Originally Posted by danwells
two strokes are load and are not as good on fual aconamy but the do go faster
If you run "flat out" all the time the fuel economy difference will be almost non existent. Bottom line is to get X Horsepower at the shaft you need to burn a certain amount of fuel to to get that energy to turn the prop....
If you spend a lot of time pootling around (e.g. rescue boat for a dinghy club, fishing etc ) then yes, 4- strokes generally use less, but that's only because most 4-stroke outboards are built to get round the new Emmissions regs, and the engine management / fuel injection is in there with the prime reason to reduce fuel consumption - just look at modern diesels in cars - 10 years ago they sounded like tractors - now with Common Rail injection technology & engine management control they're as smooth & quiet as petrols.
Faster is a big scary equation involving popellor pitch, engine torque, boat shape & weight etc etc etc. A 2- stroke with the wrong prop will be left standing by a smaller 4- stroke on the same boat if it's got the wrong set of blades.
I've had a series of (relatively) small old 2- strokes simply because I don't need a laptop to self service them and can buy them & spares at reasonable cost. If I'm on a rescue boat mission I'd rather have a 4 - stroke so I could hear mself think since a lot of time is spent not going anywhere fast.
With outboards I don't think you can make easy general comparisons. It all depends on the boat they're on, what you use them for, what your idea of "quiet", "fast" "cheap" etc are, whether you've had a bad experience with a particular make..... One man's dream engine is the next man's worst nightmare.
2- stroke works for me tho'