Octane in relation to gas mileage

[GotToyota?]

I had read somewhere that the lower the octane, the better your gas mileage will be. I know that this is a pretty uneducation assumption, so I wanted to know whether this was true or not.

-Matt

 

[GotTurbos?]

I had read somewhere that the lower the octane, the better your gas mileage will be. I know that this is a pretty uneducation assumption, so I wanted to know whether this was true or not.

-Matt

higher octane is more efficient

 

[da89soup]

higher octane is more efficient

Yes and no!!! I belive the cutoff is 9:3:1. If your engine compression is higher than this your car will most likely run more efficiently with 90+. but if your compression is less than 87 octain is more efficient.
Soup

:ugh2:

 

[GotTurbos?]

Yes and no!!! I belive the cutoff is 9:3:1. If your engine compression is higher than this your car will most likely run more efficiently with 90+. but if your compression is less than 87 octain is more efficient.
Soup

:ugh2:

I didnt know that Thanks!

 

[JustAnotherVictim]

Holy flying squirrel nuts Batman!!!

 

[Nick M]

The number on US gas pumps represenst resistance to detonation. Efficency as you are thinking is not a factor.

There is not more BTU's in 93 vs 87.

 

[forcefedsupra]

If you want to save gas and keep your Supra, let off the gas a little.

 

[NDBoost]

If you want to save gas and keep your Supra, let off the gas a little.

He's NA enough said..

 

[jester1341]

isn't forced induction a factor as well.... like SCed and T'd vehicles are to use higher octan ratings to prevent knocking[pre-detonation]

i remember a thread somewhere before[maybe a different board]

as da89soup said high compression engines would recomend it to ward off knocking.....using FI we are 'low compression' but also are adding extra compression other engine don't have

am i at all on point here??...do we have anyone with PHd in fluid dynamics...

john

 

[dbsupra90]

isn't forced induction a factor as well.... like SCed and T'd vehicles are to use higher octan ratings to prevent knocking[pre-detonation]

i remember a thread somewhere before[maybe a different board]

as da89soup said high compression engines would recomend it to ward off knocking.....using FI we are 'low compression' but also are adding extra compression other engine don't have

am i at all on point here??...do we have anyone with PHd in fluid dynamics...

john

yep its called effective compression ratio. base compression ratio + psi boost = effective compression. higher the boost, the higher the ecr. thats why oftentimes there is a reference to safe boost level on pump gas and running big boost requires higher octane fuel.