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BSFC for E85

EFI Tuning Fundamentals

Discussion and questions related to the course EFI Tuning Fundamentals

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When sizing injectors and fuel pumps the BSFC plays a major role in the calculation. It takes more E85 then gasoline so how is that figured into the calculation?

Well, bsfc is the parameter that demonstrates how effectively the engine burns fuel to produce power. In our words how much fuel mass it needs to produce 1hp in 1 hour. Since spirits contain less energy per mass unit than gasoline, you need more mass of spirit to generate the same power level like on gasoline and that is why your bsfc is going up. By the way, bsfc is not constant throughout engine revs range - it changes. If forced induction aplications usually have a bsfc around 0.55-0.6 with gasoline, they would be using 0.7-0.75 bsfc with E85 and even bigger figure with methanol fuel.