I am thinking about getting a mail order tune done to my LT1. I was wondering if you also get better gas mileage with a tune along with power. My car is fairly stock...mods in sig. I hear the LT1 runs alittle rich from the factory, so i would guess a tune would give better mileage because they tend to lean it up a bit???

 

correct.

 

Not really. They "run rich" only at WOT. At part load/part throttle, the A/F ratio is carefully controlled at the stoichiometric value of 14.7:1. That number is hard coded into the PCM and very difficult to change unless you run almost all the time in "PE" mode (WOT tune).

The problem is that at WOT, with stock programming, the PCM calculates a target A/F ratio that is generally around 11.7:1 and that's a shade too rich for peak power/torque. Leaning that out will improve power but its not going to have a major effect on gas mileage, unless you are in the habit of keeping your foot on the floor most of the time... and none of us do that

 

I didn't notice a change in gas mileage, however, the tune gave the car a noticable power increase, firmer shifts, and lower running temps.