REFLECTOR: Still test flying...battling high CHT's

[Geoff Gerhardt]

All,

Just an update on my test flying.  I've got just over 9hrs in now.  I have
been battling high CHT's, making a few changes.  I had a fuel flow
imbalance that was causing some problems (hot #2) - I think it was a
partially blocked injector.  I took all the injectors/lines out and cleaned
them and balanced the flows (mixed and matched injectors until all
injectors were putting out the same flow.  Now, in cruise, all cylinders
are pretty close and reasonably cool (or, I guess, not overly hot).  Once I
get to cruise, they all sit <380F.  But, on climb out, #3 gets way too hot
(420F) forcing me to reduce power and bring the nose down so I'm climbing
at <500FPM at ~60% power, 100kts.  But, once I get to cruise and can bring
the nose down and get the speed up, it behaves.  Still the hottest, but
it'll sit around 380F.  So, I'm thinking I have to work on my cooling
plenums.  #4 will get hot too, but it doesn't get much over 400F.

Has anyone had success putting deflectors in the plenums to direct air flow
to cyls 3/4?  Or, maybe VG's in the entrance of the runners to keep the
airflow better attached to the bottom of the runner so it can turn the
corner down to cool 3/4 (I have VG's before the NACAs)?

Part of the issue may be my cruise prop - I need to keep full power on to
get a decent climb rate.

Thanks.

Geoff
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