Chassis dyno..tranny

[bigfoot]

Thinking of chassis dynoing a oval track car..400 HP at crank....is there a difference in final HP between a 3 speed Saginaw and a 4 speed muncie ?? Thanks

[mag2555]

Any hp difference seen in such a test will fall with in the normal range of the dyno's accuracy I would say.
I would be more concerned with which transmissions gear spread would sever you best, and even then that would be trumped by which trans is likely to hold up and finish the race!

[Alaskaracer]

It will depend on rotating mass. If they are doing it right, they will make all pulls in high gear. Take both transmissions on the bench. Put both in high gear and turn them by hand. Does one turn harder than the other? If so, then yes, it will show different numbers on the dyno...change your tire pressure, it will as well because it can affect tire slip on the rollers.

How well tuned is the engine already? Is the 400 hp an actual dyno figure or just a guess?

[F-BIRD'88]

Everything affects everything.

[JodyB]

Testing on a 248 Dynojet, the most critical part is to have matched rear tires. Knuckle dragging dirt-track guys show up with 3inches difference in diameter after being educated beforehand on the outcome. Locked differential , 3inches difference in tire diameter , and it makes a low rwhp number. No shit.

[Truckedup]

In high gear the power is straight through the main shaft on both transmissions..Power loss differences should be minor

[Ladderbar]

WE always took 1st and second gear out of our Muncie trans just ran 3-4

[bigfoot]

Yes l heard of guys taking gears out..but our tech guy checks..l will get to trannys and compare them on the bench first..thanks