joshh44

hey im abit puzzled about octaine levels in the fuel.
i really never fully understand it.
many say having higher compression engines should run on 92 or 93 octaine. what happens if you run the regular stuff at the pumps? 87 octaine?
and also if you bought regular gas from the pump and you added octaine booster to the fuel. would that work for highe compression engines that needs higher octaine levels?

AlkyIROC

Octane boost additives do very little. When they say they will raise the octane level 2-3 points that means it will raise 87 to 87.3. It would be cheaper to just buy higher octane fuel.

Octane is the fuels resistance to detonation. You only need enough octane to keep the fuel from self igniting (pinging and knocking). Self detonation loses power and damages the pistons. Too much octane is also bad because the fuel is burning slower and you don't get all the power from it.

There is no more BTU energy in 87 octane than there is in 92 octane. If an engine pings of knocks using 87 octane and runs fine with 92 you'll think the higher octane makes more power but it doesn't really. Also if your engine doesn't ping of knock with 87, switching to a higher octane won't make any more power.

joshh44

ohhh ok. so getting the octaine booster stuff wont really do anything. what a useless item to have on the shelf if it only raises it that much.
so what is the highest compression your engine should have to run on 92 octaine fuel?

Sonix

iTrader: (1)

That's hard to say. Many variables effect that. A poor chamber design, bad quench, small cam, lots of timing and it'll ping at 9.5:1 CR.
A really good chamber design (lots of swirl), perfect quench, low timing (enough to make good power with a good chamber), AL heads and it'll run happily at 10.5:1 with the right cam.
Very loaded question.

And typically lower octane fuel has more of the heavy hydrocarbons giving it a higher BTU rating that a higher octane fuel.

joshh44

oh ok.
where can you go to get more octaine fuel? higher then you can get at he pump.