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Aviation Fuel - 100LL for Small Engines?


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  #61  
Old 01-06-2012, 09:06:18 AM
Andrew Mackey Andrew Mackey is offline
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Exclamation Re: Aviation Fuel - 100LL for Small Engines?

Power, bleach not a bad idea, just make sure there are no other things around that it can react with. Straight up, it will just about kill anything, even critters like mice and insects!
Andrew
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  #62  
Old 01-06-2012, 12:39:14 PM
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OTTO-Sawyer OTTO-Sawyer is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

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Originally Posted by sprkplug View Post
... If OTTO thought I was attacking Bill, then others surely did also. That was not the case. Just sharing some information.
My apologies, for misinterpreting that.

Having apparently offended Bill myself with my own posts, I just didn't want anyone else inadvertantly making the same mistake. We obviously have different viewpoints, but I still have nothing personal against Bill. I probably read more into your previous post than I should have.

Thank you for clearing it up with your next one with the explanations.
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  #63  
Old 01-06-2012, 12:59:50 PM
sprkplug sprkplug is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

No problem here, Otto, I appreciate your integrity. That quality is sometimes hard to find in the fast pace of today's society.

I enjoy your posts, as well as Bills'. After reading them, I usually find myself with questions that I wasn't smart enough to ask on my own. I consider that a good thing, as it forces me to keep an open mind, and to keep searching for answers. Thanks for posting.
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  #64  
Old 02-02-2012, 09:02:43 AM
sleeve sleeve is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

Coincidence ? We had 2 Ford 800 farm tractors that were used to mow 110 acres of airfield , runway property. The machines were equipped with Woods mowers and were well maintained, serviced regularly. At some point the management ceased buying 87 Octane gas and directed us to use the 100 Octane Aviation Fuel in the old Fords. After A time unscheduled outages began to occur. Burned valves, warped heads, problems starting. engines rebuilt only to have the problems return. I am admittedly not A mechanic , but have operated machinery and driven trucks for years. The avgas is more akin to jet A or kerosene than the highly volatile nitroglycerine type substance it was generally thought to be.Could the slower, more complete burn , over time have damaged the engine valves, pistons etc. ? We got A 80 hp diesel tractor for mowing and site use, end of problem. No one ever commented on the cause of damage to both Ford engines. Any opinions out there ? Sleeve
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  #65  
Old 02-02-2012, 07:57:54 PM
Phil P Phil P is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

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Originally Posted by sleeve View Post
The avgas is more akin to jet A or kerosene than the highly volatile nitroglycerine type substance it was generally thought to be. Sleeve

Hi

100LL is hardly akin to Jet A. I run Jet A in many diesels. 100LL would do the diesel in in very short order. Then put some Jet A in you tractor and you would be lucky to even get it started and if you did it would damage the engine within minutes. Gas engine aircraft that are inadvertently fueled with Jet A run until the Jet fuel reaches the engine. Then in just a minute the engine will stop producing power and reintroducing 100LL by changing tanks will not bring it back to life because of the internal damage.

Many engines designed to operate on 87-octane aviation gasoline have operated and are still operating on 100LL with out engine damage. However it dose produce a lead deposit problem in the low compression engines.


Now back around the mid 80’s one of the aircraft fuel providers had a leak between the Jet or Kerosene and their 100LL in one of their refining plants. The mixture was distributed to many airports. The result was a directive being issued by the FAA to stop flying certain aircraft identified in the directive by their registration numbers.

Fortunately I had spotted the smell of Jet A in my Piper PA-18 super cub and drained the fuel as a precaution. The ribbing I went thru until the directive was issued was extensive. You can guess it I never got an apology from any one but my aircraft wasn’t damaged like the others.

It sounds more like your 100LL was contaminated with Jet fuel. Are you sure you weren’t getting if from the “Sump Tank” and had a mix of Jet A and 100LL?

Phil P
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Old 02-04-2012, 02:37:19 AM
oldschoolwisconsin oldschoolwisconsin is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

Jet A is VERY similar to diesel fuel, has a lower flammability much like diesel, but also does not have as much oil and other lubricity additives in it, which is why you CAN run it in a diesel engine, BUT not for long, and the reason is because it has lower lubricity additives, it cant lubericate injector nozzles/injectors, and high pressure pumps, and causes them to wear out, and not make pressure anymore. Avgas on the other hand is WAY more flammable than regular 87 gas, and also it burns alot hotter than regular gasoline which is why it burned the valves. You want a richer mix if your running it to cool down the combustion temps. Im a toyota tech, and I build engines, transmissions, and cylinder heads on the side. Ive rebuilt 3 different cylinder heads in the last month in my living room at my house. I get the cylinder heads disassembled here in my living room, take them and the assorted pieces parts(springs, valves, caps, keepers, etc) to work, clean them in solvent, clean the cylinder heads in solvent then hot tank them, then bring them back home for rebuild/reassembly. I used to work on airplane engines, and Ive seen the inside of a cylinder assembly that the pilot ran to lean. It melted the valve head clear off the stem, and pitted the inside of the cylinder head and melted the top of the piston. That valve came out of a Lycoming TIO-540. it was a sodium-cooled valve. It was turbocharged, and injected. The TIO part of the model number means Turbocharged, Injected, and opposed, as for a flat type air cooled engine. The cylinder heads normally reach around 420 degrees F. The 540 is the cubic inch displacement, which means that particular engine was 540 cubic inches. 6 cylinders. The pistons are about 4.5 to 5 inches in diameter. Lycoming also makes a TIO-720 engine. This particular one I havent ever seen or worked on because they are kinda rare and hard to find, but its an opposed 8 cylinder thats turbocharged as well. Oh wow, I just said alot of stuff, sorry for rambling on about airplane engines and stuff. But that was one of my most favourite places of employment ever. I cant believe Im only 24, and Ive worked on airplanes, among other things.
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  #67  
Old 02-04-2012, 06:18:21 AM
Phil P Phil P is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

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Originally Posted by oldschoolwisconsin View Post
Jet A is VERY similar to diesel fuel, has a lower flammability much like diesel, but also does not have as much oil and other lubricity additives in it, which is why you CAN run it in a diesel engine, BUT not for long, and the reason is because it has lower lubricity additives, it cant lubericate injector nozzles/injectors, and high pressure pumps, and causes them to wear out, and not make pressure anymore.
Hi

Sorry to burst your bubble.

Aircraft Service International ran Jet A in their Cummings and GM diesel aircraft fueling trucks for 20 years without any ill effects.

Phil P
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  #68  
Old 02-04-2012, 06:59:39 AM
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Default Re: Aviation Fuel - 100LL for Small Engines?

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Originally Posted by oldschoolwisconsin View Post
Jet A is VERY similar to diesel fuel, has a lower flammability much like diesel, but also does not have as much oil and other lubricity additives in it, which is why you CAN run it in a diesel engine, BUT not for long, and the reason is because it has lower lubricity additives, it cant lubericate injector nozzles/injectors, and high pressure pumps, and causes them to wear out, and not make pressure anymore. Avgas on the other hand is WAY more flammable than regular 87 gas, and also it burns alot hotter than regular gasoline which is why it burned the valves. You want a richer mix if your running it to cool down the combustion temps. Im a toyota tech, and I build engines, transmissions, and cylinder heads on the side. Ive rebuilt 3 different cylinder heads in the last month in my living room at my house. I get the cylinder heads disassembled here in my living room, take them and the assorted pieces parts(springs, valves, caps, keepers, etc) to work, clean them in solvent, clean the cylinder heads in solvent then hot tank them, then bring them back home for rebuild/reassembly. I used to work on airplane engines, and Ive seen the inside of a cylinder assembly that the pilot ran to lean. It melted the valve head clear off the stem, and pitted the inside of the cylinder head and melted the top of the piston. That valve came out of a Lycoming TIO-540. it was a sodium-cooled valve. It was turbocharged, and injected. The TIO part of the model number means Turbocharged, Injected, and opposed, as for a flat type air cooled engine. The cylinder heads normally reach around 420 degrees F. The 540 is the cubic inch displacement, which means that particular engine was 540 cubic inches. 6 cylinders. The pistons are about 4.5 to 5 inches in diameter. Lycoming also makes a TIO-720 engine. This particular one I havent ever seen or worked on because they are kinda rare and hard to find, but its an opposed 8 cylinder thats turbocharged as well. Oh wow, I just said alot of stuff, sorry for rambling on about airplane engines and stuff. But that was one of my most favourite places of employment ever. I cant believe Im only 24, and Ive worked on airplanes, among other things.
Thank you to all for the AVGAS info. . The amateur thermodynamics genuises , myself included, all have an opinion , usually wrong. To make matters worse we are dealing with skydivers , not pilots. I mow to jump and noticed the sudden jump in engine problems seemingly coinciding with the switch to AVGAS. The tractors were also operated by other volunteers who could not comprehend the need to raise the mower deck and select A lower gear when dealing with grass 2 feet high on A 90 degree day. As A truck driver I was accustomed to the results of trying to ascend A steep grade too fast, loaded. More HP means burning more fuel while lugging the engine. Air and water flow drop off , oil pressure decreases and temperatures climb until you drop down A few gears and reverse the problem situation. A HP is 33000 ft. lbs. per minute . Doing the work in 2 minutes reduces the power need by one half. There are 2545 BTU per HP hour , the engine converts about 1 fourth to mechanical energy, the rest must be dissipated via radiation losses from the block, oil, radiator coolant etc. . Conservation of energy laws......How many times have you seen someone turn it up, increase the HP and wonder why the engine now overheats ? Thanks again..Sleeve
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  #69  
Old 02-04-2012, 01:30:33 PM
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Default Re: Aviation Fuel - 100LL for Small Engines?

Quote:
Originally Posted by sleeve View Post
... The machines were equipped with Woods mowers and were well maintained, serviced regularly. At some point the management ceased buying 87 Octane gas and directed us to use the 100 Octane Aviation Fuel in the old Fords. After A time unscheduled outages began to occur. Burned valves, warped heads, problems starting. engines rebuilt only to have the problems return... Any opinions out there ? Sleeve
As I've noted before, My old hit & miss engines LOVE high octane racing gas and/or AVgas when they're running slow as the slower burn rate smooths them out instead of jumping when they fire, but if I were working them and running at higher RPMs then I wouldn't use it as the fuel is still burning as it's going out the exhaust.

In a High Compression engine that NEEDS High Octane fuel, the higher compression speeds up the burn rate again and the higher octane is used mainly to control detination, keeping the fuel from exploding violently.

My 37 Ford truck is low enough compression that it will run on pretty much anything I put in it, but it is geared so low that it runs 4,000RPM at 60MPH and would most likely end up with burned valves in it for the exact same reason I mentioned above if I ran racing fuel or Avgas in it on the street. Driving it at low speeds in parades it would probably be OK, but then I would need to switch back to regular 87 or 89 octane for the drive home again so it's not worth it.

I hadn't thought about warped heads till I read your post, but there again with that much heat going out the exhaust, it stands to reason. Set the timing too late and you end up with the same results.... All the heat going out the exhaust and a hotter running engine. Seen way too many wanna-be hot-rodders back off their timing to make the exhaust sound nicer (to them anyway) and then wonder why they were always overheating. I always ran as much advance as I reasonably could for maximum power, and ran cooler doing so.
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Old 02-05-2012, 08:53:25 PM
oldschoolwisconsin oldschoolwisconsin is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

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Originally Posted by Phil P View Post
Hi

Sorry to burst your bubble.

Aircraft Service International ran Jet A in their Cummings and GM diesel aircraft fueling trucks for 20 years without any ill effects.

Phil P
Perhaps I could be wrong about jet fuel not having enough lubricity for diesel injection systems.
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  #71  
Old 02-06-2012, 07:38:29 AM
Phil P Phil P is offline
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Default Re: Aviation Fuel - 100LL for Small Engines?

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Perhaps I could be wrong about jet fuel not having enough lubricity for diesel injection systems.
Hi

I think that is mostly an “old wife’s tail”

The same with the 100LL. We have been using it in the ground equipment including the mowing machines for many years without any problems. It does create a lead problem on the valves of low compression engines but that is all.

We do have trouble with the guys using the very bottom of the “sump fuel” barrels. Then we have fuel filter problems because of contamination and microbes.

A properly maintained high volume Jet A fuel farm generates 50 to 100 gallons of Jet A in one week that gets put in barrels.

It’s a shame we have to give at least half of it to the disposal company to keep the pollution police happy.

Phil P
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Old 02-06-2012, 07:03:16 PM
Andrew Mackey Andrew Mackey is offline
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Exclamation Re: Aviation Fuel - 100LL for Small Engines?

When using higher octane fuel like AVGas, you have to reset the timing to accomodater the slower burn rate. If you do not, it's like running the engine with retarded timing, you are allowing burning fuel to flow out the exhaust, which will burn valves and erode valve seats. It will also increase heat dissapated into the head and block. When I worked at a service station, back in the '70s (dating myself a bit here), we always set the timing to the fuel being used. After tuning to factory specs, we would thoroughly warm the engine by taking the vehicle up I-280, for a 10 mile run. After the run, the vehicle was run up a steep grade, about 2 miles long. (Eagle Rock Ave, up Garrett Mountain in Montclair NJ). After 2 runs up the mountain, a timing light was used to advance the ignition timing by 2 degrees, and the double run was repeated. The advancing was repeated until pinging (pre-ignition) was heard, then the timing was retarded by 2 degrees and the run was once more repeated. After no pinging and maximum advance was set, a 20 mile run on I-280 was repeated, this time from the bottom of the big grade, out of Newark, NJ up to the top of the second mountain at Livingston, NJ. If all was well, the vehicle was returned to the shop, where a hot and cold start test was done. If the vehicle started OK, off it went with a complementary tank of gas. Higher compression vehicles were set to run on high test, lower on regular. Some engines ran great, but wouldn't start worth a damn, once set up. The late 1960s Chevy 307 was a prime example. That engine could be advanced to 28 degrees BTC, without pinging on regular, and would run like a raped ape. Problem was with that far an advance, you could not start it! Max advance (by road test) was about 14 degrees (give or take 2 degrees), without starting problems. We did have one fellow that beat the starting problem, and could do the max advance on the fly! He altered the distributer hold down clamp, so that it would be able to allow the distributer to turn without binding, even when tightenned. He then hooked up a lawnmower throttle control cable to the distributer! Push the control in, timing was about 4 degrees BTC a little advanced from factory spec (TDC) Once the engine fired up, pull out the control, and he could go to about 28 degrees advance. He usually set the control to where the engine did not ping, and left it there until he was done driving. When the key was shut off, a buzzer would sound until the cable was set in to the full in position. The only problem was that the movement of the distributer would wear out the base after while, and we would have to replace the distributer when timing became erratic due to the movement. I think we put 4 distributers in that car, until he wrecked it about 7 years later. Now days, with computer controlled ignition, most cars (except high performance), come with a warning only to use regular, or a specific octane rated fuel. This is done because the computers cannot adjust the timing enough to accomodate the higher octane fuel needs. using high octane in the low octane requirement vehicle will result in valve and other engine da,age. In return, using regular in a high performance vehicle (like the high end Cadillacs), will result in pre-ignition damage, even a blown engine, fot the same reason: the computer cannot compensate for the low octane fuel. With todays crap E-10 fuel, you might not even hear the pinging, but it is still there.
Andrew
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