Transmission power loss ?

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12-21-2010, 08:04 AM

#31

gbduo

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Originally Posted by MB,Dec 21 2010, 04:42 AM

It can vary. Also FWD has less loss than RWD, which has less loss than AWD. There are diffs and prop shafts to factor in before it hists the wheels.

Ah good point, thanks!

Graham

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12-21-2010, 08:23 AM

#32

garyo

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And if they do not have them done, and not to a traceable standard every bit of kit is likely to be all over the place, so only figures off of a single machine should be compared and even as some one said only before and afterwards compared when done in a short space of time.

It gets even more complex than that - your cars tyre pressures and weight at the time will affect your transmission losses on the rollers, hence why the higher the gear you're in, the less power the rollers measure. So it's not even that scientific even when you've measured the same car on the same rollers three months apart. Then there are the fiddle factors for ambient temperature. How many rollers measure coast down losses through the rev range now - has that become the standard? It seemed like the best way to net out all of the above when I used to visit rollers regularly...