[s-cars] FW: Re; RS2+

[CaptMagu at aol.com]

Mihnea

The correct name of the hub driven dyno is the DynoPack.The Dynojet is a 
roller type that does in fact use the tires in contact with a roller. Both of 
these can be used for 2 wheel drive as well as all wheel drive vehicles. I won't 
argue with you on the losses being less for the DynoPack because they are. 
Without the weight of tires and wheels there is less mass to turn. There is also 
the lack of friction loss between the contact surface of the tire and the 
roller once again in favor of the DynoPack. I will argue however that this does not 
make up the biggest drivline losses. 

I just had along conversation with Scott Lampkin concerning his HRSB 
installation. He owns a heavily modified urS4 and he is also the North American 
distributor for DynoPack. He mentioned 22% as their given all wheel drive driveline 
loss. I'd also make the point that the, as you put it "real", chassis dynos 
that use rollers do a relatively poor job in car vs car analysis. With the 
differences in wheel weights, vehicle weights, tire compounds, and such things as 
suspension camber, you can come up with significant performance differences 
from car to car that make side by side analysis difficult. With an "unreal" 
Dynopack, all those diffrences are thrown out the window and you end up with a very 
consistent appraisal of "real" performance. Sport Compact Car ran a dyno 
comparison of DynoPack dynos and found that with the same car and ambient 
atmospheric conditions as near as possible they were within 1 horsepower between 6 
dynos. Now that's what I'd call a consistent tool for tuning.

I sure hope this clears up any confusion you might be having about the dynos 
we use here in the good ole USofA. Cheers.

Hap, fumblin along with "unreal" dyno numbers in Everboost, Maguire