New Merc 300HP-V8 (4.6L)

[kmoose]

Originally Posted by 77SceptreOB

Thanks Ken. When I repowered with a new fuel efficient 4-stroke 300 HP motor my goal was 3.2 mpg cruise. My old 2-stroke Yamaha 225 was around 2.6. So I'm VERY happy with the ~ 3.4 mpg I'm seeing now at 30 mph cruise. That's a 30% improvement in fuel mileage vs. 2 stroke. Does that sound about right?

Yes, that seems about right and completely expected considering the tech in these new motors. I ran the numbers on my 300 after converting everything to nautical MPH and you are almost 5% better across the board in average speeds we run. Make sure to keep tabs as you start to run trips with an average fishing load as it will be interesting how the numbers hold. The Rev 4 is a great prop with lots of stearn lift and looks like a good match for your set up.

I'm not sure how it will go with Merc but my Suzuki gained fuel economy after the the beak in timers hit. I think that is when the ECM allowed the motor to go into lean burn mode. Keep us posted as you put more hours on it.