So im rolling past 550 hours on my Formula 370SS with 500efi's, owned since new. What a beast of a boat!!! If you havent had the pleasure of boating in the 370 or 40SS line from Formula put it on your list.
My question is REPOWER/UPGRADE?? Im due for an engine rebuild, motors are still sealed from factory and on borrowed time, Tic Tock....
Looks like im looking at 10k per engine for rebuild. im seeing adds that i could swap for 525 or rebuild my 500's to higher performance specs 550-625 hp for basically same cost. My drives are bravo 3X and think 28P 3blade SS wheels.
I dont want to kill the reliabilty and general running of the boat. Most of my time is spent cruising 3400 rpm at 38mph. The boat seems tuned and propped correctly i hit 5200 rpm (cool days) and seen 62.6 mph. She will run 60mph most days with light fuel and one hot chick for stick handeling purposes!!!
I would enjoy the boat to be able to run north of 70mph if possible and elevate my cruise speed. How do i get there?????
Oh and for comical purposes and hitting powerball how about the *100MPH in the title, 1075's??

I think Mercs 1350/M8 package would get you into the triple digits



good luck with the Powerball

oh and as far as techincal input for the thread the Bravo III's are gonna hold ya back the faster ya go. that front prop starts to drag when you get into the high 80's and up.

i could deal with 80's. How we getting there?..

on a trailer !! Buy a faster smaller boat w the money you will save fixing **** thats going to keep breaking after you increase power and $$$$$

Took me awhile to learn that !! It cost's money to go fast how fast can you afford to go?

Back to the real point, what would you do on a rebuild??

The 500 efis are great motors to get hp out of. I have close to 650 from mine. If you do the rebuilds with the good heads and comp upgrades as well as fuel system you can get it and get plenty of tq to move your big boat. Dave at MDG did everything for me with a tune from precision marine. By doing that and beefing up the bravo 3s a bit you could enjoy the best of both worlds.
as for what to do, afr heads, cam,new throttle body, fuel system and comp upgrades and can still run on 87 octane. Ill be selling my intakes and setups in the next few months if you are interested.

A friend had 800 hours on his 500EFIs before he had to do anything more than valve springs. They are great motors.

If you go any higher in HP, I think you are going to waste your drives quickly. I'd look into upgrading them to the B3-XR specs, now offered by Mercury.

what do you think about the B3's vs a single prop XR for speed? We have always had trouble with them in mid 80's and above. The extra prop becomes a drag at higher speeds. He's definitely gonna need XR's but i think getting away from the B3 is gonna help. Pretty heavy boat at almost 15K dry so maybe even an Arneson conversion (thinkin lottery again lol)

Rob (offshoredrillin) has had great luck with the builds Dave did at MGD. Strong turn key stuff and pretty much the most HP i have seen out of an ASM intake. Without introducing wind your just not gonna get much more then that plus you retain all the reliability. I was VERY impressed with Robs motors and what they got out of them.