Examples of Dyno Result vs. Track Result not matching?

Posted By: BradH

Examples of Dyno Result vs. Track Result not matching? - 11/12/11 01:33 AM

Anyone else got examples of your engine dyno result vs. actual track result not matching up? I'm not necessarily talking about peak HP #s on "happy" dynos not showing up as expected MPH. This is along the lines of something that tested positively on the dyno not translating into any difference at the track, or just the opposite where the dyno showed no improvement, but the track did.

Example from my own tests: Engine dyno comparison between my "tried and true" Holley 850 and my then-new Holley "950 HP" 80496-1. Dyno showed basically NO difference in peak torque or HP between the two carbs. However, the track showed a solid .2 ET and 2 MPH improvement with the "950 HP" during a same-day swap of the carbs. Why? Because the dyno didn't factor in the shift recovery characteristics of the smaller-venturi "950 HP" enabling the car to pull back up the RPM quicker after each shift.

Posted By: Performance Only

Re: Examples of Dyno Result vs. Track Result not matching? - 11/12/11 02:19 AM

good example. i wish i could look over the complete data sheet from the dyno pulls. there's a lot more to examine other than torque and horsepower. sometimes you have to look very closely at the other measured data and then of course, know how to interpret it.

Posted By: Bob_Coomer

Re: Examples of Dyno Result vs. Track Result not matching? - 11/12/11 02:32 AM

This car here is one very nice car, the chassis, and engine are nothing short of best of the best show car.
I was blown away by the engine detail... 600+ Cubes Hemi, custom tunnel ram. Everything polished billet. CNC Indy heads etc...
Owner told me the engine dyno'd 1200+ HP.
It ran 10.20's

I think later it did dip into the high 9's...
I walked back by later through the pits he had the hood up, I asked him what was wrong he said nothing.. I wanted to ask him if he had 3-4 plug wires off LOL...
Again nice car.

Posted By: BSB67

Re: Examples of Dyno Result vs. Track Result not matching? - 11/12/11 02:40 AM

Quote:

Anyone else got examples of your engine dyno result vs. actual track result not matching up? I'm not necessarily talking about peak HP #s on "happy" dynos not showing up as expected MPH. This is along the lines of something that tested positively on the dyno not translating into any difference at the track, or just the opposite where the dyno showed no improvement, but the track did.

Example from my own tests: Engine dyno comparison between my "tried and true" Holley 850 and my then-new Holley "950 HP" 80496-1. Dyno showed basically NO difference in peak torque or HP between the two carbs. However, the track showed a solid .2 ET and 2 MPH improvement with the "950 HP" during a same-day swap of the carbs. Why? Because the dyno didn't factor in the shift recovery characteristics of the smaller-venturi "950 HP" enabling the car to pull back up the RPM quicker after each shift.

Same experiance as yours, the 950 (over the 850) picked up a solid .15 et and 1 mph, all in the shift recovery, most of it in the 1-2 shift. However, did not do dyno comparison between the two.

Posted By: cheapstreetdustr

Re: Examples of Dyno Result vs. Track Result not matching? - 11/12/11 04:43 AM

Quote:

This car here is one very nice car, the chassis, and engine are nothing short of best of the best show car.
I was blown away by the engine detail... 600+ Cubes Hemi, custom tunnel ram. Everything polished billet. CNC Indy heads etc...
Owner told me the engine dyno'd 1200+ HP.
It ran 10.20's
I think later it did dip into the high 9's...
I walked back by later through the pits he had the hood up, I asked him what was wrong he said nothing.. I wanted to ask him if he had 3-4 plug wires off LOL...
Again nice car.

If i was a betting man i doubt the owner of this car would stand firm on the dyno number...
He probably said 1200 because it sounded good..
not realising you knew how to calculate it based off et..
I know a guy with a blown bigblock chevy in a nova..(show car also) he always claimed 800hp when ever anyone asked..and because it looked the part no one doubted him...I noticed him only once at the track..I chatted with him in the lanes and he stated.."my car feels like its running good so im making a few passes tonight"
The car ran 12.20..that doesnt add up..fwiw either.lol.
heck one of my cars dyno'd at 300 rwhp and it ran 11.64 et..???
but i digress..

fwiw I installed new front wildwood race disc brakes and the car picked up a bunch with no other changes..so..other factors could contribute

Posted By: Dartman928

Re: Examples of Dyno Result vs. Track Result not matching? - 11/12/11 02:26 PM

I have one of them cars but it will get figured out someday.

572 made 760hp runs 9.7's on pump gas