As the meth cars run high CR's with big boost on top, (I searched and found a 1.8-liter Honda running 13.8:1 with 35lbs. on top), I'm now wondering if a higher CR would be benefical on an ethanol fueled car running up to about 25psi?
Ethanol is technically alcohol and has a serious cooling ability,just like methanol,so given that E85 likes about 8:1 AFR (Meth 5:1(?) and gas 12:5.1) would a CR in-between the low 7:1 for gas and the high 13+:1 for meth be benefical? Like 10:1 or so?
Opinions welcome...verbal bashing is not. (I've had a hard day)
-Bjørn
"Impossible? Nah...just needs more development time"
E85 runs about a 9:1 AFR. With the extra cooling benefit, increasing the compression will help produce more power as long as you don't exceed the capability of the 105 (+/-) octane.
Need to know the application. For say drag only you could stay lower in the static compression and take better advantage of cylinder filling with more boost. But for a street car, increasing the static compression will limit the amount of boost but provide major benefits in driveability.
It's a street/strip Volvo 850,with bias to street use,I reckon 80% so. Being a 600hp+ FWD drivability is an issue... And,we're trying to get the most hp with the least boost,so we'll try to stay below 22 psi... The "norm" here is (for gas) 8:1 or less and 30+ psi boost,we're trying to go for higher static CR due to fairly long cams (high rpm) and restrict the boost somewhat. I'm just curious if close to 10:1 would be considered high with regard to the fuel. I know 10:1 on gas with boost on top is pushing it,but I'm not sure how the ethanol reacts..
-Bjørn
"Impossible? Nah...just needs more development time"