Impeller selection help

# Thread: Impeller selection help

1. ## Impeller selection help

So we know this person that just bought a jet boat. It's a light boat with a split bowl Berk.

The engine makes 700 HP at 6,000 RPM and keeps it there to 6,500 RPM.
it makes 650 ft/lbs at 4,000

If this person were to attempt to pick the correct impeller. What the best direction to go?

2.

3. Originally Posted by Infomaniac
So we know this person that just bought a jet boat. It's a light boat with a split bowl Berk.

The engine makes 700 HP at 6,000 RPM and keeps it there to 6,500 RPM.
it makes 650 ft/lbs at 4,000

If this person were to attempt to pick the correct impeller. What the best direction to go?
Bronze or stainless "B" would be my first guess. I spin an AB to 6200 with about 100 hp more.

19' Tunnel hull medium lay up
950HP
6500rpm

5.

6. ## info

Originally Posted by rIVERtRASH

19' Tunnel hull medium lay up
950HP
6500rpm
if you want your motor to spin that rpm.i would go "B".i have 845hp and it spins it at 6200

7. Originally Posted by rIVERtRASH

Man 3rd post is a thread jack.

So... if a "B" is the ticket. What does that do to a holeshot vs an A or AA? And do you put an inducer in it to make up the difference? Or a HH C?

8. How many cubes? Forced induction or not? Ron at AT once told me most aa cuts are either stock, or blown/ forced induction application. I'd go aa or a , it's hard to cut it backwards

9. ## Holeshot

How big is the boat?

10. It's a Rogers Dragstar. Engine is 450 cubes big compression and alcohol carbs on a tunnel ram.

11. If it makes 700 HP at 6K why spin it on up
an A shows 700 HP at 6K on the chart then you can always cut it if its too much IMO

12. Originally Posted by Outlaw
If it makes 700 HP at 6K why spin it on up
an A shows 700 HP at 6K on the chart then you can always cut it if its too much IMO
I must have an old chart. Can you post it pleezzz...

13. sure It will be a few , Im on my PC in the shop
and its on my Home one

14. REMEMBER YOU CAN ALWAYS CUT A BIGGER IMPELLER DOWN, ITS HARD TO PUT IT BACK ON...LOL

15. The chart above seems to be the most consistent with what I've found.
Ron, IMO, if you know the engine's power curve, just put the biggest impeller in it that the engine can stay ahead of, up to the engine's peak power. As long as the engine's power stays ahead of the impeller's power consumption, the impeller should continue to pull. If you think you want more rpm on top, then you can start trimming the impeller...that is, if you know someone with a lathe...
Like said above, it's easier to start big and go smaller. Don't forget the impeller chart is showing actual power at the impeller, not corrected dyno power.

16. ## chart

after looking at the chart posted.maybe i have an "A". it has alot of detailing done to it. might be cut down.

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