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advice on prop pitch


DIRTYORR4

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Hi, would like to know what pitch to use on my 94 echelon with 454 that will give me top speed and best performance.Current prop is 13/13, the guy i bought from said he put this on to wakeboard.I want it for barefooting and speed.Also whats the diff between 3 and 4 blade.Thanks

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Dirty,

I just went through this process and I have to tell you you are in for a nice surprise. When you get your new prop you will give that CVP a paperweight status. I have the same boat as you, except no big block, I do have the fuel injected scorpion however so we should be fairly similar.

I have been meaning to post my findings, but here they are in short.

I stuck with OJ, always liked them, and tried 2 props

#324 - 13 X 11 LC 1 1/8" 3-BLADE .090 CUP

#410 - 12.5 X 12 LC 1 1/8" 4-BLADE .090 CUP

I ended up with the 3 blade, they both were really nice on the low end, had similiar RPM ranges and speeds and each RPM interval I tested. However for me the 4 blade made the boat feel a little loose at WOT, which was about 48. That made me a little timid.

Since I see you are new to the site you can do a search and find a lot about the CVP props. There have been more than a few instances of them coming apart and the potential of a blade coming through the bottom of your boat is there.

Galaxy is 100% on the newer CNC props being totally differen't. you can't compare a 13X13 non CNC to a 13 13 CNC. For me the 13X11.5 CNC and 13 X 13 non CNC were comparable on the top speed range.

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As it is today, what's the rpms at WOT? speed?
Hi, approx.45mph.

RPM is the more important measurement. Generally prop to get near the top of your recommended RPM range.

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Acme #1595

Unfortunately the classic differences between a 3 and a 4 blade propeller have been totally blurred now that CNC NiBrAl props are on the scene. Blade shape, cup shape, 'peak' location, and the ability to machine a 3 blade propeller (such as the one I listed above) that has more surface area than the 4 blade of the same dimensions, has thrown those right out the window.

Thanks.

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Dirty,

I just went through this process and I have to tell you you are in for a nice surprise. When you get your new prop you will give that CVP a paperweight status. I have the same boat as you, except no big block, I do have the fuel injected scorpion however so we should be fairly similar.

I have been meaning to post my findings, but here they are in short.

I stuck with OJ, always liked them, and tried 2 props

#324 - 13 X 11 LC 1 1/8" 3-BLADE .090 CUP

#410 - 12.5 X 12 LC 1 1/8" 4-BLADE .090 CUP

I ended up with the 3 blade, they both were really nice on the low end, had similiar RPM ranges and speeds and each RPM interval I tested. However for me the 4 blade made the boat feel a little loose at WOT, which was about 48. That made me a little timid.

Since I see you are new to the site you can do a search and find a lot about the CVP props. There have been more than a few instances of them coming apart and the potential of a blade coming through the bottom of your boat is there.

Galaxy is 100% on the newer CNC props being totally differen't. you can't compare a 13X13 non CNC to a 13 13 CNC. For me the 13X11.5 CNC and 13 X 13 non CNC were comparable on the top speed range.

Thank-you and every one else for taking time to help educate me on best prop for my boat.Someone locally told me 13/15 3 blade was factory prop and that would increase top end, but if i went to 4 blade it would be much smoother. From the info you have provided higher pitch does not seem to relate to more mph and i also need to consider cup.Thanks again.P.S.what is cvp/cnc?

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Yes, cup plays a huge role in performance. I am searching for the correct prop for my boat, 98 Echelon with Monsoon. I've had the original 13x13 CVP 3 blade stainless on since day one and it has never been damaged, but all the reports of a blade separating and causing hull damage convinced me it was time for a new prop.

I've tried only the 3 blade OJ XMP and used perfectpass tach numbers and speed numbers...not gps...but it was on a small private lake so I was looking for number differences knowing the actuals numbers might be off. Long story short, I tried the 13x12 with .090 cup, 13x12 with "less cup"...unknown exact measurment, and 13x11.5 with .090 cup.

The 13x12 with less cup and 13x11.5 with .090 cup performed the same, which for me was an increase of about 300 rpms and drop in top speed of 2 mph over the 13x12 with .090 cup. Also had an increase of 300 rpms at 34 and 36 mph.

The 13x12 with .090 cup dropped nearly 2 mph and 200 rpms over the CVP, but perfectpass baselines were within 15 rpms at 34 and 36. However, I was seeing a consitent difference of about .3 seconds quicker in acceleration test from one ball to five ball with the OJ...pretty significant for such a short distance I thought.

After talking with Eric at OJ, the correct prop for my boat will probably be the 13x12 with slightly less cup than .090, so I can get the 200 rpms back without losing top speed. Yes, top speed is somewhat important to me as I also barefoot longline and and weigh 240lbs.

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what is cvp/cnc?

CVP = Central (?) Valley Propeller

CNC = computer numerically controlled (prop is cut with a machine, consistent results every time)

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I would simple give the guys at ACME a call, tell them what you want...as you can imagine they've forgotten more about props then we will ever know. They will have the ideal prop for your setup. You will be amazed at the performance difference, its like driving a totally different (better) boat.

-Chris

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