I was debating wether or not to leave the cooler open inside the cowling or to dump the air overboard via it's own exit plenum, and I just decided to go ahead and build the plenum. The plenum will allow the cooler to have it's own fine tuned air path that won't be fighting the air coming in through the CHT boxes. At this point, I've never taken the time to really design a smooth flowing exit plenum and now that the engine is removed, it's the perfect opportunity. the inlet is just under 12sq. in and the exit should be about 13sq. in. If that isn't big enough then it won't be a hassle to open it up even more. But for now, the giant 18 row cooler should do it's job just fine. We shall see. I haven't quite decided if I'm going to attach the plenum to the cowling or cooler yet and if I'm REALLY going for a sealed system then I will need to seal it to the cooler side. This may be the best overall option. An exit ducting on the cowling will then accomidate the fixed plenum with tolerances as tight as I can get them. I already hacked off the bottom of the cowl behind the plenum so I'm comitted. :) More fun tomorrow.
