here are some formula's I came across that some may find interesting,Torque X RPM divided by 5252 equals hp. Hp X 5252 divided by RPM equals torque. I checked it against my dyno sheets and it is pretty close.

OK, I ran the boat yesterday for the first time with the AV Gas. It ran really well. I had 50 gallons of the 100LL and 200 gallons of 93. No huge difference, but I like the idea of having a little lead in there for the valves. :) ;)

in a past powerboat issue "Teague on tech" he said to add a small amount of 2 cycle oil to the av gas for top cylinder lube as the av gas is drier than auto gas , other than that he said it was good to run

Will EGT's be lower using avgas or race gas?

Interesting that Teaque said that.
AV fuel, is designed for a motor that is air cool with a LOW piston speed, ( RPM is kinda a BS number.... it is feet pre second that matters ). Anyhow, AV gas has an additive thats sole purpose is to flash any oil in the cylinder. Fouled plugs in an airplane can't be good. Add that ring wear due to low piston speed isn't much of concern. Now I don't know much about 4 strokes, but I know enough about 2 strokes, and it halves the life of our rings and bores due to this additive...... ever hear the comments on how AV runs dry.... that is why.
Basically... if you need race gas... buy race gas.

Oh and who ever mentioned Nitro Methane... DONT ADD IT TO GAS, IT BECOMES SHOCK SENSITIVE!.
If you want a power increase add Coxoc, or Nitro Propane... but that are BAD for you and anyone that breathes your exhaust.
Tolulone is a good octane booster, about 130 octane... burns real slow.

RT

I know it's a 13 year old thread , but many say AV gas will burn valves and melt pistons in boat engines ....in fact I've run it in my boat (572 cu in engines w/AS&M Efi's )
and reading the O2 sensor showed it was burning lean and if continued would probably do what most people think or say, burn up valves and melt pistons.....I've heard AV
gas burns leaner for a given jet size/injector pulse width compared to auto gas....So wouldn't running larger jets in the carb or slightly longer pulse width for efi injected engines
take care of the "burning up valves" or "melting the pistons" issues?........

And JP-5 (Aircraft Carrier/Navy JP) is even less volatile.

Av gas gives a higher knock point, runs cooler but combusts lean (vs automotive gas), attracts moisture and more expensive/gal....So, to run Av gas, you have to add fuel to keep it from melting adding to the additional expense of the AV vs high octane at the conventional gas pumps. If you are after the av gas for the lead protection, add the additive to your tanks.

The old adage of "Know you limits - stay within it" readily applies to combustion.. Sometimes, it's just simpler to have the boat conservatively tuned to a given hp on pump fuel that you can readily get.

So I've had pump gas go bad in my boat even with the added gas treatment for long stored periods so I like the longevity of Av fuel. but that's not my main reason for asking or wanting to use Av gas.
Although longevity of fuel is up there.
What I'm asking is, Can I safely increase the pulse width on my as&m efi's to safely burn Av fuel without harming my valves or pistons?

I road raced motorcycles and tuned them myself. I used av gas in one of my high compression 600cc bikes. It is definitely something you want to tune for, including adding timing and fuel. It needs more fuel due to the specific gravity and you can add timing because of the higher octane. The only problems it causes long term are with o2 sensors. You will go through them much faster than with unleaded fuel. You current injectors, unless on the high side already, should have enough to tune with the av gas. Not something you just wanna dump in your boat and hope its close enough. Probably would wanna dyno tune it. I have easy access to av gas. Just today I picked up a turbo charged snowmobile that will be running av gas!