Chassis Dyno #'s-vs- Track #'s

[5.0 HOtrain]

I'm very curious about my chassis dyno #'s. I'm having an awfull hard time believing them. I had my 418 dynoed on an engine dyno, and once in the car on the chassis dyno, #'s in sig. My track times however tell a different story. Going by weight to mph the car had to be making somewhere between 510-525 rwhp Wich is where it should have been. If the #'s were real on the chassis dyno, I lost 22% from the engine dyno with a 5spd I had a messed up run with missing 2nd and having the wrong rpm chip in the msd wich caused a rev-limiter hit in 1st,2nd,3rd,and 4th gear and the car still ran 119.1mph so I know that the 126.66 was not a fluke. Dont know, what do you guys think???????????????????????????????
Mike.

 

[Michael Yount]

Not sure why you're trying to resolve it. Neither approach to measuring actual HP is foolproof. The programs that convert et/mph to rwhp assume something about traction - a HUGE variable. Most assume nothing about aero which is a bigger and bigger variable the quicker you go -- and 126mph traps are quick enough that aero is at play. And the dynos are only really useful for making changes to a setup at the same strapdown session, and even then if you're looking for small changes, you may not see them.

Both approaches to measuring HP are estimates at best. The sob is quick - are you happy with the way it's running/driving? If so, don't worry about the times/numbers, and enjoy racing the car.

 

[5.0 HOtrain]

. The sob is quick - are you happy with the way it's running/driving? If so, don't worry about the times/numbers, and enjoy racing the car.

Not sobbing, SUPER happy with times, just curious. Who wouldnt be happy with 126.66mph
mike.

 

[IndyBlk5.0]

Thats awesome numbers, congrats...
One day...... I might be there

 

[90Notch]

"I lost 22% from the engine dyno with a 5spd"

Did you use same headers, exhaust and same accessories on engine dyno? Seems most don't then when they install the restrictions on and hit the dynojet they're surprised at the losses.

 

[5.0 HOtrain]

"I lost 22% from the engine dyno with a 5spd"

Did you use same headers, exhaust and same accessories on engine dyno? Seems most don't then when they install the restrictions on and hit the dynojet they're surprised at the losses.

I dont think I lost that much, dyno#'s dont match track #'s. Michael Yount made some good points as always.
mike.