My Bluetooth OBD2 and Torque Pro app give estimated wheel horsepower after you input your vehicle profile. What is the general formula to convert that back to engine HP in our SS Automatic? I know there are a ton of variables just fun to see it before I can actually get to a dyno. The site below has a calculator and I've seen other forums suggest DIVIDING the wheel HP by 0.75 but that seems to yield way to high of a number. Any ideas?

http://www.mk5cortinaestate.co.uk/calculator4.php

 

I have had a few vehicles on a dyno locally. The owner used to say that the driveline loss was about 20% for an auto trans and about 15% for a manual trans.

By dividing by 0.75 (as you mentioned), you are assuming a 25% loss in the drivetrain which seems high.

Steve

 

That's what I thought thx. I'll go with .80. Doing that gives me 284hp at engine only hitting 20lbs boost on the run. I'll be interested to see the numbers I can get. I know there see variables and much room for error. It's just fun lol. This app and obd2 is awesome.

 

That's a handy utility you linked to eaglefreak, good for getting a reasonable guess at the horsepower at the wheels.

And as fastsuv pointed out, a 20% driveline loss is a more accurate figure than 25%.

Of course nothing beats an actual dyno run, that way all the variables are taken into account and corrected for.

Ambient temperature, humidity, altitude density, frictional losses, etc., will all impact a vehicle's horsepower output.

 

Hit 239whp on the obd2. Can't wait to dyno