Challenger 4tec Upgrade

[IDoSeaDoo]

What's the taper like on the steering nozzle? Do you have much cavitation when you floor it? You also probably have the larger 159mm impeller. Mine is the lowly 155. It is from before they upped it.

 

[beerdart]

Near zero cav off the line yes 159 just change your wear ring and go 159.

 

[IDoSeaDoo]

Near zero cav off the line yes 159 just change your wear ring and go 159.

Wish I could. I'd have to change the impeller, driveshaft and wear ring to go 159. Once I kill this impeller, I will. I actually got closer to this over the weekend. Took my boat down to Wilmington and rode all over the intercoastal. Even touched the atlantic for a few minutes, but I know this isn't an open ocean boat. Anyway, during low tide I ran up on a little sand bar and got something in my pump. It stayed in there for a bit, not allowing me to go past 3500. Once it passed, I realized I couldn't take the throttle much past half way or it would cavitate really bad. One glance at the front of the impeller told me that I killed the wear ring.

The prop has a few very light dings to the leading edge, but it's super minor. The wear ring looks like it chewed some shells, so it's going in the trash. Now that I think about it though, I think that may have been my problem all along. This is one of those cheap chinese knock-off rings and I don't think it was ever perfectly round. I do recall that it had areas of higher gap. I think it was all in spec, but could have been tighter in those areas.

I ordered a brand new Genuine seadoo ring. Should be in this week. Really curious if this doesn't solve my cavitation issues once and for all... Also wondering if I shouldn't change the pitch of my impeller while it's out. Right now it's 11/19 or maybe 11/20. What do you guys think the pitch should be on a 1400lb boat and 185hp?

 

[IDoSeaDoo]

Had some confusion with the new wear ring. Unlike the white derlin SBT ring I had in there before, this one would not slip right in after spending a night in the freezer. Also, it was a solid piece of blue plastic. At first, I got all mad thinking I got sold a cheap knock-off, but after lots of research, it turns out that Seadoo now makes them like that. I was still puzzled over why it didn't fit, and didn't know what ski my pump was off of. 2003 GTX had a plastic one, and mine was aluminum. Turns out, mine's from an 08 RXT, and is completely interchangeable with the 155 pumps. So I pounded the ring in with a rubber mallet and a board, and the tolerance is amazing. It's something like .10mm I also bored the steering nozzle another 1mm. Now the reduction/steering nozzle ratio is 84mm/89mm respectively.

Been 3 solid days of rain here. Soon as it lets up, I'm going to the lake to test

 

[IDoSeaDoo]

YESSS!!! The new wear ring did it! No cavitation!! The boat takes off much faster now, and has a lot more thrust in turns. Challenger 3.0! Moral of the story is: if you cheap out on a wear ring, you better return it if you don't have less than .14mm clearance (mine was .1mm) We had a blast sliding it around at full throttle with the trim up. Hardly slows down!

Now if I could only figure out why it's refracting water out of the steering nozzle. I'm starting to think there is no diameter I can bore this thing to to stop that...

 

[IDoSeaDoo]

It's been a while since I've posted here, but I'm still having the issue of water spraying back out of the steering nozzle. Beerdart said that his speedster nozzles are 84/86mm (venture/steering diameters) Mine is now 84/88mm. I wonder if the extra wide steering nozzle I now have is what's making the water refract. My theory is that the water has more room to expand after it exits the venture and hence shoots back out. What do you guys think?

 

[SteveDavisLP]

I finally got around to reading this entire thread.....your patience is incredible. I started off thinking this is a great idea and half way through I'm thinking he is nuts
I'm heading to Miami tomorrow for the weekend to take in the beach, listen to MNG and Big Rock and enjoy a private party. Hope you have a great weekend!

 

[IDoSeaDoo]

Thanks In this world, you sometimes have to be a little nuts. The concept worked beautifully, the boat's a blast! I'm just north of Miami. This boat already has a dozen hours clocked in and around Biscayne Bay/South Beach and intercoastal areas there. Fun as hell chasing those huge yachts throwing 8' wake I even made it down to Key Largo to do some snorkeling near the John Pennekamp Park. I don't that place has ever seen a boat like this there.