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Mogas in O 320 lycoming.

P

Python

Member
Hi, I’m looking at running mogas in my O 320 D2A engine, i stumbled sometime ago on some information about certain year models having hardened valve seats that could cope with mogas. I have been looking but can’t find any references to this can anyone point me in the right direction ?Regards 🐍
 
I ran an O-320 E3D on mogas for 1000 hours. The only issue was occasional vapor lock on a quick turn. I am no engine expert but I don’t think lead has anything to do with hardened valve seats. It mostly screws up valve stems and guides, and fouls plugs.

I am planning to start running non ethanol mogas in my O-540 8.5/1.
 
Python said:
Hi, I’m looking at running mogas in my O 320 D2A engine, i stumbled sometime ago on some information about certain year models having hardened valve seats that could cope with mogas. I have been looking but can’t find any references to this can anyone point me in the right direction ?Regards 🐍
Click to expand...

Look for the letter "C" stamped on the cyliders just above the intake manifold. That indicates that the cylinder has the newest valve guide and valve seat material.
 
Mconner7 said:
I ran an O-320 E3D on mogas for 1000 hours. I am no engine expert but I don’t think lead has anything to do with hardened valve seats. It mostly screws up valve stems and guides, and fouls plugs.

I am planning to start running non ethanol mogas in my O-540 8.5/1.
Click to expand...

Why do you think Unleaded fuel screws up valve stems and fouls plugs? As far as I know it does the opposite. It's a much cleaner fuel than 100LL, the lead is what fouls plugs and coats the stem of the valves and clogs the guides. Vapour pressure is indeed an issue at hot ambients though and must be considered.

I've run my 0-320 on and off on unleaded and not seen any issues. I've run it on it ever since my recent rebuild, as not using dispersant oils for the break in, I wanted as clean an engine as possible.

In the past I've run one tank with 100LL and one with unleaded and switching tanks I didn't see much difference on the temps and power. Nothing that I could discern.

I'm going to try it again shortly as last time my timing was out (long story). When I go back on to W100plus I'll fill one side with the E5 and see what I can see. It's about 5 years ago since I tried the exercise and fuel have been further 'greened' since in support of the climate scam.

Unleaded fuel also has the advantage of being able to use semi synthetics, though as the availability at airfields around Europe is variable I'll be sticking to W100 plus to go touring.

Regards, Clive
 
Service Instruction No. 1070AB aproves the use of Mogas for your engine.
Lead in aircraft fuel is only there to increase the octane rating, that is the fuels
ability to resist self ignition in high compression/performance engines.
100 LL has a octane rating of 130 rich mixture.
Maximum inlet temperature from a supercharger is 200 C.

Good luck
 
Clive J said:
Why do you think Unleaded fuel screws up valve stems and fouls plugs? As far as I know it does the opposite. It's a much cleaner fuel than 100LL, the lead is what fouls plugs and coats the stem of the valves and clogs the guides.
Click to expand...
Perhaps read his post again, that's exactly what he said...
 
Python said:
Hi, I’m looking at running mogas in my O 320 D2A engine, i stumbled sometime ago on some information about certain year models having hardened valve seats that could cope with mogas. I have been looking but can’t find any references to this can anyone point me in the right direction ?Regards 🐍
Click to expand...

Paul Bertorelli's take... https://www.youtube.com/watch?v=ovJBJjZTjsk&t=4s



RV8JD said:
Lycoming SI No. 1070AB, "Specified Fuels for Spark-Ignited Gasoline Aircraft Engine Models":

Click to expand...

I note that SI 1070AB notwithstanding, Lycoming makes a distinction between MOGAS and pump gas in the ASTM4814 realm. They have a 3-part series explaining their concept of "airworthiness" of certain aviation fuels.

https://www.lycoming.com/content/unleaded-fuels-part-1
 
1400 hours on MOGAS. Only problems I've ever had (other than it smells terrible) was when I had to run 100LL for awhile. The excess lead will foul the plugs and blacken the oil very quickly.

Be sure to use ethanol-free fuel, and I use "mid-grade" which is 89 octane if I remember correctly.
 
71459 said:
1400 hours on MOGAS. Only problems I've ever had (other than it smells terrible) was when I had to run 100LL for awhile. The excess lead will foul the plugs and blacken the oil very quickly.

Be sure to use ethanol-free fuel, and I use "mid-grade" which is 89 octane if I remember correctly.
Click to expand...

If the fuel delivery system is designed to handle ethanol, the engine itself really doesn’t care what it’s burning. About the only thing that’s of any real concern is letting that ethanol sit for very long. If you’re always running fresh fuel through it, the engine will run just fine. Both SDS and EFII systems handle ethanol laced auto fuel just fine, and with their high pressure fuel rail and constant fuel delivery/return line plumbing, vapor lock is never an issue.
 
93 Oct pump gas

Mark33 said:
If the fuel delivery system is designed to handle ethanol, the engine itself really doesn’t care what it’s burning. About the only thing that’s of any real concern is letting that ethanol sit for very long. If you’re always running fresh fuel through it, the engine will run just fine. Both SDS and EFII systems handle ethanol laced auto fuel just fine, and with their high pressure fuel rail and constant fuel delivery/return line plumbing, vapor lock is never an issue.
Click to expand...

I've been running premium (93 Oct) pump gas for the last 1500 Hr's. The above statement is a concern, but not if you are a frequent flyer. Otherwise, at least mix it with 100LL in the planes tanks.
The other issue is vaper lock. The fuel FROM the tank should be under pressure at all times. It is impossible to get an operational vapor lock if the fuel is always under pressure. The automotive industry achieved this by putting the fuel pumps IN THE TANK. I did it by having a AUX fuel pump in the cockpit AFTER the fuel selector. This pump turns ON automatically if the carb/fuel servo fuel pressure goes below a certain setting. I've NEVER had a fuel vapor lock using this Technique. Yes, after HOT restarts on a HOT day, I have seen the pump cycle fsometimes for :30 min, but that what the system has to do to maintain vigilance over vapor lock.
The last issue is fuel system component selection that are ETHONOL compliant. Tank quick drain "O" rings, Oil quick drain "O" rings, fuel hoses, and all other fuel system components MUST be ETHONOL compliant. This is what the auto industry has done to cars since the late '70s.
As far as engine valve guide and seat wear issue are concerned, Lycoming changed over to non-LL materials in the '70s, continental sometime after that. If you have a Lycoming engine, look for a "C" stamped on the cylinder head just above the intake manifold. That denotes the changed valve guide and seat materials.
Right now 100 in Florida is averaging $6.00/Gal. 93 OCT pump gas is around $4.10/Gal. Major savings per year for hauling gas to the airport when you're flying over 150 Hrs/yr at roughly 8gals/Hr..........
 
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Fuel Pump AUTO circuit

Fred.Stucklen said:
I've been running premium (93 Oct) pump gas for the last 1500 Hr's. The above statement is a concern, but not if you are a frequent flyer. Otherwise, at least mix it with 100LL in the planes tanks.
The other issue is vaper lock. The fuel FROM the tank should be under pressure at all times. It is impossible to get an operational vapor lock if the fuel is always under pressure. The automotive industry achieved this by putting the fuel pumps IN THE TANK. I did it by having a AUX fuel pump in the cockpit AFTER the fuel selector. This pump turns ON automatically if the carb/fuel servo fuel pressure goes below a certain setting. I've NEVER had a fuel vapor lock using this Technique. Yes, after HOT restarts on a HOT day, I have seen the pump cycle fsometimes for :30 min, but that what the system has to do to maintain vigilance over vapor lock.
The last issue is fuel system component selection that are ETHONOL compliant. Tank quick drain "O" rings, Oil quick drain "O" rings, fuel hoses, and all other fuel system components MUST be ETHONOL compliant. This is what the auto industry has done to cars since the late '70s.
As far as engine valve guide and seat wear issue are concerned, Lycoming changed over to non-LL materials in the '70s, continental sometime after that. If you have a Lycoming engine, look for a "C" stamped on the cylinder head just above the intake manifold. That denotes the changed valve guide and seat materials.
Right now 100 in Florida is averaging $6.00/Gal. 93 OCT pump gas is around $4.10/Gal. Major savings per year for hauling gas to the airport when you're flying over 150 Hrs/yr at roughly 8gals/Hr..........
Click to expand...

IF anyone is interested, here's the electrical circuit that I am using to maintain fuel pressure & flow in my RV-7A.

https://vansairforce.net/community/attachment.php?attachmentid=11426&d=1620687547
https://vansairforce.net/community/attachment.php?attachmentid=11427&d=1620695090
 
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