SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: bwray919 on March 21, 2016, 12:52:08 AM
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I apologize if these have been asked before but I have questions, I searched with no luck.
I just bought a boat with a detailed A impeller, what does "detailed" mean?
What is stuffing a bowl? (Just curious and want to learn)
I'm having a 454 built by Bostick, supposed to be around 500hp, will the detailed A be a good setup?
What kind of Rpm's should I shoot for?
I know this is rookie stuff but I just want to learn!
Sent from my iPhone using SoCal Jet Boats
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I apologize if these have been asked before but I have questions, I searched with no luck.
I just bought a boat with a detailed A impeller, what does "detailed" mean?
What is stuffing a bowl? (Just curious and want to learn)
I'm having a 454 built by Bostick, supposed to be around 500hp, will the detailed A be a good setup?
What kind of Rpm's should I shoot for?
I know this is rookie stuff but I just want to learn!
Sent from my iPhone using SoCal Jet Boats
1. Detailed - Means the impeller has been cleaned up/sharpened/modified to flow the best it can and not create cavitation. usually means thinning the blades out and leaving it somewhat sharp. Think a butter knife
2. Stuffing a bowl - REfers to adding a plate behind the impeller bolted to the bowl that will take up volume/space. Theoretically increasing the efficency of the pump. I dont know if they help or not, but i now have one
3. I think the A would be a good fit for you
4. 5500 or so. check with mrblueeyesnick if its the "jet boat package" that Bostick does then it should be similar to his engine. Im not 100% sure but i think hes running an A impeller, he will be able to tell you his rpm's and what not
5. the only "stupid" question is the one not asked.
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Here is a picture comparing a front-side detail to a box stock impeller. Both are the same American Turbine casting.
As Steve pointed out, the blades are thinned and asymmetrically sharpened, dulled only enough so to prevent getting cut while handling. The shape of the blade surface is recontoured to reduce a low-pressure area. The transition from the shaft to the hub is worked to improve quantity and quality of flow in that area. The shroud, near the wear ring, at the impeller inlet eye is thinned and trued to smooth the transition of flow into the impeller in this area. All of this is done reduce cavitation. The result that the end-user experiences is, a harder bite with the most dramatic affects being on the launch.
A good working front detail job will make the impeller "act" like it is one full cut size larger. Basically, it makes the impeller work more efficient by reducing cavitation. The pump will pull the engine down harder, approximately 200 RPM. This usually corresponds with an adjustment to the cut size to allow the engine to operate at peak power.
Notice, that at no point did I mention polishing or surface finish. In a jet boat, polishing makes absolutely no difference whatsoever. If we had access to the instrumentation that NASA has for testing liquid rocket engines, we might be able to measure the slight difference. A good detail is all about the shape and not how pretty it looks.
I will post up pictures of a back-side detail, where the trailing edges of the blades are foiled, later
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I'm having a 454 built by Bostick, supposed to be around 500hp, will the detailed A be a good setup?
What kind of Rpm's should I shoot for?
Bostick will provide the RPM and horsepower information you will need.
There are a lot of compromises to selecting an impeller cut. What type of hull, size, weight, and your intended usage all play a part.
First thing, run it with the A impeller you already have and see what it does. That will provide a baseline for future changes. If/when you want more, then consider a size change.
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What is stuffing a bowl?
Here is a very well planned stuffer plate (the red thing) engineered into the design of an Aggressor bowl.
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Here is a stuffer plate added to a Berkeley bowl.
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Here is a Dominator bowl without a stuffer plate, however this one utilizes an impeller with a secondary wear ring, on the back side, that registers inside the hub center of the bowl.
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Dang, this is good stuff. It makes me want to go take the pump apart on my old boat just to see how everything is set up and get some hands on time with all the parts.
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Joe,
Is a detailed impeller weaker when pushed to its limits? I.E. in my case, im pushing an aluminum pretty hard?
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Joe,
Is a detailed impeller weaker when pushed to its limits? I.E. in my case, im pushing an aluminum pretty hard?
Technically speaking, a detailed impeller will be stronger. For a couple reasons.
Once something is polished, the surface defects are, for the most part, eliminated, the second is it will run more true and smooth, reducing cavitation that can wear on vulnerable areas.
GT
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Joe,
Is a detailed impeller weaker when pushed to its limits? I.E. in my case, im pushing an aluminum pretty hard?
I believe so, because material is being removed. On boats with big power, even stainless will crack. On the front where the blades meet the hub and the rear where the blades meet the shroud. Because of this, we leave extra material in these areas.
The radii between the blades and hub/shroud influence the strength substantially. Unfortunately, they also contribute substantially to cavitation. On the low-pressure side, it can have fairly large radii without consequences. On the high-pressure side, they detract from from surface area. On the leading edges, they cause bad cavitation. Removing them makes the impeller work better, but also removes strength.
Keep in mind that detailing significantly reduces the blade thickness at the leading edges (and trailing edges optionally). Aluminum doesn't like to flex without fatigue. Now the thickness is reduced and flex is increased. If you are already walking on egg shells, don't hop.
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Technically speaking, a detailed impeller will be stronger. For a couple reasons.
Once something is polished, the surface defects are, for the most part, eliminated, the second is it will run more true and smooth, reducing cavitation that can wear on vulnerable areas.
GT
Add a little here. Take away from there...
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Add a little here. Take away from there...
I guess ultimately, it depends on what is done during the detailing process.
I feel that power for power, everything else being equal, the "out of the box stock" impeller would experience a failure before one that had been properly prepped for the application.
Obviously this is somewhat open to a lot of interpretation.
GT
Sent from my SCH-I545 using SoCal Jet Boats mobile app
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1. Detailed - Means the impeller has been cleaned up/sharpened/modified to flow the best it can and not create cavitation. usually means thinning the blades out and leaving it somewhat sharp. Think a butter knife
2. Stuffing a bowl - REfers to adding a plate behind the impeller bolted to the bowl that will take up volume/space. Theoretically increasing the efficency of the pump. I dont know if they help or not, but i now have one
3. I think the A would be a good fit for you
4. 5500 or so. check with mrblueeyesnick if its the "jet boat package" that Bostick does then it should be similar to his engine. Im not 100% sure but i think hes running an A impeller, he will be able to tell you his rpm's and what not
5. the only "stupid" question is the one not asked.
I do have the same build from Bostick, but I am running a b cut impeller. With the b cut I am seeing around 5400-5500 rpms
Sent from my garage drinking a cold beer!!!
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New question!
So the boats together, the motor is absolutely bad ass, BUUUUUT, I want just a bit more, about 2.7mph more. I know it's silly but I'd like to hit 80mph.
I was talking to the previous owner of the boat and he suggested adding .030 of shoe...well I don't even actually know what the shoe is or how to adjust it.
Any other suggestions would be cool. What I know I have is a detailed A impeller, the motor spins to 5500-5600, it has a loader, ride plate, JC pump, manual diverter. The hull is an 81 crusader.
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2.7 mph is like the last piece of pizza. You know you want it, but you're afraid you'll shit your pants or puke. Lmao.
Some simple questions.
What angle is the ride plate at in comparison to the keel?
Where are your fuel tanks mounted?
Where and how many batteries?
How does the boat ride? Where does the water break?
How is the loader trimmed?
Can you get it to porpoise?
Know any small people that can drive?
It's all about weight once the wallet goes flat. Lol
Weight distribution/reduction is gigantic.
I say two more degrees of timing, two gallons of good fuel no rear seat, a 100 pound driver and a 1-1/2" riffle and you'll have it. Lol
Good luck, sounds awesome.
GT
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Agree with GT unless you are wanting it to run 80 fully loaded. Start throwing stuff out, anchor, run light on fuel, seat cushions, tool bag ect. If nothing else throw a 50 shot of spray at it. With the time I have spent on my boat I have found every 150lbs slows me down 5 mph.
BECKY WITH THE GOOD HAIR!
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Agree with GT unless you are wanting it to run 80 fully loaded. Start throwing stuff out, anchor, run light on fuel, seat cushions, tool bag ect. If nothing else throw a 50 shot of spray at it. With the time I have spent on my boat I have found every 150lbs slows me down 5 mph.
BECKY WITH THE GOOD HAIR!
Wow really?! Always kind of wondered about weight to mph difference.
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Wow really?! Always kind of wondered about weight to mph difference.
Im not sure if that works for everyone but it's pretty steady with my boat, in all reality I don't have that much hp/tq compared to jim, Jake, Bruce, Corey, my boat is just fast because it's light and half way set up. My motor makes about 150 less than Jim and Corey, 100 less than Jake, and 80 less than Bruce. I'm also only 11:1 compression. There is really a big difference when weight is reduced. And I'm talking off bottle hp
BECKY WITH THE GOOD HAIR!
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So basically you are telling me to throw my friends in the middle of the lake with a couple flotation devices and the ice chest if a race presents itself and tell them I'll be right back?? I like it!!!!
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So basically you are telling me to throw my friends in the middle of the lake with a couple flotation devices and the ice chest if a race presents itself and tell them I'll be right back?? I like it!!!!
Pretty much. Hand them the anchor as well so they won't drift off and you can get an extra mph or so
BECKY WITH THE GOOD HAIR!
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So basically you are telling me to throw my friends in the middle of the lake with a couple flotation devices and the ice chest if a race presents itself and tell them I'll be right back?? I like it!!!!
Hell Ya "" that's what I would do Hahaha😎👍.
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That work with the wife too?
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That work with the wife too?
Wife automatically adds 10 mph. I get 7 outta my girlfriend so I'm assuming wife's must be 10
BECKY WITH THE GOOD HAIR!
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I ment throwing out extra weight I should get ten mph. But I like my anchor
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I ment throwing out extra weight I should get ten mph. But I like my anchor
Lol!!!
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i lose 5 mph with my Brother in law on board everytime, hes 275 pounds
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I'll have to check the angle, this is my first boat so I'm still trying to figure out what everything is😂
Two 8 gallon spun aluminum tanks, mounted as far back as they can be on both sides of the motor.
2 12lb AGM batteries mounted along the back wall on the passenger side.
The boat rides amazing, I can get it to porpoise if the diverter is in the wrong spot but generally it rides super nice, unfortunately I don't have any pic that is clear enough but the boat is almost back on the ride plate, you can really feel it when it's up to speed.
Not sure how the loader is trimmed or what that means??
I do know a small person that could drive but that would be like renting out my girlfriend only much worse.
77 was done with a full boat, 3 200+lb dudes and a 120lb chick, also two tool bags, anchor, ore, it's got a big sound system up front. I did a run by myself but my GPS had gone into the settings screen and didn't log anything, I was already super low on fuel and couldn't take the embarrassment of having a friend tow me back! I'm sure I'm really close to 80 by myself. Guess I'll start dieting to cut down on weight hahah!
Thanks for all the help guys!
2.7 mph is like the last piece of pizza. You know you want it, but you're afraid you'll shit your pants or puke. Lmao.
Some simple questions.
What angle is the ride plate at in comparison to the keel?
Where are your fuel tanks mounted?
Where and how many batteries?
How does the boat ride? Where does the water break?
How is the loader trimmed?
Can you get it to porpoise?
Know any small people that can drive?
It's all about weight once the wallet goes flat. Lol
Weight distribution/reduction is gigantic.
I say two more degrees of timing, two gallons of good fuel no rear seat, a 100 pound driver and a 1-1/2" riffle and you'll have it. Lol
Good luck, sounds awesome.
GT
Sent from my iPhone using SoCal Jet Boats
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77 was done with a full boat, 3 200+lb dudes and a 120lb chick, also two tool bags, anchor, ore, it's got a big sound system up front. I did a run by myself but my GPS had gone into the settings screen and didn't log anything, I was already super low on fuel and couldn't take the embarrassment of having a friend tow me back! I'm sure I'm really close to 80 by myself.
Sent from my iPhone using SoCal Jet Boats
Dude! That is a lot of flesh and stuff in your boat. Dump them in the middle of the lake, or on shore, low fuel in tanks and give it a go. I bet 80 happens pretty easy if you get 77 with all that.