Change in RPMs after switching props

[kknudsen12]

I have a 96 RLX with a Monsoon 320 and just switched from the stock CVP stainless 13x13 to the Acme 515 13x12. I was running 5500 rpms and 46mph at WOT with the old prop. Now, we're getting the same top speed but at only 5000rpms. Is decreasing the rpms like this a problem? I thought I had heard that the boat should stay running at the max rpms at WOT (5600).

Edited May 9, 2011 by kknudsen12

[eyepeeler]

I thought that max rpms on the Monsoon was 5200.

[Molarbu]

The 96 may not have a the electronic controls the new ones do, but if I could keep the same top end with fewer rpms I'd be happy. It sounds like a great prop, you may want to try a 12 x 11.5 or 11 for more holeshot, but it sounds to me like you just got your money's worth on the upgrade to a CNC prop!

[Bozboat]

redline? I would be real nervous about running 5500 rpms

[kknudsen12]

Yep, my bad. I just looked at Indmar's manual and it looks like rpms are supposed to be 4600-5200, so the new prop is actually running right in there. I hope the stock prop didn't cause too much harm!

[Slayer]

I've been looking at the 525 or 515 for my 1997 SLX. It seems that my RPM is higher than what the manual states and it has the stainless CVP on it. I have only had it in the water twice since I bought it and this is going to be one of the first major changes I make.

[Molarbu]

I've been looking at the 525 or 515 for my 1997 SLX. It seems that my RPM is higher than what the manual states and it has the stainless CVP on it. I have only had it in the water twice since I bought it and this is going to be one of the first major changes I make.

You won't be disappointed!

[Slayer]

You won't be disappointed!

That's my understanding, now just need to decide which one. According to the guys at ACME, the 525 is likely the better option for me. I don't think that there will be much of a noticeable difference between the 515 and the 525 for me.

[Molarbu]

That's my understanding, now just need to decide which one. According to the guys at ACME, the 525 is likely the better option for me. I don't think that there will be much of a noticeable difference between the 515 and the 525 for me.

I tried both and didn't notice much difference at all. That being said, I like the 515 a little more, it just 'feels' better on my boat!

[Woodski]

You can run a pretty simple test to see why there is that much difference. Run the boat with each prop at a variety of speeds (28, 34, 36, 42, WOT) and compare the readings. If there is a much bigger change in rpm vs. speed at top speed, you probably were experiencing slippage or cavitation. If the differences are a little more for each speed increase it is a pitch difference. The 515 does sound more in the proper range for general application.