ORIGINAL: bob27s
not to worry.......
the port size does not matter. Hundreds of them out running on TT, OS, ST .... about all engines, no issues.
Bolt it on, and run it. Try to target 16,000 rpm or higher with your prop selection. A 9x7 is a good place to start.
Set the needle about 600-800 rpm off of ground peak for flight.
Bob
Just making sure on the port size.. I figured it was like that on purpose but I'm no expert, obviously.
This engine/muffler is going to be used on a hydroplane airboat, so there isnt any flight involved.. (at least not intentional) I plan to set the engine about 300rpm rich of peak since it wont be unloading at all. I'm also aiming at using a 10x5 or 10x6. I want good speed from the boat.
I tried the muffler out on one short run today and managed 14,740 using 15% nitro/22% oil and an APC 10x6. I only ran it for a few minutes because my fingers froze adjusting the needle.