Octane Options

[Bulldog9]

Lets talk Octane..... What is the consensus on grade of fuel? I'm running 96 x 71 bore & stroke with .060" deck height 58.8cc chambers in the heads, and flat top pistons with no valve reliefs, and figure my CR is around 8.6:1. I'm thinking I can run regular, but no idea.

I've been running Chevron 92 so far, but dont want to wast $ and leave unburnt fuel residue. The higher the octane, the more resistant the fuel is to combustion, so unnecessary use of 'hitest' is dirtier combustion wise than regular.

I haven't done any experimenting yet, but wanted to get some experience before I do. I plan to run the current tank down to close to empty, then put in 5 gallons of regular and see how that goes, but just wondering.

[Mark Henry]

The one thing I've wondered about is if you remove the ethanol from the gas what would the octane rating be on the end result?

It's easy to remove, just add a bit of water and it will separate the ethanol from the gas.

[914_teener]

The one thing I've wondered about is if you remove the ethanol from the gas what would the octane rating be on the end result?

It's easy to remove, just add a bit of water and it will separate the ethanol from the gas.

Wow....great question.

Any Petrochem Engineers out there?

[Madswede]

The one thing I've wondered about is if you remove the ethanol from the gas what would the octane rating be on the end result?

It's easy to remove, just add a bit of water and it will separate the ethanol from the gas.

Wow....great question.

Any Petrochem Engineers out there?

Well, I'm a chemical engineer, but I haven't worked in the petroleum field since college. Still, I don't think it would be wise to put water into an ethanol-gasoline blend. Ethanol and water are soluble in each other, so the ethanol-fuel mixture would simply dissolve the water until it couldn't anymore, at which point phase separation would occur. But the mixture of ethanol-fuel will hold the water (in this case, the fuel mixture would be the solvent, water would be the solute). One might have some success by using a vast quantity of water and pouring some ethanol-fuel into it, gently mixing it to get the ethanol and water to mix, then letting the mixture re-separate, but I don't think that would work very well - it would be a competing dissolution process and I don't know the equilibrium constants for ethanol in water vs. ethanol in gasoline. Better separation technologies would be needed such as fractional distillation, solvent-extraction with a better solvent than water (I think), possibly using a resin bed of some kind as a catalyst for separation.

EDIT: see here... http://www3.epa.gov/otaq/regs/fuels/rfg/waterphs.pdf