What Octane Are You Using?

[james singleton]

While reading the topic on "What MPG Does Your 6 Cyclinder Achieve?", I noticed that several of the responses mentioned that they used either 89 octane, or 93, or whatever octane. I thought I would asked which octane everbody is using. Does it matter that much? I have a brand new rebuilt 200c.i. and would like to know if it matters much which octane you use on an older engine (like the 200); especially if it is rebuilt. Other than better performance using a higher octane, is there a reason for a higher octane; like longevity of the engine?

 

[wallaka]

The only reason for higher octane is so that higher compression ratios can be used. Octane is detonation resistance, nothing more, nothing less.

It won't make more horsepower or get better economy. If you have less than 9 to 1 compression (more is permissible on more modern cylinder heads), 87 is all you'll need.

 

[wsa111]

I am running 10.25 compression & need 93 octane.

With my combination, cam & 16 degrees initial advance + 20 degrees in the distributor = 36 total.

 

[The Plankster Prankster]

i have a 300 (yeah, what am i doing in the small-block forum) but i have to run 89 or i run into detonation. if it sounds bad on 87, switch to mid- or hi-grade and it should help.
--josh

 

[Anonymous]

I run 87 with no problem... may have to step up when I put on a new head

 

[ludwig]

I tweaked the timing endlessly to beat the knock then finally switched grades to 89.

 

[Anonymous]

93 octane for me too!

Luckily...its getting more affordable again!

Later,

Doug

 

[mraley]

93 for mine......

 

[Johnny Ray]

89 octane!

8)

 

[2v XLE]

100.

I tried it this week for the first time. Just a whole lot smoother

 

[kirkallen143]

93 for sure, that is with the turbo.
I used 93 when NA also, because of the higher initial timing setting. If I used anything less it would ping pretty bad under load.

Kirk