Let's talk about Avgas (100LL)

[stangflyer]

thurmma said
BikeRacer said
I also share a few doubts regarding the lead, but in reality, it's very low and I'm more asking about how it runs in our planes. Race gas would be another contender in this thread. The lead was the main reason we wanted to use it, there was the rumor of lower engine temps and the use of less oil for a cleaner and stronger running engine. Do I need it? Absolutely not, but I would like to get some real feedback on it for others to use because well... I'm curious.

I haven't ran the 100LL, but was thinking about it until I talked to DA and Geahart at Aircraft International, 3W rep. Both companies said that the LL would leave deposits in the engines and could possibly void the warranty should they fail. This was from 2 completely different companies with no ties at all and their answers were almost like listening to a recording, so I listened

I do smart things once in a while.

When I asked about oils to run, they both said to stay away from Amzoil because of the junk it leaves in the engines and that Redline is the preferred oil to run at this time. I had been running Amzoil and noticed that I always had black junk all over the bottom of the plane and my landing gear and it wasn't from running super rich either. All engines were running very nicely. After a couple of tanks of Redline at the same ration, amazingly no more black junk and the engines seemed to be running smoother. I run 50:1, but you need to run what your engine manufacturer recommends or what you are comfortable with.

Man, I am long winded today, somebody stop me!
I'd have to agree with this. I also talked with Gerhard regarding my 3W 157CS. He told me the same thing regarding gas and oil combinations. He as well as DLE stated that warranties will not cover the use of AV gas in their motors. At least this is what I was told.

Here are some facts for you to consider. If anyone has more input than I, then I too would be interested to hear it. 

First, I have been running Red Line in all my gassers since day one. I originally did "try" another brand of oil that was recommended. Crappy dirty fuselage and really did not like the performance of the two motors I tried it in. Went straight back to the Red Line, Fuses are clean and motors are very happy.

There are a couple of stations in the valley that offer 91 octane Non-ethanol premium for around $4.00 bucks a gallon. That is what I have been using and I have not seen or experienced any problems. A number of guys at the field have been running AV gas and they swear by it, but here is what I found. They were constantly fiddling with their DA's and like motors. Couldn't get them to idle, start or otherwise run constantly without a dead stick. Even my original RCG 50cc I would flip the prop "ONE" time and up and purring like a kitten. While these other guys are cussing and fiddling with their motors, I was flying and having a "GREAT" time. I have to believe it was the gas. 

They swear by the AV gas because it is "NOT" supposed to be harmful to fuel systems. However one of the biggest users of the AV gas had a brand new H-9 Beast with a 9 cylinder radial on it that he maidened this past summer. He got one short five minute flight and landed to check things out. Without refueling, (Guess he figured there was no need for it) took off again and after about three minutes, he did a slow roll and the motor died and "IN" she went. Nothing bigger than a quarter left of it. It was discovered that he used a recently used tank that was previously run with AV gas. Apparently the tank was still half full when the plane was recovered. Ummm, bottom half. The fuel tubing inside the tank was stiffer than a guys you know what in a brothel full hotties. (Upon preforming the roll, the fuel could not get to the clunk) I recently just went through all my flying planes that I have been using the Non-ethanol and checked every inch of fuel tubing in every single plane. Not a single one of them are showing signs of hardening of the lines. In fact the lines are still as soft and flexable as the day I put them in. Two planes over two years now. Not a problem one from any of them.

I was informed to be especially cautious of engine temps on my 3dub, so I monitor it closely. As well as my others. Mine and my son use the same fuel and the same oil. All our DLE 55's are running around 165 to 180. My 157, slightly over that. No sooty build up in the exhaust, no gumming of the motors. 

Just my opinion from my experiences, I will stay away from the AV gas as long as there is quality non ethanol to be purchased. I just can't see there would be an advantage to the risks and lack of performance as I have seen first hand. 

Wow Mark, you thought you were long winded tonight. LOL

 

[GaryToland]

Why Eliminate 100LL?
100LL, also known as 100 octane aviation fuel (100 Low Lead), is a petroleum fuel designed for reciprocating aircraft engines.  This gasoline has an octane number of no less than 99.6, adheres to ASTM Specification D 910, and contains tetraethyl lead as an anti-knock agent.  The addition of tetraethyl lead (TEL) in aviation gasoline also requires the addition of ethylene dibromide (EDB) as a scavenger to help remove lead oxide from engine components  after combustion.  The resulting emission product is mostly a lead dibromide particulate which enters the atmosphere and pollutes the environment with lead.



100LL has been the mainstay in general aviation for the past thirty years.  Prior to environmental pressure thirty years ago, the TEL concentration in general aviation fuel was double what it is today (0.53 mL/L).  100LL is being scrutinized again today by various environmental groups, as it is currently the source of 45% of annual domestic lead emissions.  On October 12th, 2006, a petition was filed with the EPA by Bluewater Network, a division of Friends of the Earth, asking the EPA to determine whether lead emissions from general aviation pose a significant risk to human health.  If sufficient information was found, the EPA was asked to make a formal Finding of Endangerment to public health and welfare.  This would result in the regulation of lead emissions caused by the combustion of 100LL.  The other driving force behind the reduction of 100LL use is the updated National Ambient Air Quality Standard (NAAQS) for lead, which was released by the EPA in October 2008.  For the previous twenty nine years, the limit for ambient air lead was set at 1.5 µg/m3.  Medical research since then has shown that much smaller lead levels can cause serious health effects, especially in children.  The new standard allows for lead levels to be reduced to only 0.15 µg/m3 of air, or 10% of the old standard, by no later than January 2017.



 



And the fact that it's just a little toxic! I'm not a tree hugger by any means, but I've already had cancer once.

 

[Ohio AV8TOR]

Well I am glad I am using Redline and glad I have not tried Avgas although thought about it.  Great posts guys

 

[2walla]

I havent had problems with avgas. Biggest benefit is it doesnt leave nasty crud in the carb after it sits for several months. The god knows what additives and seasonal blends they can put in car gas can make every fillup a retuning excercise. Good luck truly finding no alcohol car gas.. Avgas cant have too much done to it to maintain faa compliance after it leaves the refinery. Avgas has a different weight per gallon and a different energy density so you do need to retune your engines if you are switching.

 

[TazmanianDevil]

I've been using 95, 98 here in my country (we don't have Ethanol) and when I came to the US I used the 87 with Ethanol.
My engine is MVVS 175.
Sorry but didn't felt like a big difference between them, the idle did went up with the 87 but couple of clicks down in the TX and that's it.
The 87 you have is good enough, I did more than 35gal there to tell you that the engine worked like a Swiss clock.
As long as the engine is working and there is not more than a month period between the flights than the carb is good and the engine is working just fine.

 

[TiredOldMan]

The use of 100ll Av Gas is a discussion that has been around since they started adding methanol to our gas. Av Gas is not good for our engines because they were not designed to use it. The lead in Av Gas is there to prolong the life of valve seats and inhibit detonation in large 4 stroke engines turning RPM at less than maximum output. As one that has tried to clean the plugs in 100cc+ two strokes to clear lead accumulations I can assure you the lead in Av Gas is a terrible fouling agent in our engines.

Regarding the 'black stuff" on the bottom of planes and oil used. Some oils are indeed a lot better than others but the type of oil used during the first 10 to 20 hours of engine use is not going to have much effect on how much black stuff one gets. As the engine breaks in metals self hone inside the cylinder, which causes the "black stuff" Tuning an engine too rich also generates a larger amount of "black stuff" because a lot of fuel does not completely burn, creating cold carbon particles that stick to the bottom of the plane in line with the exhaust. That black stuff can slowly go away after changing to a different oil simply because the user finally got the tuning close to right or the engine completed the break in cycle.

Back to Av Gas. Don't use it, don't pay the exorbitant price for it, and instead use a quality pump gas with an octane rating suitable for the engine it will be run in. 3w, MVVS, and ZDZ engines are higher in compression and need a premium grade gas. Most others have much lower compression. The engine manufacturer provided a fuel recommendation in their user manuals. Heed their advice and your engine will last a very, very long time if you don't use it to dig holes in the ground while tuning and cooling it reasonably well. Oils DO matter but I won't initiate that battle again. It was proven and settled a long time ago. I won't bother to qualify my experience/expertise in these areas but many already know they are extensive.