I'm planning on drilling a few holes in my stock waterbox to accommodate my 809 motor. I'm just looking to free up some reasonable flow while maintaining near stock sound suppression. Does anyone have experience with this? I'd love to see a pic of the inside of the box, I have not taken mine out yet.
Modding 08+ waterbox.
- Thread starter bernard
- Start date
Seems like best course of action is sell the stock box and buy something aftermarket.
Here is a pic of how I modded a RN waterbox for my ported and pipped 718.
I added some holes on the perimeter and one extra cross tube of a slightly smaller dia than the stock tubes.
I did not do any flow calc's and I did not make this change while keeping the rest constant so I am unsure how much (if at all) it helped. ...But it should flow better, it sounds great and the engine seems happy.
I added some holes on the perimeter and one extra cross tube of a slightly smaller dia than the stock tubes.
I did not do any flow calc's and I did not make this change while keeping the rest constant so I am unsure how much (if at all) it helped. ...But it should flow better, it sounds great and the engine seems happy.
Perfect, thanks for that pic. I'm concerned with having too much volume from an aftermarket box, though the weight savings would be nice. I'm going to just split it and add another hole up on top. Thanks guys. I may even attempt to make a hole without splitting it if I can.
I think I will mathematically scale it up based on how much air I was roughly flowing with a stock 701 vs a ported 809.
There is no real engineering in jetskiing lol.
I got a tach and I know someone with a relatively stock superjet with the jm waterbox. Gonna see if I can convince him to do a tach run for us
8000
My plan is to scale the hole size in the water box by the same ratio as the increase in my jetting size and peak RPM between my old and new motors. This should represent the most accurate comparison for air flow possible, assuming the tuning is good. My stock jetting is 70 and 130= 200 total flow. New motor has 115+125= 240. So my new jets are 20% larger than my old ones. In addition, I am running 1000 RPM higher from 7000 to 8000. This calculates to a 14% increase. My total hole open area should be 34% larger. I'm thinking that my increase should be a bit smaller than that to maintain low rpm back pressure. I'm thinking around a 25% hole increase may be ideal.
Quinc
Buy a Superjet
- Location
- California
Setting your rpms to 8000, means you will hit the rev limiter at 8k (when the pump leaves the water) You will most likely be in the 6900-7200rpm range
