Impeller ?

[LVjetboy]

TTmott,
Your table has correct AT rpm data to 550 hp. But your graphs impeller sizes are shifted one size down for rpm vs. power. In other words, according to AT's data, an AT A should turn 4000 rpm w/200 hp applied to the impeller but your graph shows the AT B turning 4000 rpm w/200 hp applied to the impeller. Go back to your spread sheet and recheck your curves source data...you'll find the problem.
This is what AT impeller charts should look like based on their numbers up to 550 hp, and extrapolated above 550 hp...
http://members.cox.net/lvjetboy/AT.jpg
Besides the impeller size problem, your extrapolated numbers above 550 hp are not correct. Instead of interpolation, do a curve fit to AT's impeller data. Pumps typically follow a cubic power relationship. That's why your graph predicts a twin turbo BBC turning an AT 9.25 at 6100 RPM as well over 1000 hp. More realistic, a cubic power curve fit to AT's data like the one used by JPC predicts AT 9.25 at 6100 = 940 hp.
jer

[cyclone]

based upon data collected from my boat, LV's chart is correct.
AA impeller turning 6,450rpm-6,500 rpm
according to the dyno the my motor made right at 1,000 hp.

[LVjetboy]

396,
Those numbers most likely not a "perfect" pump, whatever that is. And I'd doubt a detailed impeller. In fact, AT's pump curves may be based on a static pit test with a production impeller and conditions where a loader makes little to no difference and excludes your intake efficiency at speed.
But your question is right on. Unfortunately, we jetters have little detailed info from mfgs other than generic pump curves and they don't seem to have much more or be willing to share. You think AT techs will enlighten us or spend RD $$ to know? Fat chance.
At least AT adds the disclaimer, "THESE RPM VALUES MAY VARY ACCORDING TO HOW YOUR BOAT ALLOWS THE PUMP TO LOAD" Yet they don't explain how impeller detailing or wear ring clearances may affect those rpms. I'd love to see detailed testing or anything from mfgs yet we get little to no real technical information. Jet pump technical data is one step above deliverance mentality and how to make good moonshine. Sad but true.
That said, published impeller curves are better than nothing...a starting point. Something to build on.
jer

[ttmott]

Thanks jer,
Your chart makes more sense and I agree. Good to get some advanced graphical data on the postings. Your graph should go in some tech archives or something for future reference....
It would be nice to see the manufacturers set up some standard parameters for pump testing (like an ANSI or SAE standard) and run the various impellers up through what they envision their limits of operation. The AT, Berk, and Seloc charts are too limited for today's applications. It used to be, of course, that the impellers were limited to 500 horsepower and 5000 RPM; maybe this is their limits of liability for the product even today. One can only speculate.
Tom

[396_WAYS_TO_SPIT]

396,
Those numbers most likely not a "perfect" pump, whatever that is. And I'd doubt a detailed impeller. In fact, AT's pump curves may be based on a static pit test with a production impeller and conditions where a loader makes little to no difference and excludes your intake efficiency at speed.
But your question is right on. Unfortunately, we jetters have little detailed info from mfgs other than generic pump curves and they don't seem to have much more or be willing to share. You think AT techs will enlighten us or spend RD $$ to know? Fat chance.
At least AT adds the disclaimer, "THESE RPM VALUES MAY VARY ACCORDING TO HOW YOUR BOAT ALLOWS THE PUMP TO LOAD" Yet they don't explain how impeller detailing or wear ring clearances may affect those rpms. I'd love to see detailed testing or anything from mfgs yet we get little to no real technical information. Jet pump technical data is one step above deliverance mentality and how to make good moonshine. Sad but true.
That said, published impeller curves are better than nothing...a starting point. Something to build on.
jer
Good info jer Thanks for the time and knowledge info. Alot of us appreciate your knowledge
396

[BrendellaJet]

6700 is a tall number with a big impeller.
Then why did you recommend he start with an AA? :argue: