[SRT Engineers]

3. I recently dynoed my 2008 Viper on a Mustang dynonometer to get a baseline figure on the stock powertrain before doing some modifications. The average of the three runs was 529 rear wheel hp and 505 rear wheel torque. What correction factor would you recommend to get an estimate of flywheel hp and torque?

Thanks for your help and for a great car. I am enjoying it immensely.

/Rich[/quote]

RICH - I always tell people to use caution when trying to get and compare chassis dyno numbers. Many things can (and do) effect the numbers – how well are fluid temperatures (inlet air, charge air, exhaust gas, water and oil) controlled? If these variables aren’t controlled precisely from run to run and dyno to dyno valid numbers and comparison are not possible. How often are the dyno sensors (load cell, tach, pressure and temperature transducers) checked and calibrated (we do it every day in engineering)? All of these variables will effect how the engine is fueled and sparked so there is a potential for big variations. I hope you get my point…anyway, I would suggest correcting to SAE J1349 (29.77 in-hg dry barometer, 77 F inlet air, thermostat coolant temp and road oil temp) conditions since that is what is the current industry standard (and what we use). SAE J606 will give higher numbers (29.92 dry baro, 60 F inlet air) will give higher numbers and is often what the tuners use.