Ethanol in Gasoline and Av-gas

LsFarm wrote:The weather here is in the mid 90's, the gasoline is boiling in the carburetor of the 1933 car, it doesn't like gasoline with ethanol in it !!

And no lead, Kind of rough on your valves and seats. I would get a drum of racing gas, the old girl should love that.

I've never had problems with valve or valve seat erosion. I think it is more common with the high compression muscle cars from the 60's.

My '33 Pierce is a 366cu.in. straight eight, with a whopping 5:1 compression ratio!! The cylinder pressures are pretty low, and this seems to help the valve erosion issue. I don't put that many miles on it each year, usually only 1000 or so. I rarely flog it up to freeway speeds. It is happy at 45-55 mph. It has 4.25:1 rear gears, so it is running pretty high revs above 55-60mph. It can do 70mph, but I don't run it that fast.

The alcohol in the fuel is a real problem though, I wish I could drain the tank and put in a load of av-gas, but at $4.90/gallon, and no nearby airport, it isn't going to happen. The car gets around 8-9mpg, so $50 of av-gas doesn't go very far.

Greg L

If my memory serves me correctly The auto companies used hardened valves and seats until sometime in the fifties when they discovered they could use softer valves and seats and use the lead that was in the gas to protect them.

Most older engines I've seen have the valve seats cut right into the castiron block or into the head if it is an overhead valve engine.

If there are hardened seats installed, it is pretty hard to tell if they are original or had been added during a previous overhaul. I know that a seat that is cut into a block or head can't fall out like some inserted seats have!

Greg L

We're getting serious 'thread subject drift' here, I may have to move the car related stuff to another thread..

I forgot about the CR, @ lower CRs the hard seats and lead aren't required. 5 to 1 is pretty low, Rudolph Diesel's coal dust fired engine ran an 80 to 1 ratio. It was powerfull but almost killed him in an explosion, that is how we wound up with diesel engines instead of coal fired trucks!

Our Cessna 140 has a 85 horsepower Continental engine. I believe it's around 7 to 1 compression. It was originally certified to run on 73 octane fuel, which I believe is zero lead content. Later on, 80 octane avgas came around with 0.25g/gallon of lead. As more modern, high compression engines for aircraft came about, 100 octane and even 130 octane avgas was developed. 100 and 130 are pretty obsolete, but 100LL (Low Lead) is the standard today, and 80 octane is obsolete. Even yet, 100LL has 2g/gallon of lead, 4X what 80 octane had.

Point being, the low compression engines (such as our Cessna) don't do well on a steady diet of 100LL. The engines don't run hot enough to scavenge the lead out the exhaust, and instead it builds up on the valve stems and inside the cylinder, causing valve and ring sticking and other issues.

Fortunately, many of these planes can be run on unleaded autogas with the proper approval and paperwork. I run ours as much as possible on autogas. Many mechanics will freak out and say the engine will be scrap! Most don't understand that the engines were originally certified on unleaded gas!

Chris

Altitude would, I believe increase the need for lead. In Canada, where leaded fuels are banned even for car racing, it is allowed in Av gas.

I think the reason lead is still allowed in avgas in Canada is that it has been proven to be an effective upper-cylinder lubricant that nobody has found an effective replacement for yet. If a valve sticks on a single engine airplane, and is hit by the piston, breaks off, punches a hole in the piston, desroying the engine, the government of Canada would get sued big time. The aircraft engines need the small amount of lead to run reliably.

The av-gas market is so small that the amount of lead being put into the environment is negligable.

When I had my own plane, a 1964 Mooney M20C, I ran it on 100LL as 80 octane was being phased out, and I couldn't find it. anymore It amazed me to see little lead balls, like tiny bubbles in the spark plugs and on valves and the top of the piston during inspections and maintenance. I never saw them when the engine ran only on 80 octane.

Greg L.

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My dad has a 28 studebaker president with the straight 8. He put an electric fule pump on it because of the vapor lock we were getting. It solved the problem. We decided that it was because of the alcohol in the fuel because it never used to be a problem. Greg, have you ever been to the old car festival at Greenfield village in Dearborn. We take the car there almost every year. I think the cuttoff for age is 1932 but I'm not sure. Anyhow it is a fun event.

Hi Blue83, I just barely fit this Pierce Arrow Society national meet into my yearly schedule, I can't get to the local cruise nights, or local shows or much else.
I'm so busy with keeping up with the farm and being gone 5 days a week, being worn-out and exhausted when I get home, 'cause the last day of my 5 days is a 22 hour day by the time I get home.

I don't even get time to fire up a car and drive down Woodward Avenue for the 'Dream-Cruise'. Just no time or energy.

I do have an electric fuel pump on the '33 Pierce, and have the fuel line on the outside of the frame instead of inside near the exhuast as originally installed. I have the fuel pump, the fuel line wrapped in heat insulation to keep the fuel cool. The problem is that the air cleaner pulls air from under the hood, the carburetor is in the direct air-blast from the radiator fan, and the intake manifold is bolted to the exhaust manifold to warm up the intake for the crappy gasoline in the 30's. So the carb is around 160*-180* all the time when the ambient air is above 90*.

I'm going to create heat shield for the carburetor, but there is no way to get fresh air to the air cleaner. I will have to remove and separate the intake and exhaust manifolds, install an insulate separator plate to keep as much exhaust heat from the intake as possible.

The car just likes real gasoline, not the stuff mixed with ethanol.

Greg L

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tetra ethyl lead was invented in the 1920's as an anti knock compund. It increased octane by 15 points. ethyl alcohol was also used back then but it was more expensive than lead,and required the same handling problems that we have today with ethanol. Even though sevral workers at the (tel factory died from lead poisoning, and the pollution it causes, it was much cheaper to produce than ethyl alcohol

I made an ugly but functional heat shield for the carb's float bowl and the fule lines and fuel pump with layers of aluminum foil. Not very good looking, but the car ran flawlessly with the mod. I'll have to be more diligent when buying fuel in the future.

Next year's Pierce Arrow National Meet is in Lxington Ky, so it may be another warm weather meet. I hope to find more time to prepare the car next year.

This year's meet had 55 cars show up. Vintage from 1903 through 1938. The Pierce was in production from 1901-1938, so we had almost the whole time frame covered. I had 6 cars in my judging class, so I was busy for several hours judging these cars, but managed to catch this image of the show field.

Greg L.

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Greg,

If you come to Lexington next year look me up.

I can show you around town, airport,shooting range and my simple coal stove.

BK