need more rpm's
 

running a 272 baja with a 572 at 32 degree timing. with xr and sporty lower pulling 4700rpms at 70-71 mph no chop. with a 28 bravo 4 blade, it comes on plane with real ease even with 3 people. mid range to top speed it pulls hard. My motors built to run 5500 rpm. any ideas what prop to try next?

update on light chop: ran a 30 bravo 66mph at 4400, ran 28 bravo at 48-4900 at 73mph.
comes out of the hole with both at major ease and from 3000 to max rpm it pulls hard

26 bravo should pick you up another 400rpm. Lab it and get right to 5500rpm.

my 28 may be labbed i bought it from an oso member on here

I built the 540 in my own 272 to run N/A and blown, N/A it made 650 gross hp with no accesories at 5600 or so, with a nose cone and std length drive it ran 75-76 with box stock 26 merc factory labbed at about 5400-5500 in PERFECT conditions so even though your motor is slightly bigger I think a 26 labbed might be what you need based on your CURRENT info. I remember your motor was supposed to be 728 hp and I figured you would be turnning a 28 labbed, sounds like maybe your not quite there hp wise when actually installed and running in your boat. When its hot or if its loaded too much my 272 is closer to 73/74 and is around 5300 or so as if a 26 labbed is slightly big , buy a 26 labbed 4 blade and have it tweaked. I have had great results with greg hittner/cutting edge props , waiting to try my 26 labbed again that he straightened out after I sent it somewhere else a few years ago only to see boat run slower even in the best of conditions , will be testing it N/A in fall again or possibly sooner if I shred my procharger between now and then! Smitty

Thanks Smitty i was waiting for you to chime in.
Im debating if i call greg or brett for a labbed prop from one of them they both sound like there good at what they do or just try find a used 26 off an OSO and try it out first to get a closer idea.
Are 3 blades on these hulls a waste of time?

In my case I tried running a 3 blade 27 with one of my blower motors years ago(650-700 hp blown 502 back then ) and it just would never quit slipping with that much tq so I doubt it will work with your 582, I would be interested to hear how one worked for you but sure don't spend money on one as it will most likely NOT work out well. Do you ever travel south from SK to go boating, your like 2000 miles NORTH of Mi/ Wi ? If you were closer I would meet up with you and let you try all my props as I have quite a collection going!

I have not travelled south yet as it is quite a distance im about 750 miles to the twin cities in MN.
My boat actually came from bay city michigan 4-5 yrs ago.
this is what my motor ended up being:
572 ZZ block with callies 4.375 crank, manly rods, bore is 4.565 coated flat top pistons that make it 10.1, coated bearings, fusion coated Brodix BB3 extra cnc 365 heads, dart intake, 1050 dominater, ati balancer, msd box and distributor. teage 14 quart pan and big teage cooler with a 130 oil t-stat, gil exhaust with long tails, roller cam is duration@ 50 with 245 Intake 634 lift. exhaust is 253 with 642 lift, with 110 lobe seperation. timing is set at 32

bump the total timing to 34,i think u will be pleasently suprised.

Those are some sizable heads for those cubes. I went from Merlin 345's down to AFR 335's on my current 580 build. What does your torque and hp curve look like? I peak torque at 4900 and peak hp at 5900. I am aiming to prop at 5700 due to the broad curves on both hp and torque. Looking at the dyno really helps explain some things when propping but looking at your previous results I would go with CEP 26 or send a bravo 4 26 in to brett at bblades and have him lab it. Should get you close to 5400 +/-. Hopefully the extra R's helps the port velocity in those gnormous heads. Those have to be a torque burden in the midrange but if you get over it may make some good power up top. Also, I am running 35*. We dynoed at 36* with the best result but left a little cushion for gas, temp, ect..

never was dyno'd all we have is car dyno's here and i was talked out of it because it would not be very accurate without the wet exhaust.
running it with the 28 and 30 bravo props the way this thing feels in midrange is amazing but then i came from a 420-450hp 454. so its quite a difference.

Well overall you'll never know without trying as they say. BBlades has an exchange program to try out props. That would be a good avenue or even keep bothering your buddies to experiment with there's. I just swapped my buddy props and we both ended up pleased with our swap. Keep trying until you get the revs close. Then look at the boat attitude from there. That's when the pros come in. They can recommend different types to change result as far as bow lift, stern lift, ect then tweak diameters, cupping, angle, ect for even more precision if you still have something bothering you....it can go on and on. The most important thing is to settle with what makes you happy, whenever that may be but just know it could be done.

whats a hydromotive prop like compared to a bravo prop?

ordered one from greg but its been lost in the mail for 3 weeks now.
So got a CE labbed 26 from Eliminated572 in swap shop. best run today was 73.9@5800 rpm mainly a consistant 72 though.
I guess i need a labbed 28 to drop me 300 rpm again and keep me at my 5500

I'm thinking some added cup on that 26 and you'd be in the ballpark. Shouldnt lose too much planning or acceleration. How did everything feel as far as stern lift/bow lift/any chining at all ect compared to your 28 bravo?

everything seemed the same actually.
with the CE 26 and 6 people full of fuel still hit 71 @5800

sent my 26 to CE this spring and he sent me a CE 28 ran 5100 @ a consistent 72.
Sent my 28 bravo to BBLADES this spring he did his Baja recipe runs a consistent 71 at 5100. It hit 73.8 on one run
Im still not at my 5500 rpm
Im only off for 6-7 days a month and depending on weather conditions so I have limited days to use it here in Canada.
CE is gonna send me a 26 with heavy cup to try so hopefully it will work out now.

Hey Zeke,

Have you considered a P-5 X round ear 5 blade. You will get great top end and better mid range cruise speed than any 4 blade. We build these in every pitch, so we can dial the rpm right in.

Thom

I really don't think a 5 blade is the correct option here. I wouldn't be suggesting a P5X in this situation. Stick to the 4 blade props at the speeds you are running.
Call me when you can and we can discuss adjustments to the prop.