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

[swamp2]

     Featured on BIMMERPOST.com

Many of the regulars here will recall my advocacy of the principles of science/math (engineering really) to the enjoyment and understanding of vehicles. Some time ago I made some detailed predictions about the performance of the upcoming M3/M4. If you want to refresh your memory have a look at that thread from way back in late 2010 here. It showed a very quick new M3/M4!

With the new rumors on weight, redline and the not so new rumors on the torque and power I thought it was time to update my predictions. Stay tuned (or skip the details near the end if you are not so inclined) as I'm reasonably confident the car will be even faster than my prior predictions. No real surprise there as the new inputs to my physics based simulations are in essence more power and less weight. However, you'll probably be able to glean some things about the effect of the shapes of the power/torque curves on vehicle performance, the advantage of a high redline (disadvantage of a lower one...) and how we can extrapolate changes from the E60 M5 to F10 M5 to better understand what likely lies in store with the next generation M3/M4.

Relatively high torque, low (or even high) power, low redline engines as compared to low torque, high power high redline engines simply must be geared differently. The cars must delicately balance acceleration, peak speed in gears and utilizing the full rpm range. The former cars are great for more lazy driving with adequate torque to pass in higher gears whereas the latter have an addictive linear power band that is noisy, thrilling and takes more shifting to extract the total available performance. The new Ms are heading in the former direction, however, with good news that the new motor may rev “close to 8000 rpm”, they are not going to totally Corvette style power on us.

We can should be able extrapolate some of the changes from the E60 M5 to the F10 M5 to the M3, even though the new M4 will likely be lighter than its predecessor, unlike the progression of more weight in the M5. As far as engine and transmission we can extrapolate quite a bit. Both engine and transmission changes must go hand in hand and the changes for the M3/M4 are thus likely to be right in line with what happened with the M5 to accompany the lower displacement and forced induction. A bit unexpectedly the F10 M5 has more gear multiplication down low and less in its top gear. A wider overall range that impacts both off the line acceleration as well as providing increased fuel economy with a 7th a bit more like an overdrive gear. The F10 has about 5% lower gearing (higher gear ratio/torque multiplication) in first gear combined with a whopping 30% higher 7th gear (lower combined gear multiplication). Because the new M3/M4 will also have much more torque and peak torque will arrive at a much lower rpm its gearing should change in a very similar fashion.

I’m not also going to recall my prior statement that the new M3/M4 will require shifting at redline in all gears to extract maximum performance. The new M5 does not, only the first three shifts are done so in the M5. The rapidly falling torque curve means that you can get more thrust in a lower gear by shifting earlier for the higher gears. Basically when the force vs. speed graphs (second set below) cross before redline then the ideal shift will also be before redline. The higher the redline is, combined with this falling torque and 7 close spaced gears all lead to an inability to utilize the full rpm range in all gears. This obviously was not a problem in the current M3 because of the very flat torque curve up to high rpms (equivalently its very linear power curve). Based on this effort I also do not believe the car will have a redline "very close" to 8000 rpm. Or perhaps a slightly weaker but more confident statement is that the combination of power and torque curves that look like the ones in the M5, along with similar gearing changes like the ones I’ve chosen, do not yield significant performance improvements with a redline above about 7600. Thus my best guess is 7500-7700 tops. I really think “close to 8000” is more BMW marketing speak for a figure like I’ve mentioned.

Here are my predictions for speeds in gear comparing the existing DCT M3 on the left to the new M4 on the right:



Here are the force at the wheels comparisons. Many talk about the torque at the wheels, almost the same thing but one should really take the next step and convert that to a force. You can get an idea why folks talk about such turbo engines feeling a bit dead up top. It directly affects how much force gets to the wheels and the change to a downward slope can happen quite ubruptly (just like in the dyno itself). This is called jerk or surge and we humans are very tuned to feel this change in acceleration. The left is the existing car and the M4 is on the right.



The next key point is underrating, the 335i was, the 1M was and now the F10 M5 is as well. The M5 is likely to be underrated by about 20-30 hp. Given its weight and performance there really is no other reasonable explanation. I’ve this same CarTest physics based acceleration simulation software to model a plethora of cars performance and I’ve done so using the F10 M5 as a baseline to provide better M3/M4 predictions. Just based on the claimed ~400 ft lb of torque in the new M3/M4 and a redline near 8000 rpm, as well having a torque curve that looks anything like the F10 M5, “about the same power” as the current M3 is just not possible. I’m estimating the quoted power of the car to be 420-430 hp but actual power will be more like 440-460. For the included simulations I’ve decided on 450 hp. I have however, varied the power and weight like in the prior post and effort linked to above to provide a more reasonable range of performance figures. The complete range of simulations I’ve used is certainly not shown.

Here are the torque and power curves I have used:



Here are the basic inputs into the simulation:



Weight: My prior estimate was around 3590 lb (wet without driver). For three reasons, one stronger and two weak I am revising that estimate down.

1. BMW reports weight in the US with 165 lb (75 kg) added for driver and cargo. 3700 is about right for a typical US E92 M3, which translates to about 3550 (wet without driver). BMW will probably be saving at least 100 lb compared to the current car meaning a figure of about 3450 (wet without driver) is reasonable. The 100 figure is very roughly justified again in the post mentioned near the beginning of this one.
2. Ongoing rumors insist we’ll see a significantly lightened vehicle.
3. Less weight = more performance = an more exciting post.

Like I said, one stronger and two weak…

For completeness sake the software has a place to add the drivers weight and I have used 160 lb. Guess 165 might be better from a standards perspective, but what's 5 pounds among friends.

Acceleration curves: turquoise for the new M4 and purple of the E92 M3. These also show a fairly dramatic difference in what you feel at high rpms. First gear is obviously quite dramatic in the new car, a huge overall advantage for the M3. Despite the undesirable roll off in acceleration, even at its worst point (right before shifting) it remains with more acceleration than all except right around the peak of the existing car!



Last but not least the full comparison, first column is E92 M3, second is my initial prediction mentioned above and last is the current effort.



Summary of predictions:

• 0-60 mph: 3.5 - 3.7 s
• 0-100 mph: 8.2 - 8.4 s
• 0-200 kph: 12.4 - 12.6 s (for our metric friends!)
• 1/4 mi time: 11.9 - 12.1 s
• 1/4 mi trap: 120 - 123 mph
• Top speed: 193 - 197 mph (of course true, not indicated, indicated will be over 200 mph)
• Nurburgring Nordschleife lap time (SportAuto): Low 7:5X (will greatly depend on choice of tires)

Hope you enjoy the predictions. Like all work of this type, garbage in garbage out. There are a lot of assumptions in such simulation. If the actual car differs significantly from these inputs then the predictions will be correspondingly off. However, if the inputs are close to actuals, I'm highly confident the car will indeed have this level of performance. Will this be enough to keep the car on the top of the competitive heap?

[RMB]

Very interesting and thanks for the information. I plan on picking up the new M4 when it comes out so I am very interested in reading about its potential performance improvements.

[Needsdecaf]

Impressive analysis.

[buildbright]

I agree. The f30 chassis and new transmissions are great for acceleration. There is already a 11 sec 335i. I predict with a jb4 and some other goodies the new f80 should be a 10 second car.

[BigMacSmallFries]

Thanks for posting, but 8.3 seconds to 100mph?! An LP560 4 wheel drive/550hp/3400lbs does it in 8. I hope you're right!

[CanAutM3]

I always enjoy reading your inputs and analysis, thanks for taking the time and sharing .

I am hoping the the gearing on the new M3/M4 will be adapted to always keep the car in the power plateau (6 to 7.6k in your assumption) and only 7th gear with taller gearing for fuel economy. If that were the case, every gear could be pulled to redline yielding a very smooth acceleration curve. It should help reduce the feeling of "acceleration drop-off" nearing redline. I guess it is wishful thinking on my part .

[bimmerjph]

What software are you using?

BTW great post. Thanks for the predictions!

[swamp2]

Originally Posted by bimmerjph

What software are you using?

BTW great post. Thanks for the predictions!

Thanks, as mentioned in the post it is called CarTest.

[swamp2]

Originally Posted by BigMacSmallFries

Thanks for posting, but 8.3 seconds to 100mph?! An LP560 4 wheel drive/550hp/3400lbs does it in 8. I hope you're right!

8.4 was the top end of the range I predicted. A very quick search revealed the Lambo has done 7.8 s 0-100 mph. A 0.6 second gap is pretty significant!

Originally Posted by CanAutM3

I always enjoy reading your inputs and analysis, thanks for taking the time and sharing .

I am hoping the the gearing on the new M3/M4 will be adapted to always keep the car in power plateau (6 to 7.6k in your assumption) and only 7th gear with taller gearing for fuel economy. If that were the case, every gear could be pulled to redline yielding a very smooth acceleration curve. It should help reduce the feeling of "acceleration drop-off" nearing redline. I guess it is wishful thinking on my part .

Your welcome.

No matter how 7th is geared the large drop off in acceleration is pretty well inevitable as the accelerative force basically follows the torque curve. Now if the torque curve (shape or redline) were more S65-ish, as stated, this drop off would not occur. Of course that is NOT the same as saying torque is more important then power... But that is a whole different discussion.

I really don't think this car will be a shift at redline in every gear type of car, but at least it should for the first few shifts and that more important than the latter ones for sure. Given the more F10 M5-ish torque curve and gearing and a 7600-ish redline, something has to give and that something is not shifting at redline.

[BMW269]

M3/M4 will be fast, as I previously predicted. Your numbers are quite there swamp. But that doesn't tell how good the M3/M4 will be. GTR also is very fast, but not more fun than a Cayman, MP4-12C is also very fast, but hasn't got the feeling of a 458.

[fatmike91]

Very interesting. Could you model how a lighter M3 would perform?

The curb weight (not wet w/o driver) of my 1999 328i was under 3200.

I'd be curious what these charts would like like with a 3200lb (or 3300lb) car.



/

[ILC32]

Very interesting. 450 hp is consistent with what I was told quite some time ago by a confidential source. I don't claim to know what the current hp target is, but it will be interesting to see how things ultimately turn out, especially with respect to the actual (as opposed to specified) output .

[swamp2]

Originally Posted by Levi

M3/M4 will be fast, as I previously predicted. Your numbers are quite there swamp. But that doesn't tell how good the M3/M4 will be. GTR also is very fast, but not more fun than a Cayman, MP4-12C is also very fast, but hasn't got the feeling of a 458.

I strongly agree with you on this!

[swamp2]

Originally Posted by ILC32

Very interesting. 450 hp is consistent with what I was told quite some time ago by a confidential source. I don't claim to know what the current hp target is, but it will be interesting to see how things ultimately turn out, especially with respect to the actual (as opposed to specified) output .

As discussed quite a few times all of the rumors of; nearly 8000 rpm redline, close to existing power, a torque curve like the M5 and about 400 ft lb of torque are almost an impossible combination, something is inconsistent in this set of characteristics. I think power "about the same" will be the thing that will not be correct from that list (well and as stated about "near" 8000 rpm redline as well).

However, looking at torque per liter in the F10 M5, if it kept its ratio there but had 3.0 liters, it would only about about 350 ft lb, not closer to 400...

[ASAP]

1/4 mile trap speeds 120-123?

what kind of garbage is this? Faster than an F10 M5? As fast as a 2011-2012 GTR?

[FogCityM3]

Very nice, as usual. Based on your numbers, 7.67 weight/power ratio (acutally mentioned by one of the mods/insider guys a while ago as being similar to M3 GTS) would be in line with the M5, which was not the case w/ last generation. From a marketing perspective, especially since the M3 will be a 4 door, wonder whether BMW will not care about cannibalization (of the M5 and M4 w/ M6) if straight line performance equals M5/M6.

[solstice]

Nice to see that experience and theory now matches up. I said before that all turbo cars I've owned and driven make optimal power in the midrange not at redline. And the footage from testing at the ring indicates short shifting to keep optimal power delivery. Last time I posted this someone jumped at me saying that with 100% cofidence this was wrong and that redline shifting was going to be optimal, was that you . ( Even with all this data I'm not 100% confident of anything with this new car but I think it's likely that it will behave like other turbo cars). Impressive work nevertheless swamp2, thanks!

[rs_philly]

Thanks for the detailed analysis - it looks very thorough.

The last set of rumors (for at least 6 months) say the power will likely be similar to the E90/92, but torque qill be in the 395-400 lb-ft range. What would the performance numbers look like if you ran the simulation with 415 HP?

[vladberca]

I don't think BMW will keep the same power for the new M3/M4 because for the F10 M5 it was increased with about 10%.
I assume that 450hp is a safe number that we can expect

[VCMpower]

Reasonable doubt. Gavel drop. I feel the only info they can assure of is, less time a the fuel station, if you stay out of boost!

[Palle]

sounds great!!!! thanks a lot!

[PSTM3]

Awesome stuff.