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Scat heads and cooling

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Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
12,665
Location
CT, USA
I don't recall what thread it was in, but several people have expressed concern about the cooling ability of the aftermarket Scat heads used by Mosler as well as a few homemade conversions, so FWIW: Last night was the hottest day I've yet flown my plane, which has the 1083cc Mosler CB40. There are cooling baffles around the cylinders inside the cowling but the heats themselves just stick out into the breeze. Air temp 88°F according to the AWOS, my thermometer in the hangar said 95, density altitude at the airport 2600', I went up a little over 1000' AGL. After 10 minutes of flying, part of which was full power climb, the oil temperature was at 210°F (the max continuous is 220 with a 5 minute limit of 260 according to the manual) and the CHT still hadn't gone above 250 ("normal" is <300 per the manual and the limit is 450). The CHT probe is under a head bolt; I checked it the other day with an infrared thermometer and it's accurate, and the same as the temperature at the base of the spark plug. Happily (since I only have the CHT gauge on one side) the temps are the same on both sides. Hardly an exhaustive test, but I'd say these heads have no trouble with cooling.

On the downside, my plane (which was designed for 25% more horsepower after all) performed pretty poorly at that high DA not over 250fpm climb (not quite as bad as it sounds with only a 40-45mph climb speed), so I'll probably limit my flying to cooler days. We don't get that many days that hot around here anyway.

Dana
 
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