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Is 4tec exhaust water injected?
- Thread starter IDoSeaDoo
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red2blue
New Member
On my ski...'05 RXT...in a coupla places...
Hose comes around the motor...also hose goes into J-Pipe just before the waterbox.
Curious here...short of a water box mod....why are you "upgrading" the exhaust system?
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IDoSeaDoo
Well-Known Member
So the water is injected into the manifold AND J-pipe? I'm wondering because I'm putting a 4tec into a 1997 Challenger, replacing the 787. The exhaust will be a challenge. Normally, the J-pipe goes right into the waterbox, but my waterbox has no room right there and will have to be far to the left of the motor. I'll need to make the exhaust to make a sharp turn. I was thinking of rotating the J-pipe to aim at the water-box, but I feel like it HAS to be the high-point. I'm sure it curves up for a reason...
Sportster-2001-951C-Stock
Well-Known Member
Otherwise, the manifold would become red hot.
red2blue
New Member
w/o seeing what you're talkin about re the room you have, I can only make limited suggestions....
You can modify the waterbox...basically cut it in half and swap the inlet for the out....gives you more room for sc removal as well as more room behind. You can go with an aftermarket box....you could change the exhaust mani for a new model w/ no "J"...needed to the wb, just straight angled down to waterbox.
Aside....the 4-tec exhaust cooling lines come from the pump...you swapping that too right?
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IDoSeaDoo
Well-Known Member
My question was whether 4 tecs injected water into the exhaust stream itself. I know the mani and J-pipe are jacketed, but my problem is that I can't fit much of a water box where the J-pipe exits. The old Challenger Hull isn't configured to have a waterbox there. The fact that the J-pipe bends up leads me to believe they designed it that way for a good reason, like to prevent water from potentially coming up into the engine or some other reason I can't think of. I want my boat to be silent. I experimented having just one waterbox when I was testing my new heat exchanger, and found that having both cuts down on the drone significantly.
The problem is, if I turn the J-pipe to face where the waterbox will now sit, I lose that height it achieves as it bends up from the manifold. If I leave it the way it is, the exhaust hose may have a low point where water might collect and sit (like the goose-neck under your sink). Not sure if that's a big deal.
What about this: if I have the J-pipe mount normally, but weld a 90deg angle to divert the pipe to the side. Can that pipe come into the waterbox sideways, or does it have to come in from the top like it does by design?
If you guys want to check out my build, its located here:
http://www.seadooforum.com/showthread.php?69006-Challenger-4tec-Upgrade/
The problem is, if I turn the J-pipe to face where the waterbox will now sit, I lose that height it achieves as it bends up from the manifold. If I leave it the way it is, the exhaust hose may have a low point where water might collect and sit (like the goose-neck under your sink). Not sure if that's a big deal.
What about this: if I have the J-pipe mount normally, but weld a 90deg angle to divert the pipe to the side. Can that pipe come into the waterbox sideways, or does it have to come in from the top like it does by design?
If you guys want to check out my build, its located here:
http://www.seadooforum.com/showthread.php?69006-Challenger-4tec-Upgrade/
red2blue
New Member
Back in the day...Riva made an exhaust pipe....set for thru hull....lemme find a pic for you...
http://www.lbmotorsports.com/product/exhaust/riva-racing-rear-exhuast-for-seadoo-rxp--rxt
Somethin along this line may help you. You can find used ones for less than a $100.
http://www.lbmotorsports.com/product/exhaust/riva-racing-rear-exhuast-for-seadoo-rxp--rxt
Somethin along this line may help you. You can find used ones for less than a $100.
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Sportster-2001-951C-Stock
Well-Known Member
In 4 strokes water doesn't inject the same way as a 2-stroke would b/c in a 2-stroke the water volume is modulated to dynamically tune the expansion pipe sonic resonance for cylinder scavenging. Scavenging into a cone shaped expansion pipe works like a turbocharger in 2-stroke technology and this tuning is an art.
In any 4-stroke it's not critical except to remove heat, it's just dumping the water into the exhaust at a safe distance from the cylinders to keep the exhaust components from overheating. I dunno about any waterboxes, if the 4-tec has one I wouldn't know why but I'd try to keep it.
In any 4-stroke it's not critical except to remove heat, it's just dumping the water into the exhaust at a safe distance from the cylinders to keep the exhaust components from overheating. I dunno about any waterboxes, if the 4-tec has one I wouldn't know why but I'd try to keep it.
red2blue
New Member
Well...not much help for you but....I've tilted mine....a bit. I added an exhuast manifold spacer...called a torq plate...between my manifold and head. In order to use the stock J and wb I was forced to tilt them so that the top of the J would clear the inside of the hull.
Dunno why you shouldn't be able to do somethin.
aside....inside the J...where it enters the wb...there are three pisser holes that must be maintained and clear...otherwise exhaust temps over heat and bells go off.
Dunno why you shouldn't be able to do somethin.
aside....inside the J...where it enters the wb...there are three pisser holes that must be maintained and clear...otherwise exhaust temps over heat and bells go off.
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Sportster-2001-951C-Stock
Well-Known Member
Here's how I'm thinking you're going to plumb that cooling system, 1st diagram:
http://www.cpperformance.com/t-marine-closed-cooling-systems.aspx
Not sure how this is different from the seadoo factory plumbing but1st choice is duplication the factory setup as much as possible. I think this means you simply substitute the heat exchanger for the ride plate.
http://www.cpperformance.com/t-marine-closed-cooling-systems.aspx
Not sure how this is different from the seadoo factory plumbing but1st choice is duplication the factory setup as much as possible. I think this means you simply substitute the heat exchanger for the ride plate.
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Sportster-2001-951C-Stock
Well-Known Member
Two waterboxes????
I'm not convinced you should need a waterbox at all except as a muffler maybe or a place for exhaust gasses to be cooled (mercruisers don't have water boxes) but I'm pretty sure the exit of the waterbox is near the bottom so the box doesn't completely fill with water. If you tilt it, I'd guess the waterbox would tend to collect more water.
IDoSeaDoo
Well-Known Member
Sportster: Yea, that diagram is almost exactly how my cooling system will be, except the oil cooler will be on the coolant circuit and now raw water. I'm not planning to use the ride plate as a heat exchanger at the moment. I don't want to have pipes going in/out of the transom. Also, I had to build the ride plate up with fiberglass filler to give a V shape. Originally, it flared out into chines that didn't match the boat hull geometry. I feel that if I run hot coolant through that, the fiberglass will just fall off.
Red: I can imagine you had only a slight tilt to the wb, maybe 15deg max. I'd have to tilt almost 90. I'm not sure the baffle geometry would even work once water gets in the mix. Are there any other options for marine exhaust sound suppression? What about a stainless steel car muffler?
Red: I can imagine you had only a slight tilt to the wb, maybe 15deg max. I'd have to tilt almost 90. I'm not sure the baffle geometry would even work once water gets in the mix. Are there any other options for marine exhaust sound suppression? What about a stainless steel car muffler?
Sportster-2001-951C-Stock
Well-Known Member
A stainless car muffler can work fine, I've done that before with glasspacks the water goes through them just fine as it's being pushed through with the exhaust. Mine eventually rusted out though, it wasn't stainless inside. This was a muffler element inserted into a header collector and was an over the transom exhaust..
Sportster-2001-951C-Stock
Well-Known Member
The thing to avoid is allowing water to back up into the exhsuat manifold, it has to be all down hill so the water runs out into the lake else you get water backing up into the exhaust valves and milkshake in the crankcase.
Sportster-2001-951C-Stock
Well-Known Member
Looks like you even have the option of placing the cold side of the heat exchanger before or after the exhaust manifold (log) cooling jacket.
The big question in my mind is if the jet pump is going to provide enough water flow, it's only calibrated for cooling the exhaust manifold. So in this case I wonder if there's a flow restrictor in the jet pump or perhaps the exhaust manifold you can open up to get more flow if you need it.
The big question in my mind is if the jet pump is going to provide enough water flow, it's only calibrated for cooling the exhaust manifold. So in this case I wonder if there's a flow restrictor in the jet pump or perhaps the exhaust manifold you can open up to get more flow if you need it.
red2blue
New Member
Yes....it's been quite a while...gimme a few.
You adverse to a set of jacketed headers?
Okay...like I said..it's been a while. Here's a coupla examples of custom/ outside the box thinkin.
a lil more bling...
http://www.h2oxtremeworldwide.com/main/?wpsc-product=seadoo-header
okay....years ago...saw where a guy had used an ss muffler...glass pack lookin thing instead of a wb. Had it sent straight out the back of his ski...sounded nice( I know...you want quiet)...two things I remembered from the build. He used a down turning tip...so as to keep waves from flooding his system(dunno how it worked) and the fact that he used a small automotive muffler on his ski.
Been so long I can't find it in the archives.
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Sportster-2001-951C-Stock
Well-Known Member
BTW - I think you can install a drain tube in the bottom of your waterbox if it tends to overfill. As long as the waterbox isn't below water level you could run the drain out the transom. There has to be a high spot in the exhaust, that's currently that p-trap mounted on the exhaust manifold. Hopefully you can make the run all downhill from there.
Actually, a drain on the waterbox might even work if the box was below water level. As long as you're not getting water surge/backing up into the exhaust manifold (under any/all conditions such as a following sea while slowing or reversing, engine shutdowns, etc.) then you can do almost anything you want (including making tons of noise).
Actually, a drain on the waterbox might even work if the box was below water level. As long as you're not getting water surge/backing up into the exhaust manifold (under any/all conditions such as a following sea while slowing or reversing, engine shutdowns, etc.) then you can do almost anything you want (including making tons of noise).
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Sportster-2001-951C-Stock
Well-Known Member
Corsa makes all kinds of marine mufflers and silencer tips:
http://www.marinemanifold.com/partspages/corsa/Corsa8.htm
http://www.marinemanifold.com/partspages/corsa/Corsa8.htm
IDoSeaDoo
Well-Known Member
Wow, thanks guys, so many options... While I love the idea of jacketed headers, they are beautiful, but a bit too pricey. I'm afraid that's another constraint: my budget. It's probably the biggest reason I was trying to use the pipes I had from the donor ski. I'm going to do indoor stuff tonight as it's 5F outside. Going to wait till it's a bit more bearable in the garage and get some pics of what I'm dealing with. I think I should play around with various setups OUTSIDE the boat before settling on one. I want to try some glasspack type mufflers like you mentioned Sportster. See how loud they are. I bet tehre is one out there that's all stainless.
Sportster-2001-951C-Stock
Well-Known Member
I agree, you have many options for consideration.
I'm thinking more about that waterbox, I bet it's there to keep water from surging back into the exhaust manifold. The motor is set so deep in the bilge in these little boats, that WB configuration works pretty well to keep this from happening. I see this happen on mercruisers and volvos all the time, still can't figure out how people cause water to back up into them but it happens. Especially if the engine diesels a bit at shutdown and happens to turn backwards while it's jerking around this seems to happen, sucks water backward into a cylinder (not a problem with fuel injection).
Keeping water flowing in there to avoid the parts burning up and also configured so water doesn't back up into the manifold log are the most important considerations, exhaust valves can even shatter sometimes from cold water but usually the water just drips down the cylinder wall and contaminates the crankcase oil or causes hydrolocking (and even cylinder corrosion) The noise abatement has to be a lower priority once you get the water moving in the right direction. The waterbox takes care of most of this it seems like, so maybe you should invest the time to modify it to not change the function just the position.
I guess a muffler, if oriented in some way, can serve the function of the waterbox (keeping water from surging into the manifold log).
I'm thinking more about that waterbox, I bet it's there to keep water from surging back into the exhaust manifold. The motor is set so deep in the bilge in these little boats, that WB configuration works pretty well to keep this from happening. I see this happen on mercruisers and volvos all the time, still can't figure out how people cause water to back up into them but it happens. Especially if the engine diesels a bit at shutdown and happens to turn backwards while it's jerking around this seems to happen, sucks water backward into a cylinder (not a problem with fuel injection).
Keeping water flowing in there to avoid the parts burning up and also configured so water doesn't back up into the manifold log are the most important considerations, exhaust valves can even shatter sometimes from cold water but usually the water just drips down the cylinder wall and contaminates the crankcase oil or causes hydrolocking (and even cylinder corrosion) The noise abatement has to be a lower priority once you get the water moving in the right direction. The waterbox takes care of most of this it seems like, so maybe you should invest the time to modify it to not change the function just the position.
I guess a muffler, if oriented in some way, can serve the function of the waterbox (keeping water from surging into the manifold log).
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IDoSeaDoo
Well-Known Member
I think you're absolutely right Sportster. I did some digging on marine exhausts and companies that have been in the marine exhaust bussiness for a long time have several different types of mufflers for different engine configurations, mainly based on their position relative to the water line, and the type of engine. You're doubly correct in the fact that our motors sit pretty low. As the matter of fact, looking it, I'd guess the water line is right about at the head (when not on plane). It would be easy to imagine the water line coming higher than that if say a wave swamps the back, or I'm backing up in chop or any number of conditions.
Looking at the original exhaust system, we can note that the exhaust starts above the water line (WL), arcs high, then dips low (below the WL), then up, then down (2nd resonator), then up and down again (outlet). There are a series of times where the exhaust must come above the WL when not on plane. I believe this prevents the water from ever backing up into the head. So my idea to turn the JPipe and have it dump sideways into the waterboxes that are above the water line, then down to exit (slighly above WL) falls out. It would be too easy for water inside the waterbox to flow back into the engine. The exhaust must make that down and up motion. And I think it has to expand at the lowest point, hence the shape of the waterbox...
Centek makes the "Vernalift", a muffler designed to be partially below the WL.
http://inetmarine.com/centektypicalinstallationdiagrams.aspx
This would probably work well, but they say I need one with 3.5" inlet/outlet for the amount of power I'm pushing. Which in turn means I need a rather large muffler, which would probably also be difficult to mount and require further internal hull modification. Also, it retails for $500...
Looking at the original exhaust system, we can note that the exhaust starts above the water line (WL), arcs high, then dips low (below the WL), then up, then down (2nd resonator), then up and down again (outlet). There are a series of times where the exhaust must come above the WL when not on plane. I believe this prevents the water from ever backing up into the head. So my idea to turn the JPipe and have it dump sideways into the waterboxes that are above the water line, then down to exit (slighly above WL) falls out. It would be too easy for water inside the waterbox to flow back into the engine. The exhaust must make that down and up motion. And I think it has to expand at the lowest point, hence the shape of the waterbox...
Centek makes the "Vernalift", a muffler designed to be partially below the WL.
http://inetmarine.com/centektypicalinstallationdiagrams.aspx
This would probably work well, but they say I need one with 3.5" inlet/outlet for the amount of power I'm pushing. Which in turn means I need a rather large muffler, which would probably also be difficult to mount and require further internal hull modification. Also, it retails for $500...
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IDoSeaDoo
Well-Known Member
What if....
What if I attach a U joint to the bottom of the JPipe, and have it take the flow up, above the WL to a cylindrical style muffler, then have it dip back down to exit via the outlet. That way, if water were to come surge back in, it'd have to go up, expand in the muffler, fill that, go back down, and back up before it can go into the manifold?
With this setup, I think I'd have to keep the exhaust pipe at or below the highest point of the JPipe, but still above the WL (when not on plane).
What if I attach a U joint to the bottom of the JPipe, and have it take the flow up, above the WL to a cylindrical style muffler, then have it dip back down to exit via the outlet. That way, if water were to come surge back in, it'd have to go up, expand in the muffler, fill that, go back down, and back up before it can go into the manifold?
With this setup, I think I'd have to keep the exhaust pipe at or below the highest point of the JPipe, but still above the WL (when not on plane).
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