SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: HomeBlown57 on April 09, 2011, 09:10:37 PM
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What actually happens when too much power is put to a jet? If you were to put 1000HP to a pump with an aluminum AA. Does it just cavitate and allow the engine rev without pushing more water? Does the impeller actually come apart? If it does come apart what are the ramifications? Has anyone actually seen this before and after?
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I don't know at what point you can overpower a jet but if the impeller fails bad enough to break the intake housing you would sink faster then you could get to shore. :banghead:
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Damn.... I think Berk says anything over 500 and you should go to Stainless, but your trying to double it. Good luck :-\
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Seen or heard of a few boats making large power on aluminum impellers...
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Pretty routine these days for Folks to run 8,9 to 1k HP in jets , just sold a Stainless to a Lake boat customer in NM making 1200 and got another going to a guy in TX with 950 HP Twin turbo deal . Although we recommend bronze or stainless over 450 to 500 I do have a Bracket guy with a 19 daytona who has run an Dominator aluminum several times with much more ponies (don't advocate this !) IMO its not just about the Impeller after 450 ish one needs to think not only about the Impeller but also the Pump shaft , bowl and even the suction as well Tom
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too much hp just means you're not making use of those rpms. if u got a ton of power cant you go with a more aggressive impeller so you can make more thrust?
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Got some pictures somewhere of what was left of a bowl and suction housing of a sunk boat running a 9" or so Aluminum in a blown alcohol deal.
Not pretty. If you're gonna stick with an A or an AA, probably get away with it as long as you're not spinning it to the moon, which would be hard to do on a blower engine anyway.
Problem, as I see it and was taught, when you get to the aggressive impellers to take advantage of the extreme HP, with loaders, stuffers, etc, THATS where the internal pressures inside that pump can get nasty. A standard aluminum impeller can quickly turn into a hand grenade, and as Crewcheif said, sinking is a definate probability if that happens......
If you're gonna stick with your impy, probably be OK. But if you're gonna build the pump to take advantage of that kind of motor, Stainless is cheap insurance.......
Just my .02
Ray
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I have an opinion on this one, if your considering using that WJ pump behind 1000 hp. ::)
An aluminum impeller should not cavitate any sooner than a stainless (same cut, same condition). The difference is the strength, and at what point the aluminum one will start to crack and come apart.
That being sad, Its kind of a crap shoot as to when its going to happen. Especially if your talking about your Jacuzzi pump. I would think the Jac impeller would be a bit stronger (5 blade). But, I wouldnt bet money (or my boat) on it. In perfect conditions (perfect loading across the face of the impeller, no cavitation, no shock loading, etc) an aluminum impeller will handle more than there rated for (like Tom unofficially said ;)) as long as it has no issues (seen or unseen) from all its years of use/abuse.
You are referring to that WJ again, right ?
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Been a while since I posted this....
This boat makes in excess of 1800 HP, he spins a billet impeller made of stainless steel at over 6500 RPM. The first three impellers actually broke the vane blades clean off the hub. :screwy:
Holy Shit! (http://www.youtube.com/watch?v=IxwaJEP3YA8#)
FWIW, the problem with aluminum impellers under extremes is their unpredictability. You just never know.
Comparing them to a propeller say on a stern drive, the aluminum propellers flex to a point that they actually move less water. This is hard to prove on a jet impeller, but if it was to "flex", the design of the impeller in and of itself would cause it to "expand" almost acting like brake shoes in a drum brake system....Once the wear ring hits is when you would see a catastrophic failure...Ouch.
The other thing to consider is loading (and unloading), the aluminum impeller can actually take a lot less impact than the stainless or bronze counterpart.
As Tom states, the shaft and the thrust bearing needs to take the same 1000 ponies, the pump will only be as strong as it's weakest link.... :sly:
GT
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What actually happens when too much power is put to a jet? If you were to put 1000HP to a pump with an aluminum AA. Does it just cavitate and allow the engine rev without pushing more water? Does the impeller actually come apart? If it does come apart what are the ramifications? Has anyone actually seen this before and after?
Does anyone have pictures that they can post of a pump that has been over powered? I have heard all of the same rumors! I would expect that the pump builders would have some pictures or actual stories with facts of what happened from pumps that have come through their shops.
I just want to know what has happened in the past from people that have seen it.
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Does anyone have pictures that they can post of a pump that has been over powered? I have heard all of the same rumors! I would expect that the pump builders would have some pictures or actual stories with facts of what happened from pumps that have come through their shops.
I just want to know what has happened in the past from people that have seen it.
**BUMP**
I'd like to see these too... I know one of you has pics :sly:
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I'm lookin', I'm lookin'. I know I had a couple on my LT that blew up (Coincidentally enough.......), Now to remember who sent 'em to me..... :sly:
Gawd Alzheimer's is such a fun disease..........But Easter's Coming!! I get to hide my own eggs again!!!!!! :thumbup:
Ray
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Poor Poor Ray stepped in it again LOL ziggy
..........But Easter's Coming!! I get to hide my own eggs again!!!!!!
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Thanks for looking Ray. Do you have any details of what happened?
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Does anyone have pictures that they can post of a pump that has been over powered? I have heard all of the same rumors! I would expect that the pump builders would have some pictures or actual stories with facts of what happened from pumps that have come through their shops.
I just want to know what has happened in the past from people that have seen it.
willis in the tsunami (sp?) boat blew the bowl apart, im pretty sure it was from over pressure not from hp
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here is his boat
Willis Johns "Tsunami" Blown Gas Jet (http://www.youtube.com/watch?v=N7ZxZveeyTI#)
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Thanks for looking Ray. Do you have any details of what happened?
Naw, I never got the whole story on it, but the boat did sink, bowl almost gone, nozzle, droop, etc hanging on the thing only by the cables, and a good portion of the transom and suction housing severely damaged. I was thinking it was Proppy that sent them, but I guess not.
Ralph has given you the real reason though! ;) The HP is only a catalyst, as is throttle control, pump condition, etc. The result is the aftermath of these three things given the right circumstances. I was sent the pictures when I started this whole blown/injected E-85 dealio (Yes, it's coming along guys!!! ;) ) and was told by both Tommy at JBP and Duane at HTP "Are you friggin NUTZ??????". Moo's JE has a SS impy now..........I also upgraded the shaft, wear ring, and went with a 1350 driveline.....hence the motor mount change and pump brace idea..... 8)
If you think about it, it costs $$thousands$$, even with a BBC, to get the engines HP to the levels we're talking about. 500 HP and above is not cheap. Is the $500-$600 difference in the cost of a SS vs aluminum impeller really worth chancing it if you're at or near these levels? And the Impy is really only ONE component in the jet that should be upgraded. Would anyone try this in a car using a stock transmission or rear end????
Ray
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im probably in the 550 range, and running a brand new aluminum... the aluminum a seemed to be just fine, okay maybe a little cavitated! We'll see how the amt annodized b holds up!
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Poor quality of water to the pump, and by that I mean insufficient loading, is more of a problem than too much Horsepower in the pumps we see here. A bad bottom(trailer sag), incorrect intake grate(river use usually requires a more aggressive loader than on a smoother lake), improper intake installation(angles or depth), and generally just driving like a young jet-ski punk, generally cause most of the problems we encounter. A properly loaded aluminum impeller with a GOOD inducer will reliably absorb 1000 Horsepower when coupled with the correct combination of other parts. You can't just be a noobie and throw something together and have it reliable, or safe. We have seen locals trash a new aluminum impeller in a few weekends with 400 HP, then all but explode a new mag bronze in ONE outing the following weekend trying to "see what it will take". Good advice, good combination of parts, and good installation will get you farther than the new WHIZ-BANG, TRICK OF THE MONTH stuff installed by a moron. Just my opinion, I could be wrong... TIMINATOR
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So, Tim if all of these poor situations that you speak of were to take place, where does that leave the pump? Does it lock up the impeller on the wear ring? Then twist the bowl off of the suction housing? Does it expand the impeller and do the same? Does the impeller break and shred itself into small pieces? Does it twist the shaft off?
We are all aware that a great combo in a great boat is great!
My question is what happens when things go south in the pump? With no regard to why it happened. Choose any situation you want, then explain what happened to the pump. Anyone, please.
I thank you in advance.
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Any and all of what you mentioned..... Usually improper loading will erode the impeller about 3/8" to about 1 1/2" past the leading edge of the blades. Aluminum worse than bronze. The efficiency will fall off and the hole shot suffers, thats your clue to have it looked at. About two years ago we had a customer not heed any of our advice, and buy one of our 496 motors for a boat he just bought. We offered to look at the pump for free, he didn't take us up on our offer, as a matter of fact, we never saw his boat at all. His bro (also a customer with his own boat), said the pump worked OK as long as he pussyfooted it out of the hole, and didn't try to run faster than 75 or so, above that, it loaded and unloaded the pump continously. I recomended a different grate, and an inducer, he didn't have the cash for that, so he would just do it over the winter. A few weeks later they were racing each other and everybody else, and during a high speed run the side of the suction housing collapsed a hole big enough to put two fists thru. Made a big splash and some noise, but didn't sink the boat because of the big pump setback. The hole stopped right where the custom transom plate was siliconed to the suction housing. He was lucky. Instead of just purchasing a grate ($200.00), or inducer ($479.95 with shaft machining), he bought those, a used suction housing, a complete rebuild kit, an impeller and shaft, plus labor. With a non setback pump the hole would have been inside of the boat and sunk it, immediatly. The pump will tell you what it wants if you are smart enough to know where to look at it, listen to it, or ask someone who is. TIMINATOR
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Thank You.
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Well, at least the motor wasnt the weak link this time lol, anyone have some spare parts they want to sell?
Before.......
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi148.photobucket.com%2Falbums%2Fs8%2FDozzr%2FPirustillshots016-1-1-1.jpg&hash=d46a7c724194ee4313fcb2bd53ad8ade8e616a2b)
after.....
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi148.photobucket.com%2Falbums%2Fs8%2FDozzr%2Fpump-1.jpg&hash=d9b8b5340acdda5a767fe625a012d28dbb165ab3)
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi148.photobucket.com%2Falbums%2Fs8%2FDozzr%2Fpump2-1.jpg&hash=b7407a32c76e3197638d68eaace78f0e5e3b2a9a)
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HOLY SHIT :o :o
i can only imagine the sound that made.
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(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi148.photobucket.com%2Falbums%2Fs8%2FDozzr%2Fpump-1.jpg&hash=d9b8b5340acdda5a767fe625a012d28dbb165ab3)
WOW , I thought the bowl was thicker than that!
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I guess you are gonna find out just exactly "how much a good time costs." :o
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I guess you are gonna find out just exactly "how much a good time costs." :o
:o exactly
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why does the impeller appear to be in one piece? that had to be from pressure then right?
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why does the impeller appear to be in one piece? that had to be from pressure then right?
pressure inmo, look at the suction housing, cracked too?
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if you ever seen dozzer drive a boat you know how that could happen, he drives the shit out of it ;)
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been on the river with dozzr and i concur buddy
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Thank you dozzer. How much power do you think you were making? I assume the pump was being loaded and unloaded. Would it move after the mishap? Since there are no pics of the bowl, did you lose it? It appears that the crack would not have been bad enough to sink it.
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I was just getting it dialed in (or trying) it was cavitating out of the hole so I was messing around with loaders. When this happened there was no loader at all I was seeing if the loader itself was blocking the water intake when it raised up out of the water. There was still a little cavitating but it hooked up alot better, I took it for a spin around the lake nailed it...dam did it set me back in the seat, I was just getting ready to get out of it and I felt a small vibration, then it was over...what you see is what I took home with me....I talked to the guys in the bait shop and they said the area it happened in was about 65 ft deep. So I am just going to have to suck it up and buy all new stuff.
As far as power goes I am not positive, but it is around 850-900hp. I had the pump working great before I moved up to the bigger bower, but I moved it up a couple inches when I put the rail kit in it, and really was just starting to play around with it, so in answer to your question yes the pump worked well with the old setup i it, but with all the changes I did at once...it wasnt anywhere close to being like it was.....All that extra power screwed everything up lol
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi148.photobucket.com%2Falbums%2Fs8%2FDozzr%2F049.jpg&hash=7f3b7661fb325273625443544450db8fe116871c)
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Sorry for your loss. The bowl breaking off was the second to last thing I was thinking would happen.
RE the new blower; I think the big pulley is supposed to go on the bottom, I'm just saying.
The boat sure looks nice. Thanks for your input. Reality trumps rumors and stories every time in my book!
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Sorry for your loss. The bowl breaking off was the second to last thing I was thinking would happen.
RE the new blower; I think the big pulley is supposed to go on the bottom, I'm just saying.
The boat sure looks nice. Thanks for your input. Reality trumps rumors and stories every time in my book!
Knowing Dozzr, the pulley on the bottom is the size of a trailer wheel.......... :screwy:
Ray
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yup, Lmao the bottom is 43 and the top is is 37. I am hitting 7lbs. boost and am good with that. I tried the smaller puleys in different combinations but end up with over 10....so til I get the pump back together, I am stuck with the jumbo size setup.