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Unleaded Avgas - Thoughts?
- Thread starter bertschb
- Start date
skylor
Well Known Member
Actually, Lycoming recommends LW-16702 in the oil regardless of which fuel you use. Note that Aeroshell includes this in some of their oils such as W100+ and 15W-50.
Skylor
Yeah…that’s why lead anti-seize has been around forever….cuz it helps to not-lubricate.
(eye roll)…
(eye roll)…
Lead (tetraethyl lead) in 100LL fuel acts as a cushion and lubricant for valve seats during engine break-in. The lead byproducts coat the valve stems and seats, enhancing sealing and providing protection against valve seat recession and wear. So maybe not as a general lubricant, but it does help during breakin - at least this is what I was told, and why it was recommended to not use UL94 during break in.
I would want to see some recent data to back that up. Lycoming and CMI have used hardened valves for decades.
Tim
MythBusters: Does lead have any effect on valve life?
So remember, it takes only two things to be an expert: gray hair and hemorrhoids. The gray hair makes you look distinguished. The hemorrhoids make you look concerned.
generalaviationnews.com
LW-16702 is just their version of Camguard, isn't it?
If you fly regularly, like once a week, this is not needed at all. If the airplane routinely sits still for 30+ days, then by all means...
Lead is far more like a lubricant than an abrasive. I challenge you to use a lead bar to scuff up your paint or abrade anything else for that matter. While itmay not technically be a lubricant, it provides similar properties in many applications. It is used to coat metal parts that interface with other metal parts to prevent wear of those parts. Heck, my old lathe has a small lead storage device, as lead was put on the dead spindle as a lubricant. Back in the days before hardened valves, the lead in gasoline was critical to prevent the valves and seats from wearing. Replace that lead with valve lapping compound, an actual abrasive and you start removing metal fast.
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I think they use about 75 % lead in some Babbitt bearings. Must not be too abrasive.
What did Lycoming say about backing off on timing when using UL94? Not sure I would go on Mike Busch recommendation alone especially considering Lycoming support has taken a position on UL94 so they must have done some engineering or testing.
That article is from 2008, and and references data from the 1960s, with an anecdotal reference to engines overhauled 15 years ago. Which means those engines had been purchased likely decades ago.MythBusters: Does lead have any effect on valve life?
So remember, it takes only two things to be an expert: gray hair and hemorrhoids. The gray hair makes you look distinguished. The hemorrhoids make you look concerned.
E.g. this data is very old. Find something much more current.
Also, check the break in directions from Lycoming and CMI on engines they produce which accept 94UL. You will find no reference to adding leaded avgas.
Tim
Lead by itself, maybe. In an avgas engine it is not. Check https://en.wikipedia.org/wiki/Tetraethyllead
Look at the byproducts Lead chromide and lead bromide.
Then web search what these byproducts are used for.
TEL is an antiknock agent used to cool the flame front and increase the octane rating. Nothing more, nothing less.
Tim
You can do the research yourself and this being experimental …you have my full support. In the forum you can find the cure to morning sickness, once you start having valve sticking issues and the fix is a Lycoming service bulletin, you can do yo;itself.
I was simply responding that lead is not an abrasive, as used in fuel, or industry…however…if you think the engines have changed compositionally since 2008, you’d be wrong. Metallurgically speaking they are the same as in the 80’s…the notable exception being DLC coating for the lifter faces.
The beauty of experimental aviation is that you are free to conduct your own experiments, with your own pocketbook and backside. Beyond that…the notion that the minuscule amount to lead burned in GA in total, isn’t even worth consideration in the big picture, environmentally speaking and despite alternative fuels being around since the 70’s none have really taken hold and worked out,
I was simply responding that lead is not an abrasive, as used in fuel, or industry…however…if you think the engines have changed compositionally since 2008, you’d be wrong. Metallurgically speaking they are the same as in the 80’s…the notable exception being DLC coating for the lifter faces.
The beauty of experimental aviation is that you are free to conduct your own experiments, with your own pocketbook and backside. Beyond that…the notion that the minuscule amount to lead burned in GA in total, isn’t even worth consideration in the big picture, environmentally speaking and despite alternative fuels being around since the 70’s none have really taken hold and worked out,
Your original statement above. This is simply not correct as other have stated. Lead and other soft metals (more commonly copper and tin in my experience with industrial gas turbines) are commonly used as lubricants and/or sacrificial lubricants. Branching or expanding a position to include combustion effects doesn't change your initial statement.
Edit = anyone else remember all of the engine life issues when the car industry switched to unleaded fuels?
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Yes, I mentioned that. The lead was used to protect the valve and seat faces from wear. Lead went away and problems appeared. The industry then moved to hardened metal valves and seats to deal with it.
And let’s remember…those are water cooled engines. air cooled engines by nature have a different set of variables, thermodynamically….somwe know that lead has primary and secondary functions in our engines…
And yes…I was just taking exception to the statement that lead is an abrasive in fuel…which is incorrect.
I didn't ask them that question. All they said was that the engine with 8.5:1 compression pistons is approved to run UL94. Trying to get them to comment on the timing may be a challenge because in a podcast where Mike Busch interviewed George Braly, one piece of information that George shared (in the context of moving to unleaded fuel) is that changing the timing on a certified aircraft requires a change to the type certificate.
Octane rating/detonation margin with nameplate advance and 8.5-1 pistons was never really a hurdle for UL94 IIRC. Many such power plants were STC’d for 91 octane car gas (Peterson’s?). This question (mine) and other’s opinions are of limited to no value. As mentioned by others, the only real position is the OEM’s.
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Hi All -
I have a follow up to my previous video in February with some new learnings on hoses and bladders. I keep saying that I'm going to make the videos shorter, but there's so much information to cover.
Also, of note at the end of the video is that I have two speaking slots scheduled at airventure on the unleaded fuel topic (Monday and Thursday).
Michael
I have a follow up to my previous video in February with some new learnings on hoses and bladders. I keep saying that I'm going to make the videos shorter, but there's so much information to cover.
Also, of note at the end of the video is that I have two speaking slots scheduled at airventure on the unleaded fuel topic (Monday and Thursday).
Michael
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This is the most comprehensive real world testing of alternate unleaded fuels I have seen to date!
So glad that I stumbled upon your video series! You have taken the analysis to the next level, and presented the information in a very logical and understandable way.
Bravo Michael! Bravo!
It sounds clear from this and previous videos that G100UL is hopelessly DOA. Intrigued about Swift 100R and VP UL100E..
