Can the Titan 340CC use mogas?

[Schwbo]

What is required to use mogas on Titan 340CC?


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[Dan L]

http://www.cubcraftersforums.com/sho...-91UL-in-CC340

take a look here.

[Jon Delamarter]

At 9.0:1, the CC340 is highly prone to detonation when operated on automotive fuel (mogas). Definitely recommend against it. It has been tried with catastrophic results; twice.

[terry]

At 9.0:1, the CC340 is highly prone to detonation when operated on automotive fuel (mogas). Definitely recommend against it. It has been tried with catastrophic results; twice.

On the Titan X340 Series Engine website is recommended 93/100/100LL
In New Zealand we can obtain mogas of 91/95/98. Are the 95/98 suitable, as that is my understanding for light sport given the Titan website
What was the cercumstances for your above reference??

[kemper28]

Jon,

Can you give us some details on the destruction of the 340cc using mogas? What octane? What Altitude? What actually happened to the motor(s)?

Thanks,

Jason

[Jon Delamarter]

The catastrophic failures I mentioned in an earlier post were both on the same aircraft and in rapid succession. In both cases, the overseas customer attempted to run the CC340 on mogas. Detonation wrecked the engines within minutes of takeoff. We eventually built a detuned engine (8.5:1 compression, 20 deg ignition timing) for the customer; as far as I know, that engine is doing well on mogas.

Detonation is a function of several things: CMEP (cylinder mean effective pressure, a function of compression ratio and manifold pressure), cylinder head temperature, and ignition timing. The CC340 has high compression pistons and advanced ignition timing. These both result in CHTs that are typically a bit higher than a comparable stock Lycoming running 8.5:1 and 25 degree magnetos. These three things combined result in detonation margins that are close enough on this engine to immediately push it into detonation if an inferior fuel is introduced.

The question has been asked why a Rotax, with a compression ratio of 10.5:1, can safely run on mogas. The answer is simple; the Rotax has liquid cooled heads with a maximum temperature of 300 degrees, a full 200 degrees lower than a Lycoming and 150 degrees lower than your CC340. The drastically cooler cylinder head temps allow Rotax to push the compression ratio up while running a lower octane fuel, without the risk of detonation. (Note that the Rotax 914, typical of turbocharged aircraft engines, has a reduced compression ratio, in this case 9.0:1. This decreases efficiency, but reduces detonation margin to a manageable level.)

Please guys, don't put mogas in your Carbon Cub. You have a highly engineered engine, designed for maximum horsepower output on 100LL. There simply is no margin for mogas.

[kemper28]

The catastrophic failures I mentioned in an earlier post were both on the same aircraft and in rapid succession. In both cases, the overseas customer attempted to run the CC340 on mogas. Detonation wrecked the engines within minutes of takeoff. We eventually built a detuned engine (8.5:1 compression, 20 deg ignition timing) for the customer; as far as I know, that engine is doing well on mogas.

Detonation is a function of several things: CMEP (cylinder mean effective pressure, a function of compression ratio and manifold pressure), cylinder head temperature, and ignition timing. The CC340 has high compression pistons and advanced ignition timing. These both result in CHTs that are typically a bit higher than a comparable stock Lycoming running 8.5:1 and 25 degree magnetos. These three things combined result in detonation margins that are close enough on this engine to immediately push it into detonation if an inferior fuel is introduced.

The question has been asked why a Rotax, with a compression ratio of 10.5:1, can safely run on mogas. The answer is simple; the Rotax has liquid cooled heads with a maximum temperature of 300 degrees, a full 200 degrees lower than a Lycoming and 150 degrees lower than your CC340. The drastically cooler cylinder head temps allow Rotax to push the compression ratio up while running a lower octane fuel, without the risk of detonation. (Note that the Rotax 914, typical of turbocharged aircraft engines, has a reduced compression ratio, in this case 9.0:1. This decreases efficiency, but reduces detonation margin to a manageable level.)

Please guys, don't put mogas in your Carbon Cub. You have a highly engineered engine, designed for maximum horsepower output on 100LL. There simply is no margin for mogas.

Jon,

Thanks for the info, Any idea what the octane was on the mogas they were running? I do not plan on running mogas in my 340 but I was just surprised to see your post because I have talked to at least 10 different CC owners that routinely run high octane car gas in their 340's. They also all said they run the engine with car gas just like they would if it was running on 100LL. I have had some occasions when I had to run car gas in an IO-360 with 9.5 compression and I just wait until I am in cruise and down to 50-60 percent power to burn the car gas. Normally mogas is around 88 or 85 octane so maybe this is what caused the issues. I am just trying to figure out how one guy killed his engine with mogas instantly and theses 10 other CC owners I know run high octane car gas all the time with no "known" issues.

I am very familiar with the rotax engines, I have owned a plane with a 914 and a 912. You probably know this, but for anyone interested, the 914 is just rotax's 80hp engine with a turbo unit bolted to it due to the lower compression. That turbo unit is one thing I will miss when my carbon cub is flying. Getting 40 inches of manifold pressure when blasting out of mile hi in idaho makes for a pretty high performance aircraft. My S7 with the 914 would out perform and out climb a carbon cub at high elevation airstrips or say if I was to race a CC to 12k.


Thanks for the reply,

Jason

[Scott c]

I cannot understand why anyone would consider cheaping out on fuel when an engine costs 30k and uses hardly any fuel. Supply may be a different problem but for most it is available. Seems like tripping over a five dollar bill to pick up a nickle.

[Jon Delamarter]

My S7 with the 914 would out perform and out climb a carbon cub at high elevation airstrips or say if I was to race a CC to 12k.

Still got the S7? A race to 12K sounds like fun!


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[randylervold]

Any idea what the octane was on the mogas they were running? I do not plan on running mogas in my 340 but I was just surprised to see your post because I have talked to at least 10 different CC owners that routinely run high octane car gas in their 340's. They also all said they run the engine with car gas just like they would if it was running on 100LL. I have had some occasions when I had to run car gas in an IO-360 with 9.5 compression and I just wait until I am in cruise and down to 50-60 percent power to burn the car gas. Normally mogas is around 88 or 85 octane so maybe this is what caused the issues. I am just trying to figure out how one guy killed his engine with mogas instantly and theses 10 other CC owners I know run high octane car gas all the time with no "known" issues.

Jason

Jason, the two failures Jon mentioned were not in the US, rather the middle east. Therein lies the problem -- in the US our mogas is consistent and refined to a standard we know, but when you start getting into other non-US markets it's jungle rules (no pun intended). With it's 9.0-1 compression and it's double electronic ignition with more advanced timing than magnetos you get a challenging environment for preventing detonation with fuel of unknown octane. Then of course there's the ethanol issue.

Indeed quite a few CC340 owners have used PREMIUM mogas in the US with acceptable results, but we can't and won't recommend it because 1) we have customers all over the world with dubious fuel quality, and 2) the well documented dangers of ethanol in aviation applications.