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Discussion Starter #1 (Edited)
Had the boat out this weekend in some good wind and about 8-10in chop ( thunderstorms kicked up with 30-35mph head winds ) boat loves the air packs. my problem is When i get on it harder than 5k the rpms come up but i dont feel the increase in speed.Basically stops pulling after 5k . im pretty sure its not unloading the pump as it runs strong at 5k . Before this trip i trimmed the loader back 1/4 in and am now running level with the keel. The boat is running fairly dry and love the way it rides right now but i think im leaving some mph on the table. Forgot the gps so no actual numbers to back it up. anyone have any thoughts?

21 daytona
468 - estimated 600 hp
Turning a bronse a/b 5600
loader level with keel
2 deg back cut .150 up
place droop droop with no wedge
intake set at 4.5 deg
22in rideplate @ 2deg up
pump set back handhole 3/4in out
 

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Boat Nut
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Is your boat a flat keel boat? If so they need the hardware to hang down.... once the rounded keel is put on, you can drag less hardware.
 

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Had the boat out this weekend in some good wind and about 8-10in chop ( thunderstorms kicked up with 30-35mph head winds ) boat loves the air packs. my problem is When i get on it harder than 5k the rpms come up but i dont feel the increase in speed.Basically stops pulling after 5k . im pretty sure its not unloading the pump as it runs strong at 5k . Before this trip i trimmed the loader back 1/4 in and am now running level with the keel. The boat is running fairly dry and love the way it rides right now but i think im leaving some mph on the table. Forgot the gps so no actual numbers to back it up. anyone have any thoughts?

21 daytona
468 - estimated 600 hp
Turning a bronse a/b 5600
loader level with keel
2 deg back cut .150 up
place droop droop with no wedge
intake set at 4.5 deg
22in rideplate @ 2deg up
pump set back handhole 3/4 out
I am by no means (below a novice) a guru. but maybe it has absorbed all the power the a/b cut could handle? again no expert tho. look at the edges of the impeller have nicks in it not giving it the bite at high RPM's... again just kinda join off of what i picked up on the forums
 

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custom member
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Discussion Starter #4 (Edited)
Is your boat a flat keel boat? If so they need the hardware to hang down.... once the rounded keel is put on, you can drag less hardware.
boat has the rounded keel! was originally an i/o

I am by no means (below a novice) a guru. but maybe it has absorbed all the power the a/b cut could handle? again no expert tho. look at the edges of the impeller have nicks in it not giving it the bite at high RPM's... again just kinda join off of what i picked up on the forums
The impeller is in excellent shape! not a single nick!
 

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I decided to tap my intake so I could see how my pump was loading and take the guess work out of the equation .......even with a round keel I have my shoe hanging down a little.
Good luck with it....love my 21 tona.
 

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Discussion Starter #6
I decided to tap my intake so I could see how my pump was loading and take the guess work out of the equation .......even with a round keel I have my shoe hanging down a little.
Good luck with it....love my 21 tona.
Tapping for pressure is in the plan but was hoping to wait till the blower motor went in over the winter! looks like thats not gonna be able to wait!
 

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You stated that you trimmed the loader ramps or as many call them (stingers) even with the rounded keel.
You didn't mention when you cut the loader if you angled the stingers or left them at 90/degrees to the keels center-line.
Being the loss of pull happened after you trimmed the stingers, maybe now you're not getting enough water to the upper portion of the impeller. Or, maybe the flow is disturbed because you didn't arrow-head or follow the keels radius.
Shoe biting edge in relation to the keel .150 up???
I'll be looking for some feedback from the pump gurus too.
 

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I decided to tap my intake so I could see how my pump was loading and take the guess work out of the equation .......even with a round keel I have my shoe hanging down a little.
Good luck with it....love my 21 tona.
Curiosity has me asking...
1) where and how is your loader trimmed?
2) shoe type and biting edge location to the keel?
3) did you tap the intake in two locations or one...and where is it 'clocked'?
4) what pressures are you getting as the result of questions 1, 2 & maybe 3 ?
 

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Curiosity has me asking...
1) where and how is your loader trimmed?
2) shoe type and biting edge location to the keel?
3) did you tap the intake in two locations or one...and where is it 'clocked'?
4) what pressures are you getting as the result of questions 1, 2 & maybe 3 ?
Loader is angle trimed....like the one in your pic. Its pretty much level with the keel...maybe down a c-hair.

Off memory the shoe is back cut 2.5 degrees...and is down 1/4" to 3/16"

Its tapped high and low....prox 1;30 and 5;00

from zero to about 30 mph or so.....I don't have any pressure registering on the bottom tap. Proppy and I were talking a year or so back....he thinks that may be because my bottom tap pokes in about 1/4" or so....where as the top one is perfectly flush with the inside. One of these days I need to fix the bottom one.

At wot I have about 40-50 psi on top and bottom.

A year or so back I had a intermittent mini hop/porpose at wot...was seeing 50 psi plus. I took some shoe out and it seemed to cure that.

The best bang for the buck I did to my tona was adding a 24" ride plate (per supersoakers suggestion) and dropping it to about 1.5*.
 

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Discussion Starter #10
You stated that you trimmed the loader ramps or as many call them (stingers) even with the rounded keel.
You didn't mention when you cut the loader if you angled the stingers or left them at 90/degrees to the keels center-line.
Being the loss of pull happened after you trimmed the stingers, maybe now you're not getting enough water to the upper portion of the impeller. Or, maybe the flow is disturbed because you didn't arrow-head or follow the keels radius.
Shoe biting edge in relation to the keel .150 up???
I'll be looking for some feedback from the pump gurus too.
Yes the loader is trimmed like the pic. This was a totally different loader , although same maker and design, so looks like im going to go back to my original loader and see what affect that has. I did forget to mention i was originally running an alum impeller and just recently ( 2 trips out) put the new bronse impeller in. Im almost possitive the impeller is not the problem as it is in like new shape. not even a knick on it! just when I start moving forward I get this. Looks like im going back to a Known good tune until I have time to spend a day playing with it and recording numbers!
 

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Discussion Starter #13
What size was the old impeller?
old impeller was a/b.

Had a talk earlier today with Tom and Josh and I think figured out the problem. Im running what Im being told is probably an older Dominator Impeller. Well it originally had a 3/4 Wear ring skirt that i machined to 1in. Thus moving the impeller 1/4in away from the stuffer. IM going to test this theroy and will report the outcome! Thanks all for the help so far!
 

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old impeller was a/b.

Had a talk earlier today with Tom and Josh and I think figured out the problem. Im running what Im being told is probably an older Dominator Impeller. Well it originally had a 3/4 Wear ring skirt that i machined to 1in. Thus moving the impeller 1/4in away from the stuffer. IM going to test this theroy and will report the outcome! Thanks all for the help so far!
Also the cut ended up moving the impeller exit blades much further from the bowl stator blades/viens
 
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