Pump RPM ?

[BK]

Does this chart seem correct?
AT Impeller Chart (http://www.americanturbine.com/infor...hart_sd309.htm)
My new boat has an American Turbine SD 309 (9.5") and im turning it just under 4900 rpm's. I was turning a berkely with an A imp. 5300 rpm with this motor in my other boat. Just currious if it realy takes that much more HP to turne the AT that a berk.

[Squirtcha?]

I think the latest version of LVjetboy's jet pump calculator includes AT's 9.5" impeller in the pulldown menus.
You could figure it out but you'd need the speed numbers from both boats at WOT, or an accurate HP rating on your motor, to fill in the blanks (I think).
Or cross reference between AT's chart, and Berkeley's. Check to see how much horsepower each impeller requires to turn at their respective rpm and see if the horsepower numbers match up.
Probably some other factors to consider too, but it'd put you in the ballpark anyway.

[BK]

Do you have a link to it?

[Squirtcha?]

Sorry, no BK. My kids download everything under the sun and I got so infested with virus and popups, I ended up f disking my harddrive. Tried to fix it for weeks, got pissed and tossed the whole lot. Lost lotsa good stuff too.
I might have a copy on one of my laptops. I'll check it out. If I find it........I'll email you a copy of it. I know I have the first version, but it didn't have any AT stuff in the program.

[LVjetboy]

BK, here ya go...
JPC (http://members.cox.net/lvjetboy/JPC.zip)
Have fun. As to your questions...
"Does this chart seem correct? Link: AT Impeller Chart."
That chart is also referenced in Seloc and is the best information I have for AT Impellers. Is it accurate? I suppose the AT dudes who came up with the chart could answer best. At least they may explain their method and maybe estimate an error margin. Lacking that, I'd say it's the best we got.
"My new boat has an American Turbine SD 309 (9.5") and im turning it just under 4900 rpm's. I was turning a berkely with an A imp. 5300 rpm with this motor in my other boat. Just currious if it realy takes that much more HP to turne the AT that a berk."
Yes and no. How much power depends not only on impeller mfg (impeller blade shape) but also cut. A variation in blade shape or aggressiveness can make one brand require more power than another even w/the same cut and at the same rpm. Adding complexity, not all mfg's define cut size the same.
According to charts, at the same rpm an AT A and a Berk A absorb the same power. Their large and small diameter cut specs identical for the A. So their blade profiles must be similar. But, the AT AA and Berk AA cut specs are different. And not surprisingly, their AA impellers absorb different power at the same rpm.
That said, an AT 9.5 at 4850 rpm requires 560 hp, the Berk A at 5300 rpm 470 hp. Obviously, those numbers don't match. My first thought, similar DA conditions? Then, how well intakes loaded? Finally, how accurate the tach?
jer

[BK]

Jer, thanks for the link.
I know the tach is accurate. The pump was gone through by MPD. He built a custom back cut shoe, loader and it has a ride plate. He reworked the original AA impeller and bowl also so I know the pump is set up well. The guy I bought it from was turning the pump 5300rpm with 650 HP, mines around 500hp. I was told it takes more power with the larger 9.5" bowl?

[LVjetboy]

I don't think bowl size influences power required. When the bowl gets it, the impeller's already done with it. And the engine doesn't seem to care. Yes a larger bowl allows a bigger impeller which can absorb more power...but that because of impeller size, not bowl size. So I'm thinking if someone told you a big bowl takes more power regardless of impeller...well
But there's another possibility. Have you checked that AT impeller in your new boat to verify it's a 9.5...not cut down to A2 specs? If an A2 cut, then your 500 hp engine (turning your old Berk A to 5300 rpm) would turn an AT A2 to about 4900 rpm...and your test numbers jive. Or if the impeller really is a 9.5 maybe the blades not fully loaded (cavitation) or excessive wear ring clearance or some other typical thing not always mentioned or accounted for...later blamed on the curves?
Just kicking around ideas, don't know what you have other than this short thread. Also don't know the history or conditions of your testing. Those kinda things seem trivial but in the end may answer many questions. And maybe I'm not addressing your real question...
jer