Thread: Legend or not
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      10-23-2011, 03:41 PM   #105
swamp2
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Quote:
Originally Posted by W Cole View Post
Looking at the graph you posted, I concur the torque curve is quite flat. However, compared to an LS series engine I think the curve is about 200 (?) NM lower. Which, based on my real life experiences with the two powerplants seems to negate that benefit. The LS series engines make more torque just off idle than the M3's engine makes at its peak.
Yes there is a difference in how low of an rpm any appreciable torque is developed. However 3 grand vs. 8400 is not so different than 1500 vs. 6600. Again gear selection is the key. It also begs the question, in even loosely agressive driving why spend any time at all near idle?

Just recall that you CAN NOT measure nor feel crank torque, the transmission and rear end ratios are involved. Well, to be clear you could remove the engine and put it in a dedicated test fixture, but in the real world you NEVER feel the crank torque. Torque is always multiplied by the transmission and rear end ratios. Then that is what you feel (or measure in an acceleration test). That is why you should, more or less, ignore an engines crank torque specs.

Run the calculations yourself, it will be enlightening. Wheel torque = engine torque x transmission gear ratio x final drive ratio. You can take it one step further and actually get the accelerative force by also multiplying by the wheel radius, but as a very rough 1st pass you can even consider that a constant across different cars.