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Old    Justin Harrelson (skiboarder)      Join Date: Oct 2006       08-02-2010, 9:00 AM Reply   
I have 2010 VLX and just recently converted my Acme 14.50 x 14.25 to a 14.50 x 13.25 to improve hole-shot when weighted down.

I anticipated an increase in RPM, but at 24mph with 2,000 lbs of ballast and wedge my cruising RPM has jumped to 3800 rpm. I was at about 3500 before.

With the 350HP motor do you think 3800 is too high?? I am considering tempering the prop back to its original pitch.
Old    Jeremy (wake77)      Join Date: Jan 2009       08-02-2010, 9:05 AM Reply   
As far as hurting the motor? 3800 RPM is fine. You will use a tad bit more gas.
Old    Alan Slabaugh (alans)      Join Date: Aug 2005       08-02-2010, 11:49 AM Reply   
3800 is fine. I wouldn't cruise with full ballast and the wedge down though, not very fuel efficient.
Old    Justin Harrelson (skiboarder)      Join Date: Oct 2006       08-02-2010, 12:46 PM Reply   
By cruising speed I meant riding speed: 24mph.
Old    Dave Kiehl (dave27)      Join Date: May 2005       08-02-2010, 1:03 PM Reply   
my boat it 30 mph at 3600 RPM. I can do that speed with full ballast around 2400 plus 5-8 people. BTW I reproped my boat with a ACME 911
Old    Alan Slabaugh (alans)      Join Date: Aug 2005       08-02-2010, 1:16 PM Reply   
Dave, you must have a very different gear ratio than his indmar. If you have a 1:1 trans. With a 10.5" Pitch at 2400 RPM, you would be going 23.4 MPH with 100% efficiency, which is impossible.
Old    Cory D (cadunkle)      Join Date: Jul 2009       08-02-2010, 2:50 PM Reply   
3800 sounds pretty high to me. Sure it'll be fine but it's a lot of gas burned and extra wear on the engine. If it needs to rev that high to make the torque to maintain a steady speed then that's what it needs, but if not I'd try to drop the RPM a bit. Generally I like to cruise at 3000 RPM or less. Not much comparison but my beater is at about 2400-2500 RPM at 22 MPH or so (where I like to ride). What size engine and what ratio transmission do you have? If it's a 350 Chevy I wouldn't expect it to need to rev that high unless you're seriously weighted down.
Old    Art (rallyart)      Join Date: Nov 2006       08-02-2010, 4:10 PM Reply   
A small block Chevrolet like yours will run at 3800 all day but you would be better below 3500.
The bigger problem might be the wedge at 24 mph. You've got a huge downfoce at that speed so you'll have high prop slip. That would be why your rpm is so high.
Try running that speed with no load and see what the rpm is.
Old    Chris (rio_sanger)      Join Date: Apr 2007       08-02-2010, 6:03 PM Reply   
Art is right on here (as he usuallay is). - With the wedge down, it's acting like an anchor, so the engine needs to work harder (more rpm's) to make the boat get up to speed.
Old    Mikeski (mikeski)      Join Date: Aug 2003       08-02-2010, 6:20 PM Reply   
I would not run a prop with less than 14" of pitch on any modern V-drive. The blade shape of an OJ is slightly different, might call Eric Johnson, he's been known to let guys try props from time to time. I ended up keeping my Acme but that was for non-wakeboarding reasons. You can also get Acme props cut to different cup tolerances, a bigger cup will reduce your rpms.
Old    Justin Harrelson (skiboarder)      Join Date: Oct 2006       08-04-2010, 8:54 AM Reply   
I called Indmar and they told me that there should be no concern in running the boat at 3800 rpms as long as I do not exceed 5200 at any point in the pick-up. In fact, he said that running a lower RPM under such a load will cause more problems.

The biggest problem he sees is with boats that spend most of their time wakesurfing.
Old    Dave Kiehl (dave27)      Join Date: May 2005       08-04-2010, 10:39 AM Reply   
Alan, I will have to take a look at my RPM to MPH, again. I for some reason can't remember now if I stated it correctly, now where did I put that beer!

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