Horsepower/Torque is advertised but really is measured at the Crankshaft (end of engine before transmission-driveshaft-differential). Since the Solstice GXP/Sky Redline is rated 260HP/260ft-lbs Torque at the crankshaft and since the car is rear-wheel drive, that power has to pass through the transmission, drive shaft and rear-end- differential and axles before the power goes to the wheels. Most cars are Dyno'd at the drive wheels so there is loss from the crankshaft numbers to the numbers arrived at for the drive wheels. I've seen dyno numbers as low as 200 Hp and @200ft-lbs of torque at the wheels. As wspohn points out, on a rear wheel drive car a 15% loss is the norm for real wheel HP/TRQ.
Lets do the math! 260HP/260 ft-lbs TRQ at the crank less the drive train loss (260x15%=39 -- 260-39=221 HP/221ftlbs Trtq.) So rear wheel HP/TRQ is closer to 220/220 Again these are averages.
I had the Trifecta Tune applied to our 07GXP 5 speed and had it dyno'd. Wheel HP was 280 and wheel TRQ was 321. This car has loads of power potential if tuned.
07 GXP 5mt DDM Backbone DDM ProBeam Trifecta Tune
Last edited by skline00; 04-23-2011 at 12:59 PM.