RPM to prop for vs dyno chart.
 

I just pulled my motor off the dyno. It made 572hp @5600 when cool. After multiple pulls it made 551@5600
I am using the hot pulls to go off of.

3500-383hp
3600-395
3700-405
3800-417
3900-425
4000-427
4100-436
4200-444
4300-450
4400-458
4500-467
4600-478
4700-484
4800-490
4900-503
5000-512
5100-525
5200-538
5300-544
5400-546
5500-550
5600-551

Last year with a tired 420hp, I could spin a 23 mirage to 5000rpm. This year I was thinking either a 25 or 27 mirage plus and propping it for 5300rpm. What do you guys think my target WOT rpm should be? And what prop would get me there?

I'm curious what all did you do to your engine to go from 420 to 572 hp?

Slightly better heads, bigger cam and a supercharger.

You might be surprised, but your 23 might be the prop.
5700-5800RPM light load, opinions might vary.

I would prop to your peak HP which appears to be around 5600. Otherwise you are leaving performance on the table.

As a baseline I would start in water testing with your existing prop. Yes you may be under propped but you also haven't spun that prop past 5000 rpm either. Once you get a feel for how your boat and prop perform when north of 5000 rpm you can start with prop selection. If you need more prop then work up the pitch ladder.

trial and error. You'll prolly end up with the 25 if I had to guess but like rookie said you may end up with same prop and spin it a little more. Gotta tune it for what it likes including boat characteristics, handling etc. I can give u an example from back in the day with a twin engine 28 I had. Started out with a pair a toad 330's and then built some others with your basic 454 upgrades including worked dart heads, intakes, carbs, comp etc. ended up with 480 hp. So close to yours in regards to gains in power. 150 + -.

Boat ran came new with 23 mirage that ran 46-4700 with the 330's and ended up going with 25's that ran a conservative 5,600 with the new builds.

Will give you some kind of an idea. What were your torque numbers. Also curious what cam you swapped out to cause if I'm not mistaking the 420hp cam is the same one merc used in their 525 sc's. You running 250's or tuned 177's.

Personally I've never had any luck running bbc's much under 5,400/5,500. Anything much less than that just feels lazy.

577 torque at 3600rpm. I went from the 132561 "420" cam to a crane 134561. It made over 550lbs almost everywhere. Torque monster.

I am running a 177 525sc setup. I am running that 134561 cam and 9:1 compression. So I am a little hotter that the standard issue 525sc.

I think I'd try the 25 Mirage plus...