100LL fuel

[gmpaul]

I'm building an RV9 and starting to look for an engine. Here's the Question: How does the RV community feel about 100LL? Do ya'll think it is here to stay or is it going the way of ethel for our cars?

Thanks GP

[tacchi88]

Mr. GP,
In our group, we operate as many as 8 different ACs with mogas. In all cases, they have exibited lower fuel consumption, lower oil consumption, and vast increase in plug life. Engines include, Continentals, Lycomings, Rotax, Corvair.
In one case, the Conti powered 182 is equiped with an engine anylizer. With 100 LL, temperatures are unstable and varyiing as much as 150 deg and up, with mogas, temps stable in the 10s up or down. Some of these ACs have been running on mogas for more than 20 years, most on the average of 10 years.
The engines most sensitive, and for the worst. are the Rotax, and the Corvair.
T88

[Bob Axsom]

My guess is it will be around as long as it is not legislated out. It is too easy a market to be ignored even though you hear it is such a small part of the market ... it remains a significant amount of money that exclusive sales to make someone very rich. It's a free enterprise thing.

Bob Axsom

[Captain_John]

The article in "24 years of the RVator" is a very strong argument in support of MOGAS.

It confirms those facts stated by T88.

Cooler operation, less fouling and of course... less MONEY!

The planes with lower compression should be able to use it without any problems, so long as you don't get pre-ignition.

One problem is, you don't get that great AVGAS smell!

I first told myself that I would never use MOGAS in my plane but, I may just reconsider. Especially with fuel costs going up and up!

The IO-390 is a moderate compression (I think 8.7:1 ?) engine and *should* work adequately on MOGAS.

CJ

[Kyle Boatright]

100 LL will be here for some time, IMO.

First, there is a market for it.

Second, there are at least a handful of general aviation engines that depend on it.

Third, there are plenty of aircraft that don't have autogas STC's at this time. Without 100 LL they would be grounded.

Fourth, most FBO's don't want to carry two different fuels - the 100LL for the aircraft that need it and autogas for everyone else, so they are going to default to 100LL so they can serve everyone.

Fifth, avgas (and its lead content) is a pretty small target for the environmental crowd. They have bigger fish to fry and will <probably> concentrate their efforts in areas with what they believe to be a bigger benefit.

[tacchi88]

A few interesting facts. If any one has the opportunity to look at an old flight manual of a Cub, for example, you would find the following. Fuel of choice, pump gas, AV gas optional. Oil of choice based on SAE specification, no mention of AD oil.
The market for AV gas is based on the fact that it is mandated for most ACs. Unfortunately, aviation is riddled with heresay, and lack of motivation. The EAA was the spear head for approval of mogas, yet there are many, particularly in the experimental community, that for some odd reason do not recognize the benifits of mogas.
If we ever see the Continental /Honda or the Bombardier/Rotax, these new engines will accept mogas, av gas, and even for the mix affecionados, a mixture of the good stuff mogas, and the foul stuff,AV gas. Regardless, mogas is king, despite all the "claims" of alcahol ethonal, MTBE, etc.
How can I make these claims, simple, from racing experience, and 2 years on a dynomometer. A stock racer, who lived on my old field, even stopped using AV gas for his race cars. Mogas was better, among other "idiocincracies" was the fouling caused by the lead.
Lead is/was the easiest and most convinient means of controlling detonation, octane's purpose in life. High or low octane, gasoline is the same. Resistance to pre ignite is a function of lead or any other chemical that has that ability. Higher octane is no more powerful than low octane. The high stuff simply resists pre ignition.
Compression ratios has little to do nowadays, with the use of higher octane numbers. A look at the auto world will bear that out. Some will say, it's because of computers. Well then, why isn't aviation embracing technology that has been present now for more than 35 years, which is the root cause of the use of AV gas, and the problems it brings with it.
Do I believe in mogas, you bet.
My RV10 will be fitted with LASAR, and will use mogas as much as possible. Yes, Unison says not to, and because it was mandated by the FAA (our biggest problem). I tried mogas on my LASAR equiped Arrow, and the results were short of amazing. We're experimental, so go for it.
T88

[rv8ch]

Not using 100LL is a very good thing, IMHO. Reducing the amount of lead that we spray across the countryside is simply the neighborly thing to do.

[Capflyer]

I would love to use strictly MOGAS.

Can those of you that use it can comment on how difficult it is to get on X/C's and how you handle mix and matching MOGAS with 100LL? I would be interested in some real world experiences. Also, how do you keep your cars from smelling after hauling 20-30 gal of MOGAS in your cars. I have a hard enough time with the 2.5gal jugs for the lawnmower. Do any of the airports you hit on X/C's give you a crew car and some fuel jugs to borrow? Is this a dream or realistic?

[tacchi88]

We use the 182 for X/C and average 12 gph with mogas (87). Most trips under 4 hrs we'll go back and forth. 4 hrs. gives us a broad safety margin. Never had the experience of having to fill with mogas on a trip, nor ask to get some, so we do the dasterdly deed to the engine, and fill with AV gas. The 182 feeds both tanks at once, though I personally like one at a time. We found that if AV gas is less that 1/4 (approx) of the exiting mogas, fuel consumption increases little. with more than half, consumption rises at or above 14 gph. In addition EGTs are unstable. The added fuel consumption is largely due to adding fuel for cooling. As to harming the engine. av gas is rarely used for more than a couple of hours. Refilling with mogas, stabilizes temperatures, and when fully stable, it's clear enough that the build ups in the combustion chamber have been minimized. This has been our experience.
T88

[RudiGreyling]

Hi Guys,

I am building with mogas in mind, will still be 2-3 years before I'm flying. Consideration needs to be given to vapour lock.

If I don't like it I can always revert back to old 100LL.
If 100LL goes then at least I know I built with mogas in mind.

So I think I have both bases covered.

Regards
Rudi