I think I?ve seen/googled most of the ideas out there when it comes to cooling the lycoming in the summertime. I?m sure there are many more out there that I haven?t seen. I?ve done a decent amount of work with inlets/plenum/sealing and lastly ignition timing for temp control. Most people seem to be concerned with climb out CHT?s. I currently have no issues climbing out on a hot day, I have issues taxiing after a quick turn on a hot day and I?m carbureted. CHT?s and oil temps are fine but fuel seems to be boiling, erratic chugging during taxi. Idle mixture is correct and an excessively lean mixture and RPM?s above 1000 help.
With my stock cowling I used to see heat radiating out of the upper inlets while fueling. I don?t see it with my sealed inlet boots. During ground operations the pressure diff between the upper cowl and lower cowl is very small. How many people pop the oil door open after they land in hot temps?
Most cowl flaps are installed in conjunction with the lower outlet, I?ve stared at this space on my cowling for months trying to come up with ideas. I?ve shrunk and contoured my exit to approximately 35 sq inches, not a lot of room for a cowl flap with a vertical induction carb and 2 exhaust pipes.
I?ve also been staring at the rear of my upper cowling, what about an upper cowl flap, similar to the old 30?s cars/trucks had in front of the windshield? With the low pressure diffs on the ground it would take advantage of convection in addition to a larger exit area during climb out. I kept hoping for an easy test without months of work and downtime.
I?m currently finishing an oil change and making room behind the upper engine mount to possibly add an upper cowl flap when it dawned on me, why don?t I spend 2 minutes and remove the oil door and go fly several quick turns? On 4 cylinder lycomings the oil door is behind the upper plenum and part of the lower cowling volume/pressure. Roughly 5x5 (25 sq in) in the upper cowling that is convection friendly on the ground, also pretty easy for anyone else to test fly and and see what kind of cooling the extra exit area gives them.
With my stock cowling I used to see heat radiating out of the upper inlets while fueling. I don?t see it with my sealed inlet boots. During ground operations the pressure diff between the upper cowl and lower cowl is very small. How many people pop the oil door open after they land in hot temps?
Most cowl flaps are installed in conjunction with the lower outlet, I?ve stared at this space on my cowling for months trying to come up with ideas. I?ve shrunk and contoured my exit to approximately 35 sq inches, not a lot of room for a cowl flap with a vertical induction carb and 2 exhaust pipes.
I?ve also been staring at the rear of my upper cowling, what about an upper cowl flap, similar to the old 30?s cars/trucks had in front of the windshield? With the low pressure diffs on the ground it would take advantage of convection in addition to a larger exit area during climb out. I kept hoping for an easy test without months of work and downtime.
I?m currently finishing an oil change and making room behind the upper engine mount to possibly add an upper cowl flap when it dawned on me, why don?t I spend 2 minutes and remove the oil door and go fly several quick turns? On 4 cylinder lycomings the oil door is behind the upper plenum and part of the lower cowling volume/pressure. Roughly 5x5 (25 sq in) in the upper cowling that is convection friendly on the ground, also pretty easy for anyone else to test fly and and see what kind of cooling the extra exit area gives them.