Malones set back pump

Legdragger

Legdragger

Bringing it back
Location
New Hampshire
I heard Malone's hull has the entire pump set way back to give him more leverage, hookup and pop on rolls and flips. Has anyone ever seen it or heard how much it is set back?

I was just doing some brain storming and almost had a good idea.....maybe....
 
Speedfreak

Speedfreak

Location
So. IL
Ok I might be slow or something but can someone explain how moving the pump back 2 inches would help.... I understand the shorter hull is just the opposite as an extended ride plate but moving the thrust rearward inline I don't see that helping. It is still the same thrust exiting at the same angle.
 
Legdragger

Legdragger

Bringing it back
Location
New Hampshire
Imagine the ski is floating in the water alone and you need to spin it around 180 as fast as possible. If you put your hands on the hull 3/4 of the way to the rear you would have less leverage than if you put your hands at the very back of the hull.

It also gives the pump shoe more volume which theoretically will propel you longer when you are popping off a set up wave.

Ramjet,
That sounds like a pretty easy way to set back an entire pump. Just cut the shoe off and add more in the middle. I need to look my pump over closely to see how that would work. The pump liner might interfere with it.
 
Speedfreak

Speedfreak

Location
So. IL
I understand the pump volume and that would help a considerable amount. But couldn't you achieve the set back effect by making the exit nozzle longer.

Has anyone ever tried a ski with both setups kinda side by side comparrison. I can move my pump before I finish my ski but don't know if it is worth the effort.

What about taking the wear ring part of another pump and cutting it down so that it is only 2 inches long and attaching it to the front of the existing wear ring. That would increase the length of the inlet.
 
Last edited:
Flash-FX

Flash-FX

No Square..No Round..FX-1
Location
South Jersey Shore
Speedfreak said:
I understand the pump volume and that would help a considerable amount. But couldn't you achieve the set back effect by making the exit nozzle longer.

Has anyone ever tried a ski with both setups kinda side by side comparrison. I can move my pump before I finish my ski but don't know if it is worth the effort.

What about taking the wear ring part of another pump and cutting it down so that it is only 2 inches long and attaching it to the front of the existing wear ring. That would increase the length of the inlet.
Click to expand...

Basically, the less volume there is between the back of the impeller to the exit nozzle, is less mixed water and AIR there is to compress. Also more pressure makes the air bubbles in the pump smaller = less cavitation. Just Like in the Skat-Trak 1" setback pumps (setback with a big hub diameter). The drawback is that the higher water velocity going through that big hub/setback pump also creates more water friction, that requires more HP operate. It would be too easy just to add on a Super loooong exit nozzle to achieve the same thing. Sorry....
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
Legdragger said:
Imagine the ski is floating in the water alone and you need to spin it around 180 as fast as possible. If you put your hands on the hull 3/4 of the way to the rear you would have less leverage than if you put your hands at the very back of the hull.

It also gives the pump shoe more volume which theoretically will propel you longer when you are popping off a set up wave.

Ramjet,
That sounds like a pretty easy way to set back an entire pump. Just cut the shoe off and add more in the middle. I need to look my pump over closely to see how that would work. The pump liner might interfere with it.
Click to expand...
In this instance it might be easier to use the 750/800 pump, and make your own custom long pump shoe from glass. That way the pump mounts up similar as to in the 750/800 hull. Oh, and a longer driveshaft, perhaps out of a sit down Kawi.
 
Legdragger

Legdragger

Bringing it back
Location
New Hampshire
Me and my Dad came up with a relatively easy way to set back the pump 2 inches and stretch a driveshaft without even cutting up two to make one. The recipe requires one 750/800 pump, one 650 pump, one driveshaft two drive couplers and a piece of thickwall aluminum pipe.

The driveshaft will just be slid back two inches and an extra long coupler made from 2 couplers and the aluminum pipe which will be made by a competent machinish. The only drive shaft mod would be to build up the spot the bearing ride on the driveshaft with some wel them have it turned down to fit the rear bulkhead bearing 2 inches up from before.

I figure a 750 pump will be just as easy to work with to cut the first 1/2 inch off the aluminum body around but not through the wear ring. But either pump would work. Next cut the shoe plus 2.5 inches off the 650 pump including the wear ring. Remove .5 inch of the wear ring from inside the 650 section but don't hurt the aluminum body attached to the shoe. Press fit the shoe of the 650 with addational 2.5 inches of body over the .5 inch of of exposed wear ring on the 750/800 pump. Hold it together with some weld in a few spots. Relocate the mounting ears for the pump body 2 inches up. Extend control cable with stainless connector nuts.

It doesn't seem like brain surgery and I might as well use a 750/800 pump so I don't have to adapt the TBM to work on it. Plus I my modified impeller will set back 6mm further in the 750/800 pump does to it's set back hub design. As long as the blades don't drag just ahead of the stator blades where it gets narrower. On second thought I might have to use a 750/800 impeller that is as cut back as mine are or the blades will probably drag at the rear edges. If it did work it would be the same as a 12mm set back 650 pump.
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
5mm setback fits the stock 750/800 pump, but I wonder if it still fits with the TBM in there.
 
R

ROTATION

Why must I build it??????
Location
South Africa
Setback will work with TBM. I have a 16/20 that I have set-back 6mm, about a 1-2mm gap to TBM, blade-tips sit right at the taper in the pump
 
Legdragger

Legdragger

Bringing it back
Location
New Hampshire
Here is the first mockup of a 2" setback pump for an X2. It is built using a 750/800 pump with 2.5" of 650 wear ring and shoe grafted to it. I need to cut .5" of wear ring out of the 650 section and it will slip fight over the exposed wearring on the 750/800 pump.

I could do the same with a pair of 800 or 750 pumps.

pump002.jpg

pump004.jpg
 
feartheride

feartheride

feartheride
Location
St.Catharines,On.Canada
Would it not be easier to cut driveshaft in middle and extend it 2 ".Cut in half ,chamfer ends drill holes,make up 2" spacer with 1" spigot on each end press togethe,weld and staighten.Don,t have to make new coupler=less odd ball parts
after welding a new bearing surface you will have to straighten shaft anyways
 
G

geraban19

X
feartheride said:
Would it not be easier to cut driveshaft in middle and extend it 2 ".Cut in half ,chamfer ends drill holes,make up 2" spacer with 1" spigot on each end press togethe,weld and staighten.Don,t have to make new coupler=less odd ball parts
after welding a new bearing surface you will have to straighten shaft anyways
Click to expand...

That's not easy to play with driveshafts... it has some strengh treatment.

two years ago Lenzi tried a 2nd impeller hoousing betwen intake duct and impeller housing using some "longer shaft" made by a braziliam company.

I cant tell U the results BUT I am sure he is not using it anymore.

BTW... if U have 2 housings U will need to move or add 2 pump inserts in the back.

just a cent.

Gera
 
You must log in or register to reply here.
Top Bottom