Process Driveline Loss Assumptions
How do we know we're right on this?
I have recently learned that when the ITAC uses "what they know" to change the multiplier to a number other than 25%, they use the assumption of 15% driveline loss in a FWD car and 18% in a RWD car. Where did these numbers come from? How have they been verified accurate?
It makes a big difference in the minimum weight of a specific vehicle, and sure fits with my belief that FWD cars are favored in ITA and down. I think the arguement is that there are more moving parts in the drivetrain of a RWD car and thus greater loss since the LSD and FD are all housed inside the transmission casing of a FWD car. I could argue that switching to better lubricants in the RWD car minimizes the loss moreso than switching in a FWD model.
if we take a hypothetical vehicle....
140hp * 1.25 * .85 = 148.75whp
140hp * 1.25 * .82 = 143.5whp
140hp * 1.3 * .82 = 149.24whp
140 * 1.25 * 14.5 = 2537.5
140 * 1.3 * 14.5 = 2639
you can see here that the ITACs assumption of driveline loss effectively adds 100lbs to all RWD vehicles if they examine a car based on "what they know." does that just not sit well with anyone else? maybe it's right, but i'd have to see some data to be convinced of such.
Travis Nordwald
1996 ITA Miata
KC Region
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