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turbophil

XMP- 12 or 11.5- need advice

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turbophil

I've done a lot of research and am down to the three blade XMP. The million dollar question is 13x12 or 11.5... I'm somewhat new to the Malibu family, but I think many of you are running more ponies than I am, which is why I'm so uncertain...

I've got a '95 21' Sun Setter with a 350 TBI EFI. I think it has 285 horse (previous owner thought this anyway, any insight here would be great), but I don't have a spec sheet and can't find it on the motor tag.

We never foot (I'd like to try sometime), ski a ton (open water mostly and sometimes with two skiers), and board a little (still trying to get into that). Most of you seem to be running the 13x12. Is that going to be too much prop for my older 'bu? On the otherhand, I've seen a lot of posts about possibly hitting rev limiters with the 11.5?? I don't want to do that either... Am I splitting hairs? Should I just buy flip a coin, buy one, and call it good?

Thanks for any help here!

Phil

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kbtheboz

Phil,

I just recently put a 11.5 pitch XMP on my SLXI. I've got 325 HP and was some concerned about over revvin' the engine, but it isn't a problem. I think that the CNC props have so much more surface area that they are pulling a greater load with a lower pitch. If I had it to do again, I'd get the 11.5 and not the 12. The boat feels like it almost drives itself now. It pulls hard and holds speed without any effort at all.

I might have some concern that with fewer ponies you might not be able to pull more pitch.

my 2cents....

Kirk

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mlange

Phil,

If you do a search you'll see a pretty long thread regarding both the OJ vs. the XMP debate as well as my debate of going with the 13x12 vs the 13x11.5. Martho, Oz and some others have some good test data on a few of the props in that thread as well.

When I was deciding I still had a 2000 Sunsetter with the 325 Monsoon and Max at Skier-to-Skier felt I was on the border between the two.

In your case, especially since you don't foot at all, I would without a doubt go with the 13x11.5.

Out of curiosity, why are you stuck on the OJ instead of the ACME?

I actually went with the OJ myself, but I would have gone with the ACME if I were to do it again.

Mike

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turbophil
Phil,

If you do a search you'll see a pretty long thread regarding both the OJ vs. the XMP debate as well as my debate of going with the 13x12 vs the 13x11.5.  Martho, Oz and some others have some good test data on a few of the props in that thread as well.

When I was deciding I still had a 2000 Sunsetter with the 325 Monsoon and Max at Skier-to-Skier felt I was on the border between the two. 

In your case, especially since you don't foot at all, I would without a doubt go with the 13x11.5.

Out of curiosity, why are you stuck on the OJ instead of the ACME? 

I actually went with the OJ myself, but I would have gone with the ACME if I were to do it again.

Mike

Thanks Guys-

I don't know that I'm "stuck on the OJ", but I like trying new things for one, and it seems like the XMP has been real crowd pleaser with the Malibu. Not that I would be able to tell the difference, but from what I read it looks like the XMP inches ahead of the ACME in overall performance...

...plus... I was proud of myself to widdle my choices down to just two props, the 12 and 11.5 XMPs ;)

It looks more and more like I should go 11.5...do I have the lowest output 'bu or what? It doesn't feel under-powered compared to a friend's 22V Tige' with 330 horse, but maybe it is...

It's weird that a later 'bu with a carb would have more ponies than my EFI engine, even if it is few years older. Is there a chart or something that I can reference the advertised output for our boats?

Thanks,

Phil

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CarveItUp

Phil,

My advice is to contact OJ (or ACME) directly. They respond to emails quickly and will be able to put you in the right prop for your engine. The guys at OJ advised me to go with the 11.5 for our 325 HP Monsoon 2. They told me it was at least the equivalent of the 13 x 13 CVP we have now.

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edwin
I actually went with the OJ myself, but I would have gone with the ACME if I were to do it again.

Mike

Mike - did you ever try the 13x12" XMP on the Sunsetter? I had offered on two occassions to send you mine to try.

FWIW, I've tried both the 13x12 and 13x11.5 XMP on my 2001 SLXi. As Max from skiertoskier.com mentioned, the boat is truly on the fence between the two sizes.

Pros and cons of each

13x11.5

Pros - outstanding holeshot, rock solid pull

Cons - spins approx 150-175 more rpms across the entire power range.

13x12

Pros - great all around performance, closer to the 100 rpm per 1mph we're used to with standard direct drives (3000 rpms is approx 30mph), slightly faster top speed than 11.5

Cons - not quite as firm out of the hole as the 13x11.5

We normally have 15-20 minutes of riding in the boat to get to our skiing spot. Given that, spinning a few less rpms does make a difference. I just shipped the 13x11.5 back to Max today after trying them both out.

I've tried a bunch of props on my boat over the years (OJ 13x14 4 blade, ACME 13x12.625 3 blade, ACME 13x12.5 4 blade, OJ 13x13 4 blade stainless, OJ 13x12 4 blade, ACME 13x11.5 3 blade, OJ XMP 13x12, and an OJ XMP 13x11.5). Best all around prop for my boat is the 13x12 XMP. YMMV....

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Addictedto6

I actually went with the OJ myself, but I would have gone with the ACME if I were to do it again.

Mike

Mike - did you ever try the 13x12" XMP on the Sunsetter? I had offered on two occassions to send you mine to try.

FWIW, I've tried both the 13x12 and 13x11.5 XMP on my 2001 SLXi. As Max from skiertoskier.com mentioned, the boat is truly on the fence between the two sizes.

Pros and cons of each

13x11.5

Pros - outstanding holeshot, rock solid pull

Cons - spins approx 150-175 more rpms across the entire power range.

13x12

Pros - great all around performance, closer to the 100 rpm per 1mph we're used to with standard direct drives (3000 rpms is approx 30mph), slightly faster top speed than 11.5

Cons - not quite as firm out of the hole as the 13x11.5

Edwin, any noticable difference from a slalom perspective?

Edited by Addictedto6

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Sunsetter95

I have a 95 Sunsetter with a rebuilt 350 with ~300 hp carberated engine. I went with the ACME 13x11.5. At 3000 rpm I am going about 30mph, at 4000 rpm I am going ~44 mph.

I actually gained speed and pull by going to the ACME prop.

The pull is amazing even loaded with 1400 lbs of ballast, a Wedge, and 6 people.

This past weekend I took allot of water over the front, driver error ;) , and I didn't even realize that the bilge pump wasn't pumping it out. Still with all the ballast the same, it still pulled well.

You won't be disappointed with the 13x11.5.

My Prop

Edited by Sunsetter95

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Lakenut

Edwin,

The 12 pitch gets the nod over the 11.5? More details please....What are you turning WOT? Being the slalom guru that you are, I assume it pulls strong for slalom. How does it wakeboard?

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mlange

Edwin,

I was going to take you up on that, but I sold my boat after having it out on the water for only a couple of weeks.

I think I would have preferred the 13x12 because I lost too much top end with the 13x11.5. I also wasn't real impressed with the balancing marks on the back side of the XMP. I was expecting some from Martho's comments, but not marks that consumed a good 1/2 of each blade. I haven't seen a whole lot of the ACME's, but the one I have now looks perfect and makes me think that the ACME manufacturing process is a bit further along. That would probably make sense since they have been doing CNC props in mass for a couple years more than OJ.

Mike

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edwin

Ato6 - slalom pull is very similar with either prop. Only real difference I could tell was the firmness of the pull once you lock into position after the turn to cross the wakes. The 11.5 was spinning right at 3600 rpms at 34.2mph (gps). The difference was small, but there's a small diff.

Sunsetter95 - if you're going 44mph at 4000 rpms, you must be able to run low 50's with your boat at WOT?

LN - WOT with either prop was 4950 - 4975rpm, 44.9mph (gps) with full fuel and a light load of passengers. I was surprised that I couldn't spin the 11.5 more rpms at WOT, but my Monsoon just couldn't do it. As Martho has mentioned before, the OJ does seem to be a more efficient prop with less slippage in the water than the ACME.

Either prop worked well for boarding, but I'd lean toward the 11.5 for boarding. I had a boat full of folks with me Sat and Sunday this past week. 2 Thumbs Up and clan was along on Sunday, I think he can attest that the 13x12 didn't hold me back from busting some huge sausage grabs landing wayyyyy out into the flats.

Mlange - last trip I had to the Merced factory back in Feb, saw more than a few ACMEs with the same sanding on the back side...it's not just an OJ thing.

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Sunsetter95
Sunsetter95 - if you're going 44mph at 4000 rpms, you must be able to run low 50's with your boat at WOT? 

Mind you, that is with the dash speedo.

I would like to use a gps to see how close they are.

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2 ThumbsUp
2 Thumbs Up and clan was along on Sunday, I think he can attest that the 13x12 didn't hold me back from busting some huge sausage grabs landing wayyyyy out into the flats. 

You would not have known Edwin is a slalom guy the way he was grabbing the old sausage.

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edwin
Sunsetter95 - if you're going 44mph at 4000 rpms, you must be able to run low 50's with your boat at WOT? 

Mind you, that is with the dash speedo.

I would like to use a gps to see how close they are.

Not to be rude, but dash speeds aren't even close to gps actuals. Dash speedos with pitot pickups can be dialed in to be accurate at a small range of speeds. If it's accurate at slow speeds, it's not gonna be accurate at high speeds, and vice versa. The new paddle wheel pickups are an improvement but still not like gps.

I'd expect you'll be surprised to find the 44mph at 4000 rpms to be quite optimistic. According to the 1995 WSM test, your boat tops out at 45.8mph with the Merc 350 Mag EFI / MP powerplant.

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doughickey

Here's my OJ 13" X 11.5" results. (Net is I am working to get it replaced with the 13" X 12").

MY BOAT: 1998 RLX; 310 carb; (posted redline by Indmar is 4800 rpm). Weight 2450 pounds. Main usage is skiing. No wedge. No fatsacks. Minimal boarding.

BEFORE: With the CVP 13" X 13" stainless

Good hole shot, good midrange. At 4800 redline I got 47 mph (GPS). Top speed 49 mph (GPS) at 5000 rpm.... just past my redline

AFTER: With the OJ XMP 13" X 11.5" Nibral

Great holeshot, great midrange. At 4800 redline I only get 43.4 mph (GPS). At 5000 rpm I get 45.4 mph, and have throttle left that I can't use. Would over rev the motor if I burried the throttle.

I'm not a strong enough or good enough skier to notice any difference in wake characteristics.

NET: I've got power left that I can't use.... and I'm revving higher than I have to for any chosen speed. I lost about 4 mph. The 12" pitch will be a better choice.

Edited by doughickey

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Addictedto6
Here's my OJ 13" X 11.5" results. (Net is I am working to get it replaced with the 13" X 12").

MY BOAT: 1998 RLX; 310 carb; (posted redline by Indmar is 4800 rpm). Weight 2450 pounds. Main usage is skiing. No wedge. No fatsacks. Minimal boarding. 

BEFORE: With the CVP 13" X 13" stainless

Good hole shot, good midrange. At 4800 redline I got 47 mph (GPS). Top speed 49 mph (GPS) at 5000 rpm.... just past my redline

AFTER: With the OJ XMP 13" X 11.5" Nibral

Great holeshot, great midrange.  At 4800 redline I only get 43.4 mph (GPS). At 5000 rpm I get 45.4 mph, and have throttle left that I can't use. Would over rev the motor if I burried the throttle.

I'm not a strong enough or good enough skier to notice any difference in wake characteristics.

NET: I've got power left that I can't use.... and I'm revving higher than I have to for any chosen speed. I lost about 4 mph. The 12" pitch will be a better choice.

Doug - what happened? thought you were going with the 12" originally based on the amce/oj thread.

now I'm sure I need to go with the 12" pitch.

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doughickey

Hmmm... how will I say this nicely.

I ordered the 12" pitch. They sent the 11.5" pitch.

I reviewed everyone's tests. I assessed my needs. I decided on the 12" pitch.

I sent an email with my boat info. I spoke with them on the phone. I explained I wanted the 12" pitch. I placed my order on-line for the 12" pitch. For some reason.... they sent the 11.5" pitch. Needless to say, I was very disappointed. They apologized.

Since it involved a border crossing and taxes and handling charges etc etc....

Rather than go ballistic and report the wrong shipment to the world, I said I would try it out. So I did....

... and my original gut feel was correct. The 11.5" pitch is just too mild for my boat/motor/application/needs.

I sent an email this am saying that I want to exchange for the 12" pitch... what I ordered in the first place.

Story is not over yet.

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edwin

Can't speak for him, but I'd bet Max will get ya taken care of...he's great peeps, about as good as they come.

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doughickey
Can't speak for him, but I'd bet Max will get ya taken care of...he's great peeps, about as good as they come.

I think (and hope) you're right.

I decided everyone needn't hear all the details.... wait until the story ended.

However, since other Crew members are/were making prop decisions, I felt I had to at least post my technical results. My performance tests may help others with their decisions. If they are diehard boarders with mega weight and lower hp, then then the 11.5" may be right for them. However, for folks with the lighter hulls (Response and Sportsters), and especially with the high torque/lower revving 310 carb (4800 rpm redline), then the 12" is quite likely the better choice.

(Again, when I was doing my homework, I was advised by a technician at ACME that the 310 carb has MORE torque than the lower model EFI's. The lower EFI's show more "HP" partly because they are set up to rev higher. In fact, a 320 EFI at 5200 RPM has less torque than a 310 carb at 4800 rpm. It's all in the math formula. The ACME guy explained that when malibu started shipping the early EFI's, they asked ACME to supply flatter pitched props.... to match the lower torque.)

Re the shipment error. They initially offered to replace it right away.... apologized for the mis-shipment..... but I hate the hassle of X-border shopping.... and the time delay. Since I had it, might as well try it out.

As stated, simply not a good fit for me or my boat.

So.... it's time to start over again. I suspect 2 weeks for them to get this prop back, then 2 weeks for me to get the new one. I also always get nervous about damage in transit.... then figuring out WHO to deal with. US postal Service will point at Canada Post, and vice versa. I hope to talk to them on Monday and at least get the process started.

For some good news: I love the prop kit I bought. The padded case holds my prop, and the removal tool works like a charm!

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edwin

Best of luck Doug. I'd ask them to ship the 13x12 asap rather than wait for the 11.5 you have now to arrive in FL.

Best of luck...

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doughickey
Best of luck Doug.  I'd ask them to ship the 13x12 asap rather than wait for the 11.5 you have now to arrive in FL. 

Best of luck...

Good plan. I'll ask Max.

Thanks.

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Lakenut

Does anyone know if the guys at Malibu or Indmar figure in the drag that the wedge creates when figuring WOT? You can't use the wedge above 25 mph or so. It adds a lot of drag and has to drop RPMS. In my boat I run around 4800 rpms with a medium loaded boat. ( 2-3 adults and 1/2 tank of gas) Fill the gas tank and add 2-3 more people and I am probably running right above the bottom of my RPM range (4600) Now slow down to wakeboarding speed and put the wedge down and fill the ski locker ballast and theoretically I am below my rpm range by a few 100 rpms thus working the engine harder than it should at wakeboarding speed.

Does anyone know what kind of RPM drop there is between a wedged boat vs. non-wedged boat at say 20 mph?

This is driving me crazy as I am looking at new props. My prop (CVP) does fine at skiing speeds but I am concerened that I am bogging down the engine a bit at wakeboarding speeds. Work has been too busy lately and the wind is blowing like crazy on the weekends so I havent been out in the past 2 weeks to find out.

Thanks

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Lakenut

Got out for a couple of hours before the wind picked up. Here are my findings with my 01 SLXi w/ monsoon II and CVP 13X13:

3/4 tank of gas 400 lbs people no wedge no ballast 20 mph=2150rpms

" " wedge ski locker MLS 20 mph =2300rpms

Wedge and ballast requires the boat to turn an extra 150 rpms to reach a given wakeboarding speed thus making the boat work harder.

Here is my theory. Someone please pick this apart: If I am getting 4800 WOT and go to wakeboard speed and configuration and loose 150 rpms that would be an est. equivalent of 4650 rpms WOT. Is this bogging down the engine too much? If I add any weight I would likely be below my WOT range.

Edwin stats have him turning around 4950 WOT. Given my theory, his est. equivalent RPM (assuming wedge+ ballast = 150 less rpm) would be around 4800 RPMs. At lower speeds his boat would be working less hard to maintain a given speed. Right?

This is all getting confusing and I need to get a new prop this week. I have a small crack on the leading edge of my cvp and am afraid it is on the verge of self distruction. I am really on the fence between the 11.5 OJ and 12.

Edited by Lakenut

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doughickey

Based on everything you've described.... I think the 11.5" is better for you. (This is all based on my experience with my own 13 X 13 CVP, and the 13" X 11.5" OJ.... which has been sent back for a replacement with a 12" pitch)

Here's why:

Your motor has a redline of 5200 rpm (I believe).... but you're not getting there. (You say WOT is at 4800 rpm) That says you need something that is "effectively" a flatter picth than your current 13 X 13 CVP.

Although your motor has a rated HP of 320 or 325 or 330 or so (assuming EFI Monsoon), it's currently not able to get enough revs to put out that HP.

Although the Skier-to-Skier website says the 13" X 11.5" prop is equivalent to your current 13 X 13 because it has more surface area... therefore more efficient, I think the 11.5" will still bump your revs up a bit. This is GOOD in your case. But still well within your 5200 redline limit.... and also able to take advantage of the higher HP that gets put out at the higher revs.

Yes it's true, there is more surface area (see the digital shot below of the OJ XMP 13 X 11.5 vs my 13 X 13 CVP).

You have "motor turning room" left to run a flatter pitch prop. I think the 13 X 12" OJ will likely be more prop than your motor and application plan can handle well.

NET: I think if your choice is between the OJ 12" and 11.5".... it should be the 11.5".

My guess based on my own tests.... but on a different application.

Good luck.

(Also, I love the prop kit that Skier-to-Skier sold. Includes the padded prop case.)

Edited by doughickey

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doughickey

Prop Case, with slots for wrench, prop tool, extra nut, cotter pin. Although I would have liked a bit more padding around all sides of the blades, it's still a good way to carry/store your spare prop.

By the way..... do you notice any "prop burns" on the blades of your CVP. (See the rough spots near the outer edges of my blades in the previous image on the right.?)

Edited by doughickey

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