Propeller selection for 4.3 motor with 5.7 drive

[liveside23]

Hi all and thanks in advance for your help. I have a 4.3l motor (432APWXS) in a 17ft runabout open bow boat. It is the 175 hp 2 barrel model. My problem is the drive is from a 5.7 (985273) and the best i can find is that the gear ratio for this drive is 1.41. The 4.3 would of had a ration of 1.68 per the manual that I own. It's the first boat that I have owned, the performance is not horrible but I think that the prop which is now a 15x17 needs to be changed to help the v6 out. Right now I get about 3800 RPMs at about 37-39 MPH at WOT. So I need someone to point me in the right direction for a propeller that will help the boat out.

Thank you

Danny

 

[Howard Sterndrive]

Re: Propeller selection for 4.3 motor with 5.7 drive

14P if you can find one. There was actually a 14P OMC Stainless on eBay or kijiji I saw the other day- I remember thinking it was odd to see an even pitch OMC splined prop.
13 works mathematically too, but I find once you get below 14 the big gearcase props lose a lot of efficiency.

 

[liveside23]

Re: Propeller selection for 4.3 motor with 5.7 drive

Hi again and thank you for your reply Howard. So I should stay with the 15" diameter?

 

[Howard Sterndrive]

Re: Propeller selection for 4.3 motor with 5.7 drive

14.25" dia is going to be the most common and should work fine I suspect.

 

[liveside23]

Re: Propeller selection for 4.3 motor with 5.7 drive

Thanks again Howard.

Danny