I've been considering redoing my tune for 87 octane instead of the 91 I've got it tuned for now. 87 seems to average about 20 cents cheaper. My thinking is with the meth I don't need the high octane so much. Or rather, I can afford to run the lower octane... Anyone else having similar thoughts with these gas prices?

 

Well im just n/a but I have to run3-4* less timing on 87 than 93 or i see kr in the 5000-6000 range. I know the meth will help you though.

 

That's not too bad. I could probably run the same timing with the meth on. Worst case scenario, turn the gain up a bit. I'd deal with a tiny loss in part throttle power to save a little cash.

 

my opinion...for a 26 gallon tank a total fill would be about a $5 difference. The Higher octane (tuned) will net better performance and if you keep your foot clam better economy....

 

personally id keep running the higher octane with a modded engine regardless what was done. just keep your foot outta it haha.

 

I've definitely kept my foot out of it. Past few weeks I haven't gone WOT cause of the smaller turbo...whose replacement is actually sitting right next to me Its been nice getting somewhat better mileage. Gone 2 weeks on one tank so far. It got me curious on how I might stretch my summer dollars.

I wonder about the performance side of things though, because yeah with less timing you'd produce less torque. But in the areas I'm concerned about, cylinder airmass is so low I can run a lot of timing anyway.

All my engine has is a cam anyway...

 

I notice 2-3 mpg difference between 87 and 93 when tuned for both. The timing I can run with the 93 keeps my kpa so low at part throttle. Like 35 kpa at 60mph. It is roughly, 5 kpa higher on the regular. I have spent time trying to see which was more economical, and in the end I spend the same money, I pay more for better fuel, but in return I run longer on it, and it all balances out....lol

 

Well then its settled. I'll leave it as it is.

 

What are you guys running for timing at cruise? I might try bumping mine up a bit, I'm sure its still somewhat conservative.

 

40-45* depending on rpm and load.