ktg

Anyone know of any stations that sell gas higher than 91 octane in Utah?

Injuneer

What elevation are you located at? The higher you are above sea level, the lower the octane requirement for your engine. That's why the don't sell higher octane fuels in "high elevation" states.

DavesLT1

I was wondering why I can only find 91 here in CO and the regular gas octane is 85 and mid-grade is 87.

ktg

I've heard that before. So I guess that 91 here is like 93 somewhere else? When an owners manual calls for 87, they mean regular so that would be 85 here?

blind527

Where I'm at its 87, 89, and 93.

Injuneer

The gasoline doesn't act any different at higher altitudes. Its the fact that you are pulling in thinner air, and not able to burn as much fuel, producing much lower pressures in the combustion chamber. A given engine's octane requirement drops more than 1 octane number for each 1,000-ft increase in elevation.

blind527

What about for a decrease in elevation? There are some parts of this world that are really under sea level. What would be the outcome of the air be on the engine when the elevation goes below sea level?

DavesLT1

aren't places like this usually like Death Valley? would you really want to be driving when it reaches 140 degrees?

blind527

Lol, I think one of the southern states is completely below sea leavel, Louisiana? Don't remember. But Death Valley is just insane. It would probably reach more than 140 on the road, and the temps of the engine combined.

ktg

So if my car requires 93 octane at say 1000', it should run fine on 89 octane at 5000'? Or in other words, if I run quality 91 octane with stock compression ratio at 5000', I should never have any real knock? (assuming a clean engine)

Injuneer

A stock LT1 engine should run without knock retard on 91 octane fuel, at 5,000-feet. Tendancy to knock can be increased by high coolant temps, high intake air temps and carbon buildup in the combustion chambers.

captaindbol

Almost, The place you are talking about is called New Orleans. There's actually a levy built around the town. Elevation is in the 300's up here in the NORTH where I'm from.