Jacuzzi 12wj w. Chevy 350 question.

[justaddfuel]

Hi, hope everyones summer is going well. We haven't had much hot weather up here.
My boat is a 16' flatbottom. My pump is a Jacuzzi 12wj 'A' impeller. It has a loader grate. My motor is the GM Performance 350/290. Headers are O/T, dry. Top rpm is 4000. Top speed is 47MPH on gps. Motors still fresh, pump's nice and quiet. I have a Custom Speed Marine diverter.
My questions are; 1. Is there anything I can do to get more thrust? The motor still has another 1000 RPM to offer. I like the jump out of the hole it has, and the low rpm cruise (32mph @2600). I may add nitrous later, so am hesitant to cut the impeller. I am curious about opening up the nozzle on the pump. It's stock. I learned of that mod on this site, but not many run the small block.
2. This thing is LOUD. It's an o/t system, stainless, with stainless mufflers. Could I safely inject water into the muffler, for noise restraint? The mufflers are about 16" back from the centerline of the shorty headers.
Thanks for reading. Paul.

[bakerjet]

i'd like to see a pic of this. water will quiet it down but what kind of muffler are you talking about and is there fittings for water injection? you might get a little more rpm without the loader grate but that depends on the style of grate

[Riverat84]

yeah man, there are an assload of guys on here that could help you, but pics would be the best bet so that we could see EXACTLY what you're working with...BTW...where are u located? nowhere hott eh?
welcome to ***boat...
Reid

[455Rocket]

Sounds like a case of car motor blues...

[justaddfuel]

Hope these show up. The fittings for the muffler shouldn't be a problem to install.

[justaddfuel]

Oh...sorry Riverat. I'm from Ontario, Canada. Boating gives something to do between snowmobile seasons.

[malcolm]

We should switch impellers. Mine has a B. You really need a big block to run an A. ;)

[kraig]

I have a 71 Taylor SK 16ft, sbc around 300-325 hp, O/T wet headers, WJ with a place diverter, and the SAME loader as yours. 49.7 gps, don't know the rpm but does sound like it could get a little more.http://www.youtube.com/watch?v=oohf-NhuGek

[pw_Tony]

We should switch impellers. Mine has a B. You really need a big block to run an A. ;)
Doesn't a WJ impellar B cut more close to an A cut berkeley?

[OLDMANSOLDSBOAT]

My dad's boat came with a wj-b and 455 olds. I believe it was rated at 390 hp. When it was new it would run 5000 to 5500 rpm. I would think droping down to a B would give you the revs your looking for and still leave room for the juice later on.:idea:

[justaddfuel]

Malcolm, maybe we could discuss a switch when the seasons done. I just don't want to crack open the pump right now. For now, 0-47mph is a blast! But sounds like a B is the easiest for my small block. I wish I could watch your clip kraig, but I'm on dial-up here. What impeller do you run?
About the exhaust, my main concern was water into the valves. If you guys think it'll work I want to put a nozzle into the pipe just fore of the muffler, squirting back somewhat. My water regulator is set at 10psi, but shows no pressure at idle, so if I used a small reg set at 5psi to feed my pipes, it should flow nothing till I hit the gas.

[moparjet]

Doesn't a WJ impellar B cut more close to an A cut berkeley?
yes a jacuzzi b is close to a berk. A...i spin a jacuzzi b 6000

[pw_Tony]

yes a jacuzzi b is close to a berk. A...i spin a jacuzzi b 6000
But you're blown! lol, and got that packin 440 ;)
I think you would need a smaller impellar than a B cut. I called to JP marine and talked to Joe over there bout my WJ, and he told me my BBC could spin it to 4800-4900RPM if it's tight. I asked him if I could buy a smaller cut impellar, and he told me companies don't really make a smaller one for the Jacuzzi, and he advised a Energizer kit.

[napabob]

Here is a link to a web site for Youngblood boats:
http://www.youngbloodjetboats.com/
Use the link on the left for 'Jacuzzi' for some speed records set at the time of article publications.
I also managed to track down Mr. Scott Seastrom who worked for Jacuzzi before being sold to North American Marine Jet.
http://www.marinejet.com/ (Use the Jacuzzi Jet Drives' link).
Scott Seastrom
111 Stonewall St.
Hot Springs National Park
AR 71913-4702
(501) 624-0137
scottmarine@aol.com
He said that he would gladly talk about the Jacuzzi jet and its race performance modifications (The so called 12WJR).
The energizer kit only advertises about a 10% gain in speed, I would use it if there was a problem purchasing Jacuzzi rebuild parts.
Good luck,

[malcolm]

Malcolm, maybe we could discuss a switch when the seasons done. I just don't want to crack open the pump right now. For now, 0-47mph is a blast! But sounds like a B is the easiest for my small block.
Yeah, we should talk over the winter. :) My 455 is around 400 horse and I can spin this B to 5000. Northamerican marine jet owns the jacuzzi pumps now. They still showed impellers all the way down to D or E last time I looked. They're pretty expensive though. ;)

[moparjet]

But you're blown! lol, and got that packin 440 ;)
I think you would need a smaller impellar than a B cut. I called to JP marine and talked to Joe over there bout my WJ, and he told me my BBC could spin it to 4800-4900RPM if it's tight. I asked him if I could buy a smaller cut impellar, and he told me companies don't really make a smaller one for the Jacuzzi, and he advised a Energizer kit.
i spun my same pump at 4900 with almost stock 440....ran about 60 to 65 in my heavy layup....i dont think the energizer kit is worth the money for the little gain you get from it....the only thing i did was open up the bowl exit and ad a diverter

[justaddfuel]

Hey, Moparjet. Is the bowl exit mod worth the effort?

[moparjet]

Hey, Moparjet. Is the bowl exit mod worth the effort?
yes and easy to do....but only if you are going to add a place diverter.....the reason is the jacuzzi uses the cone for a nozzel,but the diverter also is a nozzel..you dont want two nozzel in the flow