Custom/Hybrid How to convert ski to a 155 Pump

[munki63]

So I'm debating converting my ski to a 155 Pump, Problem like most of us will have only a 148 will fit. I just wanted to make sure I'm not missing anything before I decide to do this project, So PLEASE correct me if I'm wrong

First off how much bigger is the 155 pump over the 148, Im assuming its not as simple as just 7mm bigger because Im pretty sure opening up the pump tunnel 3.5mm where the pump hits wont be that big of a deal.

So step on would be opening up the pump shoe with a dremel and if you have a plastic pump shoe you would fill all the voids with glass matting and epoxy?

2nd step opening up pump cavity on the hull to accept the larger diameter of the pump, Is the bolt pattern the same on the 144 thru the 155? and more important from the mounting brackets on the pump is the drive shaft the same distance away from the brackets or do you actually have to lift the pump up...i would be surprised if this was the case, but i would like to know that too

Thanks in advance

 

[Matt_E]

I'll be going through the same thing with my Footrocket soon.
I have compared my Skat 148 against the Maxx 155 in preparation. The bolt pattern and spacing is the same. The overall diameter of the pump is about 3/4 of an inch bigger. (However, the Maxx pump has a weird ring around the outside that's larger than the actual housing).
I think my biggest issue will be this:

• Clearance between top of pump and roof of pump cavity/tray
• Clearance between bottom of pump and ride plate
• Fitting a 155 pump shoe into the hull

I think it'll take some glass work.

 

[munki63]

so if the total size of the pump is 3/4 of an inch thats 3/8 a side, doesn't seem too bad, could a guy grid down the ribs about an 1/8 to save the hull a bit?

As for the ride plate, on my ski the plate is pretty thick, maybe get a carbon plate made to maintain strength but wont need the thickness of a glass plate?

 

[Matt_E]

Hey, you got the same pump! :arms:

Yes, I am hoping I could just grind the top and bottom of that ring down a bit. I don't anticipate the side to side clearance to be a big deal.
I am concerned with properly centering and aligning the 155 pump shoe in a hull that was made for 144-148 pump shoes. I hope it's not too difficult.

For the bottom clearance, I figure that the worst case scenario will be grinding the ride plate until it fits and glassing over any holes or weak spots in the ride plate, if needed.
This might be a lot more difficult for the top clearance, requiring some work inside the tray area.

 

[superwetbrett]

155 are already a thing of the past. need to go bigger. just my 2 cents

 

[munki63]

I haven't bought the pump yet, I will get a maxx155 tho when I do order

how much bigger is your 155 pump over your 148, im talking about the actual size of the pump, the outside measurement thanks I just want to know if it will fit

What the hull are you using? My 155mm measreument outside is 178mm.

 

[munki63]

If the measurement from the base of the mounting brackets is the same as all other pumps it shouldn't be that bad of a modification, and I would be surprised if it was different but it's a good idea to cover all angles b4 you pull the trigger, another issue with the side to side is room for cooling and cables, I'm running 1/2 cooling lines steering and trim, that's a lot more garbage that has to fit in there

 

[#ZERO]

I will be making a fiberglass pump cavity for the 155mm to 160mm pump conversions for use with the larger size Jet Dynamics aluminum pump shoe real soon. You will need to cut the tray open & defoam to fiberglass the pump cavity in place but the pump mounting points will remain unaltered.

 

[Billybo455]

modding a freestyle ski that was intended to use a 144 style pump won't work like it should. matt you're an engineer. figure out why

 

[Scraggly]

modding a freestyle ski that was intended to use a 144 style pump won't work like it should. matt you're an engineer. figure out why

/
you talking to me? my name is matt and im an engineer?

 

[Billybo455]

matt e

 

[kevbo]

155 are already a thing of the past. need to go bigger. just my 2 cents

OEM 155s bolt in place of 144s. The inlet needs to be widened for best results. Giant twins are working well with even bigger pumps mainly because of inlet effiecency. There is also a dynamic pressure gain with larger diameters considering their max rpm.

 

[Billybo455]

No. Just set a 148 up right.

 

[Matt_E]

modding a freestyle ski that was intended to use a 144 style pump won't work like it should. matt you're an engineer. figure out why

Not too worried about it. Some sort of compromise in every hull, and this one's compromise was pump size. I'll make it work.
Besides, I am using an archaic non-PV engine of puny size, a third-rate ignition, and other odd stuff. I'll probably overload that poor thing as it is. I hope Skat has impellers pitched low enough for me. :biggrin:
I'm not trying to build a WF Pro capable flatwater boat, just something for me to putt around on.

And finally, what is the alternative? Buying another hull instead just so that one component will fit? :clown:

No. Just set a 148 up right.

Nah, did that last year. Time for something new.

 

[ajmps1]

then why not just go with a slightly smaller pump that will "fit"

 

[Matt_E]

then why not just go with a slightly smaller pump that will "fit"

Did that last year and know how the motor does with a 148 (more than 'slightly smaller - it's a bigger step than 140 to 148). Time to try something new. I like to tinker with obsolete tech

 

[wanderer1]

Out of curiosity, I believe 160's are available now, why not go that route? If you already gotta do work why not go with the largest available? A 155 will work but a 160 won't?

 

[yankeeboy]

Too bad they cant make the footrocket compatible from the assembly shop. I'd think with all the new setups coming out hull builders would be flexible to fit all the new parts.

 

[Billybo455]

Too bad they cant make the footrocket compatible from the assembly shop. I'd think with all the new setups coming out hull builders would be flexible to fit all the new parts.

you'd think....

pretty sure they sell the pumps in a 162mm. a 155 to 160 is a big jump. if you don't have a 1200 you don't want a 160.

 

[Matt_E]

Yes, it is too bad the FR doesn't come made for that. It really was the only thing giving me pause about that hull. In the end, I loved the ride and decided to just put up with it (and hopefully, come up with a 155 solution that may not be ideal, but workable)