E46Fanatics - View Single Post - Drove an m3 the other day and wasn't impressed at all. Worth it?
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Old 01-28-2013, 08:14 AM   #51
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Join Date: Nov 2010
Location: Miami, Florida
Posts: 937
My Ride: M-3 Convertible
Originally Posted by TerraPhantm View Post
Forced induction is essentially increasing displacement. More pressure = more oxygen = greater volumetric efficiency (which is what matters moreso than displacement for torque).

My point was that 262-269 (depending on which variant you're talking about) lb-ft torque out of a 3.2L is not low by any means. And the fact that this car has a very flat torque curve (unlike the STi and other boosted vehicles) is important to consider. The only reason I even mentioned the accord engine is because you brought it up.

Finally, it's the torque at the wheels and not the crank that matters. You're not taking gear multiplication into account. Consider... an E46 M3 and an E9x 335i. M3 makes 262 lb-ft and 335 makes 300 lb-ft. M3 has a 3.62 final drive ratio, while the 335 has a 3.08. The gear ratios of the transmissions are pretty similar, and iirc the tire diameters are about the same as well.

262 * 3.62 = 948.44; 300 * 3.08 = 924. Hey, what do you know, the gear multiplication actually gives the M3 more effective torque. And since the M3 can rev considerably higher, it can still reach higher speeds in the same gear.

The STi actually does have pretty aggressive gear ratios, but it still has a low redline. So it has to shift considerably earlier than an M3 would. The net result is that the STi might be faster for rather contrived scenarios, but it would be slower across multiple gears (until tuned anyway... but I'm just considering stock vs stock here)

All that said, I don't know what you're trying to get at. It's no big secret that the M3 has a 3.2L engine and makes ~260 lb-ft torque. If you're expecting it to make as much torque as a 5.0L V8 or 2.5L engine w/ 20 lbs boost... then you're expecting too much. Torque by itself is a useless metric anyway -- you need to know gear ratios, area under the curve, and rev limits to make any real judgments. Despite popular opinion, horsepower is a much better tool than torque for judging the capabilities of an engine.
First of all, I wasn't the one who raised the example of the Honda Accord. Secondly, while a higher final drive ratio may help with respect to the utilization of torque, it doesn't really multiply the available torque (even if the end result is indistinguishable). While there is no doubt that the M3 is exceptionally efficient in terms of power delivery, it doesn't generate a lot of torque. Does it generate a healthy amount of torque for a N/A 3.2 litre? Yes, but that's not the same thing as generating a lot of torque on an absolute basis. It's like noting that Floyd Mayweather is very strong for a welterweight, and is one of the best "pound for pound" fighters on the planet. He still wouldn't last 5 seconds in a match against Wladimir Klitchko.
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