dyno runs

[mark kibort <mkibort@xxxxxxxxxxxxxx>]

Message text written by INTERNET:bmw@domain.elided
>There is of course drivetrain loss in the =

flywheel, clutch, transmission, driveshaft, diff, =

half-shafts, bearings, wheels - anything that has weight that =

must be moved by the power of the engine. If any of those are =

out of tune or not up to factory specs, wouldn't that lower =

the engine's peak hp?<

>>>>>>>>>>absolutely!   You have to make sure the dyno tech plugs in the =

atmospheric values or the test is  really worthless.    as far as
drivetrain losses,
it is fairly reasonable to assume a 1.21 of the dyno run or 84% effecienc=
y =

from the =

flywheel as the losses can be measured as well.   When you run the car on=

the dyno
have you ever just  lifted off the gas and let the engine and transmissio=
n
wind down?
this measures compression forces and all of the drive train losses.    bu=
t
if you want =

only drivetrain losses, you can engage the clutch, this would be a good
Idea for measuring
all of any losses there could be.   (I however, have only done the neutra=
l
coast down, that =

measures rolling friction and losses in the rear end that amounted to 20h=
p
at 6k and 10 hp at 4k)

Mark kibort

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