Originally Posted by JerseyOutlaw (Post 4473116)

05 25OL, roller cam 525sc, imco neutral box, imco steering, 280 k planes, 28p standard lower, 75.2mph gps

Originally Posted by IGetWet (Post 4475479)

Picked up a 26 LH bravo 1 the other day and got good results from that. But I think a lot of it came from sanding and sharpening the lower unit. I had chipped paint etc on the lower unit and was sanding and repainting too often so I decided to take it down to bare aluminum.

http://i1098.photobucket.com/albums/...4D06799506.jpg
So with same power but box/raised prop cl you haven't quite matched your best speed from before any mods? That was my experience too, I put my stellings box on after talking tp a guy who claimed he had built a roots blower 850 hp baja that picked up 5 mph top speed , I have a theory, only a theory though, IF you take to 6 inch straight edges and hold them on each side of the pad on vee to form a imaginary vee the stock prop center line (mine was 7.5") is really more like 5.5" in comparison to a vee, I strongly feel thats why no matter what prop i tried and even after spacing the drive down 1" with stellings box and when I tried imco 2" shorty my 272 slowed down, would not carry the bow, porpoised etc but this was in the 90+ mph range

After a couple short runs I calculated slip at 7.10 - 8.79% depending on exact rpm, pretty darn good for only 4.25 below the pad. My RPMs dropped because of the better grip, 67 @ 4550-4600. I did see 68 and 69 briefly on my gps but I'm using 67 and 67.5 for the prop slip calculator. The goal for now is to get setup dialed in and then add some HP next season.

Originally Posted by articfriends (Post 4476340)

So with same power but box/raised prop cl you haven't quite matched your best speed from before any mods? That was my experience too, I put my stellings box on after talking tp a guy who claimed he had built a roots blower 850 hp baja that picked up 5 mph top speed , I have a theory, only a theory though, IF you take to 6 inch straight edges and hold them on each side of the pad on vee to form a imaginary vee the stock prop center line (mine was 7.5") is really more like 5.5" in comparison to a vee, I strongly feel thats why no matter what prop i tried and even after spacing the drive down 1" with stellings box and when I tried imco 2" shorty my 272 slowed down, would not carry the bow, porpoised etc but this was in the 90+ mph range

Originally Posted by IGetWet (Post 4476354)

Not sure I follow the theory, the water is coming off the pad, it doesn't follow the imaginary V. My theory on why I haven't seen any speed increase is because I went from a perfectly labbed 3 blade to a stock 4 blade. A lot more drag, weight with the four blade. If I were to have the bravo 1 labbed I should be at or above my old top speed. If the slip numbers are good then I should be able to get the speed once HP is added. Wild Card has stated more than once that he achieved 84+mph with his 600sci and 81+mph with a 525efi, good numbers for any straight bottom V!

But another reason for these mods is a better rough water ride. Before the mods the boat felt like it sat more in the water at speed where now it really feels like the boat is up on top of the water riding across the tops of the waves.

Bblades got back to me today and told me that the 25 rev 4 I had bought was way out of balance, so that should answer why that specific prop did so poorly.

Originally Posted by IGetWet (Post 4473117)

I read your rebuild, looks like a nice setup. What HP do you figure with your motor? What's your propshaft height at 12" back? I imagine your prop slip numbers have to be way down