950 is probably the ceiling if you nail the setup. My old engine is close to that but 12.5:1 588 dry sump with a tunnel ram and 2 4s we spin it 6800 but the cylinder heads are maxed and what’s holding us back (dart 355cnc fwiw). New engine we have 2 sets of heads to do some rnd on the machine with to see what’s going to work the best.

Ive done a fair bit of combos with the 588 trying for the most power and tq including 4 cam swaps, intake and carb swaps cam timing adjustments ignition timing adjustments ect.

my personal opinion with a single carb it is going to be hard to hit that number. Atleast we struggled to get there, tried a sv632 Intake and a sv565, as well as a victor. With a quickfuel 1150 and a Holley ultra 1250 all left a good bit on the table compared to 2 4s.

It will be very interesting to see because our drag race stuff with 13.5.1 stuff makes over 1120. Witch this will have less cam and compression but still a 380 cc + head. And of course this more of a endurance build.

What kind of cam specs are you thinking? And to turn 7400 you’re going to have to be pretty big not saying it’s not possible but maybe your definition of a big cam and mine is alittle different. I’m high 270s on the Intake 290 on the ex about 800 lift On a 113. Made peak Hp 6700 on the dyno (again heads are limiting me) Standard base circle and it’s pretty hard on .843 lifters, I get about 30 hours out of a set which I check every time the boat is used. At 28-30 hours they start to move around and i replace shortly there after.

Still up in the air on the cam but it will be 60mm roller bearing deal. I would feel sure yours would make more steam with more head. I take it you also have small bore engines

Is there a reason / restriction to CI. 632 would be much easier to obtain your goals.

632 has a really bad rod to stroke ratio for endurance in a 10.2 deck block.

I understand especially for endurance. This is a good thread and a little out of the norm so there will be much gained and hopefully results in you ending up with your needs.


https://www.offshoreonly.com/forums/...ition-box.html

Just a thread for chits and grins. Not comparing just throwing it out there for some reading material.

well being on a 60mm you’re talking totally different ball game. As well that’s going to be the same direction my new motor is going. It’s 4.560 bore currently and if you believed everything you read on the inter webs those heads on a 580” motor will support 1,000 but I don’t believe it. Maybe if I sent them to fultz or someone.

But moving on to your build I would make sure your induction package with a single 4 is spot on atleast to hit 950 900 is probably obtainable pretty easily especially for your target rpm.


Can i ask what Head youre looking to run?

The top end will be a Dart based head 380 cc intake runner minimum. Will know the exact head after the PRI show this weekend. It will have jesel rockers aluminum intake and stainless exhaust. It's definitely going to be a Max effort deal with endurance a key part of the build.

What machine shop is doing the cam tunnel and lifter bores, if you want to share.