Jeremy, in the US I believe the octane number posted on the pumps is an
average of RON and MON testing methods, but I can't be absolutely positive
on that. Regardless, I continue to suggest that you use the highest rated
mogas you can conveniently find.
Regarding vapor lock, most of the refineries in the US will "blend" their
fuel for the specific season of the year, the geographic location they are
delivering to, and most importantly the expected climatic temperatures. For
very cold climates in the winter they include additives to enhance
volatility and thus cold weather starting. In the hot summer time they
reduce the additives to lower the volatility to prevent vapor lock.
Personally I had just that experience, having purchased some fuel in the
cold of the winter, but didn't get around to putting it in my plane until
the hot summer months. Indeed, I did experience considerable difficulty
re-starting the engine once it had been run up to operating temperatures.
Definitely due to vapor lock, or the boiling of the fuel in the fuel lines.
Once I drained out that fuel, and replaced it with recently purchased
"summer" fuel, all was fine. Strange, huh?
Garry Stout
N4220S A60 450hrs
----- Original Message -----
From: "Jeremy Davey" <EuropaFlyer_3@msn.com>
>
> I'm assuming you mean 93MON as I think that's the highest-rated fuel
> normally available at the pumps in the US. Can you confirm?
|