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.

[jim_hoyland]

Speaking of Ethanol; manufactures of AFR gauges and sensors warn against fuel with additives or contaminants; the sensors self destruct in their presence.

Any thoughts whether the ethanol could affect AFR sensors ?

[Mark Henry]

Anything above stock CR you likely should move up to premo, but seeing the age of our cars I use pure gas and so that is premo here by default.

Speaking of Ethanol; manufactures of AFR gauges and sensors warn against fuel with additives or contaminants; the sensors self destruct in their presence.

Any thoughts whether the ethanol could affect AFR sensors ?

I do have a hard time believing that ethanol would harm a Bosch O2 sensor, they're in millions of modern cars. They must be talking about "fuel treatments."

I know that dragsters running on methanol the AFR readings double.
So it stands to reason that ethanol is affecting the readings, but by how much I don't know, I would imagine not a whole lot.