 + 175). Drag is 0.34, and frontal area on the M3 is 24.65 sq/ft.

According to those numbers, the F8x car weighs 36 pounds less, has worse drag and greater frontal area traps 8 MPH higher with only 11 more horsepower. I haven't followed the other threads, but curious how that gets explained.

C&D recorded a 116MPH trap speed in the article released today:

http://www.caranddriver.com/reviews/...ed-test-review

And the answer to your question on trap speed difference is really as simple as average power in each gear during the 1/4 mile run. I will paste one of my other posts on this topic, which compares to a C7 and not the E9x, but the point is the same:

Then why don't we see higher trap speeds than for instance the C7 Corvette?

The C7 has the following power graph:



And a chassis dyno result:



Using this video, we see that they shift at 6500rpm and then drops to around 4500rpm for the next gear:

Let's do a simple calculation of the average power the C7 engine provides over that rpm range (average power in a gear is what determines acceleration and thereby trap speed, not a peak hp number only available for 100rpm...):

As we can see from the chassis dyno, the power drops after 6000rpm. At 6500rpm the power is at the same level as it was at 5000rpm, which seems to be around 420hp on the official dyno graph.

Since the power graph seems to have a very similar curved shape before and after 6000rpm, we can do a simplified calculation of average power for the 5500-6500rpm range:

(420+460+420)/3 = 433hp

(Note that we ideally should have used more data points to calculate a truer representative of average power here, since the graph is curved. The simplified method with only three data points underestimates average power in this case)

But as we noticed the engine RPMs dropped to 4500rpm with each gear shift, so we also need to add that to our (simplified) calculation of average power from 4500-6500rpm:

At 4500rpm the C7 engine seems to be roughly around the 380hp mark (on the official C7 factory graph).

Assuming a fairly linear power curve from 4500-5000rpm gives us the following total average power calculation:

380+420/2 = 400hp (average from 4500-5000rpm)

Total average from 4500-6500:

400+433/2 = 416hp

So, as we can see, the C7 has around 416hp in average power from 4500-6500rpm, which is the rev band used under acceleration (based on the video).

We all know that the S55 is claimed to have a average power of 425hp from 5500-7300rpm.

To me it makes sense that the M3/4 and C7 both record trap speeds of around 117-118MPH, when their average power under acceleration is 416hp vs 425hp and where the C7 has a lower weight to compensate for it's 9hp lower average hp.

If the F8x REALLY has the power these dyno results indicate, then the trap speeds should be considerably higher than the C7. Because if the 425whp is to believed, then the S55 needs to make around 470-480 at the crank. A car that has a engine that makes an average of 470-480hp in each gear, should annihiliate a C7 that only has around 410-420hp in average. That simply doesn't add up (unless the F8x starts trapping well over the 120MPH mark of course ).

In addition I would also say that if the S55 is under rated, it most likely isn't by more than the 5% allowed for by EU legislation (425 x 1,05 still is 446hp and a substantial increase by all means)

And:

What I tried to say ( ) was that if the car truly generates 425whp, that would equate to roughly 470-480hp at the crank (with a low 10-12% drivetrain loss). That's the only place in that last paragraph where I mentioned whp to crank hp

Further I pointed out (or at least tried to do ) that if the S55 really has 470-480hp at the crank (which it then has from 5500-7300rpm), also means that the S55 has an average power output in each gear of 470-480hp (the beauty of the S55 plateau power curve).

Agree so far?

My final point then was that I don't quite understand how a car with 470-480 average hp at the crank, traps at a similar trap speed as the C7, which only has 410-420 average hp at the crank (in both cases hp at the crank obviously).

A engine that has around 60-70 more average hp, should trap higher than the C7 (also taking weight difference etc into consideration).

And:

I'm no expert on Vettes, but here's what I found after a quick search:

http://forums.corvetteforum.com/c7-t...rb-weight.html

So, 3411lbs as weighed by owner.

Here is a F82 DCT weighing in at 3564lbs:

http://f80.bimmerpost.com/forums/sho....php?t=1023335

A difference of 153lbs/69kg.

To me, there is something odd about a car weighing only 153lbs more and with a claimed 60-70hp higher average power (at the crank) doesn't trap faster than the C7... (on a trap speed calculator, a 153lbs weight increase equals roughly only 1MPH lower trap speed, while 60hp more equals a 5MPH increase in trap speed...)

And if you want to, you could also calculate average power for the S65 in it's powerband (start and finish rpm in a gear during full acceleration). You will see that the difference in average power between the S65 and S55 is MUCH greater than 11hp, and THAT's what matters, not the 11hp difference in the PEAK power of the S65 and the PEAK AND AVERAGE power of the S55... The difference in peak power is 11hp, but calculate the average power for the S65 and look at that difference...

As clearly visible in this overlay of the two engine's dyno graphs (at 5500rpm, the difference in actual power output is a staggering 131PS...!!!):



Finally, here is a link to Directive 80/1269/EC on engine power:

http://eur-lex.europa.eu/resource.ht...C_1&format=PDF

[CanAutM3]

Originally Posted by Boss330

And if you want to, you could also calculate average power for the S65 in it's powerband (start and finish rpm in a gear during full acceleration). You will see that the difference in average power between the S65 and S55 is MUCH greater than 11hp, and THAT's what matters, not the 11hp difference in the PEAK power of the S65 and the PEAK AND AVERAGE power of the S55... The difference in peak power is 11hp, but calculate the average power for the S65 and look at that difference...

As clearly visible in this overlay of the two engine's dyno graphs (at 5500rpm, the difference in actual power output is a staggering 131PS...!!!):



Finally, here is a link to Directive 80/1269/EC on engine power:

http://eur-lex.europa.eu/resource.ht...C_1&format=PDF

As I have already replied to you in another thread, the chart quoted above is utterly meaningless. To be able to properly compare the power curves, you need to plot against road speed. Plotting against road speed is also not fully accurate but does provide a better visual cue than plotting against RPM. See post here.

I believe the chart below also illustrates well the important point you are trying to make regarding average power. The importance of average power is a point I have been debating with Swamp for quite a while on a variety of topics.

[Keto]

Originally Posted by swamp2

Again, appreciate some patience here.