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?

Damn....  I think Berk says anything over 500 and you should go to Stainless, but your trying to double it.  Good luck   

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

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

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. 



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....

GT

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 

Poor Poor Ray stepped in it again LOL ziggy
..........But Easter's Coming!! I get to hide my own eggs again!!!!!! 

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

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.....

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

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

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

Well, at least the motor wasnt the weak link this time lol, anyone have some spare parts they want to sell?
Before.......


after.....

WOW , I thought the bowl was thicker than that!