New Prop for 2008 RLXI Altitude at 4500

[masachan]

Hey guys,

 

Last weekend at Powell my brother bumped a rock and bent up the prop on my 08 RXLI. He is going to buy me a new one. I have not removed the old prop to check the model yet but in the meantime I would like to hear what others are using at this altitude. Motor is the Monsoon.

 

The previous prop lacked some holeshot but topspeed was 44-45. I could not max out my RPMs at WOT so I would like to get a bit more bite on my next prop. WOT RPMs about 4850.

 

Thanks for your help.

[thager]

Wouldn't less bite get the rpms up closer to WOT? Call your prop makers. They have dealt with this before.

[masachan]

Thanks guys. I called Acme and both my boat and Scot's have the 515 13 x 12. They told me to go to a 525 prop which will add 150 RPMs on top speed and give a bit better holeshot. And Thager you are right less bite will bet the rpms up. However, there is a deal on a Acme 911 here http://store.centurionboats.com/accessories/props/acme-911-prop.html for $250 and this prop would give a ridiculous holeshot but I may sacrifice some top. I just wonder if it will mess up the wakes. Just thinking out loud...

[Wayne]

I have a 525 (13 x 11.5) on my 2009. I am at a much lower altitude than you (Michigan) so I am not sure my input would still be valid but I have skied behind boats with both. I think malibu switched from a 13 x 12 (not sure which one) to the 525 in 2009. The cup must be a bit different because performance seems and feels pretty similar at sea level between the two.

[masachan]

Scot,

 

This is Darin. I know the 525 will give me a bit more but I feel this boat needs a good bit more. It doesn't pull nearly as strong as my previous boat. I know this RXLI is larger but typically Malibus have great holeshot and this boat seems a bit flat. The prop you and i have on our boat is the sea-level prop from Acme. As Wayne stated above they even changed the Malibu-supplied prop to the 525 and he is at sea-level. I have driven the RLXi at sea level and here at our altitude and there is a substantial difference in performance that I feel I can regain (a little bit) with a prop change. That is the reason why I was looking at the Acme 911 prop. I want my ski-boat to drive like a ski boat.

[Brian_M]

This question may temporarily derail this thread but I'm curious, how does altitude affect prop performance?

[eyepeeler]

Engine horsepower is rated at sea level. The engine loses about 10 HP for every 1000 feet of elevation. The OP skis at 4500 feet above sea level, so he has lost about 45 HP. He wants more power prop to compensate for the HP loss.

[DW]

You could add cup to the 911 your looking at to gain some top end.