Originally Posted by Poinas2

There is a lot of different types floating around in the ebay etc. It's sometimes hard to define what engine you have but in any case there should have been an instruction letter following your engine telling the exact Go part# and from there you can determine the ports etc.

Usually if it's grey/silver case and the heatsink is not milled it's RTR/Sport engine meaning 3port. If it's black case then it could be some "special" version as I know there are some models with up to 8 ports I believe.

Were did you get the engine ?