Have a customer that only dynos with slicks on, and he was wondering what the difference would be using regular street tires instead of 28" ET Drags. Is it like a 20 rwhp difference? We had them set at 14 lbs pressure on the dyno FWIW.

 

there will be a diiference, but not 20 horses worth

 

Hey Ryan... Allan said he see's slicks consistently dyno lower than radials.... couldn't explain why though. On the last set up, he said I'd see ~ 10-12 more rwhp with the same gear(4.10's at the time)on 26" radials verses the old 26" ET Streets.

Wonder what I'm loosing w/the 28"ers on a 4.56?
Still 'bout half tempted to swap in/dyno a 10 bolt/3.42's and radials w/this combo for the "internet" #'s

 

We'd call you Gomer #2

 

The stickier the tire, the more drag loss you encounter and the more power you lose on the dyno.

Rick

 

OK thanks guys. I could care less, but was trying to come up with a number for a customer. I'll tell him 10 to 12

 

i gained 14 rwhp going from et drags to nittos. drags were at 15 psi nittos at around 25 psi

same exact wheels (prostars) - just remember that wheel weight has to do with it too. not many have done a true test like i did eliminating the wheel as a variable. this was on a 340 rwhp car.

 

I've seen about 5-7 rwhp on my car by going from the 17x11's and 315/35/17's to a 16x8 and 245/50/16 nittos on the dyno.. same day testing.

 

Thats why I own a Dynapack, tuning without the tire variable. Much more accurate.

With a dynojet, anything can change the rate of acceleration. Tie down pressure, tire pressure, tire size, tire width, ect.

Rick

 

I swapped on the dyno from 17X9" radials to 28" et drags and gained ~20rwhp. this was over a year ago with my old 383 setup.

 

if he spins the radials on the dyno then it may be no change or worse

 

But all those things that can change the rate of acceleration will also come into play on the track, so maybe they have their ups and downs right?