SoCal Jet Boats
Discussion => The No Wake Zone => Topic started by: pw_Tony on October 02, 2007, 06:01:53 PM
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Just cause we were talking about it earlier. This is known as the "extended impeller RPM chart". This isn't made by Berkeley, but it's made for berkeley impellers. I can't remember right now who made this chart but I can find out if you wish. Sorry if it doesn't go low enough, it was meant for higher horsepower motors, it's just a general chart, not to the dot of every motor and pump, but pretty close. But I still don't think it takes 600hp to turn a Berk A 5500RPM....
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi20.tinypic.com%2Ffep3r8.jpg&hash=67189c7764b6d2e61bcc5858a79d3c0899b55a42)
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;D
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Yea I know there's that one, but he doesn't believe that chart is somewhat accurate at all
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Yea I know there's that one, but he doesn't believe that chart is somewhat accurate at all
One is for more HP than the other. It has seemed to me that there is a 50/50 split as to how accurate it is. I think the bottom chart is a Berkeley chart. The chart is designed to be a general guidline in which relatively stock pumps are used. A friend of mine has a Eliminator with a 516 c.u. Ford, full roller 600+ gross lift, flocker hasn't GPS'ed it yet, should be 75 - 85 mph, chart says he has about 380 HP.
::)
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Well different impellers make different RPM's. Being detailed and all that fun stuff makes differences too. The extended chart is just for general berkeley impellers. It was made with many boats with many different horsepowers. But it's as close as you can get to actually representation. The normal chart worked for me, but UNDONE had said it isn't even close to real life, so I had this chart and I know it's from research and development
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Berkeley hasn't done research and development since the 70's all of their stuff is circa the 70's. Call them up and ask them how many engineers they have working there... They don't even make their own parts. A lot of it is sub-conned out. some of it sub-conned out to mexico. Berkeley is now on their second or third set of stockholders and they base production off of old drawings and molds. You have shops like Tom's who tweak them and make them do what they should do, but Berkeley plays a minimal direct role in the development of go-fast and the collection of data that comes along with go-fast.
I trust nothing Berkeley has to say. Everytime I had a question for them, they couldn't find anyone to answer the question. I am sorry, I was mixing up aggressor numbers with the berkeley. My boat was turning a clean 550HP and was hitting 5100RPM's with the A-cut. Like I told you in the chat room the Aggressor is a bit more aggressive in it's cut than the Berkeley.
The point being, if you're turning that many RPM's and making that much power. You should be doing more than 64 MPH.
Oh shit, I just remembered he's running a B cut impeller........ So now he's just wasting fuel and sacrificing MPH....... oops.
P.S. That second chart is much closer to right on. It suggests about 530-550HP to push 5500 with the A cut.
The B suggesting 430-450.
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Actually that's what I was figuiring too undone. I thought the aggressor impellers took a different bite than berks. I've been told my Jacuzzi B impeller is closer to a Berk A. But this is a cool chart for all you high horsepower guys. This chart is as close as you can get ;)
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Just to mix things up a bit :D
My Hondo has a mild 454 with unknown hours, a Jacuzzi WJ (tag says B impeller) that I was told has a recent $1000.00 overhaul (nobody could produce receipts)
On ok water at Parker the best I've been able to get is GPS 52mph at 4500RPM ???
Engine sound good, seems to run strong but I ASSUMED that I would be running in the 60s without to much effort :'(
Where would be the best place to start looking for more speed?
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What kind of things are done to the 454?
My father has a t-deck Hondo I've tinkered with. Do you have a diverter?
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Berkeley hasn't done research and development since the 70's all of their stuff is circa the 70's ...
I am not sure why 1970's data for stock 1970's pumps wouldn't work in the 21st century as well as it did in the 1970's... ??? IMO most people who try to use the chart and are disappointed with the chart don't have stock Berkeley pumps, or for that matter don't even have Berkeley pumps. That's like trying to degree your BBF roller cam in with spec's for a Chevrolet flat tappet cam, the results are going to be different. ;D
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It still works, but thats exactly it. A lot of equipment is modified, or mix matched with other companies. To boot you have tolerances to consider, impeller size. Some bowls/impellers are only 9", most are 12", how many vanes does the bowl have? The chart leaves a lot to be desired and remember HP does not create RPM, torque does. If you're spinning 500HP and 200 ft/lbs, don't expect any 5000RPMs like the chart suggests.
So the chart is nothing more than a basic reference. Not a guideline. If anything it's a baseline. Thank you for clearing that up a bit Rod. Sorry I didn't elaborate.
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I wish those charts disappeared.
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I wish those charts disappeared.
Lol, why is that Brad?
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Lol, why is that Brad?
because they are misleading and sometimes get thrown around like they are factual information (which I know you stated you weren't) ....but it usually starts threads like this where theres miscommunication from both parties. They should never be used to make a point.
I think using them is like trying to predict the weather with an almanac. good for reference...and thats about it.
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I would trust the extended chart before the original berkely. I know it was made with research, Ill find the shops in just a second.
But what the chart doesn't show, like UNDONE said, is how much torque or horsepower it takes to get to that mark. It's just, your around this horsepower, at around this RPM. Doesn't mean if a motor makes 700hp at 6500 RPM is gonna turn that Rpm.
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Well said Brad. What time are you getting to Bako this weekend?
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Well said Brad. What time are you getting to Bako this weekend?
We will be rolling into camp Thursday night.
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For my experience, and that may not hold true for everyone and I not saying it will, this chart has been within "my ball park" approx. 200 rpm's either way. Let me do a little math: 6,000 rpm x 3% = 180 rpm. Well since I'm not building a missile here, just trying to push a boat at 100 mph I figured that was close enough.
It's not my chart and I don't have to defend it. Jac Seastrum put it together some years ago based off of information that he had accumulated over years of boat racing and wrenching as a "guide" to help people see if their set ups were " in the Ball Park". That's all it is just a guide and for my purposes it has been with in my margin of error, which would seem to be within yours(3%) also.
In any case I posted the Chart to be an aide for those who wanted more information than was available from the old Berkley chart. If it doesn't fit your needs ignore it.:idea: But for the average boat guy, about 95% of them I think it might be instructive.:)
Sleeper CP
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I understand, and you're right. That chart is much better than the Berkeley chart.
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I understand, and you're right. That chart is much better than the Berkeley chart.
I just wish that Chart went low enough for my shit! >:( ;D
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I just wish that Chart went low enough for my shit! >:( ;D
::) That's what the Berkeley chart (bottom of the two charts) is for...
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What kind of things are done to the 454?
My father has a t-deck Hondo I've tinkered with. Do you have a diverter?
Yes, it has a manuel Place diverter. I can feel a little change in speed by adjusting the diverter but nothing serious
I'm gonna guess low compression 454, I was told it has an Erson cam ???, short Offy tunnel ram with two 600 vacuum secondary holley carbs, Mallory dual point dist. I've got timing up to 33 total with no ping on pump gas.
From what I've learned so far, if the tolerances in the pump were excessive it would be pulling higher RPM, but since I can't get over 4500 RPM and have crappy top speed I think the engine is tired :-\