Df 300

i have fitted a new 300 to my

i have fitted a new 300 to my 680 patriot in Australia . it has replaced the 250 etec which was previously on it. the question is how close to maxium rpm should i prop to . as the motor is still being run in but in a short burst it went to 6100 rpm and levelled off . at present i swing a 3x16 x18.5 . i have loaded the boat with 8 people and gear and fuel and it has pulled up on the plane quite well . should i go to the 19 and lose some top end revs or aim i right on with what i have . fuel economy and cruise is the main target though this motor holds the boat up better slower in rough seas i must say. i am very pleased with your product thank you.

Hello Graeme

You will get

Hello Graeme

You will get the best fuel economy and speed if you prop the DF300 to run between 6000-6200 eng rpm. I found through my own testing that fuel economy and speed come together if you prop for that RPM range. That engine seems to makes peak HP at 6100/6200 eng rpm. You will have better throttle resolution with the above RPM range. The engine should feel strong all the way through the RPM range. You can try the 19 it's only a half pitch maybe about 75 to 150 eng rpm drop. I have mine propped to turn 6100 to 6200 trimmed out min load. So when I load the boat it runs about 6000 to 6100 eng Rpms at wot.

Something eles to keep in mind. As the engine wears in you will gain some engine RPMS I have seen as much as a 100 rpm increase around 100-200 hr of use.

Last but not least don't baby that engine. Running it to gently during break-in will glaze the rings over. No synthetic oil during the break in. Don't abuse it. Use it like you normally would.

They are a sweet running engine.