Notices
General Boating Discussion

RPM Drop

Thread Tools
 
Old 01-05-2015 | 12:29 PM
  #1  
Thread Starter
Registered
 
Joined: Sep 2014
Posts: 108
Likes: 0
Default RPM Drop

I have a question for the guys who experiment with gear changes. How many RPM drop will there be from a 1.50 to a 1.34 to a 1.25 Using the same prop?? Would I be close assuming about 400RPM per gear? What do you guys think?
C1000 is offline  
Reply
Old 01-06-2015 | 12:18 PM
  #2  
Thread Starter
Registered
 
Joined: Sep 2014
Posts: 108
Likes: 0
Default

ttt any Ideas?
C1000 is offline  
Reply
Old 01-06-2015 | 08:19 PM
  #3  
Tinkerer's Avatar
Registered
20 Year Member
 
Joined: Jan 2002
Posts: 4,612
Likes: 7
From: ALTO, MI
Default

I went from 6000 RPM at 1.5 to 5400 at 1.34 with a 28 Bravo 4 blade. One other factor that comes into play is does your engine have the torque to turn the lower ratio? Mine didn't.
Tinkerer is offline  
Reply
Old 01-07-2015 | 12:44 AM
  #4  
Griff's Avatar
Charter Member # 55
25 Year Member
Charter Member
Super Moderators
 
Joined: Oct 2000
Posts: 20,232
Likes: 2,482
From: Omaha/LOTO
Default

1.5 to 1.35 is about 600rpms. I would guess going to a 1.25 would be another 500-600rpm decrease.
Griff is offline  
Reply
Old 01-08-2015 | 08:33 AM
  #5  
Thread Starter
Registered
 
Joined: Sep 2014
Posts: 108
Likes: 0
Default

Great info, helps me know that I will stick with what I have. Thanks guys for the answers,
C1000 is offline  
Reply
Old 01-08-2015 | 08:02 PM
  #6  
Tinkerer's Avatar
Registered
20 Year Member
 
Joined: Jan 2002
Posts: 4,612
Likes: 7
From: ALTO, MI
Default

I am planning on building a 598 that will be able to turn the lower ratio. As usual I am doing a bunch of changes at once. Makes for interesting dial in.
Tinkerer is offline  
Reply

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



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.