17.5' Deep V 350 Alpha prop input

[joncbrand]

I have a 1989 Sea Sprite 175 SS
Came from the factory with 4.3L 175hp and Alpha 1 drive with 1.84 ratio.
Previous owner didnt winterize and the block split, I bought the boat like that.
I decided to go with a 5.7L 260hp rather than the 4.3L.
New motor is reman marine 350 roller cam with 4bbl air gap intake and new edelbrock carb.

Looking for top end.

Im currently running a13.5 x 23p quicksilver stainless, boat runs out at 52mph and i have plenty of torque left and can hit rev limit easily. Boat comes on plain just fine.

Im still running the v6 tach so I cant say for sure what my wot RPM is

From what I have researched a mercruiser supplied v8 boats with the 1.5 ratio I dont want to change gears if i dont have to.

Im just wondering if I am leaving more speed or is 23p about the limit.

Any thoughts??

 

[Starcraft5834]

Re: 17.5' Deep V 350 Alpha prop input

52 seems fast enough to me

 

[Bondo]

Re: 17.5' Deep V 350 Alpha prop input

I have a 1989 Sea Sprite 175 SS
Came from the factory with 4.3L 175hp and Alpha 1 drive with 1.84 ratio.
Previous owner didnt winterize and the block split, I bought the boat like that.
I decided to go with a 5.7L 260hp rather than the 4.3L.
New motor is reman marine 350 roller cam with 4bbl air gap intake and new edelbrock carb.

Looking for top end.

Im currently running a13.5 x 23p quicksilver stainless, boat runs out at 52mph and i have plenty of torque left and can hit rev limit easily. Boat comes on plain just fine.

Im still running the v6 tach so I cant say for sure what my wot RPM is

From what I have researched a mercruiser supplied v8 boats with the 1.5 ratio I dont want to change gears if i dont have to.

Im just wondering if I am leaving more speed or is 23p about the limit.

Any thoughts??

Ayuh,.... Welcome Aboard,... You absolutely Must know the Rpms to prop a boat,...

My guess is, yer leavin' Many mph off the table, because of the gear ratio,...

 

[jestor68]

Re: 17.5' Deep V 350 Alpha prop input

You need to be running a 15 inch diameter prop on there to match that gear ratio.

Check out the Solas Rubex S3 (Scorpion) 15-1/8 X 23. That would be like adding almost 2 inches of pitch and work well with the gear ratio. The motor will need all the torque it's got to turn that prop to near 5000 rpm.

But if that's not enough, it's available in one inch increments from 23-28 pitch; same diameter.