Challenger 4tec Upgrade

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dcia3231 said:
Cant wait. Boat looks like it has plenty of power now. Looked like it was going pretty quick at half throttle.
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Ya, it takes very little throttle to get it up to speed and on plane. I think it cavitates during the whole rpm band. Anyone know if aftermarket carbon seals are as good as oe?
 
sounds like it might get good fuel economy then. Someone else needs to chime in on this. Personally i have ordered aftermarket and oe but as you know...i never keep my boats/skis more than a year or 2 so i doubt i put enough hours on mine to know.
 
If after sealing it up, etc you still have cavitation, I wonder if you might be able to update (down-date? downgrade?) to the seal/bearing carrier for better seal.This seems like phase 2 or 3 in grand scheme of things, but something to consider when it comes up. looks like TONS of power, perhaps a more aggressive impeller pitch might also help gain even more top end doesn't look like you are needing any bottom end power (next year or two)...Video was awesome! Enjoy the fruits of your labor!
 
ialonso said:
If after sealing it up, etc you still have cavitation, I wonder if you might be able to update (down-date? downgrade?) to the seal/bearing carrier for better seal.This seems like phase 2 or 3 in grand scheme of things, but something to consider when it comes up. looks like TONS of power, perhaps a more aggressive impeller pitch might also help gain even more top end doesn't look like you are needing any bottom end power (next year or two)...Video was awesome! Enjoy the fruits of your labor!
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Lol I don't want any more top end, this thing gets scary fast. Maybe I'm just new to it and not used to it, but I think 50mph is fine for this hull. I'm afraid to break it lol. I do want more holeshot. My gel coat dye should come in tonight, so maybe I'll paint that ride plate and seal it up properly. That might be where it's coming from, as the carbon seal seemed okay. The little driveshaft hat had a few light scratches on it though. Very small, but that may be affecting it too.
 
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Awesome build!

Really makes me want to get mine done now, can't wait to get it in the water.

What hp engine is that?

Andy
 
Thanks, it's been quite a project. If ihad to do it over again, i would have designed some sort of way to flip the thing so as to better work on the bottom. Also, It's the 185 engine. Seems like enough for this hull
 
So my Gel-Coat dye finally came in. I had been planning to gel coat the bottom of the ride-plate and seal it up really well. I believe that's the source of at least some of my cavitation. The dye came in a small bottle and supposedly could turn a whole gallon of resin black. What they didn't say was to not mix too much of it into the resin. I only had white gel coat (do they make a clear?) and went to town. Well, the best I got was a dark grey. Okay, I'll settle for grey. I added about 50% extra hardner because I wasn't sure how it would harden with the dye. This morning, I found the shit still completely uncured, and about 10 bugs embedded in the goo.

Looks like today's lake trip (on the warmest day of the year thus far) is cancelled. I quickly mixed up some polyester resin with about 100% extra hardner and painted a layer over. Hopefully it'll at least harden the Sh!t underneath enough for me to get it the hell off. I bet I'll be completely redoing the entire ride plate before this is all said and done. :facepalm: Lesson here: Don't use resin dyes!
 
Resin dyes work fine but you have to use them with neutral gelcoat , it just like if you go to Lowes and have paint mixed up, they use a mixing base and add colorant to it to get the color you want. They don't grab a gallon of white and start tinting it. The reason for this is all you will get by mixing with white are pastel colors or grey. White is pigmented primarily with Titanium dioxide, a whole lot of it.

Here is my suggestion if you want it, follow the link below ang buy a quart of black tooling gelcoat, I know its tooling gelcoat which makes it a bit harder to sand but it's cheap and it works just fine, I have used it for many things besides molds with no issues.
If you still have some resin dye left and want to use it get the neutral gelcoat add the dye and mix it up, it will work just fine.

http://www.uscomposites.com/polyesters.html
 
I built a hot rodded Sportster 215 years ago, bigger charger, fuel, cooler, etc. Cavitation was obviously an issue. You have some options just by swapping out the steering nozzle and exit nozzle. Any idea whats on it now? 83mm or 87mm? Also, a lucky 13 pump cone with adjustable washers is a great tuning tool and obviously a more aggressive prop (3 blade skat)
 
MPower said:
I built a hot rodded Sportster 215 years ago, bigger charger, fuel, cooler, etc. Cavitation was obviously an issue. You have some options just by swapping out the steering nozzle and exit nozzle. Any idea whats on it now? 83mm or 87mm? Also, a lucky 13 pump cone with adjustable washers is a great tuning tool and obviously a more aggressive prop (3 blade skat)
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You're saying that I'm boiling the water at the trailing edge of the prop? Damn! I'm not sure that's it as I can hit max rpm even at full throttle. I think I'm cavitating the whole time. I want to eliminate the obvious culprits first, like new carbon seal and properly sealed ride plate. Damn that pump cone is expensive. Anodized aluminum my ass, it's made of platinum! I don't know the nozzle on it, I know that it's for an rxp. Also, I bet if I can find someone with a 3d printer, I could print up some variations on this cone
 
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MY WORK HAS A 3D printer!! but i dont know the stipulations on use. I know it was donated by lenovo and i happen to know the director of the program. = ) i was thinking about asking him to build my arm rests for the sk awhile back but i ended up creating them in fiberglass.

I do happen to like the idea of a larger nozzle. I wonder if the smaller nozzle isnt allow the water to escape fast enough?
 
Smaller nozzles are typically used for top speed at the sacrifice of low/mid end. Larger nozzle better for low/mid end at the sacrifice of top end.

What has been found with the adjustable pump cones is you can effectively run larger nozzles and tune the pump pressure with the cone to eliminate the top speed loss and in some cases improve top speed.

I haven't seen this tested on a boat though.
 
I'll second the US composite. I've spoken to them and they will tell you everything you need to know. Ninety that you bought white and not neutral. Good answers are a phone call away, I'll always lean on a pro for a new project.
 
racerxxx said:
I'll second the US composite. I've spoken to them and they will tell you everything you need to know. Ninety that you bought white and not neutral. Good answers are a phone call away, I'll always lean on a pro for a new project.
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Ya, I wish this thing stayed lost in the mail. I can't even get polyester to cure on top of this crap. What the hell do I do now... can't sand it off, it's still tacky, can't seem to put a crust on it....
 
Nice work on the video! I love the sound of that 3 cyl and the whine of the supercharger :D

In the past I have used acetone to remove unhardened resin, but not sure how well that would work in your case.
 
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