87 perf vs 93 perf

[Fred]

I wouldn't think it would be a huge deal on an unmodified, naturally aspirated engine for a short period of time, but as you add mods or forced induction you definitely would not want to do this. And personally, I would not do it unless it was a necessity, i.e. you had the 93 octane tune loaded and you had to stop for gas and all they had was 87 octane. Detonation is not a friend of any motor.

Yeah..I was thinking just by accident...

 

[DubbsFaris]

The computer will pull the timing, so you wont detonate, but other parameters in the tune will make the truck not run very happy on under octane fuel.

Now, if you have a supercharger on it, that might put you at risk a little more, but I have done it in a pinch on my GT500 when the only gas I could find was 87, and I had no gas to get me the 90 miles to the next station...but I just couldnt get into the throttle and limped into the next town.

 

[saltiballs]

i have a 91 perf tune and i just drove down to the keys from stuart... about 178 miles... and i averaged about 14 mpg hwy. yes i was going about 80 mph but even when i put it down to 70 mph i only saw like 15.7 mpg.... city i get about 12 ish... anyone else get better numbers on hwy and how???

 

[Fred]

i have a 91 perf tune and i just drove down to the keys from stuart... about 178 miles... and i averaged about 14 mpg hwy. yes i was going about 80 mph but even when i put it down to 70 mph i only saw like 15.7 mpg.... city i get about 12 ish... anyone else get better numbers on hwy and how???

Nope...but around 70 is my sweet spot for mpgs...I am around 11mpgs in the city...