REFLECTOR: High temps

John Dibble aminetech at bluefrog.com
Sun Feb 6 13:08:18 CST 2005


Thanks, Jim.  My next question is if the auto gas is compatable with the standard velocity tank?  The octane additive in auto gas is an ether which is in a chemical family close to alcohols and acetone.

John

Jim Sower wrote:

> <... Has anyone with a Lycoming tried a lower octane fuel ...>
> I have used hi-test auto gas (93 pump octane =~ 87 motor octane) and did not notice any difference (except on my bank card bills :o).  About 75% of flat aviation engines are designed for 80 octane.  Regular mogas is 82 octane.  There's a lot of interesting reading (about a dozen documents) on mogas on the EAA web site - search on auto gas.  Unleaded regular auto gas IS the unleaded avgas of the near future.
>
> Embry Riddle has used nothing else for years ... Jim S.
>
> John Dibble wrote:
>
> >I have a Franklin, not a Lycoming and no temp problems.  Has anyone with a Lycoming
> >tried a lower octane fuel?  My experience with Rotax engines is that using a higher
> >octane fuel than what the engine requires results in high CHTs (50 F higher, enough to
> >sieze the engine).  I think 100 LL is higher octane than any normally aspirated engine
> >should need.  Several Cessnas in my flying club use 50/50 avgas/regular.  In a pinch,
> >I have topped off my tanks with regular and couldn't see any difference in performance
> >or other problems.
> >
> >John
> >
> >Jim Sower wrote:
> >
> >
> >
> >>I am running a LIO-360-C1E and even after a lot of work on the baffling
> >>have CHTs around 375 - 400 with occasional excursions to 425 which I try
> >>to correct for.  From the beginning, my oil temp never ever budged off
> >>of 180, but more recently I have had oil temps up to 210 - 220 on
> >>occasion.  I think part of this might have to do with the firewall oil
> >>cooler which exhausts right into the plenum - the high pressure air for
> >>cooling the cylinders.  There can't possibly be much air flow through
> >>that cooler, and I regard it as a significant design defect.  At some
> >>juncture (after I get the engine running again and the plane annualed) I
> >>am going to exhaust it to outside air under the cowl.
> >>
> >>Glad I'm not the only one with high CHTs ... Jim S.
> >>
> >>
> >>
> >
> >
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