Updated BMW F82 M4 Performance Simulations-Predictions - Even Faster...

[CanAutM3]

Originally Posted by swamp2

I did note that the only shift at redline in your set of suggested gears was 1->2.

I expected this because of the slight power drop off after ~7500 RPM in your simulated power curve and me picking a ~7600/6000 spacing between gears. Using a ~7600/5900 ratio would have yielded red line shifts in every gear. A ~7500/6000 ratio would have better optimized the power band for acceleration but without redline shifts. (Note that my RPM numbers are only aproximations based on the graph you provided in the first post.)

[Bowser330]

Originally Posted by BigMacSmallFries

Sorry, just telling it like it is. I'm a rather classy fellow. lol

humble too

[swamp2]

Originally Posted by OrangeCrush

Thanks Swamp...this is awesome as always....now the real question....are you going to trade your M3 for an M4?

Thank you.

Good question. I am thoroughly undecided on a next car if any. I'm doing a few bolt on (& software) mods to get to around 450 crank hp. Even without those the car remains well beyond many of my skills. The engine is simply glorious at or anywhere near full boil. I still smile about every time I get into my car. However, I've also owned an E46 M3 and E36 M3 thus it may be time for a change. The current car that does the most for me visually is the Maserati GrandTurismo Sport. The Porsche Panamera is also growing on me. On somewhat the opposite end of the spectrum the Cayman S is a wonderful smaller sports car. I'm sure it is obvious but I remain a big fan of NA engines.

[Dave2011M3]

Great job Swampy, I just don't think we will see 7600-7700rpm out of the S55, I hope I am wrong. I mean the M5/6 redlines at 7100rpm I believe and yes I realize they are V8s but it just seems to me that BMW is keeping the revs down to a more pedestrian level with the new M cars.

Dave

[mkoesel]

Extremely thorough analysis as usual, swamp.

Lately, I can't help but wonder if we won't see even less weight (less than your latest simulation), but also a bit less power too. BMW is doing a great job of keeping us guessing, that's for sure.

[GIdriver]

Awesome job as always, Swamp!!! Very thorough analysis. Thanks for sharing!!

[swamp2]

Originally Posted by Dave2011M3

Great job Swampy, I just don't think we will see 7600-7700rpm out of the S55, I hope I am wrong. I mean the M5/6 redlines at 7100rpm I believe and yes I realize they are V8s but it just seems to me that BMW is keeping the revs down to a more pedestrian level with the new M cars.

Dave

Thanks the correct F10 M5 redline is 7200 rpm.

[solstice]

Originally Posted by mkoesel

Extremely thorough analysis as usual, swamp.

Lately, I can't help but wonder if we won't see even less weight (less than your latest simulation), but also a bit less power too. BMW is doing a great job of keeping us guessing, that's for sure.

If BMW has choosen to focus R&D efforts and material/production cost mainly on weight reduction and not the engine I applaud them. Cars are IMO way to heavy today and not underpowered by any measure. If they read these blogs I hope they realize that they are doing the right thing if this is what they indeed are focusing on and not get desponded by all/only engine talk. A paradigm shift to end the hp war and start a weight reduction/handling war is what many of us want and are eagerly awaiting. As long as the engine is a good match and in balance with the rest of the car it doesn't need to rev. to the moon or put down monster power. It would be nice if it does but cars are built to cost and if they can save on the engine to build a lighter, tighter car that's a good thing in my book.

[iceman335]

I was told that F82/F82 will be 440hp, with optional competition pkg add some extra hps.

[RMB]

Originally Posted by iceman335

I was told that F82/F82 will be 440hp, with optional competition pkg add some extra hps.

It sounds like BMW will offer the competition package right in the beginning. It would be great if they did but I cringe at the price of the carbon ceramic brakes (whether that will be a stand alone option or not, who knows). Any chance you can divulge your source Iceman?

[swamp2]

Originally Posted by Skullbussa

So are we eliminating other variables such as aerodynamics or, hell, physics too?

CarTest is a physics based simulator, certainly many effects are missing from the enormous range of subtleties in any real world car, however, the dominant effects that allow accurate absolute predictions and even better relative predictions of all common vehicle performance metrics are all present. That includes but is not limited to power, torque (full rpm dependent curves for both), weight, weight distribution, weight transfer, gearing, parasitic losses (drive train, tires and others), traction, friction and wheel spin, tire size, wheel growth with speed, environmental effects such as pressure and air density, road slope, shift times and last but not least aerodynamics including drag coefficient and frontal area.

Now that being said, I think you misunderstood what I mean by "eliminating variables". What that means is that if you compare car A and car B you can change one and only one parameter between the cars and ALL other inputs (variables if you like) are held completely fixed and identical. It is this sort of control and parameter isolation that is not at all possible in real world test, no matter how much care is taken.

[BigMacSmallFries]

Originally Posted by iceman335

I was told that F82/F82 will be 440hp, with optional competition pkg add some extra hps.

That would be amazing. Last I heard, the competition package is supposed to be released for the 2016 MY, after the M3 is launched as a 2014 MY, and M4 as a 2015 MY. Kind of like like there was a 2012 M5, but now a competition pkg on the 2014 is available.

Anyone have sources the competition pkg will be available at launch?

[Dave2011M3]

Originally Posted by swamp2

Thanks the correct F10 M5 redline is 7200 rpm.

Sorry man, haven't been keeping up with the joneses. Just read that the S55 should have close to 8k rpm....very interesting.

Dave

[pootytang]

Originally Posted by swamp2

CarTest is a physics based simulator, certainly many effects are missing from the enormous range of subtleties in any real world car, however, the dominant effects that allow accurate absolute predictions and even better relative predictions of all common vehicle performance metrics are all present. That includes but is not limited to power, torque (full rpm dependent curves for both), weight, weight distribution, weight transfer, gearing, parasitic losses (drive train, tires and others), traction, friction and wheel spin, tire size, wheel growth with speed, environmental effects such as pressure and air density, road slope, shift times and last but not least aerodynamics including drag coefficient and frontal area.

Now that being said, I think you misunderstood what I mean by "eliminating variables". What that means is that if you compare car A and car B you can change one and only one parameter between the cars and ALL other inputs (variables if you like) are held completely fixed and identical. It is this sort of control and parameter isolation that is not at all possible in real world test, no matter how much care is taken.

Seems like the biggest source of uncertainty in a 0-60 or 1/4 mile sprint would be the tire model. But maybe you can correlate your model and known benchmarks for the M5?

Also, I'd guess suspension modeling plays a big part with the weight transfer, how is the suspension modeled? I know there are 2 types in the industry, one such as Carsim which uses parametric models and 2nd order approximations (look up tables), while others actually model the linkages and multi-body stuff (is it called ATOM model?). I'm no expert on this as you can probably tell...

[swamp2]

Originally Posted by drob23

Seems like the biggest source of uncertainty in a 0-60 or 1/4 mile sprint would be the tire model. But maybe you can correlate your model and known benchmarks for the M5?

Also, I'd guess suspension modeling plays a big part with the weight transfer, how is the suspension modeled? I know there are 2 types in the industry, one such as Carsim which uses parametric models and 2nd order approximations (look up tables), while others actually model the linkages and multi-body stuff (is it called ATOM model?). I'm no expert on this as you can probably tell...

Good questions/comments.

The tires are not modeled in any explicit fashion in this level of simulation. The key ingredients are simply the static and dynamics friction coefficients, i.e. whether the tire is spinning or "hooked up". There is probably room for some improvement here but again, above all power and weight are by far the most dominant factors.

Suspension is also not modeled explicitly, in fact there is really no suspension modeling. The only effect is weight transfer which affects the maximum wheel torque possible before wheelspin. A fully rigid chassis is assumed here as suspension movement is not a prerequisite to properly cover basic weight transfer. Of course one can still model RWD or AWD and friction/traction along with weight transfer on both axles.

From my extensive use of this program and the one I wrote myself, the largest uncertainties are parasitic drivetrain losses, drivetrain inertia and tire modeling (again just the two friction coefficients). Getting shift times correct is also a key factor in results, however, this is fairly straight forward (despite some debate here on the forum as to how fast a "fast shifting" human can shift). DCT obviously shifts significantly faster than even the fastest human.

One does need to engage in some ongoing simulation vs. test activities to always keep the simulations correlated to the real world. However, care must be taken as to what is a "real" number from testing. Test result vary quite widely.

The goal here is overall vehicle performance. The tool is both simple enough and complex enough to provide a suitable balance of accuracy, flexibility and speed. Simulations take mere seconds...

[Carl L]

Originally Posted by BigMacSmallFries

That would be amazing. Last I heard, the competition package is supposed to be released for the 2016 MY, after the M3 is launched as a 2014 MY, and M4 as a 2015 MY. Kind of like like there was a 2012 M5, but now a competition pkg on the 2014 is available.

Anyone have sources the competition pkg will be available at launch?

This was my understanding too, so I'll plus one this question.

On this topic, I must say the "power package" is a true cash gouge tactic taken straight from Benz. There should only be a full fat M3 and M5, not two outputs. Wanting 8 grand for 15hp on the F10 is a joke, at least the AMG gets a 50hp boost.

But if they insist on offering one, it should be available at launch, so I hope Iceman is correct as then we can weigh up if it's worth getting or not (I'm a sucker for most options, except CC brakes).

[swamp2]

Originally Posted by Carl L

This was my understanding too, so I'll plus one this question.

On this topic, I must say the "power package" is a true cash gouge tactic taken straight from Benz. There should only be a full fat M3 and M5, not two outputs. Wanting 8 grand for 15hp on the F10 is a joke, at least the AMG gets a 50hp boost.

But if they insist on offering one, it should be available at launch, so I hope Iceman is correct as then we can weigh up if it's worth getting or not (I'm a sucker for most options, except CC brakes).

Fully agree. I can't stand the overpriced "power" option. But my strong suspicion is that they will offer it. A few lines of code, no physical parts and thousands of dollars is simply too much profit for BMW to resist. We know they'll do anything for the $$ (as they ultimately should) given that the entire change to turbocharging and an I6 is driven by the exact same motivation.

[flinchy]

Originally Posted by swamp2

flinchy: The links you provided are entirely irrelevant. The torque curve I am using for the new M4 is nearly exactly like the FACTORY DYNO from BMW for the M5, just adjusted for a bit higher redline. The method to calculate shift points is precisely as I described earlier and this is precisely what CarTest is doing. Until you can offer some proof of your proposition on the F10 M5 gearing/shift points, with a clear description of how the calculation is being performed, you're positively contributing to the discussion here.

Last but not least you should also do some reading on some of the (epic) debates here on the forum about power vs. torque. I used to think about vehicle performance a bit like you are. It is kind of a crutch for truly understanding the power (no pun intended) and simplicity of power (over torque).

i did offer proof

if you hold power flat from 6000-8000RPM, you will ALWAY NO MATTER WHAT shift at redline for maximum acceleration, as ONLY there will the next gear provide better acceleration

in fact, even the factory N54 powered cars dyno indicate that peak acceleration is ALWAYS redline, it's only once tuned that it shifts from redline to upper midrange.

until YOU can show any evidence otherwise, that's the fact...

heck.. i just plugged a stock F10 dyno into MULTIPLE calculators (Like the ones i posted) and STOCK it's redline shifting, it's not until tuned (like the graph i posted) that the midrange overtakes.


calculation being performed via any number of calculators (spreadsheets etc.) that use various points of torque curves + gear ratios+FD to work out at what point it's more effective to change

i even posted links to EXACTLY what i was using.


you know.. that and logic, logic goes a long way.

Originally Posted by swamp2

Last but not least you should also do some reading on some of the (epic) debates here on the forum about power vs. torque. I used to think about vehicle performance a bit like you are. It is kind of a crutch for truly understanding the power (no pun intended) and simplicity of power (over torque).

LOL it sounds like you're the one lacking understanding

you should google:

'Why-horsepower-torque-quot-changes-quot-dynos-quot-read-low-quot-peak-torque-is-not-when-you-accelerate-hardest-and-gearing-matters'

an article on 'the other site'



a crutch for truly understanding power? yeah no, more like how power actually works

power is torque over time (ie at an RPM), torque is power without time (hence torque is also called a 'moment of force')
anyone who disagrees with the above is simply wrong, as they can't prove anything otherwise (and conversely, proof in abundance for the CORRECT case)

torque as read on a dyno graph is without gearbox+final drive multiplication ('at the flywheel' even though it's not a true 'flywheel' value)

i studied mechanics of force at university, FWIW.. one of the few subjects in that degree i didn't fail HAH


ED: i can tell you know a LOT.. and i'm not debating anything else you're saying, as i'll just assume you're correct in that

but you seem to be lacking core understanding of torque+power+gearing+acceleration etc relationship.

[fuddman]

Originally Posted by flinchy

if you hold power flat from 6000-8000RPM, you will ALWAY NO MATTER WHAT shit at redline.....

OMG!!! Tell me it isn't so.

[flinchy]

Originally Posted by fuddman

OMG!!! Tell me it isn't so.

D:

it'll be ok, i promise.

[CanAutM3]

Originally Posted by flinchy

if you hold power flat from 6000-8000RPM, you will ALWAY NO MATTER WHAT shit at redline for maximum acceleration, as ONLY there will the next gear provide better acceleration

I'll assume you meant "shift" and not taking a dump...

To be able to assess the accuracy of your statement, you need to specify the redline and gearing of the assumed drivetrain.

Originally Posted by flinchy

in fact, even the factory N54 powered cars dyno indicate that peak acceleration is ALWAYS redline, it's only once tuned that it shifts from redline to upper midrange.

IMO, based on my calculations, the stock N54 power curves have sufficient drop off in the upper rev range to warrant a shift before redline in the higher gears to maximize acceleration.

Originally Posted by flinchy

power is torque over time (ie at an RPM), torque is power without time (hence torque is also called a 'moment of force')
anyone who disagrees with the above is simply wrong, as they can't prove anything otherwise (and conversely, proof in abundance for the CORRECT case)

The term "moment of force" (sic) has nothing to do with the notion of time. The term "moment" refers to the perpendicular distance of the force vector to the point of reference. Torque, moment of a force, couple are all synonyms to define a twisting force.



1M shift points example:

[flinchy]

Originally Posted by CanAutM3

I'll assume you meant "shift" and not taking a dump...

To be able to assess the accuracy of your statement, you need to specify the redline and gearing of the assumed drivetrain.

my bad haha

yeah of course, you have to work it out car by car.

but if power is held to redline (which by definition means torque doesn't drop off sharply ENOUGH)... then regardless of gearing, peak acceleration is redline.

Originally Posted by CanAutM3

IMO, based on my calculations, the stock N54 and S6344Tu power curves have sufficient drop off in the upper rev range to warrant a shift before redline in the higher gears to maximize acceleration.

stock power curve is pretty close to peaking at redline, with little to no taper, the best graphs i could find are from ****** though sadly so can't link them haha

even tuned, 1-2-3 are still shifted at 7000RPM, then later gears rapidly taper.

Originally Posted by CanAutM3

The term "moment of force" (sic) has nothing to do with the notion of time. The term "moment" refers to the perpendicular distance of the force vector to the point of reference. Torque, moment of a force, couple are all synonyms to define a twisting force.

yes, moment of force is what torque is, if you have a read of what i said, i clarify that torque is the force 'at a moment' and power is torque over time.


ED: at those 1m shift points... what's happening there?.. shift at 4250rpm? i can't read that graph haha

ahh is it some misc 'acceleration value'?

but yes, the 1M being a bit beefier in the midrange shifts a bit sooner than totally stock 135i's.... though it's still a case by case basis.. N54 to N54, you can have shift points varying up to 500rpm depending on the gear.