For an older high compression engine, that was originally made to run off pure gas and high octane.

Without the option of having 92 free. Which would you choose

90

There was a pretty cool, in-depth study done on octane ratings and the effect that ethanol has on it.

Don't quote me on this at all but our gas in the states that is 93 rated with 10% is closer to 84-86 octane

Besides. Leaded gas never hurt anyone. All these tree hugging fuckers out there that think the earth is going to melt.... Go to Wisconsin in late january and tell me the world is warming up...

edit -- Before someone jumps me about the 93 to 84 octane rating, it was based on power output per amount, not an actual rating of the fuel.

This post was edited by jimmyhoud on Aug 4 2015 01:43pm

the ethanol is harder on your engine than the lower octane

Yeah this was my concern, older engines don't detune themselves. When lower octane is introduced.

Pretty sure I wouldn't get engine knock at 90, but for the longevity of the car I worry about ethanol eating away at anything rubber that it comes in contact with.

This post was edited by kclla on Aug 4 2015 04:44pm

The e10 will eventually corrode the rubber in the fuel system but it would take a very long time. I'd run either. The octane rating is what it says it is. The e10 will have a slightly lower total power output but it is only a few percent. If it is carb'd just richen it up slightly and it will be fine.

So that said i'd run either.

you would really want to be running the ethanol free gas because it will eventually become a problem, will eat carb gaskets, fuel line, also it likes to create build up when it sits in the lines, killed a holley blue pump last year for that reason



But i run regular 93 right now in the car, that being said everything has been upgraded to run e85 in the future less the fuel pump and carb, so i wasn't as weary as the ethanol as most should be.

That being said octane is resistance to detonation, high compression = detonation



Not 100% certain but id imagine that the ethanol would raise the octane rating, as pure ethanol is around 100 octane.

This post was edited by TanKiE on Aug 8 2015 08:03pm

E85

Methonal

That's correct. However, pure (leaded) fuel has a higher output than mixed with ethanol.

I could go really deep into this but if I had the choice of these two on a big CI n/a motor i would run 90. If it were boosted it would be a different story that I could write a novel about how and why but I'm pretty sure most of you can understand.

Fixed

edit -- omg double post. Plz no ban tyty

This post was edited by jimmyhoud on Aug 11 2015 05:52am