300/440/550 81' j440 whats the largest engine that fits

[the WaTeRhAwK]

This is how I have my set up right now. It has around 180 psi compression, westcoast pipe (not cut down has 5 rings on it), pjs top loader intake grate, and I had a straight 16 prop sent to impros and turned into a 10-16 prop so let it rev up faster. I also got the nozzle bored and cleaned up all my veins in my pump to a nice teardrop shape.
After all of this the ski has no problem gaining RPM's fast at all it is just not getting that low end hit from the pump.
On the other side my other friends 550 I helped him build has way less work into his ski then this 440 and his hits twice as hard. I am no tuning expert but just what I have noticed.

well, here's another thing to consider with my 440/550 setup, on this old pipe I have the headpipe literally dumps 3/8" of water flow directly into the exhaust stream at the conjunction between the headpipe and the chamber, so that has a lot to do with the differences between the two setups of mine I listed. so they are the exact opposite from the two you have mentioned, the only difference being the design of the pipe. you can tune B-pipes for a superjet motor for low-end power with the water screws on their headpipes the same way. a water injection system works the same way.

the only drawback to the old setups like this is that after your initial holeshot is done, the full-flow of water through the chamber from the headpipe/chamber junction, and no stinger fitting diverting the water away from the expansion chamber to the stinger end, it cools the pipe off too much, and you will literally hear the rpms drop off considerably in the middle of a pinned run. jetworks makes a badass water injection setup, I'm thinking about trying it on my 550 and see if I can get close to the same type of performance.
although, again, I have tried the full-flow setup on the modded 550 and still never got the holeshot jump capabilities of the 440 pump setup, even with the modded engine over the stock setup. the prop in the 440 is two degrees lower pitch, but I don't know. that bastard is just mean.

 

[Sanoman]

here you go

http://www.x-h2o.com/threads/54549&highlight=stroker

Well l looked at that thread and it turns out to be a kawi motor after all.This thread is leaning more about pump flow than conversion.l guess l'm getting off the subject myself by asking about useing an old 440 hull and placing a 701 in it.Or is that just something that is useless to do???

 

[MADMAT]

I think all of this is useless. The pumps limit you.

Get a square nose SJ and give this old thing to the kid...as is.

Then widen the gunnies in the square and prop it and be done.....Summer will be here fast!

 

[the WaTeRhAwK]

I think all of this is useless.

if that was true matt, they would still be using mixed flow setups on sxr's, superjets, and hs's.


the 550 pump was designed to create decent thrust with low horsepower and a medium pitched prop, and low rpms. it's like squeezing your thumb over the end of a waterhose. the problem with it is that if you squeeze it off too much by trying to over-prop it, it will try to send pressure back to the source. an axial flow pump will infact do the same thing, but it can handle way more pitch and flow volume before that tries to occur. that's why they don't use them anymore and haven't since the early 90's, other than the ultra.

 

[firemedicmonkey]

I think all of this is useless. The pumps limit you.

Get a SXR and give this old thing to the kid...as is.
:arms:I second that emotion!:arms:

Then prop it and be done.....Summer will be here fast!

I say find a cheap 440 motor slam it in there since the thing is so complete and run the dog shiot out of it! Then down the line if he wants to get silly then do a swap... I would like to see a modded 800 in it with a steep prop and but the debate to an end... But summer is coming fast so lets just get it on the water!!!