REFLECTOR: Cylinder Cooling

[Pat Shea]

Chuck,

With the o/h naca and plenum system, the #6 cylinder
tends to run hottest as it is closest to the firewall.
The consensus seems to be that the air coming down the
naca runner tends to flow over the #6 cylinder. The
same is normally true for the #5 cylinder but to a
lesser degree. 

I believe some have had success installing turning
vanes in the co-pilot naca to direct more air over the
#6 cylinder. On mine, I actually changed the shape of
the co-pilot runner during istallation by splitting it
down the side and then opening up (lowering) the end
that attaches near the engine. My #5 and #6 cylinders
tend to run about 20* warmer than the others. I
considered installing some 1/2" high Vg's in the
runners about 6" ahead of the #5 and #6 cylinders but
haven't tried that yet. 

With my angle valve IO-540, I have noticed a similar
increase is oil temps as you when increasing RPM from
say 2,400 to 2,500 RPM while maintaining a constant
power setting (24" X 2,400 or 23" X 2,500).

Pat

 

-- Chuck Jensen <cjensen at dts9000.com> wrote:

> Hiroo,
>  
> My #6 runs the hottest on my IO540 but I always
> attributed that to the
> oil cooler tapping off NACA air right in front of
> it.  I have the
> pressure box on top of the engine with CHT in the
> 340F-360F common and
> #6 about 400F.   




 
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