Reply
 
Thread Tools Search this Thread Display Modes
 
Old 04-21-2009, 05:37 PM   #1
Lieutenant

 
hybris1's Avatar
 
Join Date: Mar 2008
Location: Houston, TX
Posts: 74
Default Engine RPM/Prop pitch

I recently installed a new carbureted vortec 350 on my 2700 SCR. It has a Bravo 2 outdrive. At 3400 RPM it runs at only about 18mph. Full throttle, it gets on a good plane at about 25-30 mph at 4200 RPM. According to the engine manual, max cruise rpm is 4000 and max rpm is 5000. I pulled my prop and am planning to have 2" of pitch removed that should give me about a 500 increase. My hope is that it will cruise in a better part of the power curve for the engine. I obviously don't want to cruise at WOT. I am hopping that it is just bogging down the engine too much since my new engine has a much higher RPM range. The prop shop said 2" is the most pitch they can remove. Any suggestions would be appreciated.
__________________

__________________
1998 2700 SCR
hybris1 is offline   Reply With Quote
Old 04-21-2009, 07:23 PM   #2
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default Re: Engine RPM/Prop pitch

taking 2" out of the prop will increase your WOT and lower your cruise speed....you want to add 2" of pitch which will lower your wot and raise your cruise speed....

IF I read your post correctly...the main thing is that WOT should be about 5k rpm.....that should be just before the hi rpm cutout engages.....

so...run the boat wot and see where she settles down at..then go from there...your boat should max out at about 42mph...5k rpm....

SP
__________________

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 04-21-2009, 07:49 PM   #3
Lieutenant

 
hybris1's Avatar
 
Join Date: Mar 2008
Location: Houston, TX
Posts: 74
Default Re: Engine RPM/Prop pitch

My boat maxes out at about 4200 RPM and less than 30 mph wide open. I think the motor may be over loaded since it has a higher RPM range than the old 1998 350 (5.7L). The 350 may be a little small for my boat but I figured a 60 HP boost from the OEM engine would help. My new vortec 5.7L is rated at 300hp at 5k RPM. The OEM engine blew shortly after I purchased the boat. From what I remember of my sea trial, the cruise was close to 25 mph.
__________________
1998 2700 SCR
hybris1 is offline   Reply With Quote
Old 04-22-2009, 03:48 AM   #4
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default Re: Engine RPM/Prop pitch

well..I'd then reduce pitch by a couple inches..or see if you can borrow some props...try them out...see how it works....some prop shops will let you try a few props for a credit card number and then when you decide what prop works...you get to buy it...then save the old one as a spare..


SP irate:
__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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 Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Seawater leak, but from where? Tommyfmu Maxum Owners General Discussions 5 10-15-2009 06:11 PM
Only getting 4200 rpm @ wot??? Maxumhiredhelp Engines 9 08-28-2009 02:04 PM
navigation light switch problems tha89sx Electronics 3 05-31-2009 09:29 PM
Annoying Beep! andy Maxum Owners General Discussions 5 08-27-2008 02:54 AM
Specs for 98 2300SR maxumrunner Maxum Owners General Discussions 3 06-28-2008 09:25 PM

Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 10:14 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.