On 08/30/2010 01:28 PM, Guerner Remi wrote:
> "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?
> "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.
> "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...
> 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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