Talked to a guy that has a Maule with a Continental IO 360 in it. He was wondering about running 91 octane eth free auto fuel. He said that there is an stc for the plane but not that engine. We all know that there are two reasons why some engines do not have stc for mogas. First, not enough market to pay for testing and Second it was tested and failed.

The IO 360 is 8.5 to 1 compression. The Lycoming O 360 A1A is also 8.5 to 1 and it has a Peterson stc for mogas (91 octane). Then how about a Continental IO 470 with 8.6 to 1 comp ratio in a C 180.

Your thoughts. I know the legality but what if these engines were in an experimental.

Tim

The main reason there is no STC for mogas on an injected engine is vapor lock as I understand it?
Has to do with the fuel system and spider!
That's what I have been told, also that if under 5000' it was not a problem, have run mogas in a io520 one time on an emergency, but was at sea level and did not use all the HP.

My $.02
GT

There is more to the auto gas STC than a piece of paper and a sticker. My O 540 has the Peterson STC. 2 electric fuel pumps besides the engine driven one. Engine driven pump has a scoop and scat tube directed in the pump. Scoop to the gascolator. One electric pump runs all the time the engine is on. The 2nd pump is turned on by a switch during TO and landing. A very detailed operation manual for most scenarios you may encounter.

You can burn what you want and be a test pilot I guess

As gmdv said, the IO-470 in a Debonair has a STC for mogas - thats the 225 hp one. Thats the only injected one I know of, but I don't know much about the Peterson STCs.

qmdv wrote:Your thoughts. I know the legality but what if these engines were in an experimental.

Tim

That just becomes part of your experiment.

OregonMaule wrote:... My O 540 has the Peterson STC. 2 electric fuel pumps besides the engine driven one. Engine driven pump has a scoop and scat tube directed in the pump. Scoop to the gascolator. One electric pump runs all the time the engine is on. The 2nd pump is turned on by a switch during TO and landing. A very detailed operation manual for most scenarios you may encounter. ............

The Petersen website sez the mogas stc for the lycoming powered maules are available from Ray Maule. Does petersen own the stc & ray maule sells/controls it? Apparently the mogas stc for at least some of the cherokee models is similar to the maule stc-- extra fuel pumps, etc.
What did that stc cost, with the extra pumps etc, and what was the installation time? Normally a mogas stc costs $1.50/horsepower & installation costs are minimal-- paperwork, placards for the engine & airframe, & checking to make sure a plastic carb float is not installed.
Yes Petersen has an stc for the IO-470 Cont, it even looks like it is for 87 octane, but it looks like that's the only injected engine-- no IO-360 Lyc, no IO-360 Cont, no IO-540 Lyc, no IO-520or 550 Cont. No 220 Franklin either.
BTW EAA only holds 87 octane (low compression) mogas stc's, Petersen has both low-comp (87 octane) & hi-comp (91 octane) stc's.
A guy named Blue Leader from the 170 site (may have been on here also?) used to swear by mogas for his IO-360 powered C170, claimed he never had a problem. I think he wrecked it but don't believe that had much to do with the fuel.

sure would be nice to go to mo gas....

Can someone who has experienced vapor lock describe the conditions under which it occurred? I've never had the problem before or heard of it other than someone on the ground in TEXAS after shut down at 103F outside. Is it possible to get vapor lock while flying at 10,000 feet? 5000ft?

premium 91 octane ethanol free mogas in the 8.5:1 experimental io360d on a 10 hour test flight in level cruise at 24 squared full throttle at 5000ft, switching tanks to the mogas yields about a 10 degree increase in egt and zero notable increase in cht.
I'm confused as to why vapor lock would be an issue unless it's 100 degrees in Texas at high altitudes, or after shut down on the ground? If there is a documented test that failed with mogas please let me know, I'm not aware of it. Never lead fouled a plug either!

I have put 1500 hours on my 540 with the mogas STC. 14 GPH is 21000 gallons.

I can't get mogas on most cross country trips. If I had a injected 540 with Gami injectors I could run LOP and burn 8-10 GPH ???? Average GPH probably 11.5 So the same 1500 hours is 17250 gallons. Mogas today $3.50 is $73,500.00 Avgas is $5.30 is $91,425.00 That is $17,925.00 difference.

So you decide which is best for you. For me mogas is the way to go.

Cheers

OregonMaule wrote:I have put 1500 hours on my 540 with the mogas STC. 14 GPH is 21000 gallons.

I can't get mogas on most cross country trips. If I had a injected 540 with Gami injectors I could run LOP and burn 8-10 GPH ???? Average GPH probably 11.5 So the same 1500 hours is 17250 gallons. Mogas today $3.50 is $73,500.00 Avgas is $5.30 is $91,425.00 That is $17,925.00 difference.

So you decide which is best for you. For me mogas is the way to go.

Cheers

I couldn't find an stc for the 540, is it just the O540, or is there one for the IO540, too? For the reasons you've mentioned, I'm in interested in learning about that as much as possible before I commit to looking for a cherokee six.

Found the post. Nevermind.

hpux735 wrote:

OregonMaule wrote:I have put 1500 hours on my 540 with the mogas STC. 14 GPH is 21000 gallons.

I can't get mogas on most cross country trips. If I had a injected 540 with Gami injectors I could run LOP and burn 8-10 GPH ???? Average GPH probably 11.5 So the same 1500 hours is 17250 gallons. Mogas today $3.50 is $73,500.00 Avgas is $5.30 is $91,425.00 That is $17,925.00 difference.

So you decide which is best for you. For me mogas is the way to go.

Cheers

I couldn't find an stc for the 540, is it just the O540, or is there one for the IO540, too? For the reasons you've mentioned, I'm in interested in learning about that as much as possible before I commit to looking for a cherokee six.

Found the post. Nevermind.

Pretty sure the only way to get moGas STC for IO engines is by going with the methanol injection system as per the peterson website...

Yah. I saw on the piper owners form that they won't do an stc for the pa32 anyway.

The lycoming (bendix ) injection won't work with mogas. Peterson tried but had vapor lock issues while in flight. He tried for a while to make it work but decided if they did find a way to fix it it would probly not be economically feasible. The continental fuel injection works fine with mogas.

Can someone who has experienced vapor lock describe the conditions under which it occurred? I've never had the problem before or heard of it other than someone on the ground in TEXAS after shut down at 103F outside. Is it possible to get vapor lock while flying at 10,000 feet? 5000ft?

I had it in a C-150/150. I had stopped to visit a friend in Aztec, NM . Took off a 1/2hr or so later, right after I got of the ground it started starving for fuel. I started messin with stuff while looking for a place to land. Was able to keep it in the air, but wouldn't clear good for long, went back to the airport where I had just left. Figured the vapor lock was in the engine driven pump. Loosed the line to let the pressure off, put in as much 100LL as I could and went on to AZ. That airport was probly around 5000' elevation.

That's my story
Gary

I had a similar possible/probable vapor lock issue with my C150/150. Unseasonably warm spring day, with (probably) winter-blend mogas in the tanks. Landed, parked for 5 or 10 minutes, then took off. Had erratic fuel pressure readings and sputtery running, in spite of the electric boost pump being on. Scared the crap out of me. Happened on two different occasions, then I started running 50/50 mogas / 100LL. Never happened again after that.

I've run 100% mogas since I got my 180. No problems. Previous owner ran all mogas too except on trips when he couldn't get it. Right now I'm paying $2.89 for 87 octane mogas at Cenex vs $5.80 for 100LL at my airport, and at 11 gph that really adds up. But also no lead fouling, and no digging lead clinkers out of the plugs at annual time.

whee wrote:The lycoming (bendix ) injection won't work with mogas. Peterson tried but had vapor lock issues while in flight. He tried for a while to make it work but decided if they did find a way to fix it it would probly not be economically feasible. The continental fuel injection works fine with mogas.

I'd wager this is due to the return line design that keep cool fuel constantly recirculating instead of sitting static atop the cylinders? We recently discussed this in another thread on experimental FI systems if you recall.

I did read an account from a fellow on a RV site that said he ran his IO-540-C4B5 on pure 91 pump gas without problems for years. Perhaps he had a different injection system than the original.

Zzz wrote:I'd wager this is due to the return line design that keep cool fuel constantly recirculating instead of sitting static atop the cylinders? We recently discussed this in another thread on experimental FI systems if you recall.

I did read an account from a fellow on a RV site that said he ran his IO-540-C4B5 on pure 91 pump gas without problems for years. Perhaps he had a different injection system than the original.

I do remember that discussion. Mr. Peterson and I talked for 20 minutes about mogas and fuel injection. It was his opinion that the lack of a vapor return line was the issue on the Bendix injection. He said he would never consider running mogas on an engine equipt with Bendix injection. I think I have read that same account on the RV site but I decided that for me the risk is too great. If Peterson couldn't make it work then I don't even want to try.

Well, Bob talked me out of injection again the other day. Every time I call him.

Zzz wrote:Well, Bob talked me out of injection again the other day. Every time I call him.

Can we know why?

Stop calling him Honestly if I were to go with a O540 I think I'd be happy with a carb. Blackrock is a great example of how economical they can be. I think he has even run his LOP successfully.