So I'll add some fuel to the fire. I have a stroker big block Ford that made 820 hp @ 6400 and 730 ft/lbs at 4800 at the crank on a Super Flow dyno.

With an identical tune on a Mustang chassis dyno we saw 503 RWHP, 465 ft/lbs. This is just shy of 62% or a 38% drive line loss. The car, a 4220# wet, 71 Mustang convertable, has run 10.80's at 127 in fair air and excellant track conditions, and yes there is more in the chassis set up, but it's street car right? The drive line is a Lentech AOD, Stange 9" and MT 325/50 28" Drag Radials.

As a way of validating the %'s, a 100 hp shot of N2O yielded a 61 hp gain at the tires.

Another car, a 10.60's 3600# GTO, made 423 HP at the tires on the same chassis dyno and with a 175 shot made 110 more at the tires. That car has a 200R4, 12 bolt and 295/65 MT Drag Radilals. The well sorted GTO semed to have a slightly better 37% driveline loss based on quarter mile calculators.

We found five hp with a change in tire pressure and spun the tires on the drums with larger N20 shots.

At the end of the day the chassis dyno or engine dyno are great tuning tools but trying make comparisions between different machines with different operators is futile. use them to make your ride better and let track be your standard of comparison, DA adjusted of course.

[addsig]