I'm getting close to having my engine done and hope to have the boat running and ready for testing in a couple weeks. The boat is a 98' 280 that came with a 502 (415 hp) and had a 26p bravo 1 from the factory. I'm building a 509 with 741 cam, mild head work and a b&m 250. After reading others builds I'm expecting 650+ hp. I aquired a 28p bravo 1 before I decided to go with the blower and now I'm questioning if the 28 is going to be small or if it will be ok. I'm planning on spinning the motor 5700-5800 max rpms.

Thanks in advance.

I would think you should be able to spin a Bravo 1 30p easily with that much HP.

I guess I may look at getting a 30 and sell the 28.

I would start with the 28 as a baseline.

I agree. You may not be that far off with a 28. You also have to remember that stock 502 was setup to only turn in the high 4k range to no more than 5000. With an additional 2" in pitch and 700-800 more rpm the 28 might be the prop.

At 5700, 12% slip, speed is in the 88-89 range.

You are doing this all backwards.
Buy the biggest size prop that fits then add HP to accommodate the bag A$$ prop. & That way you only have to buy one prop.

I'm doing everything backwards. I pulled the motor to freshen it up. Then started a 550-600 n/a motor and now I'm building a blower motor. If I don't get the motor done and installed soon I may end up with a 1000hp quad rotor and a alpha drive.

I'm running a 30p bravo 1,... similiar hp 650 ish ..5300rpm

I sent you a pm speedwad.

Real 26 ft velocity 28 pitch b- blades bravo 630 hp 1.65 gear 88.9 mph at 6500 rpm 15% slip no nosecone