SX/SXi/SXi Pro 750 SXI exhaust question

Little_Franny

Little_Franny

Location
Cape May Court House, NJ
I bought a friends project ski and am finally getting around to finishing it up. He filled the exhaust tube to the rear and planned on running a front exhaust setup. I have some tubing that he welded together but can't say I am all that happy with how it looks.

It has a factory limited pipe, and he has a whole punch of tubes and plumbing. Can I just come out of the bottom of the expansion chamber (faces down), turn 90 degrees toward the left of the ski, then turn 90 degrees toward the rear of the ski and attach to an exhaust outlet? Or do I need to at some point in the plumbing go up and then back down to keep water from backflushing into the system?

I also thought I could come out of the expansion chamber and go towards the right side and then plumb up around the front of the fuel tank to get back to the left side.

If anyone has pics of similar setups they would be greatly appreciated.

Thanx
Jon
 
J

jetman624

Location
South OC, CA
That thing will be loud as F^CK if you don't go through a water box. Other skis get away with it because their water box is up front. I have ridden an X2 (which of course has a front exit and water box up front) with a aftermarket water box and it gave me a headache after a few minutes-- no water box would really be a no bueno. Also I do believe in that gun-whale that the exhaust runs down on the SXi there is a big camel hump to keep the water from coming back up.

Not a lot of room up front of an SXI. But if you did do it that way at least you would maybe have some space for an inline silencer.

Yeah, yeah-- call me a p^ssy for not liking loud skis-- I will be the p^ssy with two working ear drums.
 
kevbo

kevbo

Location
dfw
Little_Franny said:
I bought a friends project ski and am finally getting around to finishing it up. He filled the exhaust tube to the rear and planned on running a front exhaust setup. I have some tubing that he welded together but can't say I am all that happy with how it looks.

It has a factory limited pipe, and he has a whole punch of tubes and plumbing. Can I just come out of the bottom of the expansion chamber (faces down), turn 90 degrees toward the left of the ski, then turn 90 degrees toward the rear of the ski and attach to an exhaust outlet? Or do I need to at some point in the plumbing go up and then back down to keep water from backflushing into the system?

I also thought I could come out of the expansion chamber and go towards the right side and then plumb up around the front of the fuel tank to get back to the left side.

If anyone has pics of similar setups they would be greatly appreciated.

Thanx
Jon
Click to expand...
You want to run a straight pipe out the back????? Do you have Zoomies on your pickup as well???? The answer to your question is NO!
 
Little_Franny

Little_Franny

Location
Cape May Court House, NJ
I understand it would be super loud, that wasn't really the question, I do have a metal silencer pipe and a couple of the 440/550 rubber mufflers. The question was more along the lines of other than noise would there be any ill effects from running straight out the side, like the exhaust and cylinders filling with water while ski was floating with engine off. I am fairly new to stand ups and just trying to get some info.

Thanx
Jon
 
caseville9036

caseville9036

BLRider
Location
SE MI
Those rubber baffles from 550's have way too much restriction to be used with a 750 besides the fact that the entry and exit diameters are 1/4" too small.
 
Little_Franny

Little_Franny

Location
Cape May Court House, NJ
Fair enough, can't say I had even measured them yet.

I would have never done away with the rear exhaust if I was building the ski, but it's already glassed and painted. Just trying to figure out a solution to get this thing rideable
 
J

jetman624

Location
South OC, CA
I know this isn't what you want to hear, but you may want to consider looking for another hull. People part out those skis all the time, so it shouldn't be too tough.

If that isn't an option for you, really make an effort to find a way to squeeze some type of silencer in there...
 
Little_Franny

Little_Franny

Location
Cape May Court House, NJ
Noise is not my concern in this question, I get that it would be loud, I have a 440 with rear exhaust and NO muffler or waterbox of any sort and it's loud. I am asking a question more about layout and what I should be looking to do as far as actual plumbing.

The existing plumbing that my friend has for this ski involves a whole lot of plumbing, he has it coming out of the chamber and basically doing a big 280 degree circle into what looks like 2 metal silencers before exiting the ski. The flow comes out of the big circle about level with the top of the chamber and then goes into the first silencer, goes out into a 180 bend and into the second silencer and then out the ski.

I asked him why so many turns and loops and such and his answer was to keep water from reverse flowing into the exhaust and making its way back to the engine. I started this thread to try to get more info to decide if his theory is correct or not. As of right now the hull has not been cut for an exhaust outlet and I want to actually plan out an e Bauer system that makes sense to me. Mufflers and silencers are not a huge deal to incorporate and that's why I was not so concerned with noise and more the other issue.

I am looking to better understand the actual design and flow of the system as opposed to the noise.

I don't want to go ride this thing and swamp the engine due to poor exhaust planning, I would rather learn what I can and make my own decisions and deigns.
 
sxipro02

sxipro02

Location
Arnold MO.
sorry guy, The above two post sum it up.

The water box is the perfect way to stop water from back flowing into the engine. I would be afraid to add loops and such bc they all cause back pressure and power loss. Rule of thumb with exhaust is one 90deg bend has the same back pressure as 15' of straight pipe.

I cant see it being that big of a deal to fix the stock pipe on the right side or even just cut it out and buy a piece of aluminum pipe to replace it. This would be the best way to protect your motor, make power and save your ears. (it is retarded loud without a water box, been there done that) If you dont mind the noise I cant see there being a any back flow problems with running the exhaust out of the chamber and then to a in line silencer and out the side. Water wont flow up by itself so it shouldnt travel much above the bond line when sitting tied up.[SUB]​[/SUB]
 
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Little_Franny

Little_Franny

Location
Cape May Court House, NJ
Thanx for all the input guys. I got home and talked to previous owner, turns out he just filled the rear exhaust tube with foam and glassed over the outlet at the back of the ski so I will just open that back up and put a waterbox in it. I was under the impression that he had damaged the exhaust tube when he installed the footholds. I appreciate all the info in this thread.

Jon
 
sxipro02

sxipro02

Location
Arnold MO.
That's awesome! Keep an eye out for a aluminum water box. They flow just as good as a A.M. box with a little help but don't cost nearly as much.
TDR and FP make nice ones too if you can find one
 
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