Go Back  Offshoreonly.com > Technical > Prop Talk
Switching Gear Ratios >

Switching Gear Ratios

Notices

Switching Gear Ratios

Thread Tools
 
Old 04-11-2006, 02:03 PM
  #1  
Geronimo36
Gold Member
Thread Starter
 
Panther's Avatar
 
Join Date: Sep 2002
Location: Elkton, MD
Posts: 11,972
Received 131 Likes on 36 Posts
Default Switching Gear Ratios

It's been a long time and I have a question regarding prop pitch with gear ratio changes.

Last year I was running 32" Bravo 1's to 51-5200 rpms with a 1.50 gear ratio, with about 20% prop slip.

Over the winter I picked up different drives and the gear ratio is 1.30. In addition to changing the prop pitch I am looking to turn higher RPMS (5600) than last year because of where my motors make peak TQ and HP.

I was thinking Bravo 1's with 28" pitch would do the trick? Anyone??
Panther is offline  
Old 04-11-2006, 04:13 PM
  #2  
Registered
 
Join Date: May 2005
Location: Cortez,Fl
Posts: 545
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Switching Gear Ratios

When going from a 1.5 to a 1.3 you will need to drop the pitch by 10%. That will put you at about 29. If you want to increase your rpm another 400 that's about 2" of less pitch, so that's about a 27.

You are pretty close with the 28's you thought you needed. If you have the 28's they would be a good prop to start with. If you need props to test with give us a call.

Matt
SVL4 is offline  
Old 04-11-2006, 04:18 PM
  #3  
Geronimo36
Gold Member
Thread Starter
 
Panther's Avatar
 
Join Date: Sep 2002
Location: Elkton, MD
Posts: 11,972
Received 131 Likes on 36 Posts
Default Re: Switching Gear Ratios

Originally Posted by SVL4
When going from a 1.5 to a 1.3 you will need to drop the pitch by 10%. That will put you at about 29. If you want to increase your rpm another 400 that's about 2" of less pitch, so that's about a 27.

You are pretty close with the 28's you thought you needed. If you have the 28's they would be a good prop to start with. If you need props to test with give us a call.

Matt
Thanks Matt! Where are you located, I'm in NJ.

Frank
Panther is offline  
Old 04-11-2006, 05:03 PM
  #4  
Registered
 
throttleup's Avatar
 
Join Date: Mar 2002
Location: Cajun Country
Posts: 5,143
Likes: 0
Received 1 Like on 1 Post
Default Re: Switching Gear Ratios

Sorry, I forgot to log out and back in on the last post.

We are located in St Pete, FL.

Don't hesitate to call or e mail if you have any questions.

Matt
throttleup is offline  
Old 04-11-2006, 07:49 PM
  #5  
Offshoreonly Advertiser
Offshoreonly Advertiser
 
bbladesprops's Avatar
 
Join Date: Jun 2003
Location: Princeton, Wisconsin
Posts: 3,875
Received 46 Likes on 13 Posts
Smile Re: Switching Gear Ratios

Matt, you have two user names?


Panther, the raise in gear ratio (lower #) is about 2 inches in pitch to maintain the same rpm. So dropping yet another 2 inches of pitch in the Bravo 1 propeller family should put you where you want to be. Sounds like you had it figured out already.
__________________
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
bbladesprops is offline  
Old 04-11-2006, 09:21 PM
  #6  
VIP Member
 
Smitty's Avatar
 
Join Date: Apr 2001
Location: Chicago il
Posts: 4,213
Received 0 Likes on 0 Posts
Default Re: Switching Gear Ratios

Panther,

I need a set of 32's and I have a set of 28's. Do you want to swap or whatever ?? I went from 1.36 to 1.50 which is the opposite of what you did.

Call me at 847-902-9702 and let me know.


Smitty
__________________
Want your ECU tuned right?? Call Mark at Precision www.pmefi.com
Smitty is offline  
Old 04-12-2006, 06:53 AM
  #7  
Registered
 
throttleup's Avatar
 
Join Date: Mar 2002
Location: Cajun Country
Posts: 5,143
Likes: 0
Received 1 Like on 1 Post
Default Re: Switching Gear Ratios

Originally Posted by bbladesprops
Matt, you have two user names?

No, visitors occasionally use my computer and don't log out when they are done and I don't check, prior to posting, to see under who's name my computer is logged in under.

Matt
throttleup is offline  
Old 04-12-2006, 08:15 AM
  #8  
Geronimo36
Gold Member
Thread Starter
 
Panther's Avatar
 
Join Date: Sep 2002
Location: Elkton, MD
Posts: 11,972
Received 131 Likes on 36 Posts
Default Re: Switching Gear Ratios

Originally Posted by Smitty
Panther,

I need a set of 32's and I have a set of 28's. Do you want to swap or whatever ?? I went from 1.36 to 1.50 which is the opposite of what you did.

Call me at 847-902-9702 and let me know.


Smitty
Smitty,

I'll give you a call. How old are the props, have then been "worked"?

Frank
Panther is offline  
Old 04-12-2006, 01:18 PM
  #9  
VIP Member
 
Smitty's Avatar
 
Join Date: Apr 2001
Location: Chicago il
Posts: 4,213
Received 0 Likes on 0 Posts
Default Re: Switching Gear Ratios

Panther,

They are not virgin. I bought them used from a fellow OSO'r. They appear to have been redone at some point. I would rate them a 9.5 out of 10. They worked well for me but since I have changed ratios I need something else. I'll be available tonight by phone.

Dave
__________________
Want your ECU tuned right?? Call Mark at Precision www.pmefi.com
Smitty is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
1 MAIDEN AMERICA
General Q & A
1
03-03-2007 10:44 AM
awsomethunder
General Q & A
5
01-19-2007 07:00 PM
tomcei
General Q & A
4
08-07-2006 07:19 AM
bottomfeeder05
Formula
1
03-27-2005 12:41 PM
kevin285
General Q & A
2
10-12-2003 10:06 AM

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



Quick Reply: Switching Gear Ratios


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

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.