Originally Posted by Chris1573
The reason I like the above engine is they are all single cylinder compact units and I dont think you can get a 6HP or greater in a single cylinder engine.
Can you buy props that will maximise the engine for use on a large boat (Hi Thrust)
Johnson/Suzuki do a 6hp four stroke single cylinder, same basic engine as the 4 and 5 but with different carb or something. It's what I use for an aux and v pleased with it.
From what I have read on here though, once you get to the "displacement speed" of a hull then it won't go any faster unless you pour a lot more power in. That tallies with my observation - at WOT I don't get anything like max revs on my aux, and I'm not really sure I am getting any more power out of it than I would be out of a 4hp ... I guess it probably tops out at about 4000, something like that (just a guess) and the extra power is developed right at the top end. I wondered about a "high thrust" prop too but I might also be getting a little boat just to play in so I am not sure about taking that route - and from what I found there are only 6" and 7" pitch available for mine anyway so it wouldn't make much difference.