Back when i was running 11-1 compression , I sometimes went to my local airport that would sell thier 100 octane gas for high perf. cars and boats. It made a difference . I dont need to do that anymore since the motor was rebuilt to 9.6 cr ...but, i was wondering if any of you have tried AV Fuel ? I dont think theyre supposed to sell that for cars and boats since there is no road tax figured into the price ; at least thats what ive heard.
Problem #1: Your local airport WILL NOT pump AV gas into your car. If you know someone who works there, maybe they will fill a jerry can or two for you, but don't think that you can just drive up and get in line behind that pretty lear jet. Problem #2: Av gas is leaded and tetraethyl lead poisons catalytic converters.
I certainly hope that you don't pump aviation fuel for a living.
Avgas is 100LL or low lead; not your leaded gas of yesterday. It's a great high octane fuel for high compression engines, for both aviation and road use. I doubt that any modern automobile will get an Avgas tanker nozzle in it's filler neck, so don't worry about the other guy's converter.
As I recall, Dave's vette is around a '69 and pre-catalytic converter. I don't think the lead is an issue with his vette.
Note: If you put Avgas instead of Jet "A" fuel in my Lear Jet, I'd be sticking the nozzle up your tank.
'Problem #1: Your local airport WILL NOT pump AV gas into your car. If you know someone who works there, maybe they will fill a jerry can or two for you, but don't think that you can just drive up and get in line behind that pretty lear jet.'
Reply: I used to just pull right up to the pump and pump it myself. After i paid, the guy here would always tell me to 'have a nice day' even.
'Problem #2: Av gas is leaded and tetraethyl lead poisons catalytic converters.'
What I have seen and heard, is that you take a racing fuel jug and get them to fill it up and if they ask any questions, you tell them you have a home built rig, or ultralite and can't fly in to their location. It works... Jim
Many GA (general aviatiion) airports now have self-serve pumps so you may not even have to interface with anyone. Depending upon the airport and security arrangements, you could drive right up on the ramp to the pump and pump it yourself. (Watch out for those spinning propellers.) The smaller the airport, the more likely it is you can do this. Although, Taos for example, does have an electronic security gate. And that's about as low-traffic a place as it gets. On my last cross-country flight about 2 weeks ago, 100LL in Boulder was $3.65/gallon and $4.48/gallon in Utah, Nevada and Northern California.
We use AV gas in one of our race cars. Just go to the pump, swipe the credit card, fill a 20 gallon drum and drive off. No problem. We find our car is more consistent on AV gas than racing fuel. And, they call it low lead, but compared to yesteryear's car fuel, it's not low.
Back in the mid-50s I was driving a '51 Olds 88 'vert (303 cid) with milled heads, compression ratio probably near 10:1. It "cackled" on either commercial premium or 96 octane (blue) AvGas. Green, 100/130 was about right in that engine and gave a plug life of about 5000 miles. Green wasn't pumped too often on that base--we only used it in a couple of C-45's (called them SNB's). Purple 115/145 was easy to come by--the fuel farm pumped thousands of gallons every day (and a few hundred gallons of "spillage" and "evaporation" each week wasn't a problem). One of the fuel guys suggested I try a tankful. Nice and quiet but plug deposits were a problem. After two plug changes in three months, I re-gasketed the Olds & sold it. Two cars later I got my first 'vette but never lurked around the fuel farm with that car -- the red 'vette was not as 'subtle' as the pale green Olds. :-)
Interesting point with both fuels was that spark could be advanced to the point of diminishing returns without any ping. The Olds didn't really exploit the capabilities of either 100/130 or 115/145.
I have used the aviation gas. 100 octane low lead as they call it has more lead in it than automotive fuel ever had. The only down side to the aviation fuel is it is formulated for air cooled aircraft piston engines that are designed to use just enough oil to keep the upper cylinders lubricated. Avgas is very dry and will wipe the oil film from the cylinder walls of a automobile engine which in turn causes premature ring wear. I mixed a little two stroke engine oil with the gas to help prevent damage. Also, aviation engines have duel ignition systems for safety reasons one of them being lead fouling of the spark plugs. Not a big issue in a car but in plane it is a little hard to pull over at 10,000 feet and change a fouled plug.
Leaded autogas typically used a lead content of two to three grams / gallon. Current formulation of 100LL AVGAS uses 0.57 g / gal. This is why most air-cooled piston aviation engines can be STC'd to use 'unleaded' mogas.
Piston aircraft engines' upper cylinders are lubed about like those in cars - oil from the sump. Piston skirts and cylinder walls are lubed (and in part cooled) by oil jets, valve gear by oil pumped into the heads. Lead additive in gas does not lubricate any part of an aviation piston engine, including (contrary to myth) valve stems or seats. AV engines use nice hard valve guides and seats, and often sodium-cooled exhaust valves, to let the oil do its work. Note also that essentially all piston aviation engines can be STC'd to use 80/87 low-lead mogas, and this obviously could not be done if aviation engines really needed more lead in ther fuel.
Then it'd also tend to remove oil coatings in aviation engines, which it does not.
In over thirty years of flying piston-powered airplanes I have seen exactly one fouled spark plug, and it was not lead-fouled. I have never heard any case of an aviation spark plug becoming lead fouled.
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