REFLECTOR: High temps

[John Dibble]

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.
>