OldSchool

I stopped by the local airport today and asked if they would sell me AV gas and the guy said yes. It's 100LL (I'm guessing that means low lead??) and $5.00 a gallon. He said that it is good for at least two years

My question is this. Can it be mixed with E-10 93 octane gas or do you have to run it 100% by itself? I certainly don't need 100 octane.

Next question is would mixing the AV gas with E10 gas make it better that just straight E10 93 octane. It's my understanding that the octane points drop after 2-3 weeks with the E10 whether it's treated or not. The guy said that each load that he receives has a spec sheet that come with the fuel. This load that he just got is 109 octane.

Thanks in advance,
Craig

BY U BOY

At the begining of every summer i add 10 gallons of 118 to my tank and top off with 93 E 10 and the engine loves it. I am running almost 11 points compression though.

RunninHotRacing163.1

You can add it right to your existing , we top the Skater & the Lambo with 100 and no problems to date except the airport frowns on filling the cars cause theres no road tax and tell us to fill barrels or come at nite ..

pslonaker

iTrader: (1)

You can mix it however you want and then guess your percentages to get the octane rating. The dude that told you that the latest batch of av-gas was 109 is full of it. 100LL is the highest it can go according to the Federal rules...might be a good idea for one to read the rules on av-gas...the fines can be quite healthy. If it is 109 and they get caught...somebodys butt is in deep ca-ca.

Another problem you shoould be aware of is not...""NOT""...get caught putting the 100LL in your boat or your car...anything other than an airplane by the Fereralies. You as well as the person that sells the gas to you will be in deep ca-ca. I agree with the bring a container, barrell or whatever and go at night...late night.

And the "Queen-Mother" of some people and their bright ideas...dont let some smuck talk yoou into running JP-4...aka...Jet fuel. You will be damn lucky to even get the motor to sputter...let alone start. JP-4 is just high grade kerosene.

And mixing Nitro- meth with your gas is another funny...it separates itself just like oil does in water.

Yes I am a pilot...15,000 + hours.

Chris Sunkin

Av gas is formulated for air-cooled engines running steady RPM at altitude (thin air) and is less than ideal for automotive use. That's why the racing gas producers make specific motor fuels- and in many different variations for different uses.

No fuel is "good for two years". Fuel lifespan is relational to its compounds and how it's stored. Keeping fuel in plastic containers for even a couple of days allows them to degrade. Stored in airtight metal containers with minimum airspace, fuel can last for years.

Mixing gasoline can be hit-and-miss. Too much octane can be as much of a problem as not enough. On the other hand, if you're tuning for maximum output (high compression and lots of timing) and "guessing" at your fuel- especially batch-to-batch, you're playing a dangerous game with your motors.

WildWarrior

Chris is right aviation gasoline is blended specifically for use in small aircraft. It's also commonly used by many high performance engine owners because of it's high stated octane rating (usually 100-110) and the relatively low price compared to racing fuel. Unfortunately this fuel is not all it appears to be. Av gas octane is rated on a different scale than gasolines intended for ground level use. What is 100 octane "av", is not necessarily 100 octane "ground level". Besides this, there is also a big chemical difference. Normal ground level race fuels are made up of gas molecules that have a "light end" and a "heavy end". The light end of the molecule ignites easily and burns quickly with a low temperature flame (as a piece of thin newspaper would burn). The heavy end of the molecule is not so easily ignited, but it burns with a much more intense heat (as an oak log would). This heavy end of the gasoline molecule is responsible for the hotter, more powerful part of the combustion process.

Small aircraft are constructed as very weight conscious vehicles. That's because their somewhat weak engines often have difficulty taking off with any extra weight. To help reduce this weight problem, av gasolines are blended with no heavy molecule end. This makes a gallon of av gas weigh substantially less than a gallon of ground level fuel. Since small plane engines turn very low rpms and produce so little power, the omission of the heavy end is not a horsepower issue. However, for high output pwc racing engines, there is defiantly a compromise in power. This, despite the fact that many pwc owners experience the desirable cooler operating temperatures that "av" gas offers. In addition, some blends of av gas will quickly separate from some oils used in premix situations.

Despite all this bad news, running av gas (accepting the slight power loss) is usually a better choice than

burning down a high output engine on regular pump gas. In this situation, the best choice is usually a 50/50 mix of pump and av gas. That provides "some" heavy molecule ends for the engine.

OldSchool

Thanks for the advice. As I said, I don't need the octane. I have N/A motors that are 9.5 to 1. What I do like is piece of mind of it being better quality that that E10 Chit that they are making us buy. The gas has been in my boat for about 8 weeks because it's been nice all week and pretty crappy on the weekends in my area for the last 8 weeks. I figure that it can't hurt to put 50 gallons of it in there with the 200 gallons of 93. We'll find out!! I've put 4 hours on my boat this year....the weather report looks great for this weekend. I'm looking forward to it!!


Craig

handreasen

Ran blown 502 @ 6# boost here in AZ, ran nothing but AV gas purchased at local municipal airport. This motor had over 275 hrs on it when I sold boat. Never had detination issues to motor even with 115-120 degree days in the summer. EGT's would never exceed 1300 - 1325 at any time.
Fuel was purchased and boat filled at airport, only exception they had was a 50 gal min. requirement.

hoozeyurdaddy

what is substatually less as far as fuel weight, avgas is 6.5lbs per gallon, what does auto gas weigh, some what weak engines? 540ci 6 cylinder engine, 2700 rpm, 4000lb plane and 200mph, what do you figure the torque is on that engine???

HUSTLEthis

We run it in ours all the time too...sometimes I mix it, sometimes straight...Have over 280 hrs on our engines now..
I do the same thing..pull right up to the pump...your engines will love it...and it's cheaper than the desiel I put in the Excursion now...plus over here in Cali we only have 91...