Righto! Prolly just yappin' to myself again here, but the jury is back.

This concept has its limitations, mainly due to imprecise data collection (especially in 1st gear) but it does come up with reasonable numbers.

The dyno said 71.9hp (71-72 rwhp from 5300-6100 rpm) for my A-15.


In second I got 61hp @5750, 82km//h
In 3rd I got 49hp @ 5750, 130km/h
in 4th i ran out of road @ 4750; 46hp, 126 km/h

First was pretty much a write off, the tacho needle was moving too quick

These figures are 'net hp' so they are less than the dyno due to wind resistance.

Assuming a 'barn door' cd of .55 and a frontal area of 2.25 sq.m (1500*1500mm).... both rough guesses, According to the G-tech site at:

83 km/h- 12.2 hp loss
110 km/h- 28.4 hp loss
125 km/h- 41.6......

So, based on those numbers the technique works ok for low speed work (second gear over estimates by 1hp) but as you get faster the assumptions I have made about the CD and frontal area start to screw with the results (41.6+46= 87.6hp, 37% overestimate).

I have got this in an excel sheet along with a calculator for supercharger flow rates & pulley ratios, & i was going to put a gearbox calculater into it as well.

If people are interested in using this, I will put a decent front end onto it to make it a bit more user friendly. My bro is going to test it this weekend on his VTR1000, so we can see if it still works up the other end of the power/weight ratoi scale.