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Old 11-29-2001, 05:18 PM   #1
yamarocket630
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Question Driveline power loss and dynos

O.K. theoretical question here.

Let's assume that car X makes 100 crankshaft horsepower, and puts 85 hp to the wheels stock. That gives us a net driveline loss of 15% or 15 hp in this case.

Now lets bolt on high performance part Y, that bumps this motor to 125 crank hp. Assuming that all other variables (tire size, gear selection, max power rpm etc) stay the same, would we see 106 hp (125hp minus 15% loss) at the wheels or would we see 110hp.

What I'm asking is if the drivline loss will be a fixed amount? It seems to me that it would, but I've been known to be wrong.
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Old 11-29-2001, 05:27 PM   #2
Midwayman
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Its both a fixed amount and a percentage. Ie if a 100 hp engine loses 15hp to driveline, a 1000hp will not lose 150(percent) or only 15hp. From everything Ive read that for moderate power increases its more accurate to look at driveline loss as a fixed number than percent. (IE if you gained 12whp with an intake, you probably gained like 12.5bhp or something like that.)

Anyone else with better info out there?
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Old 12-01-2001, 01:56 PM   #3
yamarocket630
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Noone?
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Old 12-01-2001, 03:53 PM   #4
p-car
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hmmm...
go here and click on "performance" in the left nav. The info is at the bottom of the page after all the graphs and discussion of hp vs torque.

http://www.mivec.co.uk/
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Old 12-01-2001, 04:49 PM   #5
Midwayman
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Yamaharocket, like I said, for small power gains, assuming the drivetrain loss is a fixed number is a pretty good bet.

There was a good discussion about this awhile ago revolving around a low pressure turbo kit. Basically if you ran percentage loss, the calculated crank power was absurd, but using straight loss, It worked out to what the turbo should be producing.
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