ACME 13x12 vs. OJ XMP 13x12

[martho]

ACME was better in this test case. The RLXi jumped out much faster with the ACME. The OJ bites harder and you can tell the engine is having problems spinning it as the RPMs dont come up as quickly.

[Addictedto6]

Ah...so much information, now I'm completely confused. I was settling in on the OJ 13x12 for my SLXI. But after hearing about doug & mike's experience, and this latest test, now I'm not to sure.....

maybe it would be easier to just save my coin for now and keep close tabs on my CVP SS prop...

Edited June 6, 2005 by Addictedto6

[CarveItUp]

I know what you mean...analysis paralysis

I emailed Max a while back and pretty much settled on the 13 x 11.5 XMP for our '00 SLXi (Monsoon 2). We don't barefoot and most of our boating is at 3500' elevation so I don't want to bog the engine down with the bigger prop.

After the latest round of tests I'm starting to consider the ACME again for the same reason.

Will it never end!?!?!?!?

[martho]

Ah...so much information,

That is all it is, information. There is no way to do controlled testing with all the variables. We have different water temps, different boats, different engines, different weights, different winds and different uses. Not to mention, that engines can vary 10% in performance.

The numbers Oz, Edwin and I have been putting up are for information only. They are as accurate as we can get them, however it is really hard to keep things constant. Each boat is going to perform a bit differently than the next.

I have said this before and I am gonna say it again. The XMP seems the way to go if you are not footing as it has less RPMs in the slalom range. If you are footing, it appears ACME performs better due to its ease of turning.

[Addictedto6]

Ah...so much information,

The XMP seems the way to go if you are not footing as it has less RPMs in the slalom range. If you are footing, it appears ACME performs better due to its ease of turning.

<{POST_SNAPBACK}>

my personal mix is 90% slalom, 10% footin short line off the boom. seems like the acme would be right route...

[martho]

What speed do you like to 5' foot?

[Addictedto6]

What speed do you like to 5' foot?

<{POST_SNAPBACK}>

around 42 when I'm on one foot

[doughickey]

Quick update re swapping the 11.5" for the 12" pitch:

Skier-to-Skier just sent me an email saying the 12" was being sent out today. As soon as I receive and test, I'll advise my results.

Yes.... so much "data". Hard to come to a solid conclusion. Prop selection is always a comprimise anyway.

However, one point for those with the lower revving 310 carb (redline supposedly 4800 rpm): This motor still pumps out 310 solid HP, and at a lower rpm (not 5200 like the EFI's).... so if all other things are equal (they never are...) then we may have the torque to handle the 12" pitch on our lighter hulls. (The Sportster is 2200 pounds... the older RLX's are 2450 pounds.) Also, if we assume we shouldn't be running our motors past 4800 rpm, there's another reason to prop "up" to the slower spinning 12".

Theory anyway.

We'll see.

Edited June 6, 2005 by doughickey

[jgouveia3]

i'm in the same boat (sorry, no i'm not), as the rest. here are some numbers with my CVP SS 13 x13, '00 rlx monsoon II (gps mph readings, Malibu Tach and PP external display tach):

32 MPH 3000 rpms

40.8 MPH 4000 rpms

47.3 MPH 5060 rpms WOT

my numbers are similar to doug's, except the 40.8 mph figure is weird.

I too am checking the CVP weekly, and trying to decide which prop/size to go with.

[CarveItUp]

I'm getting ready to order a new prop to replace our 13 x 13 CVP stainless and (as previously mentioned) have been leaning toward the 13 x 11.5. BUT, I need some help from the prop gurus with a few questions that have been nagging me.

Living in Bend, we are typically boating at 3,000' - 4,000' elevation. My understanding is that this will cut down on our top-end RPMs. This seems to be born out in some casual (non-scientific) observations on recent trips. With two adults and one child, full tank and typical loads we make 4600 - 4700 RPMs with the Monsoon 325 in our SLXi. The speedo on PerfectPass indicates around 42 - 43 MPH but this is not callibrated with GPS.

I hit these RPMs at what I perceive to be about 3/4 throttle. Pushing to WOT has no effect on RPM (or speed).

I'm not sure what this means. Could it be that the throttle arm has more "range of motion" than the throttle arm? In other words, the throttle is already effectively wide open at the engine before the throttle arm reaches the stop? Or does it indicate some mis-match in the propping?

My instinct, for the higher elevation, is to prop down (11.5 instead of 12) to lessen load on the engine. Is that on the right track? It seems like I'm going to want a prop that's a bit easier to turn, but I could be wrong.

Along those lines, it seems like we might be well-served to go with the ACME 13 x 11.5 based on comments about it being easier to turn than the XMP.

I appreciate any insight people can offer on this!

Thanks,

Mike

[WakeGirl]

I'm getting ready to order a new prop to replace our 13 x 13 CVP stainless and (as previously mentioned) have been leaning toward the 13 x 11.5. BUT, I need some help from the prop gurus with a few questions that have been nagging me.

Living in Bend, we are typically boating at 3,000' - 4,000' elevation. My understanding is that this will cut down on our top-end RPMs. This seems to be born out in some casual (non-scientific) observations on recent trips. With two adults and one child, full tank and typical loads we make 4600 - 4700 RPMs with the Monsoon 325 in our SLXi. The speedo on PerfectPass indicates around 42 - 43 MPH but this is not callibrated with GPS.

I hit these RPMs at what I perceive to be about 3/4 throttle. Pushing to WOT has no effect on RPM (or speed).

I'm not sure what this means. Could it be that the throttle arm has more "range of motion" than the throttle arm? In other words, the throttle is already effectively wide open at the engine before the throttle arm reaches the stop? Or does it indicate some mis-match in the propping?

My instinct, for the higher elevation, is to prop down (11.5 instead of 12) to lessen load on the engine. Is that on the right track? It seems like I'm going to want a prop that's a bit easier to turn, but I could be wrong.

Along those lines, it seems like we might be well-served to go with the ACME 13 x 11.5 based on comments about it being easier to turn than the XMP.

I appreciate any insight people can offer on this!

Thanks,

Mike

It means that you're over-propped, IOW, the prop you're running is a bit large for the conditions at hand. With the Monsoon, I'd suggest (based on my own experience & what the others are saying here) that a 12" should put you right where you want to be. For every 1/2" that you move down in pitch size, you'll gain about 150-200 rpms at WOT, so a 12" should put you right about where the rev limiter is on the Monsoon. It will be a little small when you go to the lower lakes like Shasta & Oroville, but it won't be too bad - an 11.5" will probably not be quite as good all around. Now whether that's an Acme or OJ, that's your choice, but based on martho's findings I'd lean toward the Acme.

[CarveItUp]

Thanks for the information about RPMs per 1/2" drop in pitch. I was at a loss to estimate how much I'd pick up dropping to the 11.5.

So, if I understand correctly, the 13 x 12 (probably ACME as the OJ may have too good a bite) would pick up 300 - 400 RPMs at our altitude and probably a bit more than that at Shasta or Oroville. So, I might max out the RPMs at lower altitude but won't be bogging things down too much up here.

Sounds like a good compromise...

[WakeGirl]

Thanks for the information about RPMs per 1/2" drop in pitch. I was at a loss to estimate how much I'd pick up dropping to the 11.5.

So, if I understand correctly, the 13 x 12 (probably ACME as the OJ may have too good a bite) would pick up 300 - 400 RPMs at our altitude and probably a bit more than that at Shasta or Oroville. So, I might max out the RPMs at lower altitude but won't be bogging things down too much up here.

Sounds like a good compromise...

Exactly. FWIW, I got that info from Jim @ Acme Marine, & it held true when we changed props.

[Tom Sawyer]

Guys,

I've been thinking real hard about the ssp. Problem is..my top end right now with my cvp 13x13 is about 45 at wot 4900 rpms. That puts me around 43-44 4600 rpms with a footer in tow. I'm afraid the ssp will leave me with a top end of only 41-42 mph which is unacceptable.

I really would prefer to go stainless which, if I understand correctly, I can't do with acme or the xmp.

Looks like the acme is going to be my best bet. Do you guys think I'll be able to maintain top end with ssp and the acme? 2001 Rlx 325 monsoon diamond hull.

[WakeGirl]

Do you have anywhere local that you can demo a prop from? My gut says that an Acme 515 (13x12) should be about right, but comparisons against the CVP are difficult at best.

[CarveItUp]

I ended up going with a 13 x 11.5 (the 525) recently for our '00 SLXi with the 325 but I don't barefoot. I think the 13 x 12 might be right for your application

We were getting 4600-4700 RPM and about 42 MPH (per the factory and PP speedos) with the CVP 13 x 13. With the 525 we are able to hit 5000 - 5100 RPM and 44 MPH. We boat almost exclusively at moderate altitude (3000 - 5000 foot elevation).

I was looking for a prop that would give better hole shot, stronger hold at wakeboard and slalom speeds, and better use of the engine's power curve. I'm happy with it so far, although it's taken a bit of adjustment to pull people without popping their arms off (See this In The Bleachers comic for more info!).

I think I would have gone with the 515 if we were at lower elevation or I needed more top-end speed.

Hope this helps,

Mike

PS - From what I've heard ACME and OJ XMP are both great props. I ended up buying the ACME because I had a bunch of points at Wakeside that brought the cost down below the OJ and because they could get the prop to me in a day since we live close by...

[BarefootOz]

Kikngls,

I agree with Wakegirl, the 515 is your best bet for what you are trying to achieve, I believe this by all the tests Martho and I have done. Also in my own personal opinion the lost of top end speed is well worth the quality of wake you're going to have with the SSP plate installed. I believe you are going to be able to pull a barefooter at 45 MPH having the plate set at Ron's specifications 3/32" I have a '97 RLX with a 320 Monsoon non-D hull, ACME 449 and got the plate cranked down almost 1/8" and still can pull a 215# barefooter at 45 MPH, last week on a calm day with a glass lake the boat WOT with no skier did 47 MPH GPS clocked by a Martho.

My advice to you is to get the plate!...

[BillFooter]

Guys,

I've been thinking real hard about the ssp.  Problem is..my top end right now with my cvp 13x13 is about 45 at wot 4900 rpms.  That puts me around 43-44 4600 rpms with a footer in tow.  I'm afraid the ssp will leave me with a top end of only 41-42 mph which is unacceptable. 

I really would prefer to go stainless which, if I understand correctly, I can't do with acme or the xmp. 

Looks like the acme is going to be my best bet.  Do you guys think I'll be able to maintain top end with ssp and the acme?  2001 Rlx 325 monsoon diamond hull.

<{POST_SNAPBACK}>

I lose 2-3 mph with the SSP. The more bend you adjust into the plate, the more speed you lose. It cut my top end from 49.8 down to 46.6 measured with a GPS. I think you will get the most top end speed with your CVP 13x13. I replaced mine with an OJ 13x13 stainless three blade. It is about 1 1/2-2 mph slower than the CVP was.

Bill

[Lakenut]

I recently went from the CVP 13x13 to the 13X11.5 oj and really like it. The rooster tail at 30 + mph has all but disappeared. I haven't had the chance to slalom much until today since the prop change. With the cvp it felt like hitting a speed bump. You really noticed it. Now it is gone.

Just something else to consider.

[edwin]

hey there 'nut...glad the OJ worked out for ya.

[doughickey]

It's been about 6 weeks since I last posted anything. I've been at a summer place where internet access is almost impossible. So, bad news is no Crew interchange. Good news is lots of time behind the boat.

I'm so glad I swapped my old 13X13 CVP for the new OJ 13 X 12. Rock solid and so smooth. What wake? What prop wash? Love it.

[Slurpee]

I think a new prop is in the works for us to. I just crawled under my bu to inspect it and took note of the prop. It's a 14x18 4 blade. Great top end, but decidedly non-linear out of the hole. It's actually kind of tricky to get up on a slalom with only finesse and there is a lot of spray. I'll probably get a Acme 537 on the reccomendation of Bill from Acme.

[NorCaliBu]

Ordered my 13x12 OJ XMP 3-blade today. It will be replacing the 13x14 OJ Legend 4-blade that came on my Sporty. I'll let you know how they compare.

[VinRLX]

You're gonna rip your arms out.

[edwin]

Ordered my 13x12 OJ XMP 3-blade today.  It will be replacing the 13x14 OJ Legend 4-blade that came on my Sporty.  I'll let you know how they compare.

<{POST_SNAPBACK}>

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