Premium fuel + E85?

You are correct. Compression in the Prius isn't unusually high, which is why Toyota recommends regular fuel. The Atkinson cycle engine gives a long power stroke, not higher compression.

Tom

 

Bingo, although this is my third post I know a bit about octane. High octane fuel will actually lower horsepower for normal applications. I even tested this with my V-Max(stock) on the Dyno. I laid down more HP on 87 octane than 93 octane. Now my nitrous busa requires above 100 octane fuel because I've added high compression pistons, thinner head gasket etc. Octane actually slows the burn of gas. High compression motors speed up the burn of gas, which is why all the high performance (high compression) cars and bikes have to use high octane gas or they get pre-ignition. This is also one of the reasons why people burn up pistons while on nitrous. Their octane is too low, burns too quick and there goes the motor.

 

Point taken. I understand then. I did experience lower power so your right. That was on e85, but I have noticed the car doesn't operate as long with premium fuel either.