Dyno Pull
Thread Starter
5th Gear
Joined: Oct 1999
Posts: 5
Likes: 0
From: Las Vegas NV
Dyno Pull
We recently ran a dyno test on our Procharger equipped L98 Vette. It is equipped with a 2.59 rear end as we road race this car at speeds up to 165 MPH. I am wondering if the dyno results, 278 hp/365 Ft-lbs torque, are effected by the rear end gears. An associated question is should we make the pull in drive or OD or does it matter?
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by DaleF
We recently ran a dyno test on our Procharger equipped L98 Vette. It is equipped with a 2.59 rear end as we road race this car at speeds up to 165 MPH. I am wondering if the dyno results, 278 hp/365 Ft-lbs torque, are effected by the rear end gears. An associated question is should we make the pull in drive or OD or does it matter?
Pro
Joined: Feb 2002
Posts: 533
Likes: 0
From: Augusta Ga
Neglecting frictional losses the gears will change the torque ratings, but not the horsepower ratings when doing rear wheel dyno runs. Normally the dyno runs are done at a 1:1 ratio. Next time you run watch the dyno as you start off in 1st the torque will be huge, but the hp will be the same. Then when you shift to 2nd the torque will drop like a step function and the hp will follow roughly the same curve as the first. That is why they run rear wheel dynos in 1:1 to get the hp/tq at the rear wheels do to the motor and not the hp/tq during gear reduction.
Since hp=tq*rpm/5252 when you increase the tq by using a lower gear you will decrease the wheel speed those to multiply to give the same hp when measuring at the rear wheels.
Since hp=tq*rpm/5252 when you increase the tq by using a lower gear you will decrease the wheel speed those to multiply to give the same hp when measuring at the rear wheels.
Thread Starter
5th Gear
Joined: Oct 1999
Posts: 5
Likes: 0
From: Las Vegas NV
Other Mods
The only other mod is a Flowmaster exhaust. An 87 L98 is speced at 240 chp.
Multiply by 1.5 for intercooled Procharger is 360 chp. Multiply by 0.8 to convert to RWHP and you get a predicted 288 RWHP so the dyno data seems reasonable.
Multiply by 1.5 for intercooled Procharger is 360 chp. Multiply by 0.8 to convert to RWHP and you get a predicted 288 RWHP so the dyno data seems reasonable.
