Prop Pitch for '96 Force 120

kinggabbo

Petty Officer 2nd Class
Joined
Nov 18, 2008
Messages
107
I am currently running a 26p SS prop on my 1996 Nitro 170tf bass boat with '96 Force 120hp engine on it. My RPMs are running lower and it doesn't seem as fast as it used to. It used to run 5250RPMs+ It would even start to chine
walk(?) I got it so fast. I I have not changed props. RPMs are around 4200 running in the water. I took it to the shop and they said it is running the correct RPMs on their dynamo (4750-5250). Or course that does not take into account the prop. They said the 26p is too much and to go down to a 21-23p. Does that sound about right?

Or course perhaps my tach was off. But why would it running at much lower RPMs with the same prop? I am taking it out tonight to try it again.

The boat weighs 1229lbs dry, plus 3 batteries in the back. Not much weight in the front.
 

Bifflefan

Commander
Joined
May 27, 2009
Messages
2,933
Re: Prop Pitch for '96 Force 120

If the only thing that changed is the power has dropped off then it is what it is. Engine issue of some sort.

Are you still getting WOT at the engine? Throttle cable maybe?
 

kinggabbo

Petty Officer 2nd Class
Joined
Nov 18, 2008
Messages
107
Re: Prop Pitch for '96 Force 120

I mentioned the throttle cable to them but they said it was adjusted right. I just had them link and sync it. The throttle cable does have a point where you can push it forward some more, but the speed does not increase any more. Like a little extra "slack" or something.

When the shop measured it on their machine it is reading the correct RPM range so they believe it is the prop. Maybe someone with experience with a similar sized boat and engine can tell what pitches they were running.
 

anple

Petty Officer 3rd Class
Joined
Aug 11, 2010
Messages
97
Re: Prop Pitch for '96 Force 120

My 1997 Force 120 does only 50mph on WOT 5250 RPM with 21p aluminum prop. My boat is Maxum 17'. Any ideas how to make it runs faster? Thanks - Anthony.
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: Prop Pitch for '96 Force 120

Anthony: It is poor manners to constantly hijack other peoples threads. Over on the Force forum, in his thread, Capri1600 asked you to start a new post about your prop and speed.

To start a new thread, you go back and click on prop questions, then at the top left, click on create a new post in the blue rectangle.
 
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