The Stovebolt Site Forums The Shop Area Engine Shop High octane fuel in a 235

I use ethanol free gas in my '59 235. My usual supplier ran out so I Bought some from the local airport. What they had was 100 octane. Is there any reason not to use such a high octane fuel in my truck?
I don't know much about octane. What I have heard is that the higher the octane the lower the volatility of the fuel.Is that correct?---Jack

Expect less power and fuel economy from the 100 octane in your engine. Try this article:

http://www.thecarburetorshop.com/Octane.htm

Jon

In my 350 I use octane books in it regularly,i like the way it runs on such..I also use lead substitute with good results.

What are "octane books"? I think you may have meant "octane boost" If so is there something that does the opposite? Some thing I can add to lower the octane.---Jack

You probably had some of your regular fuel in the tank when you added the 100 octane stuff so I would just drive it. Carbking's article points some issues that shouldn't affect your 235 too badly. Hopefully your supplier will have the E-Free when you need to fill up next time.

SimS

Come on guys, no matter what BP says about their fuel, it's
not going to 'Invigorate' your 235.
Aviation 100 - 130 octane fuels are and were formulated with
a low vapor pressure to cope with the altitude changes and the
requirements of high compression air craft engines. It did't
give them more power any more that it will give your Stovebolt
more power. It simply prevents vapor lock or pre-ignition.
Your low compression stovebolt engines needs nothing more than
a regular grade of fuel to run at their peak performance
level when they are kept in tune.
There is nothing wrong with running the E-10 fuels in your
Stovebolt and no need to gunk up you combustion with octane
booster additives. High levels of alcohol such as E-85 or
straight alcohol will cause problems with older seals,
diaphragms and alloys, but most of the materials that are on
the market now are resistant. E-10 is not that high of a
concentration that it would eat away your engine parts.

99% of the fuel being pumped today is an alcohol blend and
millions upon millions of cars throughout the world run it
on a daily basis without falling apart.

So...lets get real and start looking elsewhere if our
Stovebolt misses a beat or won't climb the hill to home.

Denny Graham
Sandwich, IL

High Octane is for High compression(we ain't got much). Slower burn to prevent pre-ignition. Won't hurt. And it won't help. A lot of air craft engines are air cooled. They tend to run hotter than water cooled. Typical hot spot for air cooled is the exhaust valve. It can light off the incoming air/fuel chsrge and cause pre-ignition. So high Octane for them. Slower burn and lower combustion temps might help at 12:1 but we see something like 7.5:1 so not gonna do much for us. Lower temps means less working pressure to move the piston. So less work per gallon means worse fuel mileage. Match "octane rating" to compression. Low for low compression engines( like truck and lawnmower) and high "octane rating" for high compression(like modified engines and air cooled motorcycle).