Gents, in this hot southeast summer with daily temps > 90F, I’ve been inadvertently exploring the temperature limitations of my Jabiru 3300.
I’m pretty sure the cowl inlets on the Sonex cowl are placed for the Aerovee and thus are inefficient with the Jabiru - mostly the right side inlet. It’s way too low and close to cylinder #1 to provide for smooth airflow into the baffling, especially considering the prop wash on the right side is in a downwards-direction which makes it even worse compared to the left.
In my plans-standard cooling setup (except I doubled the outlet size), with plenty of care given to sealing leaks and seals and everything, the left side cools perfectly fine but the right side is constantly at red-line. I have messed around with dams and ramps and things to put more air on one cylinder or the other but all it does is change the balance without actually bringing the right side average down. I think there’s just not enough air getting in there.
Has anyone experimented with ways to make the right side inlet more efficient? I’ve considered either:
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modifying the inlet by cutting away the top side by an inch or two in order to effectively move it up relative to the cylinder so more air can get into the baffle over the front cylinder, or
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adding a ram air or NACA scoop to the top of the right cowl to dump air into the right side baffle from above. The advantage of this over the first idea is it would require less work and could be relatively easily reversed in the winter or if it doesn’t work.
