Originally posted by robtmc
I can vouch that this is a fact on centrifugal supercharged engines not originally designed for forced induction. My Mustang with a 9 lb blower always needs more retard programmed in near 4500 rpm (torque peak) than above or below.
With 91-octane ethanol gas and an MRT turbo-back at 5000 feet elevation and with 15 lbs of max boost, Nathan was getting knock signals from the UTEC almost all of them at the 3650 and 3950 RPM points doing WOT pulls from 2000 RPM in 3rd, 4th, and 5th gear. Maybe that's where my peak torque is ... i have no idea since there's no 4-WD dyno here.