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82 UL MOGAS

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air.guerner(at)orange.fr
Guest

Posted: Sun Aug 29, 2010 2:09 am Post subject: 82 UL MOGAS

Hi all,



Landing at Sywell last September for the LAA rally, I was surprised  

they had both 100LL Avgas and 82UL Mogas. I decided to take 20 liters  

of this -unknown to me- 82UL. This small quantity being mixed with  

about 50 liters of the fuel remaining, I thought I was not taking a  

big risk.

Later I did some research on the internet and among available  

publications. This is what I found:

82UL has a MON (Motor Octane Number) of 82 and  AKI (Anti Knock Index)  

of 87, which translate into a RON (Research Octane Number) of 92, as  

AKI=(RON+MON)/2.

In their Operator's Manuals and applicable SI, Rotax provides the  

following instructions regarding the suitable fuels:

912 UL: minimum RON: 90 or minimum AKI: 87

912 ULS and 914UL: minimum RON: 95 or minimum AKI: 91

So it is clear that 82UL is not suitable for  the 912 ULS and 914.

In order to confirm this conclusion, could anyone provide a detailed  

specification of this 82UL Mogas as supplied in the UK?

Other questions: is there any ethanol in this fuel? Why they do not  

supply Premium or Premium Plus / Super, whatever they call it, which  

would offer the higher octane rating we need for the 912S and 914,  

with only a slight cost increase?



Comments please!



Regards

Remi Guerner

F-PGKL

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thoulihan(at)blueyonder.c
Guest

Posted: Sun Aug 29, 2010 2:29 am Post subject: 82 UL MOGAS

Hi Remi.



Thanks for the Mogas availability information at Sywell that is good to know as I plan to be there next weekend.

In answer to your point about the higher octane fuel at higher cost all I can say is thanks for letting me know that it is suitable for my 912 engine !. 

 

Tim



On 29 August 2010 11:07, Guerner Remi <air.guerner(at)orange.fr (air.guerner(at)orange.fr)> wrote:

[quote] --> Europa-List message posted by: Guerner Remi <air.guerner(at)orange.fr (air.guerner(at)orange.fr)>

 

 

 Hi all,

 

 Landing at Sywell last September for the LAA rally, I was surprised they had both 100LL Avgas and 82UL Mogas. I decided to take 20 liters of this -unknown to me- 82UL. This small quantity being mixed with about 50 liters of the fuel remaining, I thought I was not taking a big risk.

  Later I did some research on the internet and among available publications. This is what I found:

 82UL has a MON (Motor Octane Number) of 82 and  AKI (Anti Knock Index) of 87, which translate into a RON (Research Octane Number) of 92, as AKI=(RON+MON)/2.

 In their Operator's Manuals and applicable SI, Rotax provides the following instructions regarding the suitable fuels:

 912 UL: minimum RON: 90 or minimum AKI: 87

 912 ULS and 914UL: minimum RON: 95 or minimum AKI: 91

 So it is clear that 82UL is not suitable for  the 912 ULS and 914.

 In order to confirm this conclusion, could anyone provide a detailed specification of this 82UL Mogas as supplied in the UK?

 Other questions: is there any ethanol in this fuel? Why they do not supply Premium or Premium Plus / Super, whatever they call it, which would offer the higher octane rating we need for the 912S and 914, with only a slight cost increase?

  

 Comments please!

 

 Regards

 Remi Guerner

 F-PGKL

 

 

 

 

 

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 le, List Admin.

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 [b]

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frans(at)privatepilots.nl
Guest

Posted: Sun Aug 29, 2010 7:21 am Post subject: 82 UL MOGAS

On 08/29/2010 12:07 PM, Guerner Remi wrote:



 	  Quote: 	
		   Other questions: is there any ethanol in this fuel? Why they do not

 supply Premium or Premium Plus / Super, whatever they call it, which

 would offer the higher octane rating we need for the 912S and 914, with

 only a slight cost increase?


	


One way to increase the octane rating is by... adding ethanol.

So, take the lowest suitable RON number you can find. There is no

benefit to use higher octane ratings than the engine needs. The higher

the octane rating, the higher chance that the fuel contains ethanol, or

other similar unwanted additives.



I always use Euro 95 fuel, and never experienced any problems with it.



Frans

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davidjoyce(at)doctors.org
Guest

Posted: Sun Aug 29, 2010 8:03 am Post subject: 82 UL MOGAS

Remi/Tim, For what it's worth the LAA website seems to call for 95RON mogas 

for 912 as well as 912S & 914. I can't say I have ever come across 82UL, and 

would certainly be reluctant to feed it to my 914!

Regards, David Joyce, G-XSDJ

---

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air.guerner(at)orange.fr
Guest

Posted: Mon Aug 30, 2010 3:32 am Post subject: 82 UL MOGAS

Frans,



"One way to increase the octane rating is by... adding ethanol. "

In France, 98 Mogas has no ethanol while 95 contains about 4%.  So I  

prefer using 98.



"There is no benefit to use higher octane ratings than the engine  

needs. "

One benefit is to provide additional margin against detonation, which  

is critical especially with the 914.



"I always use Euro 95 fuel, and never experienced any problems with it."

I understand your experience with the Europa/914 combination is  

limited to a few dozens hours, right? Be careful, you do not know you  

have detonation until you find a melted piston or broken piston rings.  

I know: this happened to me!



Regards

Remi

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frans(at)privatepilots.nl
Guest

Posted: Mon Aug 30, 2010 5:52 am Post subject: 82 UL MOGAS

On 08/30/2010 01:28 PM, Guerner Remi wrote:



 	  Quote: 	
		   "One way to increase the octane rating is by... adding ethanol. "

 In France, 98 Mogas has no ethanol while 95 contains about 4%.  So I

 prefer using 98.


	


Well, this is confusing. Especially for our flight in France we did some

research, and found out that 98 contains more ethanol, as ethanol is a

cheap octane riser. So in France we tried to stay away from 98 and tried

to get 95 octane fuel instead as much as possible, because it should

contain less ethanol.

Do you have any references to information which states otherwise?



 	  Quote: 	
		   "There is no benefit to use higher octane ratings than the engine needs. "

 One benefit is to provide additional margin against detonation, which is

 critical especially with the 914.


	


I have a 914. But octane 95 provides sufficient margin. It doesn't make

sense to create a higher margin over the point where detonation simply

can not occur. Take in mind that the 914 has quite some protection

against that, with a TCU that lowers the boost pressure if the air inlet

temperature becomes too high, etc.



 	  Quote: 	
		   "I always use Euro 95 fuel, and never experienced any problems with it."

 I understand your experience with the Europa/914 combination is limited

 to a few dozens hours, right?


	


Yes, but the local glider club uses a 914 powered Dimona to tow gliders

all day long. They are non stop using full power to get the gliders up

to about 2000 feet, dive down and tow up the next glider. The engine has

been overhauled twice after reaching the TBO using it this way, so the

engines easily reach TBO without damage.

They only use octane 95 fuel...



 	  Quote: 	
		   Be careful, you do not know you have

 detonation until you find a melted piston or broken piston rings. I

 know: this happened to me!


	


Can you tell me more about this, under which circumstances this happened?



Thanks,

Frans

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frans(at)privatepilots.nl
Guest

Posted: Mon Aug 30, 2010 6:24 am Post subject: 82 UL MOGAS

On 08/30/2010 01:28 PM, Guerner Remi wrote:

 	  Quote: 	
		   I understand your experience with the Europa/914 combination is limited

 to a few dozens hours, right? Be careful, you do not know you have

 detonation until you find a melted piston or broken piston rings.


	


It is my understanding (but I can be wrong) that detonation usually

destroys an engine *quickly*. We are talking here about minutes, if not

seconds. If an engine lasts a few dozen hours, you can be pretty sure

that detonation is not in the equation, or am I wrong here?

If an engine that lasted a few dozen hours suddenly gets destroyed due

to detonation, there is usually a reason for it. An ignition timing that

went off time, a fuel mixture that went to lean (clogged fuel filter or

carb?) a sudden rise in boost pressure (are you sure you didn't

experience a sticky waste gate?), etc.



I think it is unlikely that Euro 95 is able to destroy a Rotax 914

*slowly*. But of course if someone can explain me how this is possible,

I would be gratefull. I don't want to destroy my 914 after all! 



Frans

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rparigoris

Joined: 24 Nov 2009
Posts: 796

Posted: Mon Aug 30, 2010 12:13 pm Post subject: 82 UL MOGAS

Hi Frans I am pretty sure you are thinking of pre-ignition that is the real killer. It is a disorderly combustion of the fuel- air mixture that will take an engine and quickly force it to play the song "silent Night". Detonation is much less sinister but over time will cause damage. In an automobile you can hear it as marbles when you step on the accelerator, anti-knock sensors can adjust to stop it. If you don't stop the pinging on something that runs at a high power setting for long periods of time it will do no good for long engine life. Plugs, valves and pistons will suffer.Ron Parigoris   [quote][b]

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creightonious

Joined: 10 Mar 2007
Posts: 40

Posted: Tue Aug 31, 2010 5:31 pm Post subject: Re: 82 UL MOGAS

Just a note regarding low octane alco-free mo gas.  

As good an octane booster as alcohol is, it ain't nothin compared to tetraethyl lead.  

A previous fill of 100LL, burned down to 30% of capacity, when filled with 92RON will test higher than the 95RON with alcohol tests. 

Creighton AO36



PS  This was knowledge won during the dark days of the '80s when we found that a mix of leaded regular and regulated unleaded gave a better AKI than either on our street rods.  And 100LL has a lot more lead than leadad regular.  Staved off extinction for a few years.

C

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