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Discussion in 'Engine, Drivetrain, and Exhaust Discussion' started by joseph falbo, Nov 30, 2019.
can i run 30% e 85 and and 70 % 91 octane without a tune in my gt2?
Yes, it ends up as c. 87 octane. That's how "they" get 87 octane, "midgrade" gasoline: they mix regular and premium. Going 30% 85 is probably closer to 90 octane.
(but, why do you think you need a tune for running under the recommended minimum octane of 91??)
You misread my post ethanol 85= e85 not 85 pump gas and mixing with 91 gas to turn it into 85 pump gas
Ah, right. Oh, well. I could make excuses. But pure ignorance was my downfall.
Yes. If it’s pure e85 and your 91 is standard top tier fuel with about 10% ethanol you will end up with about 95 octane and your ECU will adapt to the extra octane. You won’t see big difference in performance without a chip/tune but it will maximize the performance you can get with a stock tune.
It will be best to get the tune then thx guys i was curious i didnt know
Why would you want to do it with no tune? If you don’t need the extra octane for the higher boost there’s not really a point.
I wonder how many gallons to get to that 95-96 octane so I can try map 3 on
No need to guess. Buy an ethanol sensor and you’ll know exactly what’s coming from the fuel pump.
Either buy an ethanol sensor or use a e85 calculator. Here’s one example E85 (Ethanol) Fuel Calculator
Just keep in mind that too much ethanol can drop fuel pressure with higher boost levels. Most people don’t exceed 5g pure e85 with 10.9g of top quality 93 octane.
I think that's closer to 100 octane? For 95 ish I believe I read 3 gallons E85, rest 91.
The calculators do the math for you. 5g of 93 + 11g of e85 is about e33 and 96.8 octane. On 91 it’s about 95.4 octane.
A few people tested and found 96 is about the least octane you can run to get maximum timing advance & performance from map3 & 5, but that depends on the premium fuel quality too.