Quote:
Originally Posted by Soloside
stock factory tune for a stock car is the most optimal tune in terms of MPG/POWER am I not correct?
Unless you're telling me adding more power throughout the band is going to improve your mpgs
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Not really - factory tune is usually a compromise with large safety margins built in to ensure reliability with a variety of fuel qualities, environments, and usage conditions.
Specifically, aftermarket tune gains mostly come from optimization of timing advance and fuel mixture. Factory tunes usually run slightly richer than what's optimal for power, and less timing advance than what's optimal for power - both will ensure somewhat cooler cylinder temps, slightly lower cylinder pressures, and more protection against knock. Aftermarket tunes push AF ratios & timing advance curves closer to 'optimal for power'. But more optimal AF ratios & timing advance also equals better MPG. This is oversimplifying things a bit but in general optimized factory tunes should return better power AND MPG while sacrificing some margin for knock/reliability in less than ideal fuel conditions.