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Will my IO-550-N run on 115/145 fuel?

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Will my IO-550-N run on 115/145 fuel?

Old 28th Sep 2008, 16:55
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Question Will my IO-550-N run on 115/145 fuel?

Hi there,
I am planning a trip to eastern europe and have some fuel availability issues.
I know the approved fuel grades for the Conti is 100LL or 100. Continetal says the minimum grade is 100...So here is my question:
What happens if you put a higher grade in your engine?
Has anyone tried 115/145 (purple) fuel in their Cirrus SR22?
Does anyone know , and on which base, if it will /won't work?

Thanx a lot,

zh8001 is offline  
Old 29th Sep 2008, 04:45
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In ground school it's taught that if you are to use fuel different from what the engine normally runs on, use higher performance grade. It's more resistant to detonation and pre-ignition.

Even if the engine can take other than POH approved fuel, maybe some other part of the fuel system can not. I don't have the experience so I can tell...

Where I come from, some operators fly the Cessna 172 (Lycoming IO-320) on 91/96, a lower performance grade than the POH approved 100LL and 100. I have never heard about any STC for 91/96, but it exists for MOGAS. But it works!

Remember, if something happens to your engine during your flight, YOUR ass is on the line since you did not follow the POH.
172_driver is offline  
Old 29th Sep 2008, 07:41
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Check the Engine Type Certificate and the AIrcraft / Engine Combination Type Certificate and as stated before the 'Flight Manual'...
spannersatKL is offline  
Old 29th Sep 2008, 08:13
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High octane use -

I have NEVER heard an engine failing because of using higher octane than required...
The opposite (lower octane than required) has caused many accidents.
All I heard is, that higher octane burns spark plugs more frequently.
Look what it says in your pilot manual, or call the engine manufacturer.
Long ago, I used to fly lighplanes requiring 80/87 octane "red color" gas.
I recall having to fill tanks with 100 LL or 130 "green color" gas.
Never tried the purple 130/145...
I doubt you can get to FL 450 with a J-3C even using 130/145...!
Same thing with your car. Use low octane gas if it only requires low octane.
If you require higher octane, use premium or extra whatever they call it in your country.
It will not harm your engine. But "higher octane" will NOT GIVE YOU EXTRA POWER...
Va va voom -

Happy contrails
BelArgUSA is offline  
Old 29th Sep 2008, 11:22
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The fuel designation number represents the octane number. Aviation fuels run on an octane range, with the first number being the lean mixture anti-detonation or octane figure, and the second being the top of the rich range. You can think of it as anti-detonation protection throughout the engine operating range...in this case 115 being your idle protection, and 145 being your rich, full power protection for high power settings.

100 octane aviation fuel was a shortened version of 100/130 (green), with an octane range for lower power, or smaller displacement engines. Since that time, we have 100LL, which desipite the name "100 low lead" is actually quite high in lead content...tetraethyl lead being one of the primary tools used to control detonation and establish a specified detonation resistance in aviation fuels.

Use of fuels designed for bigger engines...and 115/145 is for bigger radial engines...may lead to higher incidences of spark plug fouling, especially if you're using massive electrode spark plugs. Continental recommends post-flight engine runs of a minute to a minute and a half, between 800 and 1000 rpm, to normalize the engine and clear deposits. When this is done, you should go to idle cutoff with the mixture from this RPM range and power setting, rather than retarding the power to idle first...run it for a minute and a half in the parking spot at 1000 rpm, and pull the mixture to cutoff from there without touching the throttle.

All Continental motors that were certified on 100LL or 100/130 will run fine on 115/145, but will still foul more easily and are susceptible to combustion chamber deposits as a result of the higher tetraethyl lead content. It's also recommended that you reduce your oil change intervals. I always recommend a maximum of 50 hours between oil changes, with 25 under unusual operating conditions (dust, etc). Many aren't aware that increased lead buildup in oil occurs which can have an effect on engine operation, such as sticking valves. This is most common in engines not designed for hig lead fuels, such as smaller piston powerplants that ran on 80 octane. Lead buildup in the oil contributes to deposites on valve stems and can cause valve sticking and increased valve guide wear.

When you're buying fuels in the East, take care to sample it very carefully. Globally aviation fuel tends to be fairly uniform in content and specification, but in the East you may find some variation in the quality and content. Without sending the fuel to a lab, you won't know for sure, but you can check for the obvious contaminants like water and debris. Remember to allow your fuel to settle out for a half hour after filling the tank, to allow contaminants to be available at the fuel drains for sampling.

Read over this paper for some highlights on the topic:

SNS3Guppy is offline  
Old 29th Sep 2008, 12:22
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...may lead to higher incidences of spark plug fouling, especially if you're using massive electrode spark plugs.
Entirely correct.
Recommendatios to avoid this is to fit fine wire spark plugs.
Be very careful of 115/145 avgas...it can be very caustic, if you get it on your hands/elsewhere.
Drain sumps with utmost care.
411A is offline  
Old 29th Sep 2008, 12:32
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As a side note, and along those lines, bear in mind that TEL (tetraethyl lead) is very toxic. All the dreaded lead-based paints you hear about have nothing on TEL. When you clean your airplane, all those whitish deposits you see around the exhuast, and the white sludge that you find on the belly of the airplane behind the exhaust, is lead. Be really careful, especially after burning fuels that have higher TEL content (which includes 100LL, by the way) when cleaning the airplane. That stuff can be absorbed through the skin and can hurt you. Exposure is also cumulative. Something to keep in mind.
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Old 30th Sep 2008, 07:48
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I may well be mistaken, but I seem to remember from a previous life in maintenance that 115/145 avgas was a slower burning fuel and as such could damage exhaust valves when used in unapproved engines.
mustafagander is offline  
Old 30th Sep 2008, 09:39
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In Continental powerplants certificated for, and approved for 96 octane, 100LL, 100/130, and 115/145 fuel are also approved. That includes the IO-550. See the previously referenced document.

The Type Certificate Data Sheet for the IO-550 lists 100LL, B95/130 CIS, or RH95/130. The document cited previously provides that all Continental powerplants certified for 91/96 or 100/130 may also be run on 100LL or 115/145.
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Old 30th Sep 2008, 19:09
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When we burned 115/145 in our 150s, 172s, 177s, and 310s back in the mid-70s, we had to lean the engines ALL the time to prevent excessive spark plug fouling -- not just above 5000'. IIRC, the 177RG was the most problematic because the CHT would get very close to the red line in a climb on hot days. It was a close balance between fouling and overtemp...
Intruder is offline  
Old 4th Oct 2008, 11:07
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He he.... back in 1979, when working for Nationwide Air on Carvairs we used to drain a litre of green 130LL from e3ach wing to check for water. Well it seemed such a waste, so I would save it and top up my Datsun 1200 saloon.

I have to dispute that it doesn't make you go faster. That baby went like a Ferrari.
Kiwiguy is offline  
Old 5th Oct 2008, 01:55
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Is 145 still actually available in some parts of the world?
Brian Abraham is offline  

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