Exhaust size (Volvo 62 BHP) - backpressure

[geronimo]

How does one know what size (diameter) of exhaust hose is needed, and what size of silencer is needed to avoid backpressure.

How does one know that the engine suffers from backpressure (the exhaust is too small)

 

[boatmike]

Generally a pretty good practical hint to the size of the hose you need without getting scientific will be the size of the manifold outlet it has to fit. This will probably be designed to fit a standard size of hose. Just measure it and buy hose and waterlock silencer to fit. ASAP Supplies have both.