ONEX Turbo exhaust pipe length

[pchmelir]

I'm ready to trim the exhaust down pipe below the cowling and am interested in how long I should leave it. I've asked Sonex for their input and really didn't get a definitive answer. Has anyone trimmed their exhaust pipe and if so, how much is below the cowling? With the untrimmed pipe, I have about 6 1/2" exposed which seems a bit long to me. Thanks,

Pete Chmelir
ONX0216
AeroVee Turbo 0935

[Tnhelm]

I recently flew with a pilot in his recently purchased Sonex Jabiru 3300. That setup had the exhaust tips nearly flush with the fuselage belly. Result was 25-40 ppm CO in the cockpit and over 100ppm in the baggage area. On my OneX AeroVee non turbo, I have the exhaust pipes extended approx 2” below the fuselage bottom and have zero CO. I suspect the Jabiru install may not have as good a cooling airflow as the OneX as both Jabiru powered Sonex I have flown always had cooling issues.
Based on my experience, I would have the pipe somewhat below the fuselage.
Easy to shorten, not so to lengthen!
Tnhelm
OneX137

[thomasjones42]

I left about three inches extend below the cowling on my Onex and cut it on a slight bevel, longer front than back. Seems to work fine.
Tom Jones

[pchmelir]

Thanks, Tom. That sounds like a place to start.

Pete Chmelir
ONX0216
Aerovee Turbo 0935