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Old 12-20-2009, 02:30 PM   #20 (permalink)
Allch Chcar
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Join Date: Jan 2008
Location: North Coast, California
Posts: 429

Cordelia - '15 Mazda Mazda3 i Sport
90 day: 37.83 mpg (US)
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Quote:
Originally Posted by Frank Lee View Post
I noticed the default on the EM performance calculator is 95%.

I've been under the impression it's more like 85%, what with all those meshes and all.

Haven't found a really solid number though because this sort of thing is harder to pin down than it would seem.
I know 85% is what most RWD guys use on the dynamometer numbers and it should be proven many times over by now. With 1.5% per gear it does sound about right too, 7.5% loss at the transmission for a 5 spd and 5% at the differential. That leaves 2.5% to other things like axles, wheels, etc. I've heard comments that suggest FWD only lose 12.5% but I haven't seen anything proving or even discussing it. A driveshaft for a RWD car can weigh 20lbs for Steel and 11lbs for Aluminum, which is roughly the weight of a forged wheel with no tire. I also know with AWD you get two more differentials and the loss is roughly 25% to all wheels.
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