Prop for 357 mag

[joita]

I repowered my 27' sea ray sundancer with a 357 mag with 325 horse. It was sea trialed and got up to 2800 rpm at a speed of 8mph. Before I had a 7.4 long block. Does anyone know the prop size and pitch I need? I think the wot is 4500 t0 5000.

 

[jumpjets]

What drive and gear ratio? That sounds like a bit of a power downgrade.

 

[joita]

2.2 ratio bravo 3. mag 357 with 325 horse.

 

[Scott Danforth]

your 357 Mag has 325hp at the crank. your old 7.4 had over 330hp at the prop. that was a significant step down in torque on the low end and mid-range

at 8mph, you havent even got the boat up on plane.

 

[QBhoy]

Mmm. Something wrong here. Other than torque. I don’t think there would be too much difference in power here. I know of boats that had a 330hp 7.4 4 barrel carb, that have been re powered with a 350 mag mpi 300hp...and there ain’t much difference. The weight saving alone is like 600/700 lbs.