compression and race gas?

[wired247]

That's funny I've been told the opposite, that it's exactly at 100 because it's very controlled due to the fact it runs in aircraft.

Airplanes dont use AKI as a rating standard like we do in the US as pump gas. Its sort of like when Europeans and Australians brag up how they get 97 octane out of the pump. We call that 92 octane. They use RON as a standard. AVGAS is 100 octane RON. RON+MON/2=AKI.

[Corona Mike]

Airplanes dont use AKI as a rating standard like we do in the US as pump gas. Its sort of like when Europeans and Australians brag up how they get 97 octane out of the pump. We call that 92 octane. They use RON as a standard. AVGAS is 100 octane RON. RON+MON/2=AKI.

May Be But, They Are Running Av-Gas...100 L.L. In Europe In The F-1 Boats. Why? Because They Use The Same Formula Around The Globe. Now, I'm Pretty Sure The Fuel Does Make 100-OCT. I've Run It In A Drag Motor With 26 C.C. Heads Making A Little Over 190-lbs Compression Without An Issue. Brendon Power Is The One Who Told Me That That Is The Fuel They Run When They Run Either Over Here Or Over There Because It Is The Same Here As Over There. Now, Back To The Guys Original Question...You ARE Plenty Safe @ 165-lbs Of Compression Using A 50% Mixture Of Av-Gas...

[wired247]

May Be But, They Are Running Av-Gas...100 L.L. In Europe In The F-1 Boats. Why? Because They Use The Same Formula Around The Globe. Now, I'm Pretty Sure The Fuel Does Make 100-OCT. I've Run It In A Drag Motor With 26 C.C. Heads Making A Little Over 190-lbs Compression Without An Issue. Brendon Power Is The One Who Told Me That That Is The Fuel They Run When They Run Either Over Here Or Over There Because It Is The Same Here As Over There. Now, Back To The Guys Original Question...You ARE Plenty Safe @ 165-lbs Of Compression Using A 50% Mixture Of Av-Gas...

It is 100 octane. Its just not 100 AKI octane. Its 100 RON octane which is the same as a 95-96 US AKI octane rated gas. They call it 100 octane in Europe and they call it 100 octane here but they dont use the same rating system we do in the US for pump gas. Ive run the stuff in 13:1 race motors with lots of cam overlap and aluminum heads and it runs just fine but its nowhere near the octane of 112 race gas ( also RON rated ) or any other real race gas. 100 AKI would be 104-105 RON octane.

100LL at 1.2 or so grams per gallon does have a low tetraethyl lead content compared to race gas at 8-10 grams per gallon. It is better for sure for some purposes than standard super unleaded but its not going to give 95 octane as an octane booster unless its run straight. I think where people get confused about the stuff is they factor the MON conversion instead of the RON conversion to AKI and it makes it look like the 100LL is 110 AKI octane which it is not.

EDIT...


Nevermind. I'm wrong. Called a fuel guy I know. It is MON rated which would put AVGAS in the 108-110 rating for AKI.

[capnzee]

What is best way to lower my compression if I wanted to? Thicker gasket on shaved head or stock heads and gasket? Not sure I want to worry about high octane fuel it's just a fishing boat!!!

GO STOCK AND QUIT WORRYING ABOUT IT . SOMEDAY YOU WILL FIND YOURSELF OUT ON THE RIVER IN NEED OF A LITTLEGAS TO GET HOME ON AND YOU WILL BE DAMN HAPPY YOU HAVE STOCK HEADS. WHY SUFFER THE COST AGGRRAVATION AND WORRY OVER OCTANE NUMBERS WHEN IT ONLY MEANS A FEW MILES AN HOUR ON A GOOD OL' FISH'N BOAT? fISH'N S SUPPOSED TO BE RELAXING!

[powerabout]

When it was legal to use on US waterways Merc listed av gas for use in their race motors
best comparison is here
http://en.wikipedia.org/wiki/Octane_rating

[gregt909]

I mix 100LL with 93 just to minimize the ethonal in the fuel. Is there any problem with the lead in the fuel?

[rcfreek]

GO STOCK AND QUIT WORRYING ABOUT IT . SOMEDAY YOU WILL FIND YOURSELF OUT ON THE RIVER IN NEED OF A LITTLEGAS TO GET HOME ON AND YOU WILL BE DAMN HAPPY YOU HAVE STOCK HEADS. WHY SUFFER THE COST AGGRRAVATION AND WORRY OVER OCTANE NUMBERS WHEN IT ONLY MEANS A FEW MILES AN HOUR ON A GOOD OL' FISH'N BOAT? fISH'N S SUPPOSED TO BE RELAXING!

thats what I am doing changing the heads to stock at river ranch!!or run aces 4 and leave heads on!!! lol smh

[capnzee]

Smartest thing that has been said on this thread today!

[patchesII]

I've ran all kinds if compression and several different funny fuels in my race boat and if I had a lake boat it would be as stock as the day it left the factory. I'd want it to be able to run on 87 if the need arose

[bigbluechevy454]

I've ran all kinds if compression and several different funny fuels in my race boat and if I had a lake boat it would be as stock as the day it left the factory. I'd want it to be able to run on 87 if the need arose

i agree 165 want be enough for the hassell

[Motv18]

91 should be safe. Depends on porting how hot your exhaust side is yadda yadda

high rpm rpm over the limiter also require higher. The exhaust side gets hotter then the compression ever will so the fuel needs a higher flash point (octane rating)

iso- octane is the only fuel I know that's 100 no matter how you measure it. Hard to find and pricy. Teml fuels are cheaper and easier to find. You just poison everything with lead.

[johnboy 88 vegas]

Was running mine with 155 lbs on normal 93 octane. Put 5 gallons of C12 leaded fuel in when I added the compression after breakin period and could still smell it 2 years later. That extra compression is what makes a light boat fun out the hole and no way I could do without it.

[Onetime]

It is 100 octane. Its just not 100 AKI octane. Its 100 RON octane which is the same as a 95-96 US AKI octane rated gas. They call it 100 octane in Europe and they call it 100 octane here but they dont use the same rating system we do in the US for pump gas. Ive run the stuff in 13:1 race motors with lots of cam overlap and aluminum heads and it runs just fine but its nowhere near the octane of 112 race gas ( also RON rated ) or any other real race gas. 100 AKI would be 104-105 RON octane.

100LL at 1.2 or so grams per gallon does have a low tetraethyl lead content compared to race gas at 8-10 grams per gallon. It is better for sure for some purposes than standard super unleaded but its not going to give 95 octane as an octane booster unless its run straight. I think where people get confused about the stuff is they factor the MON conversion instead of the RON conversion to AKI and it makes it look like the 100LL is 110 AKI octane which it is not.

EDIT...


Nevermind. I'm wrong. Called a fuel guy I know. It is MON rated which would put AVGAS in the 108-110 rating for AKI.

G


Glad you edited your post as you were definately wrong. Avgas is min of 5 points higher then r+m/2. It is also the highest regulated and best quality control of any fuel. It must always meet the ASTM spec for avgas. It has to do with gravity, if you have an engine failure due to fuel in an airplane gravity takes over!

[Mr. Demeanor]

May Be But, They Are Running Av-Gas...100 L.L. In Europe In The F-1 Boats. Why? Because They Use The Same Formula Around The Globe. Now, I'm Pretty Sure The Fuel Does Make 100-OCT. I've Run It In A Drag Motor With 26 C.C. Heads Making A Little Over 190-lbs Compression Without An Issue. Brendon Power Is The One Who Told Me That That Is The Fuel They Run When They Run Either Over Here Or Over There Because It Is The Same Here As Over There. Now, Back To The Guys Original Question...You ARE Plenty Safe @ 165-lbs Of Compression Using A 50% Mixture Of Av-Gas...

Mike, you know breathing that stuff will make you capitalize the first letter of every word. Scary stuff.....

[eli]

100LL is not 100 octane by AKI standards. It is approximately 91 MON or 95 ish by the US AKI standard. You'll never get to 95 octane mixing avgas with pump gas. Avgas is rock steady stabile but it is high in aromatics and can be hard to start straight. I use it in my lawnmower just because I go months between uses and it doesnt corrode the fuel system.

does it mow quicker with avgas lol should try that get er done faster