Reply With QuoteI mix 1/2 super unleaded and 1/2 Av gas.Any small airport will have it and will let you pull your boat in.Av gas has a real good record in outboards.
i can only get 91 octane fuel where i live do i buy race fuel or octane boost to get over 94 octane where i need to be what is the best way to go
I mix 1/2 super unleaded and 1/2 Av gas.Any small airport will have it and will let you pull your boat in.Av gas has a real good record in outboards.
What is the compression on your motor?
Originally posted by HavasuDreamin':
What is the compression on your motor?
it is under 130 psi
No need for av-gas, just run 91 consistantly, no 89. Stock Mercury (at least 2.4 Litre Carb Motors) compression is 125 psi, and my ran fine on 92 for years. Not until you get up around 140 or so would I consider mixing 50/50 (av-gas & 91). However, this is not to say you couldn't get some bad gas and do some damage, but I never had any problems. Good Luck
You can run up to and over 140 psi on 91 oct, 130 you can even get away with 87 if you have to. AV FUEL IS THE WORST THING YOU CAN DO TO AND OUTBOARD----NEVER EVER RUN IT. Consider this, AV fuel was designed for an air cooled 1000 foot per min (piston speed)4 cycle that cannot have a spark plug foul. The fuel has a chemical in it that is designed to disperse oil (and adding a lot of oil will not stop this). Consider that the motor in question is a liquid cooled, 3-4000 foot per min motor that require oil in the combustion chamber to run.
If you have ever heard the term "AV runs dry" that is why. It will cut your motor life in less than half.
ET
H/D, I have a 300promax stock and it calls for 92 octane and az. at martinezonly has 91 and i will run all the 92 i truck in and was going to add av gas to bump the octane but it sounds like i should run maybe a trick addive instead what do you think . S/P
I don't care what the compresion is,all you guys with outboards should run 93 octane or better.The next time you go into your local outboard shop and see an outboard being rebuilt ask them what happened?Fiftey percent of the time it's piston failure due to bad gas.I've logged thousands of hours on all different kinds of outboards and have never had fuel problems.I've been running
50-50 for 10 years now.If you have 40 gallons of fuel in your boat and av gas is on average .40 more a gallon that's only 8 bucks a tank.One motor rebuild can be 4k.Eight bucks or 4k,hhmmm.Do yourself a favor,spend the 8 bucks now.
If you are paying 4 k for a motor rebuild, I will do them all for you.
The piston failures are not anything to do with detonation, they are the ring locating pin failures. This is caused from poor design and high rpm. If for even a few seconds you detonate an outboard you WILL have a hole in a piston.
AV will do a lot more harm than good.
I have been doing this for 22years and have a few world championships to qualify that with.
Anything und 130 can run on 87, under 140 on 89, and under 150 on 91. Timing and jetting are key.
ET
Capitalist,you have not convinced me yet.I talked with Lake X yesterday and they say everything you are saying about psi and octane.However they had nothing bad to say about av gas in outboard motors.With the amount of av gas I have ran through I have never had a problem.You do bring up some interesting points though and maybe I need to do a little more investigating.
Posting Permissions