Geekin' again (and again... and again... and again)

[Jon Davis]

George Roffe wrote:

> >engine torque (minus driveline losses) is 75*5252/4250 = 92.7 ft-lb

> The fact is, we do *not* know the crank
> hp for any car on a Dynojet.

Right. No argument here. The origin of this discussion was something about
calculating engine torque from measured hp at wheels.

Measure wheel hp and engine rpm on a chassis dyno. Use the formula hp = t *
rpm / 5252 to calculate engine torque. The number you get is not the actual
torque produced at the crankshaft, it is torque at crank minus driveline
losses. This is because we used hp minus driveline losses to calculate it.
An engine dyno would give a higher number. As you can see, no assumptions
are made. Power and rpm are measured, not assumed. Torque is calculated
using a well-established formula, not assumed. There is no disturbance in
the force.

If nothing else will satisfy you, pick a dyno chart and use the hp #'s and
the rpms and plug them into the formula hp * 5252 / rpm. You will get the
same #'s for torque as is displayed on the chart!

jd