I newly discovered a gas station near me that carries ethanol free 91 octane gas which now that I'm tuned leads me to a question... If I am tuned for 93 e10 octane gas is there any benefit or risk to running the 91 ethanol free gas? I also have a 91 octane map with my tune that I could use with the 91 ethanol free gas, would that be more beneficial than using the higher octane map? Or am I just making this more complicated then necessary? I read a bunch of threads on the differences and it seems people lean towards the ethanol free being a better gas but I did not see mich in the way of the role this would play on a tuned g37... thanks for any suggestions.

 

There's no outright harm in running the ethanol free 91 octane. However, since your tune is for 93 octane E10, your ECU may pull some timing (retard) if the knock sensor detects any detonation if you're running less than 93 octane.

The only reason I can see for running the ethanol free 91 octane is for long road trips and you want to eek out more mpg, which you will certainly achieve over the 93 octane with 10% ethanol. Ethanol is not as energy dense as pure gasoline and therefore requires more fuel to achieve the same power. I'd imagine you would see 2-4 mpg more with the ethanol free gas but I'd just stick to the 93. I'm guessing the 100% gas is marginally more expensive than the 93 E10 but if the 93 is cheaper, I'd stick with it.

As to whether it's beneficial or not, that depends on your use-case. If you're going for outright power, stick with the E10 93 octane. If you're going for absolute mileage efficiency, switch to the 91 octane map and use the lower grade fuel, with 100% gas.

 

Thanks man, having the tune is what kind of threw me off. I kinda figured I was splitting hairs but since the opportunity was there I just wanted to double check. I appreciate the explanantion.

 

No problem man! I hope it was clear enough. Are you on an UPREV or ECUTek tune? How are you liking it so far? I'm planning to do an UPREV tune in the fall.

 

I'm on uprev tune. I originally went for an ecutek tune but my rom wasn't cracked and I was 6 hours from home with no way to spend an extra day or 2 waiting for it to be cracked. I only ended up netting an 8 whp and 5 wtq differenc, however my base was higher than a lot of people after a tune so I should be satisfied lol. There's definitely a difference and I'm happy I got the tune done but still feel like ecutek is the way to go right now, they are at least still updating and working on the vq platform. It seems like uprev is stagnant on development and not going much further. If you have the option I think ecutek is worth it just for the future updates imo.

 

where did you get your Uprev tune done? I'm tuned as well, but most likely will get my car dyno'd again since moving from CA to CT. I'm tuned for 91 octane, but running 93 octane gas....no issues for me, but want to see if there are extra ponies getting picked up...car feels strong.

 

I ended up going to R/T tuning in PA, just outside Philadelphia. Nice guys very friendly, I just wish I could've got a little more info after my tune besides only hp and tq #'s. And definitely want to seen what it can do with the ecutek tune... but that'll be a while lol

 

^ I'll keep an eye out on some tuning shops around here....I think there's one in CT - where they specialize in 350z's....so they are up to speed with Uprev. The tuning shop I went thru back in CA was able to squeeze out some decent gains with just the little amount of mods I had.