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John W. wrote:
<<I have the large Dolly Parton cowling on my iv-p Brent was referring to
and the cooling is so efficient that I actually have to put in baffles in
the intake to keep the engine warm enough in cold weather.  In warm weather
CHT's run in the mid 350's in the teens and average in the 380s at FL250. I
would recommend this option to those selecting their cowlings for the iv.>>

I also have a Dolly Parton cowling on my IV-P (N411WB). I think that the
cooling is very good as long as my fuel flow remains in the appropriate
range. The problem seems to be that the fuel flow starts to fall off in a
climb around 17,000 from 30 gph to 28 gph (32" @ 2500 and 160 KIAS, FULL
RICH). If the fuel flow remained constant during climb, then many other
cooling issues would concern me. However, my feeling is that everyone's fuel
flow remains constant during climb and that the engine's temperatures get
hotter in a normal almost linear fashion during climb. I have an abrupt
departure from normal heating during climb with a very rapid increase in
temperatures accompanied by a decrease in fuel flow. Does your fuel flow
remain constant during climb? If it does, then why do you think my flow
suddenly decreases? I have even tried going to high boost with the mixture
staying rich - didn't help. If I level off around 19,000 and let things cool
down, I then can continue the climb another 2-3 thousand feet with adequate
fuel flow.

Vaporization of fuel doesn't seem to be a problem since the fuel pressure is
constant and I use low boost above 10,000. I have cooling air blowing over a
fuel pump cowling and all hoses are wrapped nicely with thermal jackets.

John Lasher
N411WB

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