Octane question

Ryan A Harris

Registered User
I'm now living in a town that has no higher octane than 91. My SC was tuned to run 94. I haven't looked too much at the other closer towns to see if anything higher is available to me. Most of my driving right now is at highway speeds, and some in town stuff. On weekends I'm driving 5 hours south to my current adrress, my closing date isn't for another couple of months for the northern house. When I'm south I can easily fill up on 94, but thats the only time.

My boost level isn't really high, tops out at 12-13 PSI. I have a double IC, with a fan, the big fuel pump. How much if any damage can occur with runnning a lower octane than I was tuned for. Also with the "mixing" of one octane level with the other, does that help or hurt my SC.

Any thoughts on this?
 
Also with the "mixing" of one octane level with the other, does that help or hurt my SC.

Mixing octane levels of unleaded fuel leaves you with an average of the two based on how much of each. No problem otherwise. The old concept of increasing octane by mixing was when "regular" first went unleaded. By mixing unleaded low octane with leaded higher octane you could actually end up with even higher octane than "premium" because the lead really boosted the more highly refined unleaded fuel.
 
Guess you'll have to find another place to live..... :rolleyes: ;) :D

Ira

Thats what I was 1st thinking. But no such luck now, our offer has been accepted. :D

At this point, I'm really not beatin' on the car anyway. I never really do, but I'm always tring to keep things safe, or at least tiring to keep things from blowing up.
 
water injection

Here is a case where just plain water injected might allow you to leave the tune for the 94 while running 91. I have looked at water/alchy injection for years (back to the 70's). The original/basic use was for carbed cars with high compression to be able to advance timing back to power levels and run that low octane for the street. Original figures for power (going on my memory) were, loss ~5% just water alone. Advance time back ~ no loss, no gain. Add Alchy, ~5% gain. The oldsmobile "starfire" had water injected turbo back in the early 60's----not to mention the WWll turbo-propped fighter planes.

There is another thread on this forum about water injection with input from guys running it, that know what they are talking about. This is a case where plain water would be a benefit to someone just wanting street tuning back with lower octane fuel. I would see what they think about my suggestion for plain water----maybe they will comment. Remember, water is cheep!! Add alchy and gain more power!
 
It depends on how tight it was tuned. 94 usually means 94 but if the car was leaving some on the dyno, you might be o.k. Assuming the octane plug is still enabled, you can always pull that and have timing retarded a tad.
 
It depends on how tight it was tuned. 94 usually means 94 but if the car was leaving some on the dyno, you might be o.k. Assuming the octane plug is still enabled, you can always pull that and have timing retarded a tad.

Yeah, I still have the octane plug in. I never even that of that, never do think of it. I think my car was at the limits for what I have for bolt-ons, but I don't think my car tuned at the limits. I'll pull the octane plug out to see what it runs like.

Thanks,
 
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