AVGAS Vs: MOGAS


9 posts in this topic

Posted

I have several flying Avids with 582 grey head engines in them. I have been flying on AVGAS for the last several years with good results, as Ethanol Free gasoline  was not available here.

 

Recently one of the local stations got ethanol free gas so I switched to try some.

 

In both planes it raised both the exhaust gas temp and the coolant temp by 20 degrees, enough to cause concern. I could re-jet the carbs to lower the temps, but then if I fly somewhere and have to use AVGAS, I would be in trouble again. Has anyone else had similar experience?

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Posted

Avgas contains more octane with completely changes the way the flame front travels in the cylinder. Completely normal for it run cooler on Avgas than Mogas. As far as the coolant temps go I'm scratching my head on that one. You are too close to the limits if 20 degrees EGT is of great concern to you. Are you running a digital EGT gauge or just guessing from a needle?

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Posted

Gages are analog. The temp is not over, just higher than it normally runs. I drained the MOGAS out of the tanks and replaced it with AVGAS. Looks like maybe Tuesday I'll be able to check and see what effect it has.

The monetary savings are about 30%, but not worth wrecking an engine over.

N532SE;N533SE;N5113H Flying. Plus one undergoing rebuild, and another awaiting rebuild.

All three have heavy duty belly radiators.

Bob

 

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Posted (edited)

For what it's worth I've ran 2000 gallons of CA ethanol fuel through my 582 over the course of 6 years. The engine doesn't know the difference of 10% ethanol. It's the rest of the fuel system you have to watch. Are you premixing or injecting? Lockwood and CPS will both tell you that 100LL is bad for two strokes. The key is do what works for you. 

Edited by C5Engineer
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Posted

Funny.  LEAF says 100LL is just fine for a two-stroke, when run properly.

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Posted

Right now more worried about the fiberglass tanks. I have no way of knowing which resin was used, and what the effects of the ethanol would be. There are a lot of postings here, but not consistently pro or con.

I have one plane I put spun poly inserts in the existing tanks, and I wish I had not. It was a lot of work, and the internal crossfeeds are Mickey Mouse. I don't think you can get them any more anyhow.

 

I have two choices here...10% ethanol, which is bad on the tanks, or AVGAS, which is not good for the engine.

 

Bob

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Posted (edited)

I tried 100LL for several hours in my 582 and just didn't care for the nasty mess of lead everywhere. Who knows what it might be doing to the crankcase area but it made a concrete like coating mess of the piston tops, spark plugs and exhaust system.  I'm wondering if it is what created the extensive corrosion in my exhaust system - the previous owner used 100LL exclusively before I bought it from him.  I overhauled it before putting it in service.  I'd only consider using 100LL again if I was adding a lead scavenging agent to it - eg. Decalin which is said to reduce the tendency of 100LL fuel from creating deposits within lower compression engines.  I have original glass tanks.  We have ample supplies of ethanol-free in VA.  

Edited by allonsye

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Posted

I run AVGAS when I have to and notice perhaps a 25-50 degree F drop in EGT compared to the 90 octane ethanol-free gas I normally run.  I dont lose any sleep over running 100LL.  It is what it is..... 

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Posted (edited)

Avgas is fine in a 582, KNZ ran 100ll for the first 750hrs no problem and I have put around 400 on the clock using what was easier to use.i overhauled the top end a while ago, apart from some buildup on the piston Crowns and exhaust there was nothing to indicate that avgas was being used.the only downside to avgas I can see is it will shorten the life of your muffler.          

       Yes your egt' swill be slightly cooler but not enough to worry about , or install a Hacman.

Edited by Dusty

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