I have a 2003 Crownline 202lpx. 3400lbs boat with alpha 1 gen 2 outdrive. .
On the motor I have 383sbc. Eagle forged crank,and rods, JE forged piston, AFR 190 vortec heads, Lunati 60121 cam, with roller lifters and 1.6 roller rockers, Edelbrock RPM air gap intake, Holley 750 carb, holley blue fuel pump, EMI Thunder exhaust. And a lot of other stuff. Total of $12,000.

On the Dyno, I only did my pulls from 2700-5500 Rpm's482.7 HP at 5500 Rpm and still climbing
486.7 TQ at 4300 Rpm
At the start of my pull at 2700 rpm I already have 433 TQ, and still at 5500 I still have 460 TQ. Its a real flat TQ curve.

The Boat runs 65 MPH at 5300rpm with a Merc. Rev-4 19P, with 2 adualts, an 2 kids and full ice chest.

I know now that I should have dyno'ed it till I seen my hp start to fall off. The engine builder said everything in the motor, is good to 7000 rpm's. Beside's the cam, lunati said good power to 5800.

I already shelled my outdrive within 5 hrs of putting the new motor in, but I think it had an existing problem from before. The new outdrive has been on for 25hrs with no problems

my question's are, which 3 blade prop would you suggest for the best top speed?
How much rpms can an alpha take at this HP an TQ?
Is it better to have a 3 blade prop with more pitch to keep rpms down, or less pitch?

Before writing a lot. What gear ratio is in your drive? Is your speed GPS speed? Even with a 1.47 gear ratio your numbers don't add up.
65 mph @ 5300 with 1.47 gears and a 19" prop gives a slip of 0%, and that is not possible.

The LaserII will most likely be the fastest prop for that boat, and the Vensura is worth a try too. The Mirage+ propellers in that size, are too big for your drive anyway, and will be slower if you are looking for all out speed. Also. 7000 rpm's and 480+hp/+480 lbs tq. is a time bomb. You are getting close to where a B1 XR is needed. I wouldn't even spin it past 5500-6000. You WILL blow the Alpha apart at some point, sooner more likely than later.

The drive is a 1.47, and on my phones gps it does say 64-65. Rpm is around 53-5400. I do have a drive shower and Amsoil syn gear lube. Now that I replaced my drive I have fallowed all the alpha rules. And the prop I have on it now, I do keep the rpms down around 5400 wot. But I normal cruise at 4000 rpm about 45mph. I was just asking how fast could you spin the outdrive on short speed burst.

I know I looked at prop calculators today, it said my slip was .08 I kinda call bullsh*t. Or my phones gps is way off. But my speedo says 66-68

You need accurate numbers. Both gps speed and rpm. Pitot number is no good.

Even with 64 mph and 5400 rpms, your slip is still 3%. Again, not possible.

5400 for the Alpha with the dog clutch, is not a low number. You are running a 300 hp drive, that is build for motors that is spinning 5200 maximum. You put almost 500 hp through it. Even for short bursts, you are looking at a blown drive. At least, get the Rev4 off it. That is a big prop for the drive, with normal power, and you have alot of torque @ 2500+ rpm already. Try the LaserII 21", and keep it between 5200-5500. 7000 will destroy it fast.

I've read on this same forum, about people running alphas with 500hp an spinning them to 6500rpm. And I know my drive is living on borrowed time, but I don't have the cash right now to swap to a bravo drive.
I was just wondering why you said to take off the rev-4 and put on a vensura? They are both 4 blade props. On the LaserII is it better than the enertia prop?

I'm not trying to be down on your setup, sorry if it sounded like that.

Anyway. The reason why I think you should take the Rev4 off, is because it has a big diameter and large blades. It bites hard in the water, and that puts more strain on your drive. I don't have alot of experience with the Enertia, it might work. The LaserII has good bow lift and have poven to be a good and fast prop on many 22' and below boats. My reason for suggesting the Vensura is because it's smaller than the Rev4 and have sometimes been faster than the LaserII. The LaserII 19" is 14" in dia. and the 21" is 13.875". The Vensura is 14" in all pitches with smaller and thinner blades than the Rev4 with it's 14.625" dia.

Even though some run 500 hp on their Alpha, does not mean that it will last. Same goes when you start putting more than 600 hp through a B1xr. If you don't have it already, put a drive shower on your drive.

For the money on alpha outdrives believe it of not Solas runs just as good if not better than the high end props. Also Solas does all OEM Volvo Penta props for the SX drive in SS and Aluminum. You are running alot of hp & tq thru an alpha so really not sure if they will work on the higher hp apps but I would be more worried about longevity with Alpha outdrive not matter what prop you have on there.

I knew someone that had beefed up 383 twins with Alphas Gen II and right around the 60 to 80 hr mark it was time for a complete rebuild - he got tired of it so change over to the Bravo's and Bravo's transom assy. I told him he was lucky to even get that amount time out of them

Also Alpha's for speed do not like large diameter. 15 and under works the best. 14.25 thru 14.75 diameter usually works the best. I would go to a 3 blade less abuse on the outdrive side of things compared to a 4 blade.

jason these guys are rigth. i would use a 3blade . back in the 80s they use cleaver prop my buddy had a 22sea ray pangua. 454 alfa drive 136gears 21cleaver prop. run good 65mph my other buddy had a 1987 baja 240 sport 454 alfa drive with 136 gears 19cleaver prop did 55mph now if you use a mirage use the old stlye not the plus to much cup on the plade. 4plade prop hard on the drive

I agree with the suggested Laser II prop as a fast Alpha One application. The Laser is great for light bow narrow beam sport boats. I know for instance that my former Stingray hull (light bow/narrow beams) ran the fastest withe the Laser II 21 with a 350 Mag MPI. I tried Mirage props which robs to much rpm out of the motor which I believe was due to a much to large diameter for the alpha one. I did try a 23 Vengeance which reduced rpm but believe a 21 would have been similar to the Laser II 21 but may be worth a try on the Crownline? However, all hulls are different and I don't know the beam or bow weight of the Crownline. The key is to achieve the greatest bow lift.

With that kind of HP and TRQ your making, I would try a 21, 23 even a 25 Laser II would be worth a try.

Man, with that kind of power, I would think your smaller Crownline would be at least in the lower 70s but mid 60s is great and for me would be fine. I wonder what kind of hook may be designed into the hull?

The less boat in the water the faster your top end.

I called and talked to BBBlades, they said to try a Mirage plus in a 19p regular or a 21p labbed to still keep me under my rev limiter of 5700rpm. They also said from a labbed 21p to a 23p labbed, I probably would not see a speed increase, but my rpm would drop back down to 52-5500 rpm's