Thread: WaterBox mod question
05-16-2006, 09:46 PM #1
WaterBox mod question
Its probably been beaten to death but here goes anyway. Are the people running with the 3 holes and shorten "outlet pipe" having issues with melting the Riva plastic tube? I am going to cut my waterbox in half right behind both exhaust nipples. Leaving enough to still strap it in. I`m not going to holesaw the three holes nor cut the outlet pipe. My reasoning is that with these 2 combos it seems to me that the exhaust will want to bypass the bottom passage heating up the water (which will be greater in volume than stock) in the box. This system will not scavage the water in the box. Especially with the tube cut. Anyone with experience with this mod or cutting the box as described please comment.
My exhaust temps will already be high enough. I want all the water to escape with minimal amout of back pressure or resistance but keep tolerable decibals and stay off the rev limiter.
05-16-2006, 09:49 PM #2
James, i never did melt the Riva pipe with my modded waterbox.
05-16-2006, 09:57 PM #3
But do you see my reasonning? Do you know (or anyone else chimming in) of anyone "shortenning" the waterbox?
05-16-2006, 10:00 PM #4
The Rotax Racing waterbox is just as you described. Its shorter and has no baffle. From what i hear it works well, but is extremely loud.
I would feel safer running a metal pipe with such a waterbox.
05-16-2006, 10:04 PM #5
I plan to make one(pipe). Let me ask this so I understand. When you say, "no baffle", what exactly do you meen? Is the outlet pipe the same lenght as stock or cut as you`ve described doing on your home page? Is there no baffle at all, 3 holes or just basically a chamber with an inlet and outlet?
05-16-2006, 10:16 PM #6
Just a chamber with an inlet/outlet.
Its just a pipe with a cap welded on each end.
05-17-2006, 12:03 AM #7
One last question on this please. Although my waterbox won`t be exact, does the RR unit leave the temp sensor in the bung?
05-17-2006, 08:25 AM #8Originally Posted by HOSS
05-17-2006, 08:58 AM #9
Hoss, I had the exact same thoughts ... I posted pics of what I did on another thread, but I cut the waterbox behind both nipples too, gutted most of the baffling, but left the exit pipe intact, almost all the way to the bottom. That way the box pressurizes evenly, scavenges correctly, pulls water from the bottom and evacuates the box like stock, but with less back pressure, quicker response, quicker evacuation. All my opinion, but I have modded other waterboxes too, and I only had good results when I left the exit pipe pretty close to the bottom of the box ... that seems to be critical for proper water evacuation. And I thought with this mod, I can leave the exhaust sensor in the stock location, and the pipes would still always have the usual amount of water in the exhaust. I have not had mine in the water yet this year, still finishing other mods, hope to have it in the water by 5/31, so I don't know how it will sound.
I think you could shorten the box too ... but shorter is not necessarily better, altho I think it would evacuate water quicker and stay a little drier inside. I have been told that a waterbox that is too small actually can hurt performance ... that a larger box is more forgiving and more adaptable in some ways, and a waterbox that is too small may end up being more restrictive than a bigger one, due to less volume for the exhaust to expand into before exiting.
The RR racing waterbox is small, totally hollow and does not have the outlet pipe in the same position. In order to use the RR waterbox you would have to create/modify a thru hull exhaust to fit.
05-17-2006, 10:37 AM #10
Thanks vern. Please do let me know as I will do the same on my findings. I want to do exactly as you have. Completely gut, half the box and leave the outlet pipe as is. The reason for the stock length outlet pipe is just for scaveging water as to not get too hot. I really feel I`ll have better throttle response since there is not as much volume to pressurize. Guess we`ll both find out around the same time. I`m waiting on my RRimpeller,,,hurry Jerry!
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