av gas

[strokeracevt]

I just bought a newer boat with an 01 f115. I was previously a merc owner. Thanks to this site I was able to fix a lack of power problem by installing cleaned injectors and servicing the VST. It made a huge difference. I drained all the fuel from the tank yesterday as the boat was not used often by the previous owners. Here in Mass we have no ethanol free fuel so my only choice is to use 100LL avation gas from the local airport. What do you guys think about this fuel? Does anyone have any first hand experiences with it? Thanks in advance.

[boscoe99]

It will cause your motor to run like crap. It will severely foul the spark plugs with lead. It is full of lead.

Your owner's manual says to use unleaded fuel only.

[strokeracevt]

Thanks for the reply. Did you try to use av gas yourself? I understand that the lead is a type of lubricant and it can foul plugs more quickly than usual.

[boscoe99]

I ran it in my 1965 Ford Falcon back in the seventies when there was little gasoline of any kind available. My plugs would foul about every 150 miles or so. Even though the engine was rated for leaded gasoline.

They call it 100LL for low lead but that is just in comparison to previous grades of av gas. It still has plenty of lead in it but just not as much as there once was.

[strokeracevt]

The formulation of the fuel that you used in your car back in the seventies is different from the formulation of 100LL sold at airports today. As much as the ignition system used in your falcon is different from one in a newer Yamaha outboard engine of today. Thanks for your opinion, anyone else?

[99yam40]

If you feel like it run in your motor it even though Yamaha does not say to run that high of octane fuel and you have been told by someone it is not a good idea and let us know how it turns out for you.
We are always open to new ideas as we cannot get ethanol free fuel in a lot of places today

[boscoe99]

Certainly the ignition system on my Falcon was old school. Points and plugs.

It was the same av gas however, 100LL.

Car was designed to run on leaded gasoline. Just not with the levels of lead that are in 100LL.

I like "sperimenters". You go first and use it in your Yam and let us know of your test results.

[rodbolt17]

biggest difference on ign between that old falcon and the TCI system used on the EFI motors is ign coil primary current is switched OFF with transistors instead of point contacts.
both systems can generate upwards of 30 Kv.
now to the av gas.
will run like crap at high RPMs as it burns to slow.
that's when the plug,valve and piston skirt fouling issues appear.
back in the day my 455 olds with 11/1 TRW forged pistons liked 110 AV gas.
however at about 9/1 it wont like it.
most aircraft engines typically turn less than 3000 RPM that F115 likes to turn 5800-6000.
its your motor though,if you try it tell us how it does.

[robert graham]

And at $5.00 to $6.00/gallon for av gas, it's bad enough keeping my tank full at say $3.50/gallon at the pump....

[TownsendsFJR1300]

You didn't ask, but you can run ethonol fuel in the engine, if non-ethonol is not available.

Its not preferred but with a water separator and a good additive, specific for ethonol fuel in the marine application, it should work fine and be a whole bunch cheaper without the above listed problems...

IME, (2.5 years of using it with ethonol fuel) this product (K100) along with Non-ethonol fuel got rid of all the water in my built in tank. Others will disagree however, before hand, I would drain the VST and get cloudy, fuel(water in it) before using the product.

After using it and Non-ethonol fuel, absolutly NO water in the VST, clear as if purchased yesterday. It took awhile but the tank is 1997 vintage, NEVER been drained or removed..

It doesn't remove the water, it just keeps it in suspension so its burned off as the engine is run. Its also a stabilizer.

K100 : Fuel Treatment, Fuel and Gas Additive | K-100 HOME

Video: Demonstration Videos | Kinetic Fuel Treatment

[amahaork]

<<Thanks for the reply. Did you try to use av gas yourself? I understand that the lead is a type of lubricant and it can foul plugs more quickly than usual.>> Lead is additive to increase detonation resistance, not a lubricant.

[boscoe99]

You are correct that lead is added to av gas to increase the octane rating but the lead does act as a lubricant of sort. It helps to cushion the seating of the valve onto the valve seat. Maybe that is not an intended purpose but it is a beneficial side effect.

99.9% of all outboard motors run just fine on ethanol contaminated fuel. I have never had a single problem with ethanol myself.

I would take my chances with ethanol long before I would pay extra money for av gas which in my experiments proved it to be a waste of time. I only used it in the first place when I could not get any automotive gasoline at all, because of the gas shortage at the time.

I take exception to the "burns slower" myth. Which I would say is an internet myth but it was a myth long before Al Gore invented the internet. Tested it as well. 93 octane creates the same power as 87 octane which tells me there is no change in the burn rate.

[rodbolt17]

boscoe
its not an internet myth.
in fact on the old 225 excel Yamaha had to put out a bulliten about power loss using octane ratings over 89.
you aint got much sperience does ya?????

the higher the OCTANE rating the SLOWER the fuel burns BEFORE detonating like a BOMB.
kinda like the difference between a slow burning smokeless poweder,like IMR 4350, and black powder.

now we have a short stroked fairly low compression engine that needs to turn 6000 RPM.
95 octane simply burned to slow and had performance issues.

go back to the books dude.

we wont even try to confuse you with reed vapor pressures at various altitudes.
mostly boats operate below 10,000 ft.

most auto/marine fuels are blended to properly atomize at less than 6000 ft.

[almetelo]

Hi!

Dont want get out of the thread...
Here we just have 95 em 98 octane fuel and no ethanol so far ( a couple of years ago we had 100 octane fuel)
most of US here have the idea that higher is the octane better is the fuel burning (or can get more power if I can say so...)
Many guys use just 98 octane fuel on their bikes and they say that with 95 octane fuel the bikes dont work properly... Why?
Once tested 95 octane and then 98 octane fuel on my F100 at WOT and couldnt notice any diference...
I always use 95 because is cheaper (and seems to be even more apropriate, right?)
My Yamaha X-MAX also runs really good with 95)

[boscoe99]

Hi!
Once tested 95 octane and then 98 octane fuel on my F100 at WOT and couldnt notice any diference...

I ran an F70, an F150 and an F200 (I4) first using 87 octane and then using 93 octane. No performance difference whatsoever. Same WOT RPM, same WOT boat speed.

If, and I say if, the 93 octane burned slower then the WOT performance should have been reduced. The advance timing stays the same so if the fuel burned slower then the peak cylinder pressure would occur later in which case power would be down. Did not happen.

Here are some snippets from two fuel suppliers with respect to octane and the "slower fuel burn" myth that once started, cannot be over come. People here it from what they believe to be knowledgeable sources and then they believe it and pass it on.

It would be (is) silly to think that a race engine turning 9000 RPM and more would be using a higher octane rated gasoline that burns slower than normal. At 9000 RPM plus there is a lot less time for combustion to occur. The gasoline only has X nanoseconds to complete its burn in time to provide maximum power.

From Whitfield Racing Fuels

OCTANE NUMBER:

The octane number of a gasoline has little to do with how fast it burns or how much power the engine will make. Octane number is the resistance to detonation. If the octane number is high enough to prevent detonation, there is no need to use a higher octane gasoline since the engine will not make any additional power. Octane number is not related to flame (burn) speed either. Variations in octane quality are independent of flame speed.

From VP Racing Fuels

What does octane really measure and how important is it?

One of the most frequently asked technical questions we get at VP involves the difference between Motor, Research and R+M/2 Octane Numbers. The next most frequently asked question is why some fuel companies represent their fuels with Motor Octane Numbers, while other companies use Research or R+M/2 Octane Numbers.



Realize first that octane is a measurement of a fuel’s ability to resist detonation—nothing more.

But I will not continue to argue/debate the subject. Minds are made up and won't be confused by facts.