Customers stock 2011 Chevy Silverado 5.3L 4×4 automatic. All stock except wheels and tires.
On the mustang chassis dyno, this vehicle pulled 216hp and 275lb torque weather corrected with a slight surge at beginning of pull which made the torque number about 5% higher than it should be as these motors are suppose to peak about 4400 rpms on that torque and torque was about 260lb. Factorying a 25% drivetrain loss for this truck being 4×4 automatic puts that power at 288hp and 346lbs of torque at the flywheel. GM rates these engines at 315hp and 338lbs of torque so the percentage is pretty close. HP is low partially due to running 87 octane fuel and also due to all the torque management and poor programming on the computer from the factory.
So turning off that torque management and correcting the air fuel ratio and barely any changes to the timing since it is always going to run on 87 octane fuel. The power increased to 240rwhp and 302lbs of torque for a 24rwhp and 27lbs of torque gain. We again had a little torque converter surge at the beginning of the pull which happens nearly every time with an automatic so torque is again 5% high so corrected down to 287lb of torque. This with same 25% drivetrain loss = 320hp and 380lbs of torque at the flywheel for a very nice improvement over that stock programming.
Here are the before and then after dyno sheets.