[sixtee8gto]

I was looking for the best way to raise the octane for my motor. I do have the option of buying 110 octane right around the corner for 4 and 1/2 bucks a gallon but was looking for a little cheaper way to raise it by using 94 and an additive. Just wondering what people were using these days to raise it up a little. Running around 11 to 1 compression.

[sixtee8gto]

I was looking for the best way to raise the octane for my motor. I do have the option of buying 110 octane right around the corner for 4 and 1/2 bucks a gallon but was looking for a little cheaper way to raise it by using 94 and an additive. Just wondering what people were using these days to raise it up a little. Running around 11 to 1 compression.

[travelinscout]

From what I have read on here. most additives are crap. I mix about two gallons of 114 race gas into my tank in my 69 428 and the car runs awesome. My compression is around 10.5 to 1. In my opinion. the best thing to mix in gas is gas, so I just bite the bullet and spend the 5.40 a gallon. Its not my daily driver so its not that big of a deal.

[76TA428]

Thats the same thing I was going to say. Just buy about 5 gallons of 110 and for every 10 gallons of 94 throw in a gallon or so of 110. Should equal out to somewhere around 99 or so. I'm running 10.75 :1 and that always does the trick for me. It runs ok on 93 octane but much better when I cut it.

[firechickenman]

There was a major discussion over fuel additives a while back. It looked to me like tolulene and/or xylene were the best additives.

A lot of good info here - fuel additives

[David Jones]

From what I've been able to find out the store bought additives seem to only work (if at all) when you add them to regular grade fuel. They potentially could lower the octane of premium fuel. Find some high octane and start brewing your own.....

[runningbwdog]

Hi, You can buy 100 octane aviation gas at any airport. A lot of short track and drag racers use it in their engines. A gallon of Avgas is under $3.00. Not cheap, but less than racing fuel.
Mike

[goatman-68]

Depending on your usage,tolulene works real good. I have found that one to two gallons to 10 gallons of good unleaded premium works. Don't get any on your paint..........

[ERIC17621]

First, disclaimer: I have no scientific evidence of what additives work and what do not. Now then, the two additives that I have found that seem to work (by seem to work, I mean the car defiantly seems to run stronger, especially off idle) are VP off road formula, and NOS racing formula (with nitromethane). Problem is, they both cost about 10 bucks for a 20oz bottle. For those ten bucks, go buy two or three gallons of 110, mix it yourself, and know that it is increasing the octane.

[69GPModJ]

AV gas is okay if you also re-jet your carb. AV gas isn't as dense as auto gas, meaning it will run lean unless your carb is re-jetted.

[mrtonegto]

Here's one opinion...........


http://www.elektro.com/~audi/audi/toluene.html

[briann]

i used to buy avgas alot then my local airport wouldnt sell it to anyone unless they had a pilots license, but id have to run it straight and that wasnt good for my plugs and motor after a while so i switched to 110 uocal racing gas (which they quite making last november by the way). the highest premium octane in my area is 91 so i mix 1 gallon 110 octane to 3 gallons 91 and usually run it 50/50 for final 100 mixed octane.

[6567GTO]

I've got 12 to 1 compression and I have to run at least a 50/50 mix of Cam2 110 & 93 unleaded. Sucks, but boy does it run good! And like Travelinscout said - "Its not my daily driver so its not that big of a deal."

[Colin]

I wouldnt use the aviation fuel.My father used to work on some vehicles that were used at a smaal airport.All of the vehicles were big block powered and also a hemi powered generator.All of their engines required valve jobs on a relatively frequent basis.Lots of burnt valves....dad always said it was because of the aviation fuel so they stopped using it and never had any more problems.But then again they were running it straight not mixing it with regular gas.

[Taff]

Toluene is the best additive to use. It's cheap,it works, and it's what the fuel companies use to make their higher octane race gas. I know this because I buy my toluene from a local firm that makes race fuel for the F1 rally cars. A little goes a long way so to speak, so try 2.5% first and increase from there if you need to.