why is big pump hub better?

[aqua]

can someone tell me why a big hub pump is better for freestyle than a small hub. i understand the skat mag pumps have better vanes and better surfaces but why the big hub. everything i have read regarding pumps on the net says that smaller hub would be better to allow for more space so what is the deal with with c75 impellers, big hubs, and tbm pump cones?

 

[750SX]

Smaller area builds more pressure I believe.

This is just my hypothesis, I don't know for sure.

 

[egbrig]

It has to do with pressurizing thet water as it flows through the pump ie: velocity. With a small hub the water pressure is not maximized for the size of the pump. A large hub will keep the pressure up and exit with a better velocity.

 

[Big Kahuna]

It has to do with pressurizing thet water as it flows through the pump ie: velocity. With a small hub the water pressure is not maximized for the size of the pump. A large hub will keep the pressure up and exit with a better velocity.

about as good of a discription as there is........

 

[waxhead]

The reason is because any area after the blades has to be refilled when your pump lands back in the water
The less area in there the faster it refills

The larger hub pump has less area so it reloads faster

 

[BROSS]

More companies are doing this, Yamaha FXHO now has big hubs, SD has had them for years, all Mag pumps have them, like they said, more pressure. IMO

 

[aqua]

It has to do with pressurizing thet water as it flows through the pump ie: velocity. With a small hub the water pressure is not maximized for the size of the pump. A large hub will keep the pressure up and exit with a better velocity.

ok. i can understand that it increases velocity and builds more pressure and reloads faster like what wax was saying. but why are we so concerned when the pressure drops and velocity falls as soon as it hits all of the space a reduction nozzle has to offer. by the way our reduction nozzles are a few mm larger than our stator sections on the outside edge. then many of us install short pump cones as well which i would think would increase volume therefore reducing velocity. boring the nozzle also reduces the speed at which the water exits even though it allows a pump to blow more of its wad at once. so why?

 

[DAG]

thats exactly what i'v been questioning for awhile,,, Mag pumps have a much larger Hub, reducing the area increasing the Velocity, and its a better pump (over stock).

how come everyone says bore the stock nozzle out and get a stubby cone, all which increase the area reducing velocity, but still mods which make it better (over stock).

the both pumps increase your ski's performance over stock but one pump has a huge area and the other pump has a much smaller area?? maby something to due with the turbulence's of the flow???

 

[D-Roc]

i think with a less modded engine it benifits to pump more volume with less pressure to give some better botom end hit. once you have a stronger motor it starts to spin the prop too easy and needs more pressure to work the motor. i got to that point on my ski. the motor was revving up fast but not hitting instantly.

 

[GIL]

I went from 13/16 Solas and bored nozzle and ww stubby to a 12/16 Skat and Virgin trim w/their nozzles and lost all bottom end heavy hit/snap. I'm gonna try a stk pump cone and see if their is any improvement.

 

[BruceSki]

i just got the TBM pump cone setup that turns it into a big hub, and im ordering a 12/17 big hub prop from legdrag...we will see how it works out


i heard it gives magnum pump results with less weight and a lot cheaper

$500 vs. $1500

 

[D-Roc]

that what i got and legdrag has a combo you can buy that worked really well for my setup and also on a buddies setup. plus you get three differnt cones to try out. nice purchase i think you will like it.

 

[IceRocket1286]

I ran both a TBM super pump cone and later a skat trak mag pump. The TBM is a great product for its cheap cost, however it is not as good as a mag pump. I ran this on my full limited sxr this past season. If youre looking for a cheap alternative go TBM...its good enough. The mag was much better overall.

 

[Big Kahuna]

ok. i can understand that it increases velocity and builds more pressure and reloads faster like what wax was saying. but why are we so concerned when the pressure drops and velocity falls as soon as it hits all of the space a reduction nozzle has to offer. by the way our reduction nozzles are a few mm larger than our stator sections on the outside edge. then many of us install short pump cones as well which i would think would increase volume therefore reducing velocity. boring the nozzle also reduces the speed at which the water exits even though it allows a pump to blow more of its wad at once. so why?

Any change you make has an adverse effect, the larger hup will allow the pump to "hook up better", this has nothing to do with bottom end hit or top end hit, it is all about traction to the water and how it processes the water as it comes through the blades...

When you bore out a nozzle, you are allowing the processed water to escape with more "Punch" hence giving you more bottom end hit, but there is a drawback to this, you will loose some top end performance. But for freestylers this is not an issue. It is an issue for racers. So, Engine Builders/Racers will actually have different pump reduction nozzle combinations for different water conditions. In a rough race course like Chicago or Galveston where the water was choppy they would run a larger nozzle to have better hookup and punch for when the pump was in the water, whereas inland lakes like Macon GA they would run a smaller nozzle for more speed.

It is all about the combination, some pumps will work well with a bored nozzle and a short pump cone while others work well with only one of those (Mine was this way), alot depends on the power your motor makes and what prop you use.

 

[BruceSki]

think i'll run into trouble running the 12/17 big hub prop, and tbm pump setup??? planning on the smallest cone of the three

im gonna have a b pipe, ada head, and msd enhancer by the time spring rolls around...

i ride the ocean and the marsh, so i dont want a boat thats all bottom end and no go, but definitely dont need top speed


its about a 10 minute ride wot to the ocean from the ramp we drop in at, so i dont want to blow er up cause im revving too high