After about 700 hours and 8 years flying I have decided to design and build a new exhaust system for my RV-7A powered by a 4 port RX 8 Renesis engine.  Bobby Hughes has offered advice and greatly assisted me in this endeavor.

 

The new exhaust was designed with three header pipes routed into a 3 to 1 collector that is 3 inches in diameter.  The headers and collector direct the exhaust toward the firewall.  A combination of 3 inch and 2.5 inch pipe take the exhaust down and out the bottom of the cowl and the exhaust exits about 12 inches back from the firewall.

 

I have flown with the new exhaust and discovered it causes a lot more vibration to the airframe than the old exhaust.  (I have a ball joint in the down pipe at the firewall).  I want to add a flexible joint down stream of the 3 to 1 collector and have about 3 inches space for it.  MY Question  -  Has anyone used a flex coupling or a flex bellows as seen on Summits web site?  The flex coupling is a woven stainless joint with a liner inside and weldable ends.  The flex bellows looks like a metal bellows on the outside and has a slip joint built inside. 

 

Anyone  have any experience with these on the rotary?

 

Thanks,

 

Dennis Haverlah