Is unleaded avgas coming?

I don't see the aviation fuels changing much until we see the ignition systems on these old engines changed to computer driven variable timing. as we see in cars now.
 
Tom-D said:
I don't see the aviation fuels changing much until we see the ignition systems on these old engines changed to computer driven variable timing. as we see in cars now.
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Not necessary. While computer controlled fuel and ignition systems have some advantages, especially in detonation detection and mitigation, you're not going to run the engine on the ragged edge where those systems become necessary for normal operation.

Many of the engines that need 100LL can't accept a reduction in anti-knock capabilities, but they can accept a different fuel with similar anti-knock.
 
Ted DuPuis said:
Not necessary. While computer controlled fuel and ignition systems have some advantages, especially in detonation detection and mitigation, you're not going to run the engine on the ragged edge where those systems become necessary for normal operation.

Many of the engines that need 100LL can't accept a reduction in anti-knock capabilities, but they can accept a different fuel with similar anti-knock.
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You won't do one with out the other.

The slow burning rates that are achieved with TEL are hard to achieve with any other substance. So if you can't slow the burn rate you must change the timing.
 
Tom-D said:
You won't do one with out the other.

The slow burning rates that are achieved with TEL are hard to achieve with any other substance. So if you can't slow the burn rate you must change the timing.
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The realities are that it's not different enough to matter. If I showed you a 100LL vs 93UL pressure trace on an engine that could run 93, you won't be able to tell the difference.
 
Ted DuPuis said:
The realities are that it's not different enough to matter. If I showed you a 100LL vs 93UL pressure trace on an engine that could run 93, you won't be able to tell the difference.
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Now if it needed 100 the difference should be rather dramatic,
 
Here's how I see this working out:

Experimentals and certain low power certifieds: Mogas

High power, higher end pistons, commercial applications: diesels or turbines

Everything else not worth converting: scrap

The manufacturers have already weighted in on this. The alternative fuels are too expensive, to slow to roll out, to hard politically, and the market isn't big enough now and shrinking everyday.
 
Unleaded avgas will be easily found about the same time I make a wedding announcement.
 
This is part of why owner experimental would be beneficial. Then we could make airframe changes that would allow MoGas or Jet...
 
Skylane81E said:
Guess I'm flying scrap
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Nah, just exchange the noise machine for for an O-470 and you're good to go. And don't tell anyone, but I'm pretty sure you can burn the forbidden stuff in your mill and nothing bad would happen...:D

My Warrior II was supposed to explode due to the extra 10HP "requiring" some crazy re-plumbing and and....:rolleyes:;)
 
hindsight2020 said:
Nah, just exchange the noise machine for for an O-470 and you're good to go. And don't tell anyone, but I'm pretty sure you can burn the forbidden stuff in your mill and nothing bad would happen...:D

My Warrior II was supposed to explode due to the extra 10HP "requiring" some crazy re-plumbing and and....:rolleyes:;)
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I have an O-470, but its a U
 
Alexb2000 said:
Not at all. Mogas or diesel conversion. Look at what people are spending on the Petersen conversions. I believe a clean 182 airframe could continue to make sense with a $60-70K diesel.
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Mogas isn't an option and a diesel conversion is a very large portion of the value of the plane
 
Geico266 said:
Vapor lock is caused when there is a vaccum.
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That's only one potential condition. Fuel doesn't have to be under a vacuum to change phase to vapor.

Geico266 said:
This is why many experimentals have now been designed with the electric fuel pump in the wing root area, if not inside the tank. This eliminates the chance for VL because the entire fuel system is pressurized.
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"Eliminated the chance" is a phrase I make a habit not to use. Petersen doesn't use it either.

Geico266 said:
Many experimentals burn mogas, and have for tens of thousands of hours with no problems.
Some I know burn ethanol blended fuels.
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Sure. And the NTSB records have numerous reports of downed planes with suspected vapor lock -- certified, experimental, and RV included.

Geico266 said:
If vapor lock was such a huge problem we would see a much larger problem, and Peterson would be out of business.
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Who said huge? I'd balk on infrequent or maybe even rare.

Petersen failed in their attempts to get a mogas STC for Mooneys and Comanches, and it wasn't because of vapor causing issues with the fuel pump, but for hot fuel boiling downstream of the pumps.
 
Geico266 said:
Exactly. :yes:

My educated guess is 50% of experimentals run mogas with no issues at all.
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Most experimentals also have the engines that would be able to run MoGas just fine. O-320/O-360/O-540s aren't high-powered engines and are prime candidates.

The 310 would be more difficult with high compression 520s making 300 HP. So I'd expect similar challenges from a Lancair IV/IV-P or Evolution.
 
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