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GT Jets

  • Karma: +192/-0
Re: explain jets to me
« Reply #25 on: July 18, 2016, 03:42:43 PM »
So is this impeller trashed? Or can I detail and cleaned up to improve the flow?

For what its worth

I had the same problem before we cut it down to tighten the clearances up. And tightening it up did improve it.

You could either detail it out to smooth the shaft transition or cut the shaft for an inducer.

Where the hell is Joe?

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

69kona

  • Karma: +13/-0
Re: explain jets to me
« Reply #26 on: July 18, 2016, 03:43:05 PM »

The nose on that impeller is an obstruction causing gigantic amounts of aeration in the eye over the impeller,  blows a huge hole in the water.

Notice the thickness at the shaft shoulder? Never work.

The Berkeley impeller likely has a shoulder the same as the shaft.

Mystery solved.

GT
Mystery not solved it cavitated before the impeller was cut.... Just saying


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steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #27 on: July 18, 2016, 03:45:42 PM »
Mystery not solved it cavitated before the impeller was cut.... Just saying


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yeah that is true. It was cavitating worse before we cut it down.

But now im wondering if from the factory the AT is a thicker shoulder there and thats why it cavitated when it was new and after.

Maybe ill get down and dirty with my dremel and clean this up and try it again to see what happens.

OR just finally add an inducer
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GT Jets

  • Karma: +192/-0
Re: explain jets to me
« Reply #28 on: July 18, 2016, 03:46:06 PM »
Mystery not solved it cavitated before the impeller was cut.... Just saying


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What was cut? The thrust face or the wear ring face?

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

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Ray

steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #29 on: July 18, 2016, 03:49:47 PM »
What was cut? The thrust face or the wear ring face?

GT

If thrust face is the area that you are talking about, Yes that was cut down.

We also cut down the back side of the impeller so we could bring the clearances to .030

heres a picture where we cut, both faces where there is blue

If i remember correctly my front clearances were massive before we cut it. Somewhere around .125 and .140 between the front of the impeller, and the "back" where the .140 is in the picture



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steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #30 on: July 18, 2016, 03:50:42 PM »
these clearances were from the impeller to the suction housing.

We cut both sides enough to bring the clearance to .030 on both surfaces

BUT i had the cavitation worse before we did this. Figured the excessive clearance was why it was cavitating so badly.
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GT Jets

  • Karma: +192/-0
Re: explain jets to me
« Reply #31 on: July 18, 2016, 03:51:29 PM »
If thrust face is the area that you are talking about, Yes that was cut down.

We also cut down the back side of the impeller so we could bring the clearances to .030

heres a picture where we cut, both faces where there is blue

If i remember correctly my front clearances were massive before we cut it. Somewhere around .125 and .140 between the front of the impeller, and the "back" where the .140 is in the picture

Should have left it alone and used a shouldered ring.

JMHO, never cut the thrust face.
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #32 on: July 18, 2016, 03:56:45 PM »
Now, if i do buy an inducer, is it recommended to try to blend them together the best i can?
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69kona

  • Karma: +13/-0
Re: explain jets to me
« Reply #33 on: July 18, 2016, 04:03:08 PM »

Should have left it alone and used a shouldered ring.

JMHO, never cut the thrust face.
Right ... Steve told me to do it ..🤗🤗 lol I cut the shaft shoulder on them


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steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #34 on: July 18, 2016, 04:04:46 PM »
Right ... Steve told me to do it ..🤗🤗 lol I cut the shaft shoulder on them


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Hey now! When we talked about it we both agreed to do it!
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69kona

  • Karma: +13/-0
Re: explain jets to me
« Reply #35 on: July 18, 2016, 04:13:16 PM »

Hey now! When we talked about it we both agreed to do it!
Lol


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steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #36 on: July 18, 2016, 04:17:13 PM »
Lol


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and answer your damn phone!
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crusader1

  • Karma: +2/-0
Re: explain jets to me
« Reply #37 on: July 18, 2016, 05:57:52 PM »
Dumb question.... What makes a stainless impeller so much better than aluminum? Wear factor? I wouldn't think they deflect like a stern drive prop... I'm new too so just humor me 😁


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steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #38 on: July 18, 2016, 06:00:10 PM »
Dumb question.... What makes a stainless impeller so much better than aluminum? Wear factor? I wouldn't think they deflect like a stern drive prop... I'm new too so just humor me 😁


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Strength. I guess aluminum don't like to stick together at high rpm. Also if you shock load the pump it's hard on an aluminum one
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JordanDangerfield

  • Karma: +41/-0
Re: explain jets to me
« Reply #39 on: July 18, 2016, 06:00:39 PM »

Dumb question.... What makes a stainless impeller so much better than aluminum? Wear factor? I wouldn't think they deflect like a stern drive prop... I'm new too so just humor me 😁


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The aluminum impellers can't handle HP above ~500 or so. They crack and break.


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GT Jets

  • Karma: +192/-0
Re: explain jets to me
« Reply #40 on: July 18, 2016, 06:03:08 PM »
Dumb question.... What makes a stainless impeller so much better than aluminum? Wear factor? I wouldn't think they deflect like a stern drive prop... I'm new too so just humor me 😁


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An aluminum deflects and distorts in a major way. A stainless holds its shape much better and is not prone to the cavitation burn aluminum impellers are susceptible to.

GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #41 on: July 18, 2016, 06:05:05 PM »
The aluminum impellers can't handle HP above ~500 or so. They crack and break.


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Like this lol (about 600hp on the bottle)







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FordLover

  • Karma: +72/-0
Re: explain jets to me
« Reply #42 on: July 18, 2016, 06:14:50 PM »
The aluminum impellers can't handle HP above ~500 or so. They crack and break.


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Exactly!!!  Workin on breaking mine. Ya!!!
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crusader1

  • Karma: +2/-0
Re: explain jets to me
« Reply #43 on: July 18, 2016, 06:22:37 PM »
So a stainless one is a waste of money if I'm only pushing 350-400 hp?


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steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #44 on: July 18, 2016, 06:23:50 PM »
So a stainless one is a waste of money if I'm only pushing 350-400 hp?


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Do you suck up rocks and other shit often?
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crusader1

  • Karma: +2/-0
Re: explain jets to me
« Reply #45 on: July 18, 2016, 06:30:18 PM »
No rocks yet! But I've only had the boat a couple months. Been working some bugs out of it. Using it on one of the local lakes so nothing real shallow. Probably head to the river in the next week or two.


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steves86ta

  • Karma: +41/-0
Re: explain jets to me
« Reply #46 on: July 18, 2016, 06:40:53 PM »
No rocks yet! But I've only had the boat a couple months. Been working some bugs out of it. Using it on one of the local lakes so nothing real shallow. Probably head to the river in the next week or two.


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IMO I wouldn't spend the money
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crusader1

  • Karma: +2/-0
Re: explain jets to me
« Reply #47 on: July 18, 2016, 06:49:03 PM »

IMO I wouldn't spend the money


Kind of what I figured. Still getting used to all this stuff. Lot of info flying around on here! LOL


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GT Jets

  • Karma: +192/-0
Re: explain jets to me
« Reply #48 on: July 18, 2016, 07:02:42 PM »
So a stainless one is a waste of money if I'm only pushing 350-400 hp?


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All depends on where that hp comes from,  if it's at 8,000rpm, then you need a stainless. Under 5,500, you're good.

GT
« Last Edit: July 18, 2016, 08:04:51 PM by GT Jets »
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

crusader1

  • Karma: +2/-0
Re: explain jets to me
« Reply #49 on: July 18, 2016, 07:14:15 PM »

So a stainless one is a waste of money if I'm only pushing 350-400 hp?


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All depends on where that hp comes from,  if it's at 8,000rpm, then you need a stainless. Under 5,500, you're good.

GT

So it's more of an rpm issue and rotating mass? I was told by the guy I bought the boat from that the pump had work done to it. He didn't know exactly what though. How can you tell without pulling the pump apart what is in it? (As far as aluminum or stainless)


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