Dynoed my 427so Cobra today.... interesting to say the least!

[Excaliber]

That Mach 1 pulled in 3rd gear, again, if your not in a 1 to 1 gear ratio you can throw out the results.

[Anthony]

Originally Posted by DAVID GAGNARD

Cars 1 thru 3, all 05 Mustang GTs, all 3 bone stock except for maybe a K & N air filter, that's it..........all 3 made from 262rwhp to 267 rwhp, they are adveritsed at 300 flywheel hp!!!!!!!!!!!! that's from 13% to 11% driveline loss, I think either Ford "fudged" those #s a little or else the driveline is very efficent.............

Pull # 3; operator told him to start in second gear and do the pull in 3rd gear, again, have NO CLUE why they would do it this way, but they did, I was standing near the rear of the car watching the driveline, he was running WAY,WAY rich by now, both exhaust pipes looked like a diesel truck going up a steep slope loaded down,he made 272 rwhp!!!!!!!!!!!!! when he shut it down and the operatpr showed him the #s and the printout, he was pi$$ed and told them to unhook the car and guide him down......they had a few words and he left, was only charged for 2 runs.........

Later talking to the operator he told me the "average" loss he has seen for late model cars with a stick shift was 15%........

The old Mach I was running a 4 speed toploader and 9" rear end with 3.89 rear gears, he had on a set of drag radials and as I was watching the rear of the car of his last pull, I did not see any signs of his tires slipping or spinning on the drums.........he had a very badly tuned motor, no doubt, but still thought he should have made from 350 to 375 hp at the wheels, he was about 100hp off............

I was very surprised at the low % of loss for the 05 GTs and very suprised at the high? % loss for a 428 Cobra Jet motor, sure thought it would have done a lot better.............

I don't think that you can really make any statement about driveline loss only with information from a chassis dyno. I would think that you would have to also dyno the same engine on a stand, using the same dyno, with the same air intake set-up and exhaust system to get a real % driveline loss, otherwise you're just guessing.

Originally Posted by Excaliber

That Mach 1 pulled in 3rd gear, again, if your not in a 1 to 1 gear ratio you can throw out the results.

I don't think it really matters, as the dyno knows the overall gearing from the engine rpm and wheel speed, and I doubt there would be a large percentage loss in the transmission using 3rd gear instead of 4th. Anybody know what the hp loss would be ? Maybe 5-10 hp?