Lycoming IO540 on MOGAS?

[seat 0A]

Hello all,

Does anybody have any knowledge on the availability of a certification of the Lycoming IO540 engines on unleaded 98 octane fuel?
We`re looking into this possibility, but with no luck so far.

Thanks a lot for any info.

[A and C]

I think it is unlikely that this would work, the 300hp engine is fitted with high compression cylinders so for that type of engine the answer is "NO".

If you are talking of the 240hp engine with the low compression cylinders then the answer is "maybe".

The thing to be remembered about Avgas 100LL is that it has an octaine rating of 130 with a rich mixture and 100 when leaned off, I dont think that at full power the 300hp IO540 would take kindly to a 98 octaine fuel.

[AdamFrisch]

As far as I know, no high performance aviation engine will run low octane reliably without lowering the compression. Detonation and pre-ignition will occur. Also, Mogas contains ethanol which freezes at low temperatures up high and can cause fuel blockages. This is why 100LL has had such an extended stay despite it's unfriendly environmental footprint. However, it's coming to it's end, so a replacement is needed very soon.

[Old Akro]

See the Lycoming & TCM interviews on avweb

[mm_flynn]

There have been some successful trials running the IO-550 on 100UL (i.e. avgas without the lead). However, the IO-540 is probably second only to the TIO-540 in small detonation margins. Sadly you will not find a Mogas STC for this.

[IO540]

The situation is too fluid right now for any answer to be definitive.

Lyco are preparing an announcement for Oshkosh (when is it??) which I have seen.

[fuzzy6988]

I had a friendly bet with some mates to see whether someone with the same alias as the name of the topic would reply to that topic on the same day, within the space of this week.

In this case IO540 has replied to a topic on IO540 in a matter of hours.

Very cool. I win my bet!

[IO540]

Only because the threat starter sent me an email (which bounced due to a duff sender address so I copied it to him by PM)

[seat 0A]

Yes, sorry for the bounce. I have updated my address now.
Thanks for the replies people. The aircraft concerned is a piper aztec with the 250 hp engines.
So I guess it`s not going to be happening any time soon.
Let`s hope Lycoming is going to surprise us all at Oshkosh

[Big Pistons Forever]

There are two horsepower ratings for the Lycoming IO 540 260 and 300. I believe the 260 hp version was originally certified for 90-96 Octane gas, but all of the 300 hp versions require a minimum of 100 Low lead fuel. The only version of the 540 series that have a MOGAS STC is the carburated 235 hp
O 540.

[flyroccia]

Any news about Lyco Mogas?

I've PA32 XTC equipped with TIO-540 turbo 300hp. In Europe and expecially in Italy start to be difficult to find airport that supply AVGAS 100LL. The price has soared climbing as a rocket (depending from the airport is between 2.20 Euro/liter -8.32 usd/gal- and 3.00 Euro/liter -11,34 usd/gal). A lot are changing versus Jet A1 engine - eg. Diamond-. in Europe we have also Mogas 99-100 Octane that will solve partially the problem. Can my engine run with this fuel?

[Johnm]

This is why 100LL has had such an extended stay despite it's unfriendly environmental footprint.

There's absolutely no evidence that lead in motor fuel ever caused any real harm it was banned 'cos some environmental lobbyists in the US discovered that lead is a cumulative poison and did an extrapolation that was utter nonsense, but succeeded in getting unleaded and catalytic converters mandated. This combination is more environmentally unfriendly than any leaded solution due to poorer fuel consumption and the toxic heavy metals in CATS.

For what it's worth my generation probably ingested more lead from chewing the paint off our cots when we were babies

There is even less of a case for banning 100LL since the volumes are so low its environmental impact is negligible. However the same lobbyists are riding the same hobby horse so the same stupid outcome seems inevitable.

[mmbengt]

A nice review of the current situation of unleaded AVGAS is given by Lars Hjelmberg in he link bellow:

http://www.hjelmco.com/upl/files/43521.pdf

[Shorrick Mk2]

So does the introduction of the Continental TSIO 550K and its advertised "future fuel flexibility" bring anything new to the debate?

[Big Pistons Forever]

Continental appear to have decided that the "new" AVGAS will be 94UL and are starting to prepare for its introduction. They have an advantage because the Continental IO550/TSIO550 series seems to do better on unleaded gasoline than the Lycoming IO540/TIO540 series. Since about 2/3 of all avgas sold today in the US goes into one or the other of these engines IMO what works best for the big block 6 cylinder engines is going to be the final solution. Swift Fuel and GAMI are working on a true 100 Octane no lead formulation but it is hard to see how they will be able to make it work at a reasonable cost per gallon given the low volumes. I was a little shocked that US refineries do nto even consider AVGAS as a gasoline product but class it as a specialty chemical. The big advantage of 94UL is that it uses the existing refinery processes and distribution system, this alone has got to represent a powerfull reason to go the 94UL route.

[Katamarino]

To be honest, I'm more interested in the development of Jet-A burners; whatever AVGAS replacement turns up, it will probably not have the worldwide availability of Jet-A any time soon.

[hatzflyer]

I don't know specifically about the 540 but a mogas STC is usually dependant on the aircraft type. In some combinations it is the airframe that gives rise to problems (ie hot spots in the fuel lines/ pumps etc) .