Recall I've been experimenting with a different approach to cooling....large, low velocity inlets with a throttled exit (and a bunch of details). The cowl was modified so I could swap exit panels and thus vary the exit area.
Started with the one on the left, changed to the middle one at 15 hours or so, and just started flying the one on the right. All are smaller than stock by a good margin. I'll fly the latest into warmer weather, then consider the next step. I want to do some temperature and pressure measurements when it gets really hot this summer. Plus, from a standpoint of break-in, I'm only at 70 hours or so. his Sunday, with the smallest exit, a WOT/2700 climb at 105 knots from 200MSL to 5500 MSL at 50F OAT netted a highest CHT of 366F. CHT spread is 20F. 60% cruise is 300F or less. No cylinder has ever seen 400F. Engine is an angle valve IO-390.
Stock cowl:
It was modified right after the above photo. Pipe was also modified to raise it all vertically:
Started with the one on the left, changed to the middle one at 15 hours or so, and just started flying the one on the right. All are smaller than stock by a good margin. I'll fly the latest into warmer weather, then consider the next step. I want to do some temperature and pressure measurements when it gets really hot this summer. Plus, from a standpoint of break-in, I'm only at 70 hours or so. his Sunday, with the smallest exit, a WOT/2700 climb at 105 knots from 200MSL to 5500 MSL at 50F OAT netted a highest CHT of 366F. CHT spread is 20F. 60% cruise is 300F or less. No cylinder has ever seen 400F. Engine is an angle valve IO-390.
Stock cowl:
It was modified right after the above photo. Pipe was also modified to raise it all vertically:
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