dual fuel

[John Recine]

Well I got me an engine for my Pietenpol its a lycoming 0235C1B 108 hp from what I have been reading lately about the low compression engine 100LL lead content has a tendenacy to deposit on the the exhaust valve interfearing with a proper seal. That being the case, I am considering setting up for av and mo gas.

What changes have to be made to the fuel and associated systems to make that as safe as possible and not dangerious to the engine parts, gaskets and other areas?

John

 

[gismo]

Well I got me an engine for my Pietenpol its a lycoming 0235C1B 108 hp from what I have been reading lately about the low compression engine 100LL lead content has a tendenacy to deposit on the the exhaust valve interfearing with a proper seal. That being the case, I am considering setting up for av and mo gas.

What changes have to be made to the fuel and associated systems to make that as safe as possible and not dangerious to the engine parts, gaskets and other areas?

John

If you can manage to keep the ethanol out of your fuel, pretty much nothing needs to be changed except perhaps figuring out a way to avoid long term storage of fuel in the plane's tank(s).

 

[Greg Bockelman]

Is Mogas authorized in a Lyc 235? Does it even matter on an experimental?

Since I don't know model numbers, John, was the engine originally certified for 80 octane Avgas?

 

[John Recine]

From what I have read so far it was certified for 80 and now has a bit of a hard time swallowing the 100ll version

John

 

[Dan Thomas]

Well I got me an engine for my Pietenpol its a lycoming 0235C1B 108 hp from what I have been reading lately about the low compression engine 100LL lead content has a tendenacy to deposit on the the exhaust valve interfearing with a proper seal. That being the case, I am considering setting up for av and mo gas.

What changes have to be made to the fuel and associated systems to make that as safe as possible and not dangerious to the engine parts, gaskets and other areas?

John

Mogas often contains unacceptable levels of alcohol, which attacks rubber fuel lines, plastic carb floats and float valve tips. Some carbs have been converted to metal floats, and they should have an M stamped on the data plate. You might call Peterson Aviation about that engine model's suitability for Mogas and they could tell you about suitable fuel line material, too.
Peterson'd STCs for Mogas in certified aircraft involves mostly paperwork. They've already determined what engines and airframes will tolerate it. The only changes to the airplane itself are an STC tag clamp on the engine and a placard on the wing next to the fuel filler.
Lead from 100LL tends to foul sparkplugs, and then chunks of it break off and get trapped briefly between the valve and seat, making the RPM drop a little and the engine shakes for a few seconds until it blows clear. Scary. I haven't seen it accumulate on valve stems. Mogas, having no lead at all, makes the valve guides run with no lubrication and they'll wear out sooner or start sticking. We stopped using it some years ago in our fleet because the engine problems outweighed the fuel savings.

Dan
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Honda information

 

[Greg Bockelman]

Mogas often contains unacceptable levels of alcohol, which attacks rubber fuel lines, plastic carb floats and float valve tips.

Which is why gasoline containing ethanol is not approved.

Mogas, having no lead at all, makes the valve guides run with no lubrication and they'll wear out sooner or start sticking.

The way to solve that problem is to run three quarters Mogas to one quarter 100LL. That approximates the lead content of 80 octane avgas.

We stopped using it some years ago in our fleet because the engine problems outweighed the fuel savings.

Dan

What kind of problems? I have been running mogas for years and haven't had any problems I can attribute to using it.

 

[Henning]

Mogas often contains unacceptable levels of alcohol, which attacks rubber fuel lines, plastic carb floats and float valve tips. Some carbs have been converted to metal floats, and they should have an M stamped on the data plate. You might call Peterson Aviation about that engine model's suitability for Mogas and they could tell you about suitable fuel line material, too.

Get the metal float carb, use automotive fuel line and make sure if you have a mechanical fuel pump it has the orange diaphragms. No need for an STC in his application since it's an experimental.

 

[Henning]

Mogas, having no lead at all, makes the valve guides run with no lubrication and they'll wear out sooner or start sticking.

Dan

Never ever ever seen that. I have many times seen lead deposits on valve stems cause them to stick. If you are really worried about it, drop the valves and put a chamfer on the bottom of the guide (don't run 100LL after this).