How to increase gas octane

I have been informed (by someone whose opinion appears to be reliable) that

10% ethanol will add nearly 2 points RON, so that's half way there & might even do you (assuming you're starting from a no ethanol base & you can get ethanol fuels where you are). I'm running 92 with ethanol instead of 95 where i am at the moment to test the theory!

I would suggest you Google for "toluene". Its a gas additive that you can use to increase octane.

I haven't tried it and all I know about it is what I read, so take the advice with caution. In other words, I'm not liable :)

I believe adding c stoff will increase the octane rating

Most of these thing only work in reasonably large quantities. A

12 oz bottle added to a 16 gallon tank isn't going to appreciably increase octane, regardless of what the label says. Buying high octane fuel will be cheaper than adding enough of this stuff to match high octane fuel.

About the only thing that actually works is tetraethyl lead. A few drops per gallon can actually raise the octane rating from

2 to 12 points. It can be purchased for off-road or marine use. I wouldn't recommend it in any car with a catalytic converter or O2 sensors - that would rule out any car sold in the US in the past 20+ years. :-)

Toluene is the recommended additive to increase octane ratings for unleaded gas. However, the most common use of toluene is as a paint thinner. It is expensive, it takes a fair bit of it to raise octane ratings from 93 to 96, and the stuff is highly toxic; meaning it is difficult to handle safely.

Unless you are tuning the car for racing, I am not sure why anyone would want to go much above 93 or 94 since even the STi only recommends 93; while other turbo scoobies run fine on 91. Adding alcohol will increase the octane rating, but because alcohol has less energy per litre than gas does, it will not increase the power of the vehicle. It will prevent it from retarding ignition so you can maximize the energy available in the fuel though, and it will allow you to increase the boost pressure of the turbo, but both at the expense of gas mileage.

Ethanol burns too hot to be an effective fuel in turbocharged vehicles, keep that in mind if you are utilizing a turbocharger.

Toluene is 114 octane (R+M). One gallon of toluene + 10 gallons of 91 octane will yield 11 gallons of 93 octane.

I've been using a gallon in every tankful for the last 18 months without problem in my 03 WRX. Toluene is already present in "super" unleaded, in concentrations that vary from ~10% to as high as 25% or so. Concentrations are often higher in gasoline sold outside the U.S.

While it does improve gas mileage a bit, from a strictly economic standpoint, its not cost effective. I use it because I like the increased performance. ICI Paint stores sell it here for under 6 bucks a gallon.

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What if you ordered a 55 gallon drum from a chem supply warehouse? Should amortize out to maybe $3 a gallon. I would get a handpump and keep the drum waaaayyyyy out in my back yard.

Yeah, well my car in my garage is about 30 feet from my bedroom. Its as likely (if not more so) to explode as a drum of toluene.

Here's a place in upstate NY:

$175 for a 55 gallon drum. My guess is that you also have to pay sale tax on this. Even if adding toluene is safe (sounds like it's not likely to damage most engines/fuel systems), I have my concerns. It might cut the concentration of detergents and other additives in the fuel slightly. With a 55 gallon drum, I'd be worried that it might also degrade in storage or the drum takes in moisture.

However - the price of premium unleaded in parts of California is now about $2.50/gallon. The price of toluene isn't much more for something that's used in relatively small quantities.

Why bother? My 2004 Forester runs fine on 87 octane gas -- even 85 octane as sold in some western states.

Bill

Anybody know what chemical and in what amount is needed to raise octane from 93 R+M to, like 96?

The difference here between 89 and 93 is about 0.10$/gal. If I try to do the same thing with octane boosters, the added cost would be closer to 0.50$/gal. Meethinks somebody is getting rich, and I don't want to help them.