Gasoline

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All

I was wondering if anyone is using aviation gas 100 octane in your vehicle? If so have you noticed a significant improvement in operation or is it a determent?

Thanks

Tim Jones

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Hello Tim, I use ethanol-free gasoline as much as I can. In my part of Michigan, boating in the summer, motorcycling, snowmobiles and other recreational vehicles are plentiful enough that the demand for ethanol-free gasoline is available at several stations in the surrounding counties. http://WWW.puregas.com it think is one of several websites that provide locations of stations that have ethanol-free fuel.

Aviation fuel is my choice for fuel when putting the cars up for the winter months. the ethanol-tainted gasoline does not stay stabile for a winter usually, even with one of the fuel stabilizer products added to the tank. Regular ethanol-free fuel does very well, but aviation gasoline is the best.

Aviation fuel is virtually a synthetic fuel. The fuel has to be stabile and remain so for several years in an airplane’s fuel tanks, and small airplane’s fuel tanks are vented to the atmosphere, just like our older cars systems are. So the aviation fuel must not absorb water from humid air, causing reduced power and accumulating water in the tanks. And aviation fuel has to be consistent in performance, even with winter and summer conditions.

Ethanol-tainted [actually more of a contamination] does not work well in our low compression engines in Pierce Arrow cars. There was a study done by some old car folks, I think they were carburetor restorers, but that may not me right. They ran several engines on ethanol-tainted fuel, then on ethanol-free fuel and compared the results. The engines were run on dynamometers to test for power, and the engines had full instrumentation and added external temperature sensors.

What was discovered is that 10% ethanol-tainted fuel reduced the power by about 10%. The engines ran hotter, and especially the exhaust manifolds ran much hotter.

It has been suggested that in such a low compression engine, that the ethanol does ignite, but burns slowly, providing little if any horsepower, and has not burnt completely by the time it leaves the engine and exits through the exhaust. This is what causes the hotter engine temperatures. Ethanol needs very high compression ratios to burn explosively, ratios up around 14 or15:1. Our Pierce engines are roughly 4:1 or 5:1, some in the last few years are 6:1.

With 10% ethanol the engines make 10-15% less power. The ethanol just burns slowly and the heat and burning ethanol just go out the tailpipe.

When burning pure gasoline, all the fuel will burn in the engine’s cylinders and provide power.

I have noticed that my Pierces do like the pure gasoline. The engines have more power and run cooler.

Aviation fuel had high octane ratings, and we certainly do not need high octane fuel for our low compression engines, so it might not add as much power as the pure gasoline, but will certainly provide more power than ethanol-tainted pump-gas.

Greg Long

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Excellent read gents.

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I agree with using pure gas, no ethanol, there are a couple of local stations that sell it. It’s about 10% more expensive, maybe a little more, but it can last a little longer and gives more power, so worth it.

The real caveat with using ethanol laden gas is storage. I have a friend, called me up a while back, had two GTO’s sitting in storage for two years. Wouldn’t start, told him he’d have to remove gas tanks and have cleaned, and go through fuel pump and carb. He laughed and said I was crazy. A month later he called and asked “how’d you know?”.

Ethanol will go bad so, so easily.

All gas is different now than it was when these cars were new. I’ll put in a plug for John Cislak, he rebuilt the carb and fuel pump on my ’31 phaeton, made some jet adjustments for the new gas, I’ll tell you, it’s a different car….sounds better, more power, the whole bit….a real difference…..

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Experience has taught the Gilmore Car Museum to use Aviation fuel exclusively in the museum cars. I use it in the Pierce-Arrow Museum cars whenever possible before putting cars back into the building after exercise. Non-ethanol premium is just as good when touring, but for long term inactivity aviation gas can’t be beat. I personally use non-ethanol premium (usually 91-94 octane)in my own vintage cars whenever possible. Both our 8 and 12 P-A’s are MUCH happier than when we are forced to use a 5 to 10% ethanol mix. The east coast ethanol seems to be particularly awful…maybe a higher percentage than here in the midwest?

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Tim,

Check out this website for Ethanol free gas sellers in Maryland.

For others, the site is just: PURE-GAS.ORG

Peter

http://pure-gas.org/index.jsp?stateprov=MD

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Great discussion.

How and where do you buy aviation fuel?

I mean, at least here in New York I think you cannot drive up to an airport and fill your tank because there is no “road tax”” added into the price. Just like how we can’t buy kerosene for a vehicle — the stuff is dyed red because they don’t trust us.”

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Hello Scott.

To purchase aviation fuel I explain that I’m using the fuel for the storage of antique tractors, chain saws, weed string-trimmers, and off road quads and snowmobiles. I do not mention cars or motorcycles on the roads.

I purchase several 5 gallon cans at a time. Some fuel retailers will sell to ‘drive in’ customers, some won’t.

You may have to find a smaller airfield or try several different aviation fuel retailers.

For ethanol-free gasoline, if you do not have any regular fuel stations that have a dedicated pump, look up fuel wholesalers, they would be the heating oil suppliers as well as the companies that fill farm fuel tanks and large company fleet fuel tanks.

The fuel wholesaler I use at my farm will allow me to go to his location and buy pure gas. I do pay road tax on the fuel. But I do not pay road tax on my farm diesel fuel. My fuel wholesaler told me that he sells a lot of ethanol-free farm gasoline as well. I did not ask him if it is dyed red like the off-road Diesel fuel.

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100LL (low lead) aviation gasoline is sweet stuff and actually has 2 gms/gallon lead if I remember correctly. I used to use it as an additive to prevent valve recession – actually for a while I could get 145 octane purple used in the air racers which had 4.6 gms/gallon and required less to get some lead.

Selling to someone to use as an auto fuel puts the seller at serious legal risk for not paying road tax, however, and to use 100% av gas is going to require serious amounts of it. A person might have to rent an airplane and fly it to a private airfield to drain the gas, and then the risk is on them.

I would be interested in seeing the comparison of ethanol blend on antique cars and the rise in exhaust manifold temperature. If you ignore the rubber deterioration, water pick-up and corrosion problems ethanol is an excellent fuel, burns clean with very high octane rating – more than 6/1 compression ratio engines have any use for. There is a fundamental reason gas mileage goes down, pure ethanol has less energy per gallon. Attempts to use it in aircraft run up against this fundamental problem that range drops by 30% or more.

I think the fundamental reason that exhaust temperatures would go up on antique engines is because they tend to be set up quite rich – particularly 8’s and twelves. A problem for carbureting long multi-cylinders is getting a consistent mixture both near the carburetor and at the furthest cylinder. The fuel tends to drop out on long intake lengths and makes the far cylinders run leaner. To make sure everything fires smoothly the mixtures are set rich. They become really rich when the booster valve opens up. I once measured the Air-Fuel ratio of my Packard on the highway and anything above 50 would open the booster valve and pegged the meter at 8/1 (15/1 is stoichiometric). 8/1 is similar to what aircraft use for takeoff to keep from detonating (knock) at max power. It is using excess fuel both as internal coolant and knock suppressant. Such rich mixtures on a 6.5 compression engine were probably needed when gasoline octane ratings were so low. In 1935 average gasoline octane was 72 and “ethyl” was 78.

What does this have to do with alcohol? Besides having a lower ideal Air/fuel ratio to start with, alcohols chemical makeup includes oxygen, so it adds to the total oxygen in the combustion chamber when it fires and will burn more completely. That is my theory why exhaust manifolds would heat up. In an over rich mixture the added oxygen burns more of the gasoline. Since the octane rating is higher, the timing could be advanced significantly to compensate for the increased exhaust temperature and increase power. Our low compression engines could probably be advanced further than the point where there is actually any gain in power. Note retarded timing and lean mixtures drive up exhaust temperature and is hell on valves.

I am not too sure that our current problems with exhaust boiling out of the carb on hot days is entirely from ethanol. I think it might have to do with the vapor pressure limits implemented by EPA and has forced the refiners to have very high fractions of light distillates at the vapor pressure limits and small or no fractions of the heavier distillates. It is the heavier distillates that don’t boil out as readily when hot. My theory that I haven’t really researched yet, others probably have.

Jim

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FYI-I checked the ‘pure-gas’ website and find about 1/2 dozen vendors of real gas a few miles from down town Buffalo. Great news for our meet in a month! All the lakes in that area, boats, jet ski’s etc. and it’s really no surprise.

John.

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Just a thought,

If you took a 5 gallon gas can of the alcohol blend and put in a quart of water, then shook up the contents would the water absorb the alcohol and settle to the bottom. Then decant off the pure gas? Jim

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No Jim, that won’t work. You can filter the alcohol out with a filter. They sell a kit to do just that. You place 10 gallons of fuel in a small portable tank, turn on the pump, presto……..gas with no alcohol. You just end up with crappy modern gas and still have the low boiling point, but get back the lost BTU’s.

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Here is one article I’ve read regarding re-jetting carburetors to compensate for the lower BTU content of Ethanol-tainted gasoline.

In this article the author states that the engines run lean on Ethanol-tainted fuel and the lean mixture creates a hot running engine.

http://www.thecarburetorshop.com/Ethanoluse.htm

Greg Long

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All

Since I posted this question there has been a wealth of information shared.

To answer a couple of questions there is a small airstrip near me in Md that will sell av gas. He sells to a group of fellas that use it in their antique tractors. However on the way home from Ocean City Md this past weekend I was able to buy non ethanol gas. I intend to run the gas out of my Seagrave and while doing so take exhaust manifold temps. I will then refill it with the CLEAN gas and see what those temps are and report to the group.

Once again thanks for helping out a Seagrave guy.

Cosgrove

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Timothy, that is a great plan. Please do share the results.

Best-John

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