Thread: Drag Time !!!
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      09-17-2011, 12:25 AM   #35
erio's Avatar

Drives: e92 JB M3, 2012 GTR
Join Date: Oct 2008
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Originally Posted by swamp2 View Post
Drivetrain loss is a big factor here. You simply can not calculate engine crank power without both accurate dyno results and an accurate loss figure. What is the loss of the very complex, but also probably pretty efficient AWD system? 10%, 15%, 20%, 25%. We actually have NO idea. You did note that different dynos roller vs. hub (in the 2009 test) produced a 40 hp difference. I doubt tires in 2nd or 3rd gear can account for a 40 hp difference, 20 maybe not 40. The latter test even has a statement that you can't compare different dynos. That certainly begs this question, which is correct.
I think the loss is more dynamic in nature. Maybe this will help:

This is data from Motortrend where they use the Hyper Power dyno that helps calculate drivetrain loss. It also shows that there may be a little more torque than claimed but that's not enough to explain it's performance.

You also have to take into account the fact that it can fly if launched properly
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Last edited by erio; 09-17-2011 at 11:39 AM.