Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Prop questions holeshot versus top-end


Recommended Posts

I will agree norcal. Lots of variables. I was just trying to pass along some knowledge.

Thumbup.gif And it's good info. I was trying to do direct comparisons (on paper) of my 13X14 Legend to a 13X12 XMP and according to my calculations I was going to lose like 8-9 mph and I wasn't OK with those numbers. Max kept insisting that I would only lose a 3-4. :unsure: He was right. I went from a top-end of 52.3 (IIRC) to 49.8, both @ 5000 rpm.

I need to start up that prop database again. I lost it all in a network crash.

Cry.gif That Sux !! Cry.gif

Link to comment
  • Replies 146
  • Created
  • Last Reply

Top Posters In This Topic

  • areamike

    56

  • NorCaliBu

    12

  • D-GOOSE

    12

  • VinRLX

    10

Top Posters In This Topic

Posted Images

More confusion. You guys are relentless... Cry.gif

So you are saying as others have that I need a little higher pitch say a 13x14 in order to decrease my WOT RPMs.

That contradicts what Max says with the 13x12 or 12.5.

Bottom line is I want to decrease WOT RPM. And my current prop is a stock SS 13x13 3 blade. Don't know what cup it is.

I tried to warn you.

One thing your forgetting is that a SS 13x13 ad CNC XMP 13x13 do not perform the same, just because the numbers are.

I will agree norcal. Lots of variables. I was just trying to pass along some knowledge. I need to start up that prop database again. I lost it all in a network crash.

:) :) :)

So you’re the one that started it. Thumbup.gifYahoo.gif I had saved it a long time ago, but forgot who had the info and now have had windawg help fix her up. I started a thread about "how do you prop your boat". As you know we need people to fill in the info. Can you help out with getting people to fill out the info?

Link to comment

Here's another guy who went from a 13 X 13 SS (on a 1998 RLX with 310 carbie) to the OJ XMP CNC prop. I had ordered the 13 X 12 ..... but they sent the 13 X 11.5 by mistake. I tried it anyway. Revs were way to high at top end. (Note: carbie redline is supposed to be 4800 rpm.... but I was passing that.)

So.... sent the 13 X 11.5 back to Max..... got replaced by a 13 X 12. My boat is similar to yours, but much less hp. Works great.... but I only rev to 4800-4900 with 310 horses.

My suggestion is start with at least the 13 X 12.5, or maybe even the 13 X 13. With your added hp, I think you'll spin that 13 X 12 (even with the added blade area) way too fast.... and won't drop the top speed rpm's like you want.

If you're a deep shortline skier..... I'd suggest the 13 X 12.5

If you plan on adding lots of ballast for boarding.... again, I'd start with the 13 X 12.5.

If you ski the course, but aren't in to 40'ish off..... then I' consider the 13 X 13.

As everyone says.... it depends.

If I was a betting man (I'm not)...... I'd say 70% chance you'll end up finalizing on the 13 X 12.5; and 25% chance you'll pick the 13 X 13. That leaves only a 5% chance (just my guess) that you'll go higher or lower (pitch) than these 2 props.

We're all eagerly anticipating your selection decision, and your test results.

Edited by doughickey
Link to comment

Well. I am trying to decide on the 13x12.5 110 cup or the 13x13 110 cup. (I think Doug is right about the 13x12 may spin to much....)

Max said OJ will tweak the prop for free...just have to pay shipping back and forth I imagine.

Anyone have any final thoughts or advice on which one to go with initially?

Weather permitting, I should be able to de-winterize later this month and get her out on th water for some testing.

Link to comment
Well. I am trying to decide on the 13x12.5 110 cup or the 13x13 110 cup. (I think Doug is right about the 13x12 may spin to much....)

Max said OJ will tweak the prop for free...just have to pay shipping back and forth I imagine.

Anyone have any final thoughts or advice on which one to go with initially?

Weather permitting, I should be able to de-winterize later this month and get her out on th water for some testing.

Whistling.gif I would wait a little bit before buying.

What is OJ # for the 13x13?

I'm going to stick with the 13x12.5

Link to comment

Sounds good Goose. I'll wait a couple more weeks. Then I'll be ordering something.

Not sure the part# for the 13x13

Edited by areamike
Link to comment
So go to a steeper pitch. I have a 13 X 14 OJ Legend 4 Blade as my back-up prop for my sporty (it was the OE prop but has since been replaced) and with just a 310 carbie it'll run 53.2 mph @ 4950 rpm. Contact Max at Skier-To-Skier he was a great help in my selecting the OJ XMP 13 X 12 CNC'd 3 Blade to replace the Legend.

Is that LH or RH for a Sporty?

Link to comment

I think I am going to start with the 110 cup 13x12.5 OJ XMP for now. I'll probably order in a couple weeks. Looks like the weather will be getting up into the 40's and I can de-winterize the boat.

Link to comment
  • 2 weeks later...

OK. I just took my boat out for first time this year. I ran around the lake at cruising speeds for a while then decided to open it up. I got a GPS over Christmas and checked the speed with it. It appears my speedos are/were off.

WOT - 48.7 @ 5500RPM

THAT SUCKS!

I definitely need to re-prop since I re-built this motor. The last 500-700 RPM it doesn't even speed up at all. PITIFUL.

So do I still go with a 13x12.5 .80 .90 or .110?

Link to comment

I just received the new prop. Fastest shipping ever.

I am starting with the OJ 13x12.5 standard cup(.90). I will be putting it on the boat tomorrow and testing.

The funny thing is on the prop it says : 13x12.5 VC .65 OJ 1 1/8

I hope the .65 is not the cup size... :unsure:

Either way I can exchange it for another as long as I keep it in "Like New" condition. Rockon.gif

Link to comment

This photo may help.

On the right, is my original 13 X 13 stainless steel CVP (Credit Valley Propeller)

On the left, is the original 13 X 11.5 OJ XMP prop. MUCH more blade surface area. (Later replaced with 13 X 12 OJ XMP)

I think I recall Eric Johnson (of OJ props) explaining to me that the .65 meant that if you try and view "through" the circular area that the propeller turns through in a revolution, that 65% of the area is covered by propeller surface.

Betcha you find the 13 X 12.5 is just right. (Otherwise, the 13 X 13 NiBrAl)

post-114-1206242388_thumb.jpg

Link to comment
This photo may help.

On the right, is my original 13 X 13 stainless steel CVP (Credit Valley Propeller)

On the left, is the original 13 X 11.5 OJ XMP prop. MUCH more blade surface area. (Later replaced with 13 X 12 OJ XMP)

I think I recall Eric Johnson (of OJ props) explaining to me that the .65 meant that if you try and view "through" the circular area that the propeller turns through in a revolution, that 65% of the area is covered by propeller surface.

Betcha you find the 13 X 12.5 is just right. (Otherwise, the 13 X 13 NiBrAl)

Wow..even visually that is a big difference.

I will be putting the prop on today and testing it out. I will post back with my results.

Link to comment

you lose the bet Doug

Here is new prop info:

OJ 13x12.5 .90 cup

New prop spun at 6000 RPM. I could not even go wide open for fear of pushing it over 6000rpm Shocking.gif . So, my bad went to worse. I'm definitely spinning this new prop way too much and not grabbing the water enough so-to-speak. I HAVE TOO MUCH POWER! UGH!

So now what? 13X13? I'm thinking I am going the wrong direction. Maybe I need a 13x13 or even a 13x14? Only problem with that is I don't even see a 13x13 or 13x14 OJ prop on their product lists.

Looks like I am in the prop playing/exchanging/testing business now for the next couple weeks. Cry.gif

Edited by areamike
Link to comment

I think your best bet is going to be the Acme 449 (13 X 12.625) or the Acme 425 (13 X 13). I run the 449 on my Lxi with the 375 hp Ls1 and get around 48 mph @ 5000 - 5200 rpm. I also have an Acme 515 (13 X 12)...it spins around 5500-5600 at wot (can't remember the speed.)

It sounds as if your "Special" motor may be strong enough to spin the 425. I haven't tried it, but I doubt I could break 5 grand with it on my boat.

Link to comment

One thing about the Hammerhead, the torque curve is a little farther up the rpm range than the Monsoon or others. With that, I would certainly try to maintain 3400+ rpm for the course, basically agreeing with Max. A four blade won't buy you anything for skiing or footing and will really hit a wall at around 49-50 mph. The Hammerhead should pull that boat to 52-53 mph easily. Three blades with lots of blade area and a CNC surface will help you boat a lot. As mentioned on the other post, I think some extra cup would benefit your application. It worked for me on a prop I modified with a higher horse engine.

Link to comment

Does anyone know if OJ makes a 13x14 or even 13x13? They don't have any on their parts list.

Looks like I need to go to at least a 13x13. I actually would rather try a 13x14. If OJ does not have that option then I need to return this prop and go ACME...and man they are like 50 bucks more! Shocking.gif However if it means getting my boat DIAL-IN, I'll do it! and I'll do it with a friggin smile on my face! Biggrin.gif

Link to comment

these guys at SkiertoSkier are GREAT. I'd call Eric directly, but I don't want to step over these guy's heads. I'll just let them do the job they get paid to do.

Here's the email they sent me.

We have a couple of options. But in order to get everything on the table, I would like to know what boat and engine you have and if any changes have been made to the engine. We have found that what works most of the time with a Malibu sometimes does not work on a specific boat and we need to go with a couple of options. To get you going after I get the info, I will talk with the experts at OJ and our tech and send you a couple props to try to see what gets you the best run and then you can return what does not work. I will include post paid labels so it will not cost you anything to try the extra props.

talk about great service. Rockon.gif Who could ask for anything more? I'll keep this topic updated with my results.

Edited by areamike
Link to comment

Looks like OJ will be sending me a couple props to try. After talking with them, they think that a 4 blade will be what I need. I don't know if they are correct, but they know more about this than I do and are willing to let me try more props, so why not? They also think my rebuild increased my HP more like 25-35 and I am possibly pushing the 400HP mark. With that being the case, aren't the new 383's 400HP? What prop do they run on the new responses these days with the 400 HP motors? Or maybe that would be comparing apples to oranges?

mike

Link to comment
Looks like OJ will be sending me a couple props to try. After talking with them, they think that a 4 blade will be what I need. I don't know if they are correct, but they know more about this than I do and are willing to let me try more props, so why not?

My Sporty had a 13 X 14 4 Blade OJ Legend on it when I bought it. I was getting almost 53 mph out of it at 5000 rpm with my little 310 HP carbie. You have somewhere close to 100 more HP. Shocking.gif Not sure how the XMP 4 blades compare to the Legend 4 blades. Dontknow.gif Like you said, try it, and record the data. Yes.gif

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...