Bowl Modification Questions

[Hipshot]

I know that it is best to leave full bowl flowing modifications to the pros but I would like to know if there are any minor areas or modifications that could be addressed myself that would improve things? I have been porting cylinder heads and intakes for 17 years and I am a self proclaimed master of the die grinder, so handling the tools isn't a problem. Can anyone give good accurate advice on the areas that should be reshaped/sharpened/material removed etc. etc.? I have both a Berkeley bowl and a Dominator bowl from the late eighties that are in stock form.

[Taylorman]

Whatever you do, get proffesional advice before you do anything. I bought a used split bowl a while back, made my boat drive like shit. I did not know that the bowl was the problem cause i changed the bowl and diverter at the same time. I blamed the diverter till i sent it back to where i bought it from. HTP told me the bowl had been modified by someone who obviously did not know what they were doing. I bought a new bowl and it fixed my problem.

[Hipshot]

I here ya Taylorman that's why I am on here asking.

[sidewound]

I was advised against doing mine myself.
I saw these posted awhile back. Maybe you can get an idea from them.
VANES
http://www.hotboatpics.com/pics/data/500/3371Vanes.gif
VANE MAGIC
http://www.hotboatpics.com/pics/data/500/3371VaneMagic.gif
Peace Man! :cool:
CESAR

[Squirtin Thunder]

How about the front of the bowl ???
I was advised against doing mine myself.
I saw these posted awhile back. Maybe you can get an idea from them.
VANES
http://www.hotboatpics.com/pics/data/500/3371Vanes.gif
VANE MAGIC
http://www.hotboatpics.com/pics/data/500/3371VaneMagic.gif
Peace Man! :cool:
CESAR

[Hipshot]

Thanks for the pictures. Any idea what kind of bowl that is? It looks like they removed a fair amount of material. I am trying to decide whether or not to approach this like a cylinder head. I don't know much about water flow characteristics though and I am sure that there are things that apply differently when dealing with water flow VS. fuel/air flow. Any other before and after pictures would be cool. Does anyone know of a good physics book that talks about water flow characteristics?

[Unchained]

What I'd seen before didn't look like any rocket science so I took an aluminum cutting carbide burr and sharpened the blunt ends of the vanes myself.

[Hipshot]

Hi unchained, did you work both sides of the vanes or just sharpen from one side? Did you do the entry and exit side of the bowl.

[sidewound]

How about the front of the bowl ???
I'd like to see some of the front too. I don't have any. Anybody else?
Peace Man!:cool:
CESAR

[Cs19]

Hipshot, thats a berk flowed by MPD.
If your going to do it yourself, use caution you could screw it up in a heartbeat.
CS

[Squirtin Thunder]

I wonder what the cost of an MPD flow job is ???
vs
A new bowl ???
Berkeley Jet Drive
12JG Race Prepped Bowl
150-L-03495R
$995.99

[Hipshot]

Thanks cs19. I know I can screw it up if I just approach it half hazardly, same thing goes with cylinder heads. I have been advised by one pro through PM that it is no big deal if you just remove slag/imperfections and sharpen the backside if the vanes. I was also told where most people get in trouble is when they change angles and change the overall shape without knowing what they are doing. All the pros who know how to do this stuff had to learn it somehow, and yeah,they probably screwed up a lot of stuff along the way. I can afford to have anyone I want flow the bowl, that is not the issue for me. I like doing my own stuff and seeing the results as I learn along the way.I have two Dominator bowls and one Berk bowl to experiment with. I just refuse to believe that with the proper guidence and research that it could be that big of a deal, who knows maybe I'm wrong. It sure wouldn't be the first time.
Anyone have pictures of a fully detailed bowl they would care to post?

[sanger rat]

If you are going to do it just grind the back side of the fin to keep the water flow striaght out.

[sidewound]

HBJet had some good pics when he had his JC bowl modified. Ya might wanna PM him.
Peace Man!:cool:
CESAR

[Squirtcha?]

I did mine a few years back. Just followed the same instructions that you were given. You can see the notes in the text. Definitely not pro-grade work. Coulda done a little more work by hand sanding to smooth it out some I suppose. I did a lot of work that particular winter, so I can't say if it helped out at all. I don't think it hurt me any.
http://www.jetheaven.us/photopost/data/500/19bowlwork1wnt.jpg

[Unchained]

Here's what I did on my bowl.
http://www.***boat.com/image_center/data/520/220bowlfront.jpg
http://www.***boat.com/image_center/data/520/220bowlexit.JPG
I have to question the phrase "Watch out or you'll screw it up in a heartbeat"
That sound like a statement from someone who wants to sell bowl polishing jobs.
I get very determined when someone tells me I can't do something myself.
It's a midwest thing. :idea:
No matter how pretty and smooth you make the inside of the bowl all the water that flows through it still gets funneled down to a 3.125 hole.

[Squirtcha?]

I didn't work the inlet side of mine. Next time the pump comes apart, I'll give that a go as well. Some say that there's not much point in working the outlet without doing the inlet side as well.
By looking at the pics of the pro's work, it looks like I could've sharpened the stator blades some more too. I was a little concerned about losing strength. Apparently it's a non-issue.

[jweeks123]

No matter how pretty and smooth you make the inside of the bowl all the water that flows through it still gets funneled down to a 3.125 hole.would that imply that there is no difference between bowls cause the little nozzle hole is the big restiction
jw

[Cs19]

Mark,moving more water effeciently is what you want to do regardless of your nozzle insert size. Wether you do it with your chainsaw at home or you have it done by a pro I dont care, just do it right...I fully understand the whole do-it-yourself concept, but I believe in doing some homewrok before firing up the chainsaw.Comprende?
Got any plans to run at the race track yet? I'd really like to see a time slip on your boat,It can be a humbling experience for some.
Chris.

[mj680]

would that imply that there is no difference between bowls cause the little nozzle hole is the big restiction
jw
You are correct.Stock Berkeley bowls work better than the highly modified bowls.Why pay big bucks that might loose you performance,just because it looks pretty. :cool:

[steelcomp]

would that imply that there is no difference between bowls cause the little nozzle hole is the big restiction
jw
You are correct.Stock Berkeley bowls work better than the highly modified bowls.Why pay big bucks that might loose you performance,just because it looks pretty. :cool:
Ron...don't know if you're joking here...but I have to ask, if the bowl is a non-issue, then how could you lose performance?

[Unchained]

Got any plans to run at the race track yet? I'd really like to see a time slip on your boat,It can be a humbling experience for some.
Chris.
The nearest place to race around here would be in Kentucky so
I have plans to bring the racetrack with me by getting one of these.
http://www.nology.com/gdynoplus.html
It will datalog and graph the entire run.
The gps update time is 10times / sec which is the fastest I've seen.
It cost about $ 600. which would be like entry fees at three races.
I'm afraid I've morphed into a tech geek. :boxed:
I did run at the Southern Michigan friday night drags once this year. No timing lights, real low key. There were only about 25 or 30 boats there and we ran 800'.
I got a good write up about it on S & F from it by the guy who organized the event,
"We had probibly our best turnout ever lastnight thanks to lots of out of towners making the effort to show up . Bigdaddyhognuts, Bill [ red Allison 2 seater ] & Randy Mills all put a whoopin on me & Unchained whipped everybody with his visious twinturbo jet. This thing THUNDERS. There were also two blown Hydros that ran really strong but could'nt catch the jet in 800' even though Jim Mc Culluchs' [sp] boat had a 2 speed & the other had a 480'' Hemi"
That must have been the high point of my summer. :D :D

[mj680]

Ron...don't know if you're joking here...but I have to ask, if the bowl is a non-issue, then how could you lose performance?
All I am saying is that you can loose performance if you alter the bowl.A little
cleanup on the casting is okay,but a full port job with smooth walls is a waste of time and money.I remember one time Bill Henderson changed back to a stock Berkeley bowl on his blown fuel Jet "RATED X " and picked up 6 mph to 166+mph.His highley modified bowl had blownup. Ron :cool:

[Hipshot]

posted by unchained...
I get very determined when someone tells me I can't do something myself. It's a midwest thing.
Amen brother!
On a serious note though I can understand how just grabbing the grinder and hogging out your bowl would be detrimental, but just sharpening the vanes a little and cleaning up the casting imperfections....I just don't see that being a problem. We'll see.
I am actually thinking about having one of my bowls done professionaly and doing the another one myself to see how much difference there is between the two. This is not something that I am approaching without doing research first.

[steelcomp]

All I am saying is that you can loose performance if you alter the bowl.A little
cleanup on the casting is okay,but a full port job with smooth walls is a waste of time and money.I remember one time Bill Henderson changed back to a stock Berkeley bowl on his blown fuel Jet "RATED X " and picked up 6 mph to 166+mph.His highley modified bowl had blownup. Ron :cool:
Thanks. That's pretty interesting. :idea:

[sleekcrafter]

Damn, me too. just when I though I knew it all!! :D :D Thanks. That's pretty interesting. :idea:

[Hipshot]

posted by mj680
All I am saying is that you can loose performance if you alter the bowl.A little
cleanup on the casting is okay,but a full port job with smooth walls is a waste of time and money.I remember one time Bill Henderson changed back to a stock Berkeley bowl on his blown fuel Jet "RATED X " and picked up 6 mph to 166+mph.His highley modified bowl had blownup. Ron
As unconsistant as blown fuel jets are I would have to question the validity of the six mile an hour gain with a stock bowl. Now if he had totally screwed his bowl up I guess it is certainly possible that the stock bowl would work better. If on the other hand his ported bowl had been properly done(whatever that is) and the stock bowl still picked up six miles an hour that is definitely interesting. Hmmmmmm?????

[CompStompinSCS]

I wonder what the cost of an MPD flow job is ???
vs
A new bowl ???
Berkeley Jet Drive
12JG Race Prepped Bowl
150-L-03495R
$995.99
I agree it is OK to do a little clean up of the casting, but for anything more I would go with MPD.

[Hipshot]

Have any of you run the bowls with an odd number of vanes like the Legend 7-vane or the Aggressor 7,9 or 11 vane? Just curious as to what the thought is behind an odd number of vanes and how you go about deciding which one is right for your application.

[Outlaw]

I'm not sure if I screwed up or not, But the last time I had my pump out of my boat, I had the complete pump Powder coated inside and out including the bowl. not sure if it helped ,I pulled it because it was set at 7degrees to start with. after the first season I installed a new impeller.
Powder coat was still intact except for a few places on the nozzle

[cyclone]

i did a little testing last summer of some bowls...
berk jg with full detail and stuffer
AMT that was extrude honed and had entry and exit sharpened
AMT stock
Aggressor 9-vein stock
i didn't do any wide open runs because the lake conditioins were not conducive to running 110-plus mph but i did some cruise speed testing (2,500-3,000-3,500-4,000-4,500-5,000 rpm) and noted that the three larger bowls (amt and aggressor) outperformed the shorter berkeley bowl by several mph at most rpm levels even though the berkeley bowl was heavily modified. Bare in mind that i swapped the bowls over the course of an afternoon at a lake. Not exactly a scientific test since the water conditions were constantly changing but still worth considering.
Do i think flowing the bowl is worthwhile? Definately. How much is it worth? I found at least 1-2 tenths at the track.

[Hipshot]

When you say bigger bowls in what way do you mean bigger? Are they longer, bigger around or bigger inside?

[HammerDown]

When you say bigger bowls in what way do you mean bigger? Are they longer, bigger around or bigger inside?
I belive the key word in Cylcones post was..."shorter".

[cyclone]

I belive the key word in Cylcones post was..."shorter".
exactly. the AMT and Aggressor bowls are longer and slightly larger in diameter. You'd have to ask a pro how this translates into better performance though.

[Heatseeker]

exactly. the AMT and Aggressor bowls are longer and slightly larger in diameter. You'd have to ask a pro how this translates into better performance though.
I'm going to guess that the longer, wider bowl allows for a 'straighter' flow by streching out the vanes some. The less 'bending' of the flow the better.
Whatcha think?

[cyclone]

I'm going to guess that the longer, wider bowl allows for a 'straighter' flow by streching out the vanes some. The less 'bending' of the flow the better.
Whatcha think?
That would be my guess. but it raises many other questions like does the cut of the impeller have anything to do with the efficiency of the bowl? Would the increase in speed at a given rpm be the same with a smaller impeller? I was only able to test with a AA impeller.
Unfortunately i wasn't able to repeat the test several times so like i said, it wasn't definitive answer on which bowl worked best.
In my case though, the longer bowls worked better for my particular boat and engine/pump combination. I was able to verify that at the track. I would think that a lower horsepower/smaller impeller might not see the same benefit though. ? who knows.

[Heatseeker]

That would be my guess. but it raises many other questions like does the cut of the impeller have anything to do with the efficiency of the bowl? Would the increase in speed at a given rpm be the same with a smaller impeller? I was only able to test with a AA impeller.
Unfortunately i wasn't able to repeat the test several times so like i said, it wasn't definitive answer on which bowl worked best.
In my case though, the longer bowls worked better for my particular boat and engine/pump combination. I was able to verify that at the track. I would think that a lower horsepower/smaller impeller might not see the same benefit though. ? who knows.
Food for thought, that.

[Taylorman]

That would be my guess. but it raises many other questions like does the cut of the impeller have anything to do with the efficiency of the bowl? Would the increase in speed at a given rpm be the same with a smaller impeller? I was only able to test with a AA impeller.
Unfortunately i wasn't able to repeat the test several times so like i said, it wasn't definitive answer on which bowl worked best.
In my case though, the longer bowls worked better for my particular boat and engine/pump combination. I was able to verify that at the track. I would think that a lower horsepower/smaller impeller might not see the same benefit though. ? who knows.
Have you condidered on of AMT's 9.5" impeller for as much hp as you have. Also, Ron at AMT turbine told me himself on the phone a while back that his son's boat has a 10" impeller in it. Runs 80 at 5000 rpms.

[396_WAYS_TO_SPIT]

Well I will be working my bowl a bit here next month. I will record the changes and post them;)
396

[HammerDown]

...Also, Ron at AMT turbine told me himself on the phone a while back that his son's boat has a 10" impeller in it. Runs 80 at 5000 rpms.
Thats pretty darn efficient for a Jet...
I would like to know what Hull and HP Boat this is.

[Taylorman]

Thats pretty darn efficient for a Jet...
I would like to know what Hull and HP Boat this is.
Im 90% sure thats the numbers he told me, its been a while.

[BUSBY]

As unconsistant as blown fuel jets are I would have to question the validity of the six mile an hour gain with a stock bowl. Now if he had totally screwed his bowl up I guess it is certainly possible that the stock bowl would work better. If on the other hand his ported bowl had been properly done(whatever that is) and the stock bowl still picked up six miles an hour that is definitely interesting. Hmmmmmm?????
Hipshot ... I would take MJ680's word for it ... he's been racing longer than most of us have had boats ... and Bill Henderson's Rated X boat was a very consistant & competitive BFJ back in the day ...

[Hipshot]

10-4 BUSBY. I didn't mean to sound like I was throwing the BS flag on him. I only meant that if they put the stock bowl on and went out and ran 166mph one time with it, it might not have just been the bowl. I don't race boats and I certainly am not trying to argue about a boat I've never seen run. It is interesting though.

[BUSBY]

10-4 BUSBY. I didn't mean to sound like I was throwing the BS flag on him. I only meant that if they put the stock bowl on and went out and ran 166mph one time with it, it might not have just been the bowl. I don't race boats and I certainly am not trying to argue about a boat I've never seen run. It is interesting though.
it's all good ... just giving you the down low on who's who ... and who knows what ...

[PC Rat]

I remember one time Bill Henderson changed back to a stock Berkeley bowl on his blown fuel Jet "RATED X " and picked up 6 mph to 166+mph.His highley modified bowl had blownup. Ron :cool:
So, did he ever go back to a modified bowl?
Brian

[steelcomp]

Have you condidered on of AMT's 9.5" impeller for as much hp as you have. Also, Ron at AMT turbine told me himself on the phone a while back that his son's boat has a 10" impeller in it. Runs 80 at 5000 rpms.
My boat ran 93 @ 5500 with an MPD modified Berkeley aluminum B.

[Duane HTP]

What is the total running weight of your boat?

[steelcomp]

Don't know, for sure. Bahner 19' tunnel, (hull is probably about 500#) , full interior, stainless saddle tanks, carpeting, BB Chev w/ cast iron heads, T/R, and a pair of 800's, Berk 12JG, droop, ride, shoe, etc. Not a ligtweight AFA 19' jets go, but still, it's a small boat. Jack's B absorbs nearly as much HP as an A. The stock B would turn 61-6200.

[TRG]

Spinning a SS American Turbine imp 6200rpm, in an AT bowl with minor mods to the imp as well as the bowl, the motor dyno'd @ 764HP @ 714 ft.lb. @ 6200rpm
94 MPH in one squirly ass rogers 18 bonneville hull weighing in at 550lbs