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Thread: Impeller interchanging

  1. #1
    Fire Water
    These might be a dumb questions, but I've got to them anyway.
    My pump is a legend. What other manufacturers impellers will fit my pump?
    I'm putting a new engine in over the winter and bumping the horsepower up so my current impeller might be cut to small. Won't know untill I get back on the water.
    I know there are some differences in diameter between manufacturers. How does impeller diameter change the performance of a pump?
    One more question in regards to shock loading (high speed/high rpm loading and unloading). I understand that this can lead to failure with an aluminum impeller. How well does a bronze impeller stand up to shock loading? I know stainless is the application of choice for operation under those conditions, but at this point of my rebuild the rate at which I'm hemoraging cash is making me think of any alternatives I can.
    As always, Thanks in advance for any help.

  2. #2
    77Woodbridge
    I can't answer any of your questions, but the guys that can are going to need to know:
    1) How much horsepower do you think you'll be making
    2) How fast do you want to go
    3) What type of boat
    4) Budget

  3. #3
    Fire Water
    I think I have a pretty good grasp of how to size an impeller and match it to an engine. I'm really looking for answers to the specific questions I asked.
    Right now I have no Iidea if I can put another manufacturers impeller in my legend pump. I figure what I'll do is start with an A cut and then most likely will cut down to a B or smaller. Boat is a 15' alluminum hull whitewater boat, new motor will be a sbc 383 pushing around 425 hp at 5400 rpm.
    I've just sent my pump out to Tom "The Pump Man" Morrow down in Mississippi (I'm on the east coast). I'm sure that he'll be able to answer my question, but I was trying to get a little heads up info first.

  4. #4
    RICHARD TILL
    Tom can fix you up and answer any questions you have. i`m lucky enough to live about 70 miles north of him.

  5. #5
    Taylorman
    What other manufacturers impellers will fit my pump?
    Im not sure. Tom Morrow will know thought.
    How does impeller diameter change the performance of a pump?
    To get peak performance you need to know at what rpm your motor makes peak power and torque. If say it peaks higher than your impeller allows it to turn, you cut the impeller to allow the motor to turn faster so it gets up into the rpm range where it makes peak power. Call Duane at Hi-tech performance, he has a formula that he developed which calculates how fast to spin the motor based on peak hp and tq.
    How well does a bronze impeller stand up to shock loading?
    As Gary Snow how many alum and bronze impeller he changed a plowmans last year from shock loading. The only cure for broken impeller due to shock loading it to lift your lead foot off the gas when your pump unloads.

  6. #6
    Placecraft Dragstar
    Tom can fix you up and answer any questions you have. i`m lucky enough to live about 70 miles north of him.
    Tom can fix you up on anything :rollside: He is the BEST in the buisness period. He is not a BSer and sell you things that you dont need like some of the other people!!!

  7. #7
    sdba069
    I've never had a Legend pump in my shop but I have seen a couple of their impellers. From what I've seen, Berk, A/T, Aggressor, or Dominator impeller with the right wear ring should work. In the case of the Dominator, you'd probably need to machine the stuffer ring off the back of the impeller, simple operation on a lathe and can be done on a mill.

  8. #8
    SmokinLowriderSS
    These might be a dumb questions, but I've got to them anyway.
    My pump is a legend. What other manufacturers impellers will fit my pump?
    This one I have no clue, but has been asked on the board. One of the pump builders will have to post up in this one. In searching, I'm finding the question asked quite a bit, but never answered before the thread dies.
    There are/were guys with Legend impellers in Berks, Agressors in Legends, all sorts of mix & match. May or may not take a trip to a lathe to make the wear ring area fit, but the pros know.
    I'm putting a new engine in over the winter and bumping the horsepower up so my current impeller might be cut to small. Won't know untill I get back on the water.
    Give me every build spec of the engine and I'll build an electronic version of it in a dyno program and we'll see what the HP looks like. If nothing else changes, every 100 HP is generally going to increase your current RPM by roughly 400 RPM. For example, IF you are currently running an "A"-cut, 350 HP will spin it about 4636 RPM, 450 HP -- 5061 RPM, 120+ RPM faster.
    Also give me your current specs as well, lets see where we are. You can PM me them if ya like.
    I know there are some differences in diameter between manufacturers. How does impeller diameter change the performance of a pump?
    There should be no difference in diameter per the brand aplication. I DO know of a difference in blade "depth" (from impeller face to the impeller back) within a given "size". For example, I have a Berk, Berk impeller blades are set back just slightly from the front edge of the impeller casting face. I am running an Agressor impeller which is cast right up to the face plane, which makes it push the same water flow (and use the same HP/RPM curve) as a Berk impeller 1 cut size bigger. I had my Agressor cut to a "B" to maintain Berk "A" spec which works best for my uses.
    One more question in regards to shock loading (high speed/high rpm loading and unloading). I understand that this can lead to failure with an aluminum impeller. How well does a bronze impeller stand up to shock loading? I know stainless is the application of choice for operation under those conditions, but at this point of my rebuild the rate at which I'm hemoraging cash is making me think of any alternatives I can.
    As always, Thanks in advance for any help.
    Bronze will withstand it FAR better than Aluminum and is (IMO again) the way to go for anything over the 400 HP that is spec's by Berk (I have not found any max HP per material from other makers) UNLESS you devour a lot of rocks. Rocks will beat the snot out of bronze just as it does Aluminum. You can pour all the HP you want into the bronze impellers. It's not just shock-loading that fatigues the Al impellers, but it IS the fastest killer of them (next to rocks).

  9. #9
    Fire Water
    Thanks for the replies.
    Looks like I should be able to get by with a bronze impeller. Gravel and rocks aren't such a big issue on the blackwater rivers I've been running.
    My boat is very short, only fifteen feet and this can lead to some pretty squirlly handling when I leave the river and get out on the lake. On the river the ride is a lot smoother but on the lake in a chop it's the wildest ride on water that I've ever had. Running hard in a chop can be pretty crazy. The fact that I'm strapped into the boat with a 5 point harness makes it possible to run the boat past a point where just staying in the seat would be hard. The hull is so solid that I have a tendency to stay in the throttle longer than I would in any other type hull and occasionally the pump will take a gulp of air. When this happens the pump will almost instantaneosly reload. Most of the time I can't react fast enough to keep from shock loading. If I really get launched I can back pedal and keep the worst of the shock loading to a minimum. So far my aluminum impeller has held up but considering the increase in horsepower I'm planning, plus metal fatigue associated with aluminum, I think a stronger impeller would be a wise choice. I'd hate to really trash my pump.
    I wish we had some whitewater to run in down here. If running on the lake in a pretty good chop is anywhere close to being on a whitewater river, I can't imagine how fun that must be. Maybe I'll be able to bring the boat out west or up north in Canada someday.
    OK. One more question. This is my first jetboat so I'm pretty far back on the learning curve. Every boat I'v owned before has had a prop. Can impellers be repaired like props? I've had a few prop strikes over the years and with a bronze or stainless prop as long as you didn't lose an entire blade most damage could be repaired.
    P.S. Thanks for the comments about Tom Morrow. He sounded like a good-ole-boy on the phone.

  10. #10
    SmokinLowriderSS
    I believe they can be fixed, much the same as props, in that nicks can be sanded out, damage can be welded and sanded back to profile. I've never had it done myself tho.

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