New Merc 300HP-V8 (4.6L)

[Blackfin26]

Great job on the project and those fuel numbers are impressive. As is 2.6 on the old 225. Best of luck with the Merc. These V8's seem like real winners!

[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.

[bgreene]

Congratulation .....great achievement .

[Snookerd]

Incredible motor! Great execution on the transom and dialing it in! Bahamas 2021!!

[joshmon71]

is that a verado? impressive numbers! and jealous!

my 05 275HP verado runs about 13gph at 4500 rpm loaded. ~4200 tabs full down full load is pretty much lowest planing speed....this is loaded 125 gallons fuel, gear, 2 guys. no livewell weight.
17P Rev4....

enjoy!

[77SceptreOB]

UPDATE -- Earlier this week the weather was pretty good in SC, low 60's and sunny so I decided to spend an afternoon at the lake with my kids. The motor ran great and seems to have a little better performance since I've put a few more hours on it. With me, 2 kids and 90 gallons of fuel the cruise was at 28mph at 3.83mpg. We took a short blast to WOT and got up to 53mph (speedo reading off my GPS via NEMA 2000) when trimmed up and wound out to 6,000 RPMs.

[DonV]

Very nice Jimbo!! I need about 3750 rpms to get to the 28 mph, that is the boat's happy number!!!

[DonV]

What's this I see Mercury is coming out with a V-12 600hp, you should have waited to re-power!!

[kmoose]

Already taking measurements.....

[DonV]

Yeah Ken, the only measurement I'm thinking about is the price tag!!!! Another engine for the top 2% of buyers, maybe 1%. However those folks don't really care about the $$$$, just have to have the latest and greatest!!

Come on power ball........