Discussion about M3 torque

[riyatch]

hope this has not been posted here but i found this on another board and thought it was an interesting read. anyways, heres a link

http://forums.carmudgeons.com/showthread.php?t=23608

[lucid]

It's been discussed in many threads here, and wheel torque plots have been posted as well. The E9X M3 does not lack torque at the wheels thanks to its aggressive gearing that is made possible by its high redline, and people should stop comparing torque at the shaft numbers by staring at dyno charts and concluding this or that car has more torque etc, which is pretty much meaningless.

The most detailed plots by member mixja are here:
http://www.m3post.com/forums/showthread.php?t=157633

And the thread which went downhill that started this kind of discussion:
http://www.m3post.com/forums/showthr...ght=335+driver

[arr0gant]

Ya, this is awesome. It shows that our M3's have a very torquey engine if you look at how long that very decent amount of 295 lb-ft lasts from 3000RPM to like 8000RPM.

Most cars that are considered torquey might have 400 or more but from 3000RPM up till like 5000 they are below ours then surge to 400+ but only till 6500/7000RPM before they drop off or hit red line!!

[lucid]

Originally Posted by arr0gant

Ya, this is awesome. It shows that our M3's have a very torquey engine if you look at how long that very decent amount of 295 lb-ft lasts from 3000RPM to like 8000RPM.

Most cars that are considered torquey might have 400 or more but from 3000RPM up till like 5000 they are below ours then surge to 400+ but only till 6500/7000RPM before they drop off or hit red line!!

The main point is that the M3 has aggressive torque multiplication due to its gearing, so the actual torque numbers at the wheels are high despite the fact that 295 lb-ft at the shaft does not seem that impressive. That is only possible because the redline is high. Otherwise, you couldn't hold a gear for very long and would have to shift constantly.

[riyatch]

yeah, always here people say the M3 has no torque but in fact its the other way around.

[lucid]

Originally Posted by riyatch

yeah, always here people say the M3 has no torque but in fact its the other way around.

Most people don't understand what gearing does, and the fact that dyno charts do not display actual torque at the wheels figures confuses them further. Dynos measure actual wheel torque, but then when displaying the output, factor gearing (divide the actual measured wheel torque values by the overall gear ratio for that gear) to go back to the engine torque numbers. That needs to be done, or otherwise you'd see different numbers at each gear obviously. Some will throw in an estimated drivetrain loss percentage as well, which complicates things even further...

[Ca$hOnly]

Originally Posted by riyatch

hope this has not been posted here but i found this on another board and thought it was an interesting read. anyways, heres a link

http://forums.carmudgeons.com/showthread.php?t=23608

Great read! Thanks for posting. I had no idea.

However, to me, the M3 still "feels" like it lacks power below 3500rpm compared to some 400lbs torque cars I've driven.

[arr0gant]

Originally Posted by Ca$hOnly

Great read! Thanks for posting. I had no idea.

However, to me, the M3 still "feels" like it lacks power below 3500rpm compared to some 400lbs torque cars I've driven.

I had a 911 Turbo before my M3. And they both feel about the same till the Turbo hits 4500 or 5000, then from there to around 6500 or 7000 the 911 Turbo just slams you back in the seat and you shift, while the M3 just builds and builds..

[TRZ06]

I dont care what others say. unless you are 5.5 or above the M feels slow to me

[arr0gant]

Originally Posted by TRZ06

I dont care what others say. unless you are 5.5 or above the M feels slow to me

Ok, to me It feels slower above 6 or 7k RPM up to redline, but you look down and you have an amazing amount of speed. The car actually feels fast around 3000 to 4k to me. The deal is by 6k rpm the HP has taken over and you don't feel any pull. in my old car you still felt a lotta pull up till red line. In this car it feels like it *pulls* most, at around 3k to 4k then it just builds as torq hands off to HP. 295lb lb-ft relative to 3000 rpm at low speed is a very, very decent amount of torq. Problem is, it never goes up from there. So I think this makes sense.

[riyatch]

Originally Posted by Ca$hOnly

Great read! Thanks for posting. I had no idea.

However, to me, the M3 still "feels" like it lacks power below 3500rpm compared to some 400lbs torque cars I've driven.

I agree, it does not "feel" as fast compared to some of the high peak torque monsters out there, but it is, and it's soooo damn smooth.

[powertrip]

My track car puts down 352 lb/ft at the wheels (think it equates out to 440 lb/ft because of AWD drivetrain loss). My M3 feels every bit as torquey as that car. It's deceiving though in its' electric-like power delivery.

[Serious]

The high redline in addition to short gearing allow cars like m3's and s2000's to accelerate as quickly as much larger displacement cars.

effectively what you have is a lance armstrong vs. a body builder in a bicycle race. the body builder may have legs twice as strong but he can only pedal so fast... whereas skinny athletic lance armstrong can pedal alot faster and use a lower gear so he doesn't have to be as strong... this allows him to go faster then the body builder. m3 vs. mustang or corvette.

Simple analogy obviously you have to account for weight, traction, etc.

[arr0gant]

Originally Posted by seriousm3

The high redline in addition to short gearing allow cars like m3's and s2000's to accelerate as quickly as much larger displacement cars.

effectively what you have is a lance armstrong vs. a body builder in a bicycle race. the body builder may have legs twice as strong but he can only pedal so fast... whereas skinny athletic lance armstrong can pedal alot faster and use a lower gear so he doesn't have to be as strong... this allows him to go faster then the body builder. m3 vs. mustang or corvette.

Simple analogy obviously you have to account for weight, traction, etc.

Don't forget about the 911 GT3. 415 BHP, 300 LB-FT and redlines around 8400. Sounds familiar??

[1MOREMOD]

yep. can i have one of each?

[Serious]

Originally Posted by arr0gant

Don't forget about the 911 GT3. 415 BHP, 300 LB-FT and redlines around 8400. Sounds familiar??

agreed you can throw the v8 ferrari's in there as well. and a bunch of other cars, the s2k and m3 just came to my mind quickly.


Another good component of the concept of high rpm/short gearing concept is the 7 speed SMG/DCT boxes... especially in the m5/m6 which allows them despite their weight to compete acceleration wise with lighter cars with similar hp numbers. (may be different for DCT because IIRC it uses different final drive then manual)

[lucid]

Originally Posted by seriousm3

Another good component of the concept of high rpm/short gearing concept is the 7 speed SMG/DCT boxes... especially in the m5/m6 which allows them despite their weight to compete acceleration wise with lighter cars with similar hp numbers. (may be different for DCT because IIRC it uses different final drive then manual)

That kind of partially holds. You don't raise the redline of the engine by changing the gearing. In other words, you can't change the peak power it produces. So benefits of chaning the gearing on a given engine are limited as we discussed in detail in the swapping LSDs thread. See post #47 in this thread:

http://www.m3post.com/forums/showthr...+torque&page=3

[Serious]

Originally Posted by lucid

That kind of partially holds. You don't raise the redline of the engine by changing the gearing. In other words, you can't change the peak power it produces. So benefits of chaning the gearing on a given engine are limited as we discussed in detail in the swapping LSDs thread. See post #47 in this thread:

http://www.m3post.com/forums/showthr...+torque&page=3

Simply saying gearing (for most gears) in a 7 speed gearbox is going to be shorter then a 6 speed manual.

given same final drive ratio 7 speed car should be faster then 6 speed.

[lucid]

Originally Posted by seriousm3

Simply saying gearing (for most gears) in a 7 speed gearbox is going to be shorter then a 6 speed manual.

given same final drive ratio 7 speed car should be faster then 6 speed.

Sure, tighening the rev range a bit closer around to the peak power output engine speed makes it faster (assuming the system can shift very quickly), but not by a whole lot...

[meevo]

Has anyone felt what the Honda S2000 feels like when it hits the vtec? Would you guys describe the sensation as similar?

[arr0gant]

Originally Posted by meevo

Has anyone felt what the Honda S2000 feels like when it hits the vtec? Would you guys describe the sensation as similar?

NO, the s2000 has so little torque that it's almost not drivable under 5000RPM. It's pickup feels like a honda civic.

[meevo]

Originally Posted by arr0gant

NO, the s2000 has so little torque that it's almost not drivable under 5000RPM. It's pickup feels like a honda civic.

Yea but it hits pretty dang hard after 7k