Another setup question

[jbone]

I know there have been tons of threads on setups.
I've looked through many of them and can't find this answer.
I've got a Shockwave 21 skier with a stock carberated 502. I did the full setback, shoe, ride plate, inducer (loader), Droop, and hyd diverter. I had porposing at cruising that went away at wot. I adjusted the ride plate down slowly and got rid of the porposing. I did this a little at a time with washers for now. However, I seemed to have lost about 3-5 mph on gps. Is it possible the ride plate adjustment is affecting top speed? Did I go too far?
Also, I'm told this engine puts out about 415-420 hp. Is the A impeller the one I should be using? I'm reaching about 4700 rpm. I come out of the hole pretty good for heavy boat, but I'd like to go a little faster than the 53 I'm getting now.
Thanks,
J

[kachina]

I would go to an AB impellar or a B impellar, im going throught the same thing. I replacing my A with a AB actually more on the B side, i did the machineing my self on the impellar. My boat is a 22.5 kachina with a 454 mildly built, i m hoping i didnt turn it to much but im going to give it a shot. Your boat shoud be ok with a B with the horse power you have, good luck.

[jbone]

Thanks, do I need any special tools to remove the impeller.
Can anyone recommend a good place online to buy pump stuff?
It is the 12S Dominator by American Turbine.
J

[steelcomp]

Because your trim adjustment (ride plate) is fixed, you really won't be able to have both top end performance and mid-speed ride quality. You can have one, or the other. This is where a Place Diverter or some other type of adjustable trim control comes in handy.

[Jetmugg]

If you have a good tight pump, which it sounds like you do, just add more power. The pump can handle more HP, you'll just need more HP in the engine to go faster.
You should also contact one of the jet drive "gurus" (there are a couple of very good ones in Cali.) to help you with the setup.
My 2 cents.
SteveM.

[NorCal Gameshow]

you're diverter should handle the porpoising. if it doesn't, it might not be going all the way down.

[Wicked Performance Boats]

A Place Diverter will cure your problem but if you play with your shoe type,shoe depth.intake loader, and make sure the bottom has no hook in it. You should get a happy medium. I'd do that before I'd hang a PD on the back. Budlight :idea:

[FILUCKY]

Before cutting down your impeller remember that you "might" get more top end out of it but you will fore surely lose gas milege and ad extra wear and tear on your engine due to the fact that now you will be turning more RPM at crusin speeds. For 2-5 MPH is it worth it?

[Squirtcha?]

Before cutting down your impeller remember that you "might" get more top end out of it but you will fore surely lose gas milege and ad extra wear and tear on your engine due to the fact that now you will be turning more RPM at crusin speeds. For 2-5 MPH is it worth it?
I'd have to go along with Filucky on this one. If you intend to use your boat for skiing/wake boarding, or pulling tubes and the like, I wouldn't go any smaller than an AB impeller. I'm assuming that the above would be your primary concern considering the type boat you have. Going to a smaller impeller will almost definitely compromise your ability to pull up skiers etc.
If you want something fast, you'd probably be better off with a different hull.
Steve (Jetmugg) is right about one thing though, if you want a sure fire way to go faster, throw some more ponies into the mix. Even with 750 hp it'd probably still only be in the 70's somewhere due to it's physical size.
Do you have any idea how much the boat weighs in at?
These are just opinions.

[jbone]

Thanks for the advice guys.
The boat is about 2800-3000 lbs.
I was able to plane out with the diverter to stop the cruising speed porposing. However, I felt like I was pushing the bow down so much it wasn't running very efficient. After adjusting the ride plate, it took les down trim to avoid porposing. I'm just wondering if I went too far with the ride plate and if that could affect top speed. I still have a full range of trim to get an efficient plane, I just lost some top speed.
I'm looking to spend a lot of $$$, just get back what I had. I'll try adjusting the ride back half of what I move it originally and see if that helps.
I'm learning with jets, it is play with till it feels good.
Thanks,
J

[FILUCKY]

You want to get your ride plate set just low enough to not porpose. This should be right were you want to be for top end.

[jbone]

Thanks, I'll post results after the 4th of July weekend. We'll be at Martinez on the Picacho sandbar avoiding the big crowds.
J

[jbone]

Results are in.
Adjusted the plate back up almost to original position. It is at about 2.5 deg up. I picked up all of my top end speed and eliminated 90% of cruising porpose. I can deal with that with the diverter.
I was hitting 57 up river and 59 down river. That was with 50 gals of gas.
My next step is to raise my shoe. It is even with the keel now. I'm told I should go up from the keel about an 1/8 of an inch. I have a new thinner shoe coming so I will have one to play with. I think the one on there now is called a back cut. It is 3/4 inch at the very front, 5/8 at the back part of the cut, and 3/8 where it meets the ride plate.
The boat is running great now and I'm just trying things out to maximize the use of my hp.
Any other ideas would be appreciated.
J

[Bense468]

In my opinion you want to be running a backcut shoe with that boat. It will help lift the boat out of the water more.
Your ride plate should be right around where it is. You don't want your plate down too much because you will bury the nose and it will slow you down.
I prefer to run a bigger impeller in a heavier boat. Berk A or AA. Depends on your cam and what heads your running. More ponies will get you where you want to be. If I was you, I would stay right where you are at. If you are planning on stocking up on HP, your going to be re-dialing it back in. So if thats your plan build first, Dial in later. When building try building for a lower RPM range. This will keep your cruiser functional, pull skiers, get good gas milage, and come out of the hole hard with a bigger impeller. Good luck.

[Aduner2]

Looks like moving the ride plate increased your top speed. How much diverter did you use at wot? You want the jet thrust to be around 3 to 5 feet tall at wot. I would try another degree up on the plate to see if you pick-up some more speed. I would think your mid range porpoise should be handled by the diverter in the down position. You want to lift as much of the boat out of the water as safely possible.
Weight is everthing in a jet, and effects top end mph. Lighten your fuel load, gas is about 7 lbs per gallon.
By raising your shoe, your wot rpm should increase. A shoe forces more water into the pump to load the impeller which in turn takes more horsepower to turn. Your looking for wot rpm change. Another means of checking is a pressure gauge tapped into the intake. IMHO your not going fast enough for a shoe to be necessary, but if its to deep, it will slow you down.
Just for grins, run a straight edge along the bottom of the boat (last 4-6 feet on each side of the intake) and see if the hull as any hook built into it.

[jbone]

Looks like moving the ride plate increased your top speed. How much diverter did you use at wot? You want the jet thrust to be around 3 to 5 feet tall at wot.
I was about in the middle of the diverter range. It was throwing about 3-4 ft of roost. It gets pretty high on full up.
IMHO your not going fast enough for a shoe to be necessary, but if its to deep, it will slow you down.
Yeah, I know. I was having it built to handle lots of HP just in case I wanted to add. I'm at about 415 (so they say) with the crate 502 (carb). Any mods will probable be a couple of years down the road. After talking with the guy from American Turbine, he suggestedthe thinner shoe. I think it IS called a back cut. See discription in previous post.
Just for grins, run a straight edge along the bottom of the boat (last 4-6 feet on each side of the intake) and see if the hull as any hook built into it.
There isn't any hook. I had Shockwave blueprint the hull after it came out of the mold.
Thanks for all the input, and I hope I did the quote thing right.
J

[Aduner2]

What mfg diverter are you using? Does it have nozzle insert? If it does, try reducing the nozzle diameter a 1/16 ex: If its 3.250 id go to 3.187 id.
But maybe you know that :D

[jbone]

What mfg diverter are you using? Does it have nozzle insert? If it does, try reducing the nozzle diameter a 1/16 ex: If its 3.250 id go to 3.187 id.
It is the Place Diverter. I have no idea what the nozzle size is.
How will this improve top end?
J

[Bense468]

It is the Place Diverter. I have no idea what the nozzle size is.
How will this improve top end?
J
Volume or pressure....Its like putting your finger over the hose. Need to find the right combination for your boat. Reducing it may help

[SmokinLowriderSS]

Physics gets involved in the nozzle diameter tune. If you reduce the nozzle diameter, you reduce flow volume (weight of water) OR you increase pressure (water velocity)(likely a mix of both). Increase nozzle dia, flow is increased and pressure is reduced. (those are if nothing else changes). I think we can assume pressure remains constant as the engine would limit that (HP needs of the pump to make pressure. The best combination of flow volume and flow velocity is one of the things I consider in the realm of "voodoo tuning". :boxed: It's specific to your boat and though folks can give advice and tell their setup, it may or may not mean a thing for your situation. You just have to try different insert sizes and GPS verify the results. :cool:

[Aduner2]

Place has a web site. They call them FTN (Fine Tuning Nozzles) and are anodized different colors based on diameters. Look inside your diverter for a removable anodized sleeve. If you have calipers, you can also measure the id.
Reducing the id will increase nozzle pressure. How much is the "voodoo" part. A jet boat is propelled by thrust (nozzle area x pressure). My AT diverter has a nozzle insert also. It's another tuning device in the quest for speed.
I'm sure someone will chime in on this one :D

[jbone]

Wow!
I can't believe all the little things that can be done enhance performance. I'm learning a lot from you guys. Thanks.
I guess by the time you have perfected the ride, you have a bunch of extra parts that either came off the boat or didn't work.
I'll start my collection with the old shoe. The new one should be arriving any day now.
Thanks again,
J

[Aduner2]

There's a member Froggystyle that had a 21' Ultra hard deck called "On The Rocks" that wanted to increase his performance. He got his boat bouncing around the 80 mph mark. He posted alot of info on what he when thru to get this speed. Do a search,very interesting reading.
You know what "BOAT" stands for? :D

[SmokinLowriderSS]

Break Out Another Thousand. :supp:
;)