11-01-2011, 12:45 AM
I am trying to build a 100cc twin cylinder opposed/boxer style model airplane engine. Because this engine is design to direct drive a propeller the rpms are fairly low (around 4000) so a tuned pipe would be pretty long and I want to keep the design simple (avoid having to build a pipe and to keep the engine cool). I was wondering about the differences in the porting of a piped vs. a non-piped engine. Since this is a mildly tuned engine I have read about using a restrictive exhaust. Since I don't have a pipe to help with scavenging I was thinking that the boost port (port directly opposite exhaust port) should be smaller to prevent fuel from escaping but this is just a hunch.