The answer is going to piss you off.

All the lower numbers ate very low hp. It's not until you get near WOT that any horsepower is being generated.

Your not spinning a prop that has a pretty good bite on the water,  you are squirting water at high pressure to create thrust. You could hold your boat back with a fairly small rope. Whereas the prop boat can't be held back as easily.

The thrust required to get the hull freed up from the drag of the water is on the higher horsepower,  it has zero to do with actual rpm.

Your understanding of impeller cut is 100% backward,  the C cut impeller is much smaller than an A. You can cut an A to a C, but not the other way around.

The more impeller,  the more HP it takes to spin.

The reason an impeller is "cut down" is to get the engine the ability to turn it's optimum rpm to get the most hp out of it.



In short,  rpm is not speed,  hydrodynamic drag, nozzle volume and velocity determine the speed.

And that Spectra bottom is like the cute chubby chick at the bar,  built for comfort,  not speed. Lol

GT

Good question and good answer from the both of yuhs. 

So in short, I drop a B or C in from the A I have now I then go faster?

The way i understand it, and GT please correct me if i am wrong.

You could go to a B or C and gain some top end RPM. But you are moving less water so you may or may not go any faster.

Maybe i explained incorrectly. That is exactly how i understood the cuts. Basically i understood it as an AB impeller moving more water than a C impeller at the same RPM.

So if i understand correctly. Even though the top RPM is about the same, and he is running a "bigger" impeller i am creating more thrust?

Okay! Last question and then i promise im dropping it. I learned a lot

Im spraying pretty good out of my pivot holes for my reverse bucket (reverse cable broke) How bad is this effecting the nozzle pressure? I would htink it would have the effect of going to about an inch larger nozzle since the pins are what half inch or so?

lmao i didnt even think about that. Oh well made for a funny looking video.

Thank you for your information, this is why we come here.  And the answer nowhere near pissed me off lol

Now if you could figure out why this C impeller actually launches, vs the American Turbine B- i had that would cavitate like a mofo that would be great.

The AT measured at .012 on each side if i remember correctly. Std wear ring, and its also a brand new impeller.

Front/rear clearance was machined down to be .030"

Even added a stuffer with .030" clearance and still cavitated like a mofo

Put the box stock berkeley in, took the stuffer out (wouldnt fit) and it works great

Ok, swap out the aluminum A for a stainless A(and whatever else would need to be changed to make it work) does that improve performance? Better handles the FORD power?

The AT measured at .012 on each side if i remember correctly. Std wear ring, and its also a brand new impeller.

Front/rear clearance was machined down to be .030"

Even added a stuffer with .030" clearance and still cavitated like a mofo

Put the box stock berkeley in, took the stuffer out (wouldnt fit) and it works great