Like Tree0Likes

502 w/ 25 pitch prop, What RPM?

Reply
Old 03-30-2006, 08:56 AM
  #1
Registered
Thread Starter
Trade Score: (1)
 
wieland77's Avatar
 
Join Date: Jun 2005
Location: Bay City, MI
My Boats: 1987 Saber 28, 1985 12 Meter Fountain
Posts: 382
Default 502 w/ 25 pitch prop, What RPM?

I bought a 1987 28' Saber a couple months ago and I was able to run it for the first time this past Sunday. I dont know anything about what was done to the motor accept it was recently gone through by More Power in Grand Rapids, MI. They replaced the rings and a piston, put in new bearings and polished the crank and cam. It has IMCO manifolds and a hi-rise Dart intake with a 950hp double pump Holly carb. I do not know the HP rating for the engine.

It has a 25 pitch 3 blade mirage prop on it and when running wide open I was running around 4700-4800 rpm and on;y getting 57 - 58 mph depending how the drive was trimmed.
Is this prop a little too much for the engine. It seems like I should be in the 5100 - 5300 rpm range. I dont know a whole hell of a lot about props and what would be the best match for what I have.

Am I where I should be or should I go with a different prop, and if so what one? Any info would be appreciated.
Attached Thumbnails
502 w/ 25 pitch prop, What RPM?-4.jpg  
wieland77 is offline  
Reply With Quote
Old 03-30-2006, 09:17 AM
  #2
Registered
 
Tantrum's Avatar
 
Join Date: Oct 2000
Location: USR, NJ
My Boats: Stray Cat Statement Marine
Posts: 4,000
Default Re: 502 w/ 25 pitch prop, What RPM?

Did you do a leak down test on the motor? It sounds like you should be getting more from that set-up than you are.

The way that it is running now i would say that yes, you are over-propped. If there is no rev limiter to check I would think you want to be at 5100rpms.

There is alot of guessing here...you best bet would be to get the motor on a dyno and see what kind and where it makes its HP.
Tantrum is offline  
Reply With Quote
Old 03-30-2006, 09:28 AM
  #3
Registered
 
Pantera1's Avatar
 
Join Date: Mar 2002
Location: Winnipesaukee
My Boats: NorTech
Posts: 3,457
Default Re: 502 w/ 25 pitch prop, What RPM?

Try a 23 four blade.
Pantera1 is offline  
Reply With Quote
Old 03-30-2006, 09:37 AM
  #4
Registered
Thread Starter
Trade Score: (1)
 
wieland77's Avatar
 
Join Date: Jun 2005
Location: Bay City, MI
My Boats: 1987 Saber 28, 1985 12 Meter Fountain
Posts: 382
Default Re: 502 w/ 25 pitch prop, What RPM?

A buddy of mine has a 4 blade 22 pitch that I can try out and see what it does, I also have a 23 ptch 3 blade mirage off my 454 330hp motor that I could try also.
wieland77 is offline  
Reply With Quote
Old 03-30-2006, 09:44 AM
  #5
Registered
 
Airpacker's Avatar
 
Join Date: Aug 2001
Location: Aurora Ontario
My Boats: little cat...BIG MOTOR
Posts: 4,008
Default Re: 502 w/ 25 pitch prop, What RPM?

is it a 1.50:1 or 1.36:1 drive?
Airpacker is offline  
Reply With Quote
Old 03-30-2006, 09:54 AM
  #6
SORE MEMBER
Platinum Member
 
Wobble's Avatar
 
Join Date: Apr 2004
Location: 2950'49.74"N 95 5'17.55"W.......TEXAS
My Boats: SeaDoo RXP & RXP-X, Stryker Equalizer 28, Eliminator Daytona Jet
Posts: 6,705
Default Re: 502 w/ 25 pitch prop, What RPM?

Quote:
Originally Posted by wieland77
A buddy of mine has a 4 blade 22 pitch that I can try out and see what it does, I also have a 23 ptch 3 blade mirage off my 454 330hp motor that I could try also.
The four blade 22 bravo-1 should be a good starting point with a 1.5-1 outdrive. I would have thought that your setup would easily turn a 24 b-1 4 blade.

I run a 28' with a 509, can turn the 24 pitch b-1 prop to 5800 rpm. Probably could turn a 26, but don't want to torque the outdrive too much.

Last edited by Wobble; 04-03-2006 at 11:29 AM.
Wobble is online now  
Reply With Quote
Old 03-30-2006, 10:10 AM
  #7
Registered
Thread Starter
Trade Score: (1)
 
wieland77's Avatar
 
Join Date: Jun 2005
Location: Bay City, MI
My Boats: 1987 Saber 28, 1985 12 Meter Fountain
Posts: 382
Default Re: 502 w/ 25 pitch prop, What RPM?

My dive is a 1.5 gear
wieland77 is offline  
Reply With Quote
Reply

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
wieland77
General Q & A
14
04-03-2006 05:33 PM
zimm17
Prop Talk
5
12-14-2005 09:00 PM
plumbers crack
General Boating Discussion
1
05-31-2004 12:57 PM
Water Pistol
General Q & A
1
04-27-2004 08:08 AM
puder
General Q & A
3
08-24-2003 11:57 PM



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 01:24 PM.


Copyright 2011 OffShoreOnly. All rights reserved.