Hi Guys,

I have written something below which is just a direct cut & paste from a Scooby site, when questioned about transmission losses, so hopefully it will make people think a little more about power measurements on a chassis dyno.

I have copied the raw runs for Graemes car above, you will notice that the first image shows a peak loss at peak revs of about 47bhp



But if you look at the loss at peak wheel power (below) you will see that it is only 32bhp (due to the inherent increased parasitic power requirement of the dyno itself, as well as the vehicles speed related losses - all will be explained when you read the rest of the bumf)



Here's a few others from the day



**** knows what's happening to the resizing of this one below, but it is 33 bhp



I've also included some screengrabs of other examples of differences in wheel power V's flywheel power, the first 3 being from our own Civic







The next 2 the details are in the image





Now comes my war & peace on dyno's (part one this week & the rest when I get a minute [8-|])

























Another thing, we print the 'Speed per 1000 rpm' number on the graph, the higher this is, generally the higher the losses (this is the speed in kmh per 1000rpm in the gear used to do the test) see HERE (scroll to last post) for a recent example (we have also recently changed the software to display it as MPH per 1000rpm to make more sense)

I probably won't get a chance to reply, as I'm busy preparing for the Autosport show next week.

Enjoy

Cheers,

Gerry
Dastek