[dscott]

I agree with the +/- 15% on the dyno. That would make it impossible to tune anything. I have an engine dyno in shop and we build alot of circle track engines and do testing on the dyno. Some of the small 4 cylinder engines we build can run up to 200hp. We are always looking for that extra 1 or 2 hp with cam, carb, header, timing. The runs on the dyno need to be consistant or we couldn't tune at all. The computer does compensate for air temp, barometer, and humidity. We have to be very careful with each run to make sure it's identical to the last for comparison. Engine temp is a big hp killer. So if someone's dyno is off that far on each run I'd look for a new place to dyno. I have seen dyno sheets from other shops and they do vary from shop to shop but not by that much if it's setup properly. I wouldn't think the chassis dyno would behave any different as far as consistancy from the engine dyno.