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

[Transfer]

Entertaining read. Thanks for posting.
0-60 in 3.5-3.7 seconds from a RWD with 275 width street tires huh? I know the calculated numbers don't factor loss of traction but I'm guessing that wouldn't be possible without a serious tire upgrade.

[CanAutM3]

Originally Posted by swamp2

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.

Just for the sake of it, could you run a simulation with the following gear ratios:

FD: 3.15
1: 4.25
2: 2.57
3: 2.03
4: 1.60
5: 1.27
6: 1.00
7: 0.75

I am curious to see the acceleration curve it would generate. I am guessing a very smooth curve (except for the 1-2 shift) with progressively decreasing acceleration as the speed increases. Again here, just wishful thinking on my part .

[swamp2]

Originally Posted by 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?

It might be a more approachable reply to not dismiss something as "garbage" without providing some ideas as to specific concerns. Cars get faster, this is normal and we have not seen much slowing of this progression.

This is clearly not as fast as a 2011-2012 GT-R. I've seen low 11s reported for that car.

It's all about power and weight. If this car gets 450 hp and has a weight in line with my ESTIMATE. It simply WILL be this fast.

[swamp2]

Originally Posted by 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!

I did claim prior, not sure if in response to you or not (sounds likely) that the new M4 would shift at redline in all gears. I've since firmly retreated on that position. That's how science works...

[swamp2]

Originally Posted by 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?

I strongly believe "about the same" power as rumored here on the forum is entirely unreasonable for the new car. Also make a spreadsheet yourself exploring the shape and amount of peak torque. You'll quickly see exactly why I keep saying what I said above in post #14.

There are no excuses . Google spreadsheets are free, recall that this is always exactly true:

HP = torque x rpm / 5252

[swamp2]

Originally Posted by Transfer

Entertaining read. Thanks for posting.
0-60 in 3.5-3.7 seconds from a RWD with 275 width street tires huh? I know the calculated numbers don't factor loss of traction but I'm guessing that wouldn't be possible without a serious tire upgrade.

The simulation fully account for wheelspin, at launch and at shifts. Check out the flat parts of the acceleration vs. time plots. It also accounts for a spinning tire having less friction than a gripping one. Like I mentioned above, cars just keep getting faster and the existing M3 has already done a 3.9 0-60! My range is justified, reasonable and likely.

[Powaup]

Awesome post. 3.6-7 0-60 would be really nice and your quarter mile figures make sense when compared to other cars. Do you have any idea what the mpg will be like for the M3/M4 if shifting gears in low RPMs? and do you buy the rumors that the new engine will have 3 turbos?

[DMW2315]

I have "extrapolated" that you have done your homework...

[swamp2]

Originally Posted by CanAutM3

Just for the sake of it, could you run a simulation with the following gear ratios:

FD: 3.15
1: 4.25
2: 2.57
3: 2.03
4: 1.60
5: 1.27
6: 1.00
7: 0.75

I am curious to see the acceleration curve it would generate. I am guessing a very smooth curve (except for the 1-2 shift) with progressively decreasing acceleration as the speed increases. Again here, just wishful thinking on my part .

Generally results across gears are relatively insensitive to such changes, whereas some individual results will show sensitivity. Again it all comes down to power, peak performance depends on peak power, which means torque + gearing. If you just focus on power, gearing basically drops from the equation (given it is not something entirely unreasonable for the car).

Here are the actual acceleration profiles. Almost identical except in 1st gear.



Here is the summary of numbers. No practical change in 1/4 mi time nor trap. Surprised? I'm not. This is very much like the final drive mod debate! Did you follow one or more of those?...

[pbw]

Good read. Fingers crossed fantasy becomes fact!

[pkimM3r]

1.2g's on initial romp of the gas!

[Never Convicted]

Great stuff sir, and thanks for all the work you put into it. Really fascinating analysis.

[Karazy]

Fun read!

Thanks for sharing your thoughts.

[Mak135i]

Originally Posted by Transfer

Entertaining read. Thanks for posting.
0-60 in 3.5-3.7 seconds from a RWD with 275 width street tires huh? I know the calculated numbers don't factor loss of traction but I'm guessing that wouldn't be possible without a serious tire upgrade.

So true. I have a C63 and traction is major issue off the line. That's why the new E63 AMG will be 4-wheel drive. I cannot imagine that you can get below 4 seconds to 60 without a LSD; huge tires and a big rear weight bias in a RWD car.

[ron_jeremy]

Originally Posted by 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

Look at the M3 history.
E30M3:190-230hp
E36M3: 286-321hp
E46M3: 343hp
E92M3: 420hp

The E36 and E46 had about the same hp, but the latter was faster and better.
My guess is that the power will be pretty much like what we saw in E92M3, about 420-430, official that is.
We all know BMW are pretty modest, so 450 is likely in the ballpark.
But then again, we will see a significant bump in torch, so it will be easier and more of a daily driver with the low end torch, and faster than the excisting M3.

[rs_philly]

Originally Posted by 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

Well, I was hoping it would be 450, but all recent reports indicate no HP increase, but significant weight loss (targeting E46M3).

[NISFAN]

Nice work swamp2

[iceman335]

I think the final BMW official # for 0-60 is more like a 3.8-4.2 second car. Can't really see how it can be under 3.7s without serious tire upgrade.

[CanAutM3]

Originally Posted by swamp2

Here are the actual acceleration profiles. Almost identical except in 1st gear.

Thanks for doing this

If we assume DCT, why the interruption in acceleration on gear shifts? Also, why so much wheel spin and lost acceleration going into 2nd? If the car was able to pull 1g in first gear without losing traction, there is no reason it cannot pull 0.75g in second gear. I am guessing that we don't see benefits of the gearing due to assumed shift times and tire slippage shifting into 2nd...

Let me explain why I selected those gear ratios. I reduced 1st gear because I don't think the tires would be able to sustain 1.2g in real life, so I reduced it to slightly above 1g. I also adjusted the spacing between gears 2 to 6 so that the engine always remains in the power plateau, which should yield better theoretical acceleration.

Originally Posted by swamp2

Generally results across gears are relatively insensitive to such changes, whereas some individual results will show sensitivity. Again it all comes down to power, peak performance depends on peak power, which means torque + gearing. If you just focus on power, gearing basically drops from the equation (given it is not something entirely unreasonable for the car).

Agreed that it all comes down to power. Peak power is a great way to quickly assess overall performance. But ultimate performance is about average power produced during an acceleration run, not only peak power. IMO, this is why the power plateau will make the M3/M4 performance impressive.

Originally Posted by swamp2

Here is the summary of numbers. No practical change in 1/4 mi time nor trap. Surprised? I'm not. This is very much like the final drive mod debate! Did you follow one or more of those?...

Well this is relative. Small changes in gearing, where the average (or total) power produced during the whole acceleration run is unaltered, will not have an impact on trap speed or ET. However, if by optimizing the gearing, more average (or total) power can be produced for the same acceleration run, in such case, ET and trap speed will be better. The more extreme example is imagining doing a run in only one gear...

[Moo]

BMW probably won't allow official 0-62 times to be faster than current M5 or M6.

[Longboarder]

Originally Posted by Skullbussa

Very entertaining post.

There is no way this car is going to trap 120 in the quarter mile. That is C6 Z06 territory which is far faster than this car will ever be.

And I am curious who is snapping off 4.1 second runs to 60 in E92 M3s? Even if you take traction out of the picture, I don't think there is the power/weight ratio for that to happen.

Seriously? I played around with a VBox the day I bought my M3 (with all of 7 miles on it) and snapped off a 4.2 second 0-60 on my second attempt on a 100 degree day going slightly uphill on a desolate public road with leaves and other debris on it. Oh, and I short shifted first gear at 7,800. I know for certain I could have gotten in the 3.X range with just practice and then refined that number to possibly a 3.7 on a cooler day with my current tires (Mich PSS). I dyno'd at 365 RWHP bone stock with 91 octane.

[ChrisK]

Swamp,

No matter what the 0-60 ends up being, your calculations are impressive.

Thanks for all the hard work you put into your analysis!