![]() Straight 93 with meth gives you 104,196 BTU/gal i was hoping to prove the meth + E85 blend had more effective BTU, but it seems it was just the opposite since the E85 gets diluted with the methanol. We were still spraying a 25% E85 blend through the stock injectors at that point, so we had an effective BTU of 106,400 as listed above.Įffective BTU when we had the E85 and meth was 97,472 The Meth gave us ~10.05 GPH, assuming we used ~75% of a 14 gph nozzle.Ĩ2% of our fueling was stock injectors, and 18% was methanol. Next, if we inject methanol into that same 25% E85 blend.ģ400 cc/min total 85% IDC gives us ~2890 cc/min from the stock fuel system, or 45.80 GPH. So, using our 25% E85 blend, we basically get an effective BTU of 106,400 / gal. I'm not saying E85 is bad, its basically God's gift to the racecar, but check this out anyways: Here's some math i ran for a customer a while back when i had to explain why he was making more power on 93 and meth than when he wanted to switch to E85. The only reason tuners do not tune for blends is because they cant trust people to not screw up their fill ups, so its 100% or nothing.Īssuming you are not knock limited, you will actually make the most power with 93 and methanol since there is the most BTU available, but most people run E85 because it is cheap as dirt and a part of the factory fuel system, not an auxiliary system. In fact, the less E85 you use, the more power you will make, you only want to use enough E85 to suppress the knock. For that reason, you will 100% need a tune to run E85, as well as the specific gravity of the fuel needing to be adjusted (this basically helps your fuel trims keep your fuel targets on point). 4 gallons of E85 in a 16 gallon tank (so 12:4) only increases your fueling needs by about 10% all else equal. I was doing some testing on my last car, big turbo, making about 400 whp and went down to as little as 2 gallons of e85 per (16 gallon) tank before i started seeing slight bits of knock. What this means, is that you can get the same knock suppression with as little as about 25% E85 per tank as you could with 100%. The good thing about Direct injection is that E85 has an effective octane of about 160.
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