172D

Building a scale high wing cabin plane powered by a DA 70 twin. The plan is to build an exhaust with a single outlet on the bottom right side of the cowl. I understand the benefits of tuned pipes on 2 cycle engines and there is a lot of info available. Tuned pipe(s) are not appropriate for my project. Maximum power/RPM's is not important. Reliability is important and most of the time will be part throttle. A recent conversation warned me that the "wrong" design would not run properly under any circumstances. Pulses from one cylinder will back feed the other cylinder.

My original idea was to connect two downpipes from the cylinders into a single horizontal canister with one outlet out the bottom. Most likely aluminum and fabrication is not an issue. Perhaps two pipes could be concealed within the single exhaust outlet assuming they're small enough.

Any knowledgeable thoughts? Thanks!

ahicks

My Feedback: (2)

Noting that both of your cylinders are firing at the same time, and the sorry state of tune OEM exhaust systems provide, I'd say you have a good chance to disprove the theory discussed in that conversation you had. That said, if the pipe lengths of your extensions were the same length, I'd say reverse flow through either side would be just about impossible. Not sure how much time I'd spend on a design to accomplish that though. I don't think potential for any issues is that great. That's me though, FWIW. -Al