[lt4camaro]

Originally Posted by zx9rmal

So, being a CPA, I like fu***ing with numbers.

The SS is rated at 455 hp and dynos at around 400 hp. The ZL1 is rated at 650 hp and dynos at around 550. That's a drivetrain loss of 12% for the SS and 15% for the ZL1. Let's assume both are manuals.

Why the difference?

1st of all you need to dyno both cars same day, same dyno. 2nd, one car could be making horsepower in the high side of the range for that motor and the other car could be on low side of the range for that particular motor which could be plus or minus 1% variance on each motor. On a 455 horsepower certified sae rating, there could be variance's of plus or minus 1% or a range from 450 to 460 horsepower. there is always a variance and there will always be strong motors and weak motors. On a 650 certified SAE HP rating the range could be 644 to 656 actual horsepower from the weakest to the strongest motor. But once a chassis dyno is # is achieved on both motors add 15% to the dyno # for a good ballpark actual flywheel hp# . Drive train power loss is always a percentage of the actual chassis dyno derived horsepower numbers . Add 15% drive train loss to a 550 RWHP chassis dyno # for a ZL1 = 632 flywheel horse indicating a weak 650 horse ZL1, A healthy ZL1 should be dynoing 565 to 570 rwhp
A 400 RWHP chassis dyno # + 15% drive train loss = 460 flywheel horse indicating a strong 455 horse LT1. My calculating method has always put me in a close realistic range for all intensive purposes.