New AVGAS coming

[Rick Kirchner]

The FAA has been working on unleaded AVGAS for decades. Looks like one brand will be available at three CA airports later this year.

It supposedly doesn't degrade over three years in storage, and doesn't harm fiberglas or carbon fiber fuel cells. No data published on what it does to neoprene cells.

Slightly heavier and get this - produces 4% more HP.

[Hardingfv32]

The provider, Swift Fuels, indicates it is/was considering the use of ETBE which is similar to the band MTBE.

1) How does ETBE avoid a ban similar to that of MTBE?

2) Why did the gasoline industry not go to ETBE when MTBE was banned?

There are not a lot of economical options to replacing lead in avgas.

Brian

[Rick Kirchner]

MTBE's problem was solely that it was poisonous (where ethanol isn't) and combines with groundwater just as easily. So, given all the underground storage tanks we now have a huge problem with groundwater contamination that will not go away for decades. At least it makes the water tase bad at low concentrations, so you have an idea that something is wrong.

MTBE had a leg up in Cali because ARCO is headquarted and incorporated in the state, and they were a major producer. And Cali neither wanted to send it's dollars to midwest farmers nor deal with the transportation issues ethanol would bring.

IIRC, MTBE is pretty destructive to neoprene fuel cells. ETBE, who knows?

[alangbaker]

MTBE's problem was solely that it was poisonous (where ethanol isn't) and combines with groundwater just as easily. So, given all the underground storage tanks we now have a huge problem with groundwater contamination that will not go away for decades. At least it makes the water tase bad at low concentrations, so you have an idea that something is wrong.

MTBE had a leg up in Cali because ARCO is headquarted and incorporated in the state, and they were a major producer. And Cali neither wanted to send it's dollars to midwest farmers nor deal with the transportation issues ethanol would bring.

IIRC, MTBE is pretty destructive to neoprene fuel cells. ETBE, who knows?

Hmmmmm...maybe chemists?

[Roux]

https://digital.library.unt.edu/ark:.../metadc702496/

[Rick Kirchner]

https://digital.library.unt.edu/ark:.../metadc702496/

Nope - this was actual gas. The ETBE being an additive. Which is interesting, now that I think avbout it.

I wonder if ETBE is needed as a octane enhancer, of if they are trying to oxygenate aircraft fuel. I can't imagine using something with the water absorption and corrosion problems that ethanol has. Carbureted planes that sit around for months in a humid environment - that would be a mess.

So ETBE must not absorb water like MTBE or Ethanol.

[DanW]

ETBE is both an oxygenate and an octane improver.

MTBE has contaminated about 30% of the fresh water wells in the Lake Tahoe basin making them unfit for use.

https://www.spglobal.com/commodityin...-handbook.html

[Matt Clark]

produces 4% more HP.

we are testing it right now... as far as I know, we are not seeing any gains yet. if we were, we'd be recommending. that being said, we are testing it because we got funding to do so, not out of our own pocket.

[Rick Kirchner]

Here's the article I read:
https://generalaviationnews.com/2023...y-summer-2023/

Of course the aviation use is a bit different from ours, lower compression, lower RPM, constant throttle - that's something not discussed - transient throttle performance.

[Matt Clark]

Use & application is slightly different than a race car, for sure. But generally, fuel should have roughly the same effect in any engine.
We will see what our test results are here. I know it says Cirrus tested it, but I do not know what engine they tested it with, or much else from them. I am kinda wondering if it just cools better to get the HP gain they are saying.

Personally, I am not expecting a surprise miracle fuel. There is always a catch.