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      11-23-2013, 04:14 AM   #48
Boss330
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Quote:
Originally Posted by ersin View Post
Engine torque means nothing for performance. The number that completely trumps peak engine torque is hp to weight ratio. If you want to bring torque into the equation it has to be wheel torque where you take into consideration gearing.

Also note that the single engine torque figure is the peak torque number only at the engine speed (rpm) that gives this figure. At all other rpms the torque is lower depending on the torque curve. For performance you want the engine torque to keep this peak for as wide a range as possible, that is the torque times the range of rpm that it works over, or as they put it, the area under the torque curve. All torque curves are different for different engines and you would need calculus or a computer to figure out the real engine potential. And this can be done if you get the torque figures for the whole rpm range. However, as it turns out, the maximum horsepower IS the area under the torque curve. And this is why horsepower is the more meaningful number.

So, let me repeat this: a single, maximum torque number for an engine in a specific car alone is meaningless as an indication of performance. Horsepower has more meaning in this context and horsepower per weight happens to be one of the best single number indicators of acceleration and speed.


Cheers.
Quote:
Originally Posted by Sapper_M3 View Post


This. I wish everyone on this forum would read this. Peak Power is a fairly meaningful figure to quote without any other knowledge of a car. For one thing, peak power to weight has meaningful and accurate performance correlations.

Peak torque on the other hand means very little because of the effect of gearing. Peak torque to weight means little to nothing, and a peak torque value even with the gearing ratios is fairly meaningless without the torque curve.
"Thanks" for quoting my post completely out of context...

If you read my entire post you both can see that I emphasize the power to weight ratio when I argue that the M3/M4 should be close. As an afterthought I mention that the Stingray has more torque than the M3/M4 (you might misunderstand that and I see that it could have been excluded from the post, to avoid that confusion. But I just thought that some fact wouldn't be wrong, seeing that we discussed the power and weight of two cars, why not just mention their respective torque figures as well?).

And, didn't you know that we DO know the torque curve of the S55?

In this post we have both the power/torque chart and a statement on the rev range the S55 have peak power and peak torque.

http://f80.bimmerpost.com/forums/sho...d.php?t=892746

Peak torque is delivered from "under 2000 RPM to over 5000 RPM" and peak power is delivered "from 5000 RPM to 7300 RPM"
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