How to calculate max velocity of a vehicle from torque and RPM?

[Supercharged]

Hello,

I have recently conducted a dyno run at a MAHA LPS 3000PKW dynamometer.
My car was equipped with a 6-gear manual transmission.
The optimum gear ratio 1:1 is achieved by the 5th gear. (due to car's official ratio for that transmission: 1st 4.46/ 2nd 2.61/ 3d 1.72/ 4th 1.25/ 5th 1.00/ 6th 0.84/ R 4.06)

However, the user of the dynamometer, made a dyno pull with 4h gear.

I would like to ask you,
1) would the horsepower and torque numbers that showed me as a result be different in case there was a dyno run with 5th gear??
2) A dyno run with 5th gear would have shown me better numbers or worse in comparison with the run at 4th gear?


thank you in advance

 

[Bob S]

I would think a dyno run (with a BSFC (brake specific fuel consumption) map) would give you the engine RPM with the maximum power output (=RPM x 2π/60 x torque).
Calculation of the power required vs ground speed, including air drag and rolling resistance will give a monotonic plot of required power vs. speed. Find the max engine power on plot, then select best gear ratio to match engine to speed. I believe manuals are ≈98% efficient in the 1:1 gear, ≈96% in others.

Bob S

 

[aussepom]

Hi this may help

http://gti-vr6.net/library/engine/Schrick_howto/wheeldiameters.htm

I was doing the same thig only the other day

aussepom