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Auto fuel in a 0-360?

C

CptKelly

GONE WEST
NC
My Smith Kit is equipped with a XP-360 engine with 9:1 compression. Auto Fuel STC's (91 octane) are available for the 0-360's with 8.5:1 compression.
Does anyone think that half point in compression would preclude using 93 octane auto fuel that has no alcohol in it? Comments and suggestions would be appreciated as I am not near any airport that has 100LL, and of course there is the cost savings as well.

Mike
 
Jim C wrote

They're both lighter than the O-320 as well. I would expect them to run OK on car gas if the compression were jacked up to 9.5 and perhaps even 10.
Click to expand...

This was in the O-340 thread a ways back.
 
I know in cars not having having high enough octane can cause sometimes serious problems. Air cooled engines are not built to such tight tolerances as autos. But still, how often do you run your car engine at 100% like a plane motor at takeoff?

I've heard of some who cut oxygenated mogas with avgas in the winter to help with fuel ice. Don't know if that works or not. If fuel cost is the concern this might help.

The problem is if something happens to your plane, i.e. incident or accident insurance is not going to pay. I was told by my insurance man even though my plane is STC'd for auto fuel if I don't have the paperwork my policy is void for a claim that could be related in any way to fuel
:o
 
From Superior website FAQ:

2. What is the type and minimum grade of fuel?
The 180HP engine is approved for 91 octane unleaded auto fuel and a minimum of 100LL-aviation fuel. Superior recommends 100LL, although this is not a requirement. A 170HP, 87 octane version is also available with 7.2:1 compression ratio pistons. The 185HP version which incorporates 9.0:1 pistons requires the use of 100LL.

Looks like you are out of luck for auto fuel in 9:1.

http://www.xp-360.com/faq.asp
 
Hi! This here may be a very interesting question for me flying in very remote places in the north. In the case I do not have anough 100LL in my tanks to fly to the next 100LL fuelstation but I can get regular 88 cargas and can start on 100LL (I have a Lyc 360 in my Cub). What will happen or can happen, when I continue cruising on 88 oct. with less than 50% or 21 MP ? How large is the fail-safe factor?
 
Hi

I have an o-360 with the 9 to 1 pistons ,balanced ,flow ported,flow matched,electronic ignition ,tuned exhaust and I tried running the high octane car gas after I had 40 hours with 100LL, but it would run ruff and smoke black smoke on straight high octane car gas.
I then tryed running mixtures of 100LL and high octane car gas ,and I have 120 hours on it now and the last 40 or so have been with a 50/50 mix of 100LL and high octane gas and the exhaust is a nice brown and all temps are good.
Just my experience !!
 
heege-brigmann wrote

In the case I do not have anough 100LL in my tanks to fly to the next 100LL fuelstation but I can get regular 88 cargas and can start on 100LL
Click to expand...

I was with someone in a 185 on floats at sea level that did that. I couldn't tell any difference in the way it ran when we pulled the power back and switched. Didn't hear that the engine fell apart after I left either.
Marty
 
Bugs..

Bugs,
I already know that Superior "recommends" that no auto fuel be used with the 9:1 engine. I have a distinct feeling that their recommendation is due to the variations in auto fuel throughout the USA. They say that 91 octane is ok for the 8.5 version, but 93 is not ok for the 9:1. It is a "safe" recommendation for them for liablity reasons. I know of two other guys who have the exact same engine that I have, who use nothing but 93 octane auto fuel, and none have had any problems at all.
For Christmas, my two sons gave me a set of 8.5: 1 pistons for my engine, with new rings and gaskets. I could change them anytime I want. However, I hate to give up performance if it really isn't necessary. I am thinking about buying a bore scope unit, and just borescope my cylinders from the top plug holes at 25 or 50 hour intervals, to check on the conditions of my pistons. I could do this for a couple of hundred hours, and either confirm the successful use of 93 octane auto fuel, or confirm the need for changing to the 8.5:1 pistons. Nothing ventured, nothing gained....
The only thing negative about auto fuel is the stink if you get it on your hands.
Comments?

Mike
 
Car Gas

I bought a 170B Cessna with a 180 Lycoming in it and the previous owner has used alot of car gas in it for some time. I know others that use it as well with no lead build up on the plugs. I think the bottom line would be your insurance coverage, is it a loop hole so they dont cover anything in a wreck ?

Bill
 
Re: Bugs..

CptKelly said:
Bugs,
I already know that Superior "recommends" that no auto fuel be used with the 9:1 engine. ...Mike
Click to expand...

Mike, the FAQ said "requires" not "recommends" for 9:1.
 
auto fuel

Thanks for the facts Crash, made a believer out of me. I will pay a little more just for the fact the engine will last longer. I don;t see any damage to this engine having run on gas, but why take the chance ?

Bill
 
I have seen...

I have seen pistons melted and galled too. 99% of this is due to over agressive leaning, not improper fuel, according to my IA.
Anybody else have a comment?

Mike
 
180Marty said:
Mike, I know what I'd do if I were you with an experimental. Go to one of these places and get some 105 octane clean burning stuff, add 1% biodiesel for lubricity and coating the metal parts, bore the jet in the carb out 25%, and go have fun. :D Check out the second link and make sure you scroll down their page.
Marty
http://www.e85fuel.com/database/locations.php?state=ncNorth Carolina
http://www.rune85.com/turbocobra
Click to expand...
180Marty,
The problem with E85 is that it draws moisture into the gas. CARB ICE!!
PR
Click to expand...
 
Re: Bugs..

CptKelly said:
Bugs,
For Christmas, my two sons gave me a set of 8.5: 1 pistons for my engine, with new rings and gaskets. I could change them anytime I want. However, I hate to give up performance if it really isn't necessary. I am thinking about buying a bore scope unit, and just borescope my cylinders from the top plug holes at 25 or 50 hour intervals, to check on the conditions of my pistons. I could do this for a couple of hundred hours, and either confirm the successful use of 93 octane auto fuel, or confirm the need for changing to the 8.5:1 pistons. Nothing ventured, nothing gained....

Comments?

Mike
Click to expand...

For crying out loud, Mike! You're experimental. GO EXPERIMENT! Just because the manufacturer says you shouldn't doesn't mean you can't. YOU"RE EXPERIMENTAL! (But please keep good records and report back to us on the outcome :D )

BUT...what performance is it that you are going to loose? You don't fly out of 300ft strips (or significantly confined strips), you operate at less than 1000ftMSL, you aren't on floats, you usually fly around pretty light and you don't fly truly long distances (what's the difference between 112mph and 108mph anyway?) :o .

It would cost you less than the cost of a bore scope to chang out to the pistons you were GIVEN. You can then "safely" run the auto gas. Is the difference in the cost of 93 octane and 100LL worth potentially damaging your engine and having to pay for an overhaul or worse yet having an engine failure and damaging/destroying your plane?

Sounds like you may be grasping at straws for justification to continue to be able to say my XP-360 engine makes X amount of HP (at the cost of common sense and safety).

No offense intended.

John Scott
 
Auto fuel cost savings per gallon, Versus 100LL.........about a dollar.

Number of dollars saved each flight hour, using an average of 8 gallons per hour.........about 8 dollars.

......multiplied by the 2000 hours between overhauls...16,000 (sixteen thousand) good reasons why using autofuel is worth a little reasonable experimentation, even if it stinks when you get it on you :lol: .

Obviously one wouldn't use it with "high" compression-ratio engines.
 
Dave Calkins said:
Auto fuel cost savings per gallon, Versus 100LL.........about a dollar.

Number of dollars saved each flight hour, using an average of 8 gallons per hour.........about 8 dollars.

......multiplied by the 2000 hours between overhauls...16,000 (sixteen thousand) good reasons why using autofuel is worth a little reasonable experimentation, even if it stinks when you get it on you :lol: .

Obviously one wouldn't use it with "high" compression-ratio engines.
Click to expand...

We have the MOGAS STC for our Maule MX-7-180 and figure that the fuel savings around here averages about $1 per gallon at the pump and another 40 cents cheaper once we get the tax refund from the road taxes added into the cost of auto fuel. That savings adds up to about $1,700 per year when you figure we fly around 150 hours at 8 gph. That's $22,700 over the course of 2,000 hours between overhaul.

cabinflyer said:
The problem is if something happens to your plane, i.e. incident or accident insurance is not going to pay. I was told by my insurance man even though my plane is STC'd for auto fuel if I don't have the paperwork my policy is void for a claim that could be related in any way to fuel
:o
Click to expand...

By the way as far as MOGAS pertains to insurance coverage, this is a non issue. If the aircraft is legally converted with an STC then there should be no problems with insurance coverage. An aircraft with a MOGAS STC is still a legally airworthy aircraft and should have no effect on your coverage. Be sure to disclose this information on your application when asked if any mods have been made from the original factory setup.

The insurance information should be true in most all cases, but be sure to check your policy just to be certain.
 
auto gas

I know of a 0320 converted to 160hp that flew about 2000hrs, half on 100 and half on plain jane low grade cheapest you could buy unleaded. engine was tore down at 2250 hrs just because and everything looked great. IF you do run auto gas in a high compression engine do not lean as aggressivly and you will do fine. Have even heard of car gas in I0520D cessna ag wagon in a pinch.

Dave

PS: the 0320 always had great compression even at overhaul it was 78/80 on all 4
 
I can guess which overhaul facility has problems with automobile fuel. Any FAA liscensed facility or mechanic is obligated to bring and problems to the attention of the regulators (FAA). Where are the service difficulty reports on mo-gas put out by the repair facility. Ask the person if they turned in a report on the problem. Of course if they turn in a report they have to say they can prove what caused the problem. Because of the low volume of av-gas produced there is a current project to change to certified auto fuel. The only difference will be in tracking and monitoring of the fuel. I wonder when this will be implemented? This will solve the whole question because they will stop making av-gas as we know it. I bet the engines we use will not all blow up at the same time.
 
My FBO is charging $4.29 for a gallon of 100LL.

They bad mouth auto-fuel yet tie down theirs' and others a/c with chains :crazyeyes:
 
Savings by using auto fuel...

In Aiken, 100LL is around $4.25/gal. In Wagener, 93 octane auto fuel is $2.24/gallon. Isn't that around a $2 savings? If my Cub uses 9 gallons per hour, my hourly savings would be over $18 per hour. Right? John Scott is correct, I am experimental, and I will be experimenting. Thanks for the slap John, I needed that. Hey John, when you gonna come down to my strip? It 'aint that far from York....

Mike
 
Crash, you might wanna read the STC instructions for your 160 HP O-320. I believe you will find that it calls for a minimum of 92 or 93 octane.

DAVE
 
Auto fuel and piston change in O-360

In reference to the chatter on December 27 06, my question is: is there a field approval known that makes it possible change an 0-360 with 8:5 compression pistons to 7.2:1 so that a person would be able to us 86/87 octane mogas. I realize it would reduce hp to 168.
 
I think the mogas STC for the 160 & 180-horse Lycomings call for 91 octane. This is with stock pistons,of course,whatever compression ratio that is.
For higher compression engines, how about running 91 octane and if you get pinging/detonation, retard the timing a bit? Probably 2 degrees or so less advance would do the trick. Of course, you're giving up a bit of power, but if it saves you $8-16 per hour it might be worth it. If you're gonna operate high and heavy, re-advance the timing and fill 'er up with 100LL.

Rooster
 
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