OEM 155 Pump Talk

[D-Roc]

On a side note about water density has anyone else notice a difference in the way ones ski rides in dirty thick water vs clean fresh water? I find the hookup in dirty water to be better but my hull handles with a more drag type feel.


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[WB1994]

I was using it as an example of how a little can make a big difference. Yes I use my tail cones to change the pumps internal volume behind the prop. If a pump is not compressing the water to create pressure what does it do? You seem to know more about it than me so enlighten me if you don't mind. And yes please explain the prop pitch.


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Are you more worried about the overall volume in the cone or the size of the exit nozzle? What is the importance of the volume of water in the cone?

A pump is not compressing the volume of water , the exit nozzle is , no? Your changing the pitch of the prop due to HP vs exit nozzle , no?

Im in no way proclaiming I know alot about this , just having winter discussion's.

 

[D-Roc]

I am stating that when water does not compress, it will result in building pressure quickly. the internal volume behind the prop can effect at what rpm the engine will be at when it makes the thrust. I have big carbs and TL so I have good bottom end power. So I want my pump to start pressurizing at low Rpm's. I do this by increasing my tail cone size to reduce internal pump volume. The reduction nozzle is just as important for the amount of load and can compensate quite a bit. I would say that if you have a big hub prop and stator section the tail cone volume is not as critical as the reduction diameter but having three sizes to play with sure helps find the sweet spot that I like my ski to hit at. Timing is everything on flat water. If your ski does not respond when you expect it to, you get hurt lol.


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[WB1994]

Big carbs and tl make for good bottom end? I think your missing a few variables.

I kind of understand what your trying to say about internal volume but like I said before the slight change of volume your talking about , imo , is so minimal that even in absolute perfect conditions you couldnt tell a difference in when your pump is at max fill. We are talking a few cups at most thats being prossesed at a fraction of a second. Isnt the exit nozzlediameter more important to what your looking to achieve?

 

[DAG]

I am stating that when water does not compress, it will result in building pressure quickly. the internal volume behind the prop can effect at what rpm the engine will be at when it makes the thrust. I have big carbs and TL so I have good bottom end power. So I want my pump to start pressurizing at low Rpm's. I do this by increasing my tail cone size to reduce internal pump volume. The reduction nozzle is just as important for the amount of load and can compensate quite a bit. I would say that if you have a big hub prop and stator section the tail cone volume is not as critical as the reduction diameter but having three sizes to play with sure helps find the sweet spot that I like my ski to hit at. Timing is everything on flat water. If your ski does not respond when you expect it to, you get hurt lol.


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This is a great wright up, keep going guys. D-Roc that last post seem pretty accurate, great putting thoughts into text. I can clearly understand what you are trying to convey

 

[WB1994]

Shouldnt this sweet spot you speak of be achievable by any pump with just adjusting the prop and exit nozzle volume compared to HP? Is the overall volume important to the sweet spot or is the overal volume , 144 vs 155 , more important to the amount of mass it can move when a sweet spot is achieved?

 

[WB1994]

"So I want my pump to start pressurizing at low Rpm's. I do this by increasing my tail cone sizeto reduce internal pumpvolume"

Isnt this achieved with a change of pitch in the impeller? And isnt increasing the tailcone size increasing internal volume?

 

[WB1994]

Couldnt a volume change in a pump exit nozzle along with a certain size and shape of the tailcone that seals the rear bearings actually creat a turbulance thats nonbenificial to the flow out the nozzle?

 

[air blair]

Totally sweet thread, im digging this discussion. Too darn bad there is not a chart to figure out what prop to run based on engine size and cone size to reduction nozzle all the way to steering nozzle length and diameter. Dark magic tricks of do and try. Tunnels are still so key as to how much volume is even allowed to enter along with the scoop grate or no scoop. Keep digging. This is good

 

[kevbo]

The point of restriction should be at the end of the nozzle. The cone should take up unnecessary volume without restricting internal flow. IF you gain performance by making the cone smaller, it was too long and throttling the pump internally. The pump designer needs a kick in the ass for that. With that said, a long thin extension into the nozzle can be an effective method of changing the outlet area. That is a waste of effort, we want the biggest nozzles with the impeller controlling load.

 

[kevbo]

Totally sweet thread, im digging this discussion. Too darn bad there is not a chart to figure out what prop to run based on engine size and cone size to reduction nozzle all the way to steering nozzle length and diameter. Dark magic tricks of do and try. Tunnels are still so key as to how much volume is even allowed to enter along with the scoop grate or no scoop. Keep digging. This is good

That was easy 20 years ago. Now there are too many products and combinations to make a simple chart that could be of any use. Fortunately there is probably someone around that has tried whatever combo you have or want.

 

[air blair]

That was easy 20 years ago. Now there are too many products and combinations to make a simple chart that could be of any use. Fortunately there is probably someone around that has tried whatever combo you have or want.

If there was that person for every situation he would have some money in the bank. I'm sure that is the case with some of these pros at world finals but as far as cheap little power pushers here we sit wiggling out finger tips gaining grains of wisdom. Thanks again

 

[D-Roc]

Yeah no kidding. Even having the adjustable intake grate to play into the hull speed at any rpm makes the combos infinite. To have a formula that we get to plug in all the data and push a button would be the answer but according to my calculation is like totally impossible man.

 

[sneds]

I agree, interesting conversation.

 

[JT_Freeride]

Time for an update. I finished my ski and rode it yesterday. Rickter FR2 with a Riva ported cylinder, ADA head 185 psi. bpipe, and MSD. I used a B2 pump with solas wear ring and a impros 7/12 with a stubby cone. This ski rips and rips hard, the bottom, mid range, and even top never stop pulling. The stubby cone has to go tho you can feel the pump loading up just off idle but it loads pretty fast with zero cavitation I'm. Gonna put the stock cone on and try again

 

[JT_Freeride]

To elaborate a little more on what it took to set up the 155 pump. First thing is if you don't have an intake duct big enough for a 155 I wouldn't go through the trouble in trying to make one but if your ski already has it and you have/ are putting in a new pump shoe why not do it. The only problems I faced was trying to find an oem pump seal (yamaha discontinued them) I bought the R&D seal and it was to thick it caused the pump to be pushed back to far like 2-3mm. Luckly someone else started making them (Thrust and Jetmaniac both sell them) it fit right in no problem. 2nd problem was the new impros impeller and solas wear ring combo when I installed the prop it would not turn at all turned out one of the leading edges on the prop would grab unfortunately i had to file a bit off of it after that spun like butter. After riding the ski yesterday with a brand new engine I was more than happy on how it came out this ski feels like it has a huge motor in it I even think a Flat water flip could be possible it jumps right out of the water. Don't let anyone think that the big pump and low pitched impeller is going to make you slow. The mid range and top (though I didnt hold it WFO because of the new engine) on this setup is by far the most powerful i have ever felt it was unbelievable. Now the cons: a mag for a 155 pump is beyond ridiculous in price i cant justify spending $2200 for a pump. so if you want a mag i would stick with the 144 unless money isn't an option for you than go for it. Ill be at WaveDaze this year and anyone who is thinking about putting in a 155 can give it try.

 

[yamanube]

So did you run this back to back with a stock 144 pump?

 

[Jr Freestyle]

Also really curious to know if anyone has done a 155 Oem to a 144 mag solas , for budget set up they cost around the same . I really wounder which performs better with a limited setup.

 

[schicks]

nice write up.

can you explain the difference between the R&D seal and the one JM & Thrust sell? I am in the same boat as you were, i bought the R&D seal and it ended up being to thick as you described. I made a jig and milled it down to fit my setup. I assumed the JM & Thrust ones would have been the same as the R&D, but it sounds like they are different.

 

[JT_Freeride]

So did you run this back to back with a stock 144 pump?

I did my buddy was out with his fr2 and we swapped we have pretty much identical setups expect he has a solas 144 mag. The difference I felt is hard to explain but it felt like the solas was loaded faster at IDLE, right off idle the 155 was the clear winner in thrust and power. I cant give a full explanation because he was still tuning his engine and mine was fresh so i couldn't go WFO. If it makes a difference his hull is almost 400lbs (his is unbreakable lol) and mine is 330lbs