Someone please clarify fuel for a Rotax 912ULS

[Kyle Communications]

I have been trawling threads regarding the correct fuel to use for the 100hp Rotax. There seems to be so many different opinions on the correct fuel. Can someone give me a diffinitive answer on what is the minimum fuel you can use please Mogas is the general term but that can mean unleaded 91 or premium 95 or premium 98. I know you can use Avgas of course with restrictions but there seems to some conjecture whether standard unleaded can be used seeing it is Mogas as well. is there a official octane rating using this countries reference for the 100hp Rotax?

 

This question was bought about by a thread on the sav threads about using a 80hp Rotax because it can use std unleaded (91) but I was under the impression it is classed as mogas and should be able to be used in the 100hp even with some restrictions in hours similar to Avgas

 

Mark

 

 

[ahlocks]

The specs direct from the horses mouth.

 

http://www.rotax-aircraft-engines.com/portaldata/5/dokus/d04851.pdf

 

The document won't allow copy and paste unfortunately. It specifies the minimums as;

 

91 RON unleaded in a 912UL (80 hp)

 

95 RON unleaded in the 912ULS (100hp)

 

d04851.pdf

 

d04851.pdf

 

d04851.pdf

[Guest basscheffers]

Octane ratings in this country are RON.

 

I tend to fuel my 912ULS with 98 as many 95 octane fuels have ethanol in them. Rotax allows up to 10% ethanol, but I'd rather not...

 

Never had a problem with Mobil, Shell or BP 98.

 

You can run AVGAS, but Rotax only says 100LL, not the green 100/130 crap you get in the central and western states. Unfortunately, sometimes I don't have much of a choice. The recommendation in that case is to run at higher RPM and thus temperatures to help get rid of lead. (5200 RPM is my choice)

 

 

[eightyknots]

The specs direct from the horses mouth.http://www.rotax-aircraft-engines.com/portaldata/5/dokus/d04851.pdf

The document won't allow copy and paste unfortunately. It specifies the minimums as;

 

91 RON unleaded in a 912UL (80 hp)

 

95 RON unleaded in the 912ULS (100hp)

I read on one of the US sites that they use the lower octane "gasoline" (I think it was 89) because it was readily available where they operated their plane. They then poured in a specified amount of an octane boosting additive.

 

 

[Guest basscheffers]

Remember in the US, they don't show RON at the pump like we do, but rather an average between RON and MON called AKI: http://en.wikipedia.org/wiki/Octane_rating#Anti-Knock_Index_.28AKI.29

 

So their "87" petrol is the same as our "91".

 

Still, 89 is a bit low even for them, but not as low as you might think.

 

 

[eightyknots]

Remember in the US, they don't show RON at the pump like we do, but rather an average between RON and MON called AKI: http://en.wikipedia.org/wiki/Octane_rating#Anti-Knock_Index_.28AKI.29So their "87" petrol is the same as our "91".

 

Still, 89 is a bit low even for them, but not as low as you might think.

Thanks for that link which explains a few things I was wondering about, such as the octane ratings in the eighties in North America. When I was in the USA a few years ago, at a large service station in Seattle, they had no less than four octane ratings of petrol (or "gas") for sale with different levels of 'performance additives'.

 

 

[Dieselten]

All I have ever put in my 912 UL S is 98 Octane BP Ultimate. Runs like a top. Oil and filter-changes every 50 hours (AeroShell Sport Plus 4). I have never found alcohol in BP Ultimate. I found 10% alcohol in 98-octane unleaded from a discount supplier. Fortunately it wasn't destined for my aircraft.

 

 

[Paul Turner]

Remember the issue isn't just the engine, its the effect of ethanol on the rubber fittings in fuel tanks and fuel hoses in your aircraft. I wouldn't want fuel with added ethanol sitting in my aircraft (on the ground) for any length of time.

 

 

[bones]

basically anytghing you put a match to and it burns that motor will burn :) averaging about 120lt per day through mine now, these motors arent real chooosy what goes into them