Challenger 4tec Upgrade

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IDoSeaDoo

IDoSeaDoo

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Well everyone, I've finally begun repowering my Challenger. The donor is this 03 GTX S/C, and the recipient is this 97 Challenger 110. I've blown my last 787 in this baby, and will either repower it with a real engine or just get rid of it altogether. I absolutely love this boat and for financial and aesthetic reasons refuse to get the newer 15' boats. So here we go.

20140318_185056.jpg

So far, I've pulled the old motor and cleaned up the engine bay of all the grease and grime that built up over the 100 or so hours that I used it last season. That Amzoil is some sticky stuff! I measured the space between the thru-hull fitting and the tip of the fuel tank and it seems that I have 26" of room. Measuring the 4tec, it also appears about 26" from the rubber driveshaft cover near the PTO to the tip of that electrical connector on the cooling assembly. I measured the intake channels on the bottom and they both measure 5", so no problems there. I'll just have to widen the 140mm outlet to 155mm to accommodate the new pump. Might even get to keep the weedless system :) I wish the new skis came with a way to adjust trim as I'm pretty sure this boat is going to porpoise a lot when I'm done.

Before I pull apart the GTX for the rebuild, I want to make sure it's running tip-top. It's got 200hrs on it, but seems to have been well maintained by pro-shops. It runs smooth and strong, but used to cavitate badly. The old wear ring had deep grooves in it and two of the trailing edges were bent, one badly. I got a new SBT wear ring, and sharpened the leading edges on the impeller. I noticed that the wear ring wasn't quite round, and that at one spot it was out of spec. I decided to try it anyway, but saw that I lost 5mph. RPMs were 7600, but I was only doing 54 max. Unacceptable, with the bad ring, it did 58. I put an SBT reman impeller on there and will try again, but I'll probably end up shipping that wear ring back to them with the core impeller. I'm really curious to see what this ski will do with a perfect pump.
 
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Well, made some progress yesterday. Despite it being 45 out, I tested the new prop on the donor ski. With the new prop and defective wear ring, I managed 58 on the GPS. Good but not great, it def. had some cavitation off the line. If I floor it from idle, the rpms peak and stutter before it hits top speed. I'm thinking they put too shallow of a pitch on this ski as well. Should be just right for the boat :) I'm sending the core prop and defective wear ring back to SBT. I took a bunch of pics of the wear ring measurements and proved that it was the ring and not the pump. Cesar, their customer service manager is a pleasure to deal with and has been very receptive.

Anyway, I can't wait any longer, so I started to tear into the GTX. Pulled apart the fuel system, cooling lines, wiring harness, intake mani and J-pipe. Most of the motor is exposed. Today I have a few buddies coming over to help me with it. I'm going to pull the 4tec and dangle it in the Challenger hull. I THINK I have just enough room. The fuel tank in the Challenger MAY have to get adapted to give me that last inch that I need. I may have to shave off that protrusion where the baffle comes in. If only it wasn't centered... If I do need to do this, does anyone have any hints on how to weld plastic?

I pulled the VC on the 4tec and checked the valve part numbers. They're the time-bomb 72's :( Last night I ordered a whole set of Supertech's. The S/C had very little play in the compressor wheel. I felt that if I were to really push, I could make it slip the clutch washers, but it felt right. I didn't suspect them anyway, as this machine pulls strong and feels right (except the cavitation).

It appears that the motor mount configuration is similar to the 787 (two in the rear and one up front), so that's good. What does worry me is the ride plate: It's a crucial part of this system and is much longer than the one on the boat. I may have to build some sort of support to brace it once it sticks past the boat's hull. I'll also have to ream out the existing thru-hull fitting and put in the wider 4tec one and glass it in. I have an alignment tool, so i'll be sure to get it just right. The only pic I have is dark and is of a half taken apart GTX. Nothin' exciting ;) More tomorrow!
 
Can anyone tell me why Seadoo used a different exhaust water box on the challenger vs the skies?

Likewise, does anyone know why the GTX has two water boxes but only one outlet? With this setup, you'd think it would be quiet, but I found that it has a super awesome (and loud) exhaust note :D Anyway, I'd rather it be more silent in the boat, but I don't want to stifle the power. If I could get away with one water box, I'd rather do it. Save on weight/complexity...
 
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One is the waterbox that the J pipe attaches to and the other is the resonator, then the exhaust outlet. I would remove the resonator and run the waterbox strait out ;)
 
What would the advantages of that be? I assume it'd be louder? Can I run just the resonator (if it's easier to plumb in)? The ski seems plenty fast as is, spools right up to redline when I punch it, and runs right at red-line too. This might be due to cavitation though. Too bad we won't know as the next time this thing runs, it'll most likely be in the boat.
 
No you need the waterbox. Yes it will be louder but once your past 20 mph you cant hear anything anyways so sound doesn't matter IMO. Does the gtx have a plastic pump? Being s/c make sure you use a metal pump if you don't have one already and a good wear ring on the install.
 
Already been upgraded to aluminum pump. Waiting for new wear ring, as SBT sent me one that was out of round. I'm working w/ their customer support guy, so good so far. Hope the next one is better.
 
The Big Hurdle

Well, if anything, this might stop this project before it really even began. I finished pulling the engine out of the ski.

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Check out my engine puller contraption :) It's a 600lb boat winch VERY SECURELY bolted to the wall. A pulley attached to an engineered beam going down to a hook. Works GREAT for all seadoo purposes :thumbsup:

I spilled that green antifreeze all over the already nasty GTX. Looks like this is the first time this engine has come out. Everything was nice and rusted ESPECIALLY thhe driveshaft. It never did separate from the seal hat. Looks like a new shaft is in my future as well...

Next I cleared out the hoses and whatever else I could in the Challenger to dangle the engine in there.
 
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Challenger hull.jpg

There it is all clean and ready to accept new life. I didn't remove everything in case I decide to abort this mission or decide not to go through with it.

Dangle.jpg

There's the 4tec going in to check initial fitment.

it doesn't fit.jpg

Aaaaand it's in. Well, the engine just about fits in lengthwise but here's the problem: it doesn't fit height-wise. Turns out the 4tec is lot bulkier and the bottom portion of the engine needs a deeper hull or a higher thru-hull fitting. I'm about 2" too low. Also, there doesn't appear any room for the exhaust components. The Challenger hull ends pretty abruptly past the thru-hull fitting whereas the GTX has these deep caves for the exhaust pipes to sit in.

So now I must ponder and decide what to do next. I REALLY wanted this boat to have smooth, reliable 4tec power, but it may prove impossible. I'm considering cutting the lower half of the GTX hull and mating it with the boat, that way everything would have a place. However, that would elongate the boat just to about where the swim platform ends (If I include the front mount stand, it puts it PAST the platform). Not sure how that would look. Also, not sure if it would hold. I would probably have to sand the fiberglass back 6" back on each side of the seam and lay new glass over it, then sand flat again. Not something I'm afraid to do, just wonder if it'll be strong enough.

I could also try to glass in just the GTX tunnel (the part that contains the thru hull fitting. But then there's the heat exchanger ride-plate to worry about. That thing goes all the way to the end of the GTX hull. I wonder if I can relocate it somehow. Anyway, I was pretty tired and mentally exhausted from worrying about my family in Ukraine. My problems here pale in comparison to what those poor people are going through :( I'll have another look at it tonight and try to get some BETTER pictures. These smart phones take great photos if you are a statue, sorry for the blur.

Let me know your inputs on what you think is possible.

PS: a guy out there put a 4tec into an X4. FACT! I've seen this on facebook. I tried reaching out to him, but he never responded. It's also been done in a 99xp. If any of you have a way of contacting these people, I'd be forever grateful.
 
I'm not a 4-tec expert so this question might be better answered by someone who is. But I know in two strokes the 787 is installed at an angle to make a lower profile. I'm wondering if this could be done with a 4-tec, I know there will be a limit because of the oil sump pickup but I wonder how much. Just food for thought.

Lou
 
LouDoo said:
I'm not a 4-tec expert so this question might be better answered by someone who is. But I know in two strokes the 787 is installed at an angle to make a lower profile. I'm wondering if this could be done with a 4-tec, I know there will be a limit because of the oil sump pickup but I wonder how much. Just food for thought.

Lou
Click to expand...

Good idea lou! I'll be sure to note this when I rip this engine apart to rebuild. However, I don't think that would lower the rotating center of the motor. I'm not terribly worried about this though. If I have to modify the shelf that sits on top of the engine bay, so be it. I'd sacrifice some storage for all the benefits of an S/C 4tec. The problem is motor fitment. I'm gonna have to go boat-builder here. If anyone has any fiberglass fabrication experience, please speak up. I wonder if two hulls can be bonded strong enough to withstand this kind of punishment.
 
Brian J said:
Subscribed, cool project, thanks for posting.



What might stop the project?
Click to expand...
The fitment issue. I haven't given up this soon. This boat is relatively worthless, so IF I manage to sell it, it wouln't fetch much, even WITH a running engine. The only value it has is my affinity to it. Going to look further into it this evening. There is a boat just like this with trailer in Fayettville. Maybe I'll go buy it and use it as a practice hull...
 
Does anyone know where I can find a ruined 4tec hull cheap? I just need the bottom portion. It could have any sort of damage, literally. Even a fire. I need one to practice hacking up and get some ideas.

Here's a potential idea: cut the existing tunnel completely out, mount the engine, cut a section out of the driveshaft, mount the new tunnel with pump mounted to it and then just glass everything in, being careful to include the heat exchanger ride-plate. I'd have to replumb the mufflers, but that's another story. This way everything would be spaced out properly. Then I could shim the engine to align it properly.
 
I found a good cheap hull for $45, but was wondering if the 2002 GTX 4tec would fit all the same parts of the GTX S/C. This one is actually nicer than my current hull.
 
JUST HAD AN EPIPHANY! I've had this old ruined 96xp hull laying around, waiting to go to the dump... Well, the XP has the exact same hull configuration as the Challenger!! I can cut the top off of it and use it to do my mockup!! I'm SO glad I didn't junk it yet, it's been sitting on the trailer ready to go for the past two weeks :hurray:
 
You stated the it fits lengthwise, but the problem is height wise. Will the hatch lid close? If so, then maybe the answer is to just lose some storage space. Maybe create two smaller storage spaces on each side of the engine - Just a thought.
 
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I don't think grafting two hulls together is a good idea. I have concerns about the structural integrity and also about losing the dynamics of the boat, ie rideability.

Lou
 
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