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My first several years were also marked by temperature issues. Lots of tweaking brought some relief, but I oftentimes still had my hot cylinder hit 400 deg F while in WOT cruise during the summer. I had to use the red knob to get below 400.

When my cowling started showing signs of wear and tear, I decided to jump into a wholesale overhaul of the cooling system. NASA CR3405 has some good data on the problem areas found with the conventional aircraft cooling system arrangement.

I incorporated a plenum and diffusers into a new cowling. Without changing the inlet or exit area I was able to drop cooling drag by 60%. Or 13 hp at 200 KIAS. That translated into a 5 kts increase in cruise speed while dropping CHTs by 30-40 degF.

There are many ways to skin this cat. What I like about the plenum/diffuser concept is that it provides the opportunity for a very efficient cooling system.

Chris Zavatson

N91CZ

360std

www.N91CZ.net

Sent from my spiffy iPhone

On Jun 3, 2013, at 11:10 AM, <marv@lancair.net> wrote:

Posted for PAUL hershorin <paulhershorin@att.net>:

Gilles,
When I first started flying my 360 I had many heating problem, oil was 250+, cht was pushing 450 on climb out.
The first thing I did was to close the oil air from #3 to the oil cooler and I put a NACA scoop in the cowling on the
top just behind the engine baffling. This lowered the oil temp to 210 but cht were still pushing 440. I took the
servo off and had the flow on takeoff increases. This brought cht temps down to 415--420 and on hot days in
south Florida, look out. The next thing I did was the greatest and best results for oil and cht temps, and the
simplest of all to do--I put a 3/4 inch bevel on the bottom of the cowling to deflect the oncoming air away from
the engine cooling exhaust air and oil and cht's temps came down an additional 35 degrees even on hot days.
Oil temp is now always 180 to 190, cht's are 380 to 395 and egt's run 1350-1400.

Paul Hershorin
360 N471LA (new prop ordered and engine is in shop--pain gear accident)
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