SoCal Jet Boats

Tech Talk => Jet Pumps => Topic started by: steves86ta on March 01, 2016, 04:13:37 PM

Title: Cavitation Talk
Post by: steves86ta on March 01, 2016, 04:13:37 PM
Since the boats in storage, and im bored and exercising my google-fu today. I wanted to make a thread asking a couple questions. More for knowledge/education than anything

I have a Rogers, 5.3 LS powered.

According to the impeller chart im making somewhere in the neighborhood of 400-425 hp on motor @ 5200 rpm, and about 600 on a 150hp shot spinning about 6200 rpm or so with a B- AT impeller.

The boat runs 70 on motor (repeatably have seen higher a couple times) and 85 on the bottle on GPS.

Heres where my Cavitation questions come in.

The Pump is a JC suction housing, Dominator Bowl, AT aluminum impeller. No inducer, no stuffer, everything is stock. Has a loader by GS i dont know what kind, and i believe a Backcut shoe. No Diverter, Full droop with a set of adjustable wedges. Wedges are setup at 3*up and i also have a rideplate. I dont know the angle of the rideplate somewhere around 3.75 degrees

Before the intake there is a pretty bad transition, think a Flat intake in a rounded hull. And not blended in. I have corrected this, but have not taken the boat out since.

I just put a brand new AT impeller in that was cut down for me to a B-, other than that the impeller is stock and non-detailed. I put a brand new non shouldered stainless wear ring in with this impeller. Clearance measured out to about .024" total. I did not check for runout.

What happens?

If i flat foot it from idle, the boat will literally bounce off the rev limiter as long as i keep my foot flat (rev limiter is 7200). The boat does move and accelerate)

If i Flat foot it from idle, here it come "unhooked" and back off the throttle, hold a steady throttle about half or so. Then stab it, its fine and pulls to my max RPM and holds

If i dont flat foot it, but get on it spiritedly wait til the boat planes then stab it she loads well and takes off pretty nicely. Will pull hard and run to WOT no problem

If i'm cruising from plane (say 3-3500 rpm or 45mph or so) and stab the throttle. The boat pulls to WOT and holds hard and accelerates very nicely

If i wait until the boat planes, and grab the Nitrous it hits hard as hell and pulls to the max RPM and the boat accelerates as expected.

I have not hit the nitrous from idle because i know the boats going to nail the rev limiter. Something i DO NOT want to do on the bottle.

Basically the boat blows the pump out from idle, but once im moving its fine.

I have a couple of thoughts, but id like to hear your ideas.

1. With no diverter, i go so bow up (from the droop/up angle) that it uncovers the jet intake, causing it to suck air
2. my pump is shitty and i need to stop being cheap and have it built
3. I need to buy a diverter (again stop being cheap)
4. The transition into the intake was the issue, everything will be fixed when you take it out
5. Im an idiot, and doing everything wrong
6. LS engines wont work in a jet boat

Last one is a joke, but id still like to hear everyones thoughts.
Title: Re: Cavitation Talk
Post by: jyeager on March 01, 2016, 04:19:24 PM
Your unloading, throw a diverter on there. You also may gain a few mph.

Also there's no need to grab the nitrous right off the hit. Wait a second or 2


Sent from McIntyre Park
Title: Re: Cavitation Talk
Post by: jyeager on March 01, 2016, 04:20:06 PM
Give her 2 degrees of down and 6 up 👍🏻


Sent from McIntyre Park
Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 04:30:56 PM
Give her 2 degrees of down and 6 up 👍🏻


Sent from McIntyre Park

You mean, wedge the droop down 2 degrees, and set the nozzle stop at 6 degrees up?
Title: Re: Cavitation Talk
Post by: jyeager on March 01, 2016, 04:43:45 PM

You mean, wedge the droop down 2 degrees, and set the nozzle stop at 6 degrees up?
Put a diverter on the thing. Give it 2 degrees of down nozzle on the hit. And 6 degrees of up nozzle once you are going.
Make a stop for the up nozzle( in red)
Make a stop for the down nozzle (blue)


Sent from McIntyre Park
Title: Re: Cavitation Talk
Post by: GT Jets on March 01, 2016, 04:47:21 PM
How new is the pumps packing? Is the cleanout tight?
Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 04:49:11 PM
Put a diverter on the thing. Give it 2 degrees of down nozzle on the hit. And 6 degrees of up nozzle once you are going.
Make a stop for the up nozzle( in red)
Make a stop for the down nozzle (blue)


Sent from McIntyre Park

Any ideas on how to do a stop with a manual diverter?
Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 04:50:18 PM
How new is the pumps packing? Is the cleanout tight?

Brand new rope seals. They drip water about once every 30 seconds or so

Clean out is very tight with a brand new o ring/seal thingy. Also permanently closed now that it has transom plates. If i suck up a rope im effed
Title: Re: Cavitation Talk
Post by: GT Jets on March 01, 2016, 05:08:48 PM
Brand new rope seals. They drip water about once every 30 seconds or so

Clean out is very tight with a brand new o ring/seal thingy. Also permanently closed now that it has transom plates. If i suck up a rope im effed

You're f'ed even if you had a cleanout. Lol

Just for shits and giggles,  tighten the gland nuts a little then back them off again.

GT
Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 05:39:32 PM
You're f'ed even if you had a cleanout. Lol

Just for shits and giggles,  tighten the gland nuts a little then back them off again.

GT

I'll try that. But I think I'm being cheap. Need to save up and here me a diverter
Title: Re: Cavitation Talk
Post by: 69kona on March 01, 2016, 05:44:05 PM
Hey Steve u don't think it's more of a slip in the pump ... Kinda acting like a stall convertor  in a automatic transmission?
Just throwing it out there..... From what I hear from sitting on the beach


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Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 05:44:55 PM
Hey Steve u don't think it's more of a slip in the pump ... Kinda acting like a stall convertor  in a automatic transmission?
Just throwing it out there..... From what I hear from sitting on the beach


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That's exactly what it is. But there's no gears or anything to "slip"
Title: Re: Cavitation Talk
Post by: 69kona on March 01, 2016, 05:49:19 PM
Just leave it! ... I'm still trying to get my boat dialed in too pull u now lol..
U fix it I'm really gonna have to do my homework...😜


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Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 05:50:32 PM
Just leave it! ... I'm still trying to get my boat dialed in too pull u now lol..
U fix it I'm really gonna have to do my homework...😜


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LOL!  I wanna get this fixed then start to bump the nitrous up. Picked up 2 new sets of plugs both colder for more nitrous
Title: Re: Cavitation Talk
Post by: 69kona on March 01, 2016, 05:53:57 PM
Nice! I'm gonna have to step it up a little more lol..I curious the gap from face of wear ring to impeller is?



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Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 05:55:29 PM
Nice! I'm gonna have to step it up a little more lol..I curious the gap from face of wear ring to impeller is?



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Do you mean side clearance?

About. 012 on each side

Its a non shouldered wear ring
Title: Re: Cavitation Talk
Post by: 69kona on March 01, 2016, 05:59:50 PM
No from shoulder of wear ring  even if it's not a shoulder wear ring. If the gap is executive might make it slip just throwing it out there..


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Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 06:04:42 PM
No from shoulder of wear ring  even if it's not a shoulder wear ring. If the gap is executive might make it slip just throwing it out there..


Sent from my iPhone using SoCal Jet Boats

I'll be honest I didn't measure that.  It bottomed out in the case.

And I bottomed the impeller out or so I think? 

I guess I could pull the bowl and measure that?  If I was able to bottom the impeller out is it possible its to far from there?
Title: Re: Cavitation Talk
Post by: GT Jets on March 01, 2016, 06:24:38 PM
So what you're experiencing is called low NPSH.

Look it up in engineering toolbox.

When the boat is idling at rest,  there is very little volume in the pump. This creates a fairly low pressure differential across the impeller.

When you hammer down, there is a very sudden and drastic increase in the pressure differential with the low side (suction side) being too low for the impeller to "suck" the water and the slightest little bit of air makes the impeller "blow a hole" in what should be a solid,  pressurized column of water.

The loader does "ZERO" to load the impeller without forward movement. This is where an inducer comes in.

A few things need to be checked before taking that drastic step.

Make sure there is no way air can be pulled in through the packing. I use the graphite impregnated seals and make sure it is snug. You should see approximately 1 drop every few minutes at rest. While running, it may not leak at idle,  but will drip as the intake pressure increases.

This should never exceed 10-15 drops a minute.

The cleanout is another potential air source.

One stupid trick is in the drivers control.

Double tap the throttle on take off, in other words,  blip the throttle a split second before hammer down. This purges any air from the pump.

Hull design, water conditions and overall pump set up all come into play when looking at these scenarios.

A Diverter can help, but it is still entirely dependent on forward hull movement.

Good luck
Title: Re: Cavitation Talk
Post by: steves86ta on March 01, 2016, 06:32:12 PM
So what you're experiencing is called low NPSH.

Look it up in engineering toolbox.

When the boat is idling at rest,  there is very little volume in the pump. This creates a fairly low pressure differential across the impeller.

When you hammer down, there is a very sudden and drastic increase in the pressure differential with the low side (suction side) being too low for the impeller to "suck" the water and the slightest little bit of air makes the impeller "blow a hole" in what should be a solid,  pressurized column of water.

The loader does "ZERO" to load the impeller without forward movement. This is where an inducer comes in.

A few things need to be checked before taking that drastic step.

Make sure there is no way air can be pulled in through the packing. I use the graphite impregnated seals and make sure it is snug. You should see approximately 1 drop every few minutes at rest. While running, it may not leak at idle,  but will drip as the intake pressure increases.

This should never exceed 10-15 drops a minute.

The cleanout is another potential air source.

One stupid trick is in the drivers control.

Double tap the throttle on take off, in other words,  blip the throttle a split second before hammer down. This purges any air from the pump.

Hull design, water conditions and overall pump set up all come into play when looking at these scenarios.

A Diverter can help, but it is still entirely dependent on forward hull movement.

Good luck

Thank you for the info.

My rope seals are the graphite ones. I can for sure tighten it up more

The blipping thing may help. Also the disturbance before the intake might have hurt the scenario as well.

I think I'm gtg on the clean out. Its very tight and. Brand new seal.  Buy I'll double check the tightness.

Its also silicones around it. 

I'm curious if the double tap will help.

Wouldn't the pump such air all the time regardless if I was at idle or moving? If that was the case?
Title: Re: Cavitation Talk
Post by: jyeager on March 01, 2016, 09:22:56 PM

Any ideas on how to do a stop with a manual diverter?
You can put washers in between there to stop the travel. Or just adjust it t where the first or second notch back is 2* down.


Sent from McIntyre Park
Title: Re: Cavitation Talk
Post by: jyeager on March 01, 2016, 09:23:41 PM
Also what kind of shoe do you have and what is the size opening?


Sent from McIntyre Park
Title: Re: Cavitation Talk
Post by: steves86ta on March 02, 2016, 06:07:38 AM
Also what kind of shoe do you have and what is the size opening?


Sent from McIntyre Park

This I'm not sure of. I think it's a back cut shoe

The opening is have to measure
Title: Re: Cavitation Talk
Post by: jimpen on March 02, 2016, 08:55:33 AM
GT is right most of the stuff being discussed will only help with forward movement. Install a inducer and no NOS until wide open throttle. The work you did to the bottom may or may not help but from a dig there will not be a change. 


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Title: Re: Cavitation Talk
Post by: GT Jets on March 02, 2016, 09:19:37 AM
Since the boats in storage, and im bored and exercising my google-fu today. I wanted to make a thread asking a couple questions. More for knowledge/education than anything

I have a Rogers, 5.3 LS powered.

According to the impeller chart im making somewhere in the neighborhood of 400-425 hp on motor @ 5200 rpm, and about 600 on a 150hp shot spinning about 6200 rpm or so with a B- AT impeller.

The boat runs 70 on motor (repeatably have seen higher a couple times) and 85 on the bottle on GPS.

Heres where my Cavitation questions come in.

The Pump is a JC suction housing, Dominator Bowl, AT aluminum impeller. No inducer, no stuffer, everything is stock. Has a loader by GS i dont know what kind, and i believe a Backcut shoe. No Diverter, Full droop with a set of adjustable wedges. Wedges are setup at 3*up and i also have a rideplate. I dont know the angle of the rideplate somewhere around 3.75 degrees

Before the intake there is a pretty bad transition, think a Flat intake in a rounded hull. And not blended in. I have corrected this, but have not taken the boat out since.

Ride plate should be a negative.  (Up from keel line) in other words it would read -3.75°. It should not be down from the keel line, especially with a back cut shoe.

Do you have a bowl bleed?

GT
Title: Re: Cavitation Talk
Post by: steves86ta on March 02, 2016, 09:34:21 AM
The more i think about this the more things i start to remember

When i first built the jet/boat and would launch it it would pull past the max rpm but not by much. Maybe 4-500 rpm then load up and come down. I did blend the intake in when i first put the boat together but only used regular body filler.

Then one trip out to the avi, i took a rather spirited turn and the boat caivtated really badly. The only thing i noticed different per say after this spirited turn, was my filler was gone and the bad entry is back. The cavitation issue started shortly after, probably at the same time. I cant be sure because it went on the trailer immediately afterwards.

Couple of trains of though here...

1. The entry to the intake being blended was helping, and that's why it wasn't so bad
2. Now that the engine is making good power and running correctly i'm just blowing through it and cavitating from the other reasons mentioned in this thread.

Just a little more information to share.
Title: Re: Cavitation Talk
Post by: steves86ta on March 02, 2016, 09:35:10 AM
Ride plate should be a negative.  (Up from keel line) in other words it would read -3.75°. It should not be down from the keel line, especially with a back cut shoe.

Do you have a bowl blead?

GT

Yes thats what i mean, it would be a negative angle.

And no bowl blead
Title: Re: Cavitation Talk
Post by: GT Jets on March 02, 2016, 10:54:02 AM
The more I think about this,  the more I feel you have a funky intake install.

Do you have any pictures of the intake from the bottom?
Title: Re: Cavitation Talk
Post by: steves86ta on March 02, 2016, 11:05:31 AM
The more I think about this,  the more I feel you have a funky intake install.

Do you have any pictures of the intake from the bottom?

Thats what im thinking too. Unfortunately i dont have any pictures.

i can try to explain it

Flat intake in a rounded keel.

The intkae is approx 1/2-3/4" above the keel, and then needs to be blended in.
Title: Re: Cavitation Talk
Post by: GT Jets on March 02, 2016, 11:23:34 AM
Thats what im thinking too. Unfortunately i dont have any pictures.

i can try to explain it

Flat intake in a rounded keel.

The intkae is approx 1/2-3/4" above the keel, and then needs to be blended in.

This would put the intake too high in the hull.

Without a spoon before the opening it will never really work right. IMO anyway.

Has it been set back?  I thought I read it was.

GT

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Title: Re: Cavitation Talk
Post by: steves86ta on March 02, 2016, 12:06:43 PM
This would put the intake too high in the hull.

Without a spoon before the opening it will never really work right. IMO anyway.

Has it been set back?  I thought I read it was.

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

I might be over estimating that, it may only be that 1/2"-3/4" because they took a flat intake and ground it round kinda? Its hard to explain. But the shop that did this work IMO did a pretty shotty job.

MY pump is in the stock location for the Roger's. Its what some call a half set back. The hand hole is about halfway out.
Title: Re: Cavitation Talk
Post by: steves86ta on March 04, 2016, 09:47:13 AM
Thoughts on adding a Stuffer?
Title: Re: Cavitation Talk
Post by: mash on it on March 04, 2016, 09:54:02 AM
Thoughts on adding a Stuffer?

Yes... :thumbup:

Dan'l

Title: Re: Cavitation Talk
Post by: steves86ta on March 04, 2016, 12:26:13 PM
Are all stuffers the same? Special order?
Title: Re: Cavitation Talk
Post by: mash on it on March 04, 2016, 01:03:12 PM
Mine is custom built, but its a WJ.
with your fab skills, should be easy to build one, I'm planning on building one for my Dom bowl, but has an AT impeller in it...I think thats a mis-match, IDK

Dan'l
Title: Re: Cavitation Talk
Post by: steves86ta on March 10, 2016, 02:44:47 PM
So, since i dont have it here, and its bugging me not knowing what may be going on with it. I keep reading to learn as much as possible

I stumbled across a "spoon" thread on another site. Simple theory that makes sense to me, but ive never dug into it

One of the replies was this video called the Coanda effect.

Knowing how the bottom of my boat looked before i re-blended everything in. And after watching this video a couple of times. I think that the bottom may have been creating this effect but with the spoon turned around opposite of waht you want. Example Starting at 2:12 in the video.

I can totally see this happening in my case, because of how the intake/keel was not blended. Obivously its just a theory, but good information to have anyway. Though, i do think this would be a bigger problem at speed.

But my shoe/loader could be grabbing the water at speed

Anyways, heres the video

https://www.youtube.com/watch?v=AvLwqRCbGKY (https://www.youtube.com/watch?v=AvLwqRCbGKY)

Title: Re: Cavitation Talk
Post by: steves86ta on March 13, 2016, 07:59:45 AM
I went and picked the boat up Friday night. Brought it home and pulled it apart. Just to double check everything. My clearances are not the greatest 

Impeller to suction housing is .175

 Impeller wear ring shoulder to wear ring is .145

 impeller to bowl is .170 

axial clearance is .024 

I also finished blending the intake in and now it looks great. After watching the coanda theory video I think that wad playing a huge part.  think in going to tighten the pump up a bit and bring the clearances closer as well as build a stuffer for it.   

I was thinking cutting the impeller about .110.

That would give me 

.065 impeller to suction housing 
.035 wear ring shoulder 
and making a .230 stuffer 

sounds okay to me what do you think?
Title: Re: Cavitation Talk
Post by: Flusher on March 13, 2016, 09:33:09 AM
I was thinking cutting the impeller about .110.

That would give me 

.065 impeller to suction housing 
.035 wear ring shoulder 
and making a .230 stuffer 

sounds okay to me what do you think?

Don't cut the impeller, then you will end up with some random bastard shtuff.

The shoulder on the impeller and the installed height of the wear ring should be 1.063.  That way, the clearance between the impeller and suction housing will be the same as the impeller to were ring rear surface, front and back.  Cut/shim the face of the shaft to achieve .035 front/rear clearance to the wear ring/suction housing and impeller.  If you are concerned about sucking up sand, you can open that clearance to .055.

The tighter everything is, the harder it will hit.
Title: Re: Cavitation Talk
Post by: mash on it on March 13, 2016, 09:36:40 AM
Steve-

If I remember right, when I put my pump together,

   Impeller skirt to wear ring shoulder- .017"
   Impeller axial radius- .011" (per side, .022" total)

This was an American Turbine AA, aluminum impeller, with the stainless shouldered wear ring, in a Berkeley JC pump.

When I pulled it apart, wear ring to impeller skirt was at .047" (feeler gauge)
and axial radius was at .090"/side, .180" total. (Berk A2 impeller)

Hope this helps

Dan'l
Title: Re: Cavitation Talk
Post by: steves86ta on March 13, 2016, 08:06:54 PM
Thank you very much Joe.

I understand what you are saying about cutting the shaft and not the impeller so that everything will interchange if needed.

But at this current time I don't have the time, resources, or place to pull my engine out to get the shaft out.

Since the plan is to save up and buy a stainless impeller than having the pump built and detailed I'll have everything set then.

I decided to cut the impeller this time and bring my clearances as close to. 035 as possible.

Big thank you to Lee (69kona) for helping me turn the impeller.

I'll get her installed tomorrow to check everything one last time

Daniel,
Thank you for the info. That helps out. Those clearances sound very tight to me. You didn't have issues with sand?
Title: Re: Cavitation Talk
Post by: mash on it on March 13, 2016, 08:24:11 PM
No issues with sand.

If I remember right, Berk specs were .012"/side or .024" total and .020" front to rear.
Without shims, I  was at .017", smallest shim I had was .010", and .027" seemed counter-intuitive (frt to rear).

Dan'l
Title: Re: Cavitation Talk
Post by: 69kona on March 14, 2016, 06:33:17 AM
Anytime 👍


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Title: Re: Cavitation Talk
Post by: steves86ta on March 14, 2016, 09:42:06 AM
No issues with sand.

If I remember right, Berk specs were .012"/side or .024" total and .020" front to rear.
Without shims, I  was at .017", smallest shim I had was .010", and .027" seemed counter-intuitive (frt to rear).

Dan'l

I read (cant find it now, go figure) but i read that the factory berk specs were closer to the .125 range than smaller. the only thing realitively tight was the Axial and that was .030 if i remember correctly

Ill try to find the link again.

But regardless. I should now be set right at .030 front/rear. And will be making the stuffer this weekend
Title: Re: Cavitation Talk
Post by: mash on it on March 14, 2016, 12:48:12 PM
Found the specs too, From A/T:


                           The clearance between the impeller
                           and wear ring is .012 per
                           side, .024 total. As the impeller
                           and wear ring wear this clearance
                           increases. Measure the Impeller
                           to fit with an undersized wear
                           ring. By doing this you can
                           bring the clearance back to the
                           original setting. Stock measurement
                           is 7.220 to 7.225

American Turbine spec is .030", f to r, Never could find Berk specs, I thought it was .025" GT would know  :thumbup:

from AT, On Berk pumps-

Looking in the inspection hole check the axial clearance between
the impeller and the wear ring shoulder. Clearance should be between
.025 and .035.

I guess I built my pump in march of 13, not march of 14, and was .023"/side or .056 total, not .180" total...CRS

http://www.socaljetboats.com/jet-pumps/berk-pump-specs/msg193851/#msg193851 (http://www.socaljetboats.com/jet-pumps/berk-pump-specs/msg193851/#msg193851)

Dan'l
Title: Re: Cavitation Talk
Post by: steves86ta on March 14, 2016, 12:53:04 PM
Found the specs too, From A/T:


                           The clearance between the impeller
                           and wear ring is .012 per
                           side, .024 total. As the impeller
                           and wear ring wear this clearance
                           increases. Measure the Impeller
                           to fit with an undersized wear
                           ring. By doing this you can
                           bring the clearance back to the
                           original setting. Stock measurement
                           is 7.220 to 7.225

American Turbine spec is .030", f to r, Never could find Berk specs, I thought it was .025" GT would know  :thumbup:

from AT, On Berk pumps-

Looking in the inspection hole check the axial clearance between
the impeller and the wear ring shoulder. Clearance should be between
.025 and .035.

I guess I built my pump in march of 13, not march of 14, and was .023"/side or .056 total, not .180" total...CRS

http://www.socaljetboats.com/jet-pumps/berk-pump-specs/msg193851/#msg193851 (http://www.socaljetboats.com/jet-pumps/berk-pump-specs/msg193851/#msg193851)

Dan'l

Ah i see now, Yes thats what i mean by Axial. The Axial clearance ( i could easily be using the wrong term) is between 25-35. Thats total between the wear ring and the impeller.

The front/Back clearance is in these pictures below. Keep in mind, i am not running a shouldered wear ring anymore. So the suction housing is basically the shoulder

Front of impeller to suction housing comes from this edge (where the playdoh is)

(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv643%2Fsteves86ta%2FMobile%2520Uploads%2F20160312_104630_zpshooln6pl.jpg&hash=747d9d0f303f3ef36f9bb4893a66933ce2fff9c3) (http://smg.photobucket.com/user/steves86ta/media/Mobile%20Uploads/20160312_104630_zpshooln6pl.jpg.html)


Wear ring shoulder to wear ring comes from here (again, playdoh)
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv643%2Fsteves86ta%2FMobile%2520Uploads%2F20160312_104621_zpsuli8fqqm.jpg&hash=6b13d0770623ed37bed87ec348461df4b0e9fe51) (http://smg.photobucket.com/user/steves86ta/media/Mobile%20Uploads/20160312_104621_zpsuli8fqqm.jpg.html)

And then impeller to bowl
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv643%2Fsteves86ta%2FMobile%2520Uploads%2F20160312_105433_zpszvmrshbe.jpg&hash=d5e18b91022d62349debb38a0fc13ec4824a12a5) (http://smg.photobucket.com/user/steves86ta/media/Mobile%20Uploads/20160312_105433_zpszvmrshbe.jpg.html)
Title: Re: Cavitation Talk
Post by: GT Jets on March 14, 2016, 12:56:23 PM
Axial=parallel with shaft
Radial =outward from shaft rotation.

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

Title: Re: Cavitation Talk
Post by: steves86ta on March 14, 2016, 12:57:21 PM
Axial=parallel with shaft
Radial =outward from shaft rotation.

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

So see... i am a retard using the wrong term lol
Title: Re: Cavitation Talk
Post by: GT Jets on March 14, 2016, 12:57:56 PM
So see... i am a retard using the wrong term lol

Not any more. ...   8)

Sent from my SCH-I545 using SoCal Jet Boats mobile app

Title: Re: Cavitation Talk
Post by: steves86ta on March 14, 2016, 01:02:50 PM
Not any more. ...   8)

Sent from my SCH-I545 using SoCal Jet Boats mobile app

This is kind of why i made this thread. I know i cant be the only person that has ever come across an issue similar to this. I'd rather share my information and what may improve/does not improve in the hopes that it'll help others later.

Same thing when it comes to the terms...

I have a pretty good feeling about the improvements i have made. Ill know in 2 weeks if they worked.

But im betting going from the massive amount of clearance i had to a .030 or so. Along with blending the intake in and cleaning the entire entry way up into the intake. Im expecting some decent improvements.

One question for you all...

I took a file, and knife edged my loader. Bad idea, good idea, doesnt matter?

I also went ahead and cleaned up my impeller and sharpened them too.
Title: Re: Cavitation Talk
Post by: GT Jets on March 14, 2016, 01:07:19 PM
Nothing you will be able to notice,  most folks feather the wrong side though. Which ultimately can hurt performance.

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

Title: Re: Cavitation Talk
Post by: mash on it on March 14, 2016, 01:08:52 PM
Not any more. ...   8)

Sent from my SCH-I545 using SoCal Jet Boats mobile app

Thanks GT, I get 'em bassed ackwards often  :screwy:

Steve- I knife-edged the rock grate on a WJ, while it was apart for a full rebuild. Couldn't hurt though...???

Dan'l
Title: Re: Cavitation Talk
Post by: steves86ta on March 14, 2016, 01:10:52 PM
For the experts... What kind of loader is this?


(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv643%2Fsteves86ta%2FMobile%2520Uploads%2F20160312_132821_zpsudm9bjpr.jpg&hash=085b96d74b3d2dda1f1c6e8cefd96f832f384360) (http://smg.photobucket.com/user/steves86ta/media/Mobile%20Uploads/20160312_132821_zpsudm9bjpr.jpg.html)

(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv643%2Fsteves86ta%2FMobile%2520Uploads%2F20160312_120732_zpsedpl4rnx.jpg&hash=ba17c6ecf3b433dc0f000027fb9125c3366c9599) (http://smg.photobucket.com/user/steves86ta/media/Mobile%20Uploads/20160312_120732_zpsedpl4rnx.jpg.html)

And the shoe?

(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv643%2Fsteves86ta%2FMobile%2520Uploads%2F20160312_132839_zpsanbqnbme.jpg&hash=a50fb05999694abc89458edd17aebb50d1c64f18) (http://smg.photobucket.com/user/steves86ta/media/Mobile%20Uploads/20160312_132839_zpsanbqnbme.jpg.html)
Title: Re: Cavitation Talk
Post by: jyeager on March 14, 2016, 02:40:41 PM
In my opinion those loaders are junk, made from crapy steel and the welds are 👎🏻👎🏻👎🏻

As for the shoe, looks to be to be a flat shoe. Better photos of the shoe please.


Sent from McIntyre Park
Title: Re: Cavitation Talk
Post by: steves86ta on March 14, 2016, 02:43:23 PM
In my opinion those loaders are junk, made from crapy steel and the welds are 👎🏻👎🏻👎🏻

As for the shoe, looks to be to be a flat shoe. Better photos of the shoe please.


Sent from McIntyre Park

the shoe is tapered. Its flush with the intake on the top, and forward on the bottom. I can try to get better pics this week
Title: Re: Cavitation Talk
Post by: steves86ta on April 05, 2016, 04:45:11 PM
Just thinking out loud here....

My MSD has a 2 step built in...

Anyone think it might help if i were to setup the 2 step to say 4500rpm til i feel it load then let off the 2 step?

Thoughts?

GT?
Title: Re: Cavitation Talk
Post by: Flusher on April 05, 2016, 07:58:05 PM
Just thinking out loud here....

My MSD has a 2 step built in...

Anyone think it might help if i were to setup the 2 step to say 4500rpm til i feel it load then let off the 2 step?

Thoughts?

GT?

Yes, it will help.
Title: Re: Cavitation Talk
Post by: steves86ta on April 05, 2016, 08:02:57 PM
Yes, it will help.

Thanks joe!  It was one of those afternoon epiphanies.
Title: Re: Cavitation Talk
Post by: GT Jets on April 05, 2016, 08:57:04 PM
Ever heard of a "soft throttle"?
Title: Re: Cavitation Talk
Post by: steves86ta on April 05, 2016, 09:00:03 PM
Ever heard of a "soft throttle"?
Yes. Yes I have.... if I finagle the throttle just right it launches decent enough as it is

The 2 step is essentially free after running a single wire

Figured it's worth trying it out
Title: Re: Cavitation Talk
Post by: GT Jets on April 05, 2016, 09:06:39 PM
Yes. Yes I have.... if I finagle the throttle just right it launches decent enough as it is

The 2 step is essentially free after running a single wire

Figured it's worth trying it out

Yeah, totally.

We had a soft throttle kit in the raceboat, I personally hated that son of a bitch, but our driver drove like a caffeine loaded 5 year old without it.

GT
Title: Re: Cavitation Talk
Post by: steves86ta on April 05, 2016, 09:09:19 PM
Yeah, totally.

We had a soft throttle kit in the raceboat, I personally hated that son of a bitch, but our driver drove like a caffeine loaded 5 year old without it.

GT
I'm thinking set it to 3500 or so. Putting it on a momentary button

Once it's headed towards a good plane lifting the button

After a few times and seeing if it'll work well

I'll lift off of the 2 step and then lay onto the nitrous. Should make for am interesting ride
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