Stainless vs Oem Prop!

magtec

Cadet
Joined
Jun 3, 2002
Messages
21
I just put on a Express SS prop same pitch as my OEM but it seems to be not the same pitch! PPMs to high and there is no hole shot!
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Stainless vs Oem Prop!

Prop design is a "science" and just because you have two props with the same pitch doesn't mean they will perform the same. Changing from aluminum to stainless is one parameter that affects performance. Blade design, rake, vented or not, cupped or non-cupped are all factors that can affect performance. If the engine is mounted too low or too high it can affect performance. As a starting point, the AV plate should be at least even with or slightly above the bottom of the boat. Some props simply don't perform or perform differently on different hulls. I realize this isn't much help but you need to be aware of what can happen when selecting a prop.
 

magtec

Cadet
Joined
Jun 3, 2002
Messages
21
Re: Stainless vs Oem Prop!

Thanks, Well I think the rpms are up 500-600 to much with the SS 17 pitch.I am going to put back the OEM and get a good reading on the Rpms. I gues I could go up , the next pitch up is 19. <br />Just wondering if anyone has had the same out come<br />when going from OEM to SS
 

gr8rg8r

Petty Officer 3rd Class
Joined
Mar 26, 2004
Messages
94
Re: Stainless vs Oem Prop!

Going with a higher pitch will probably not lower your wot rpms by 500 - 600, probably more like 200. And, it will hurt your hole shot. Is the diameter of the SS the same as the aluminum? I would venture a guess that you went with a prop that has too small of a diameter.
 

bigbrownbuku

Master Chief Petty Officer
Joined
Sep 17, 2004
Messages
885
Re: Stainless vs Oem Prop!

im surprised you could see a greater difference of 600 RPM. what is you outboard model and what were the original RPM with the oem prop?
 

magtec

Cadet
Joined
Jun 3, 2002
Messages
21
Re: Stainless vs Oem Prop!

I put back the oem and my full wot trimmed up is 5200. With the SS it was 5500 not full trim, I did not want to rev the motor any higher . Its probably a 300-400 rpm diff.<br />The SS is the same dio as OEM? could be just the design of the prop?
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: Stainless vs Oem Prop!

Gone to the Prop forum.
 
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