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I have a 1979 16ft Cobra Jet with a berkeley JE pump. The jet is fitted with a diverter. I was wondering if that is a good hull design and good model pump. The boat had a 396 that was junk so I'm starting to build a blown 454 for it. The blower is off a 6v-92 detroit. Its being upfitted by a company in Texas. The pump as an aluminum impeller now so I believe I will need to buy a stainless steel one do to the fact that I will be over 500hp.
So seeing that I am doing the engine and impeller do I buy the impellor and build the motor to match or build the motor and buy the impeller to match. The 396 had aluminum water cooled manifolds on it with 3" pipe going up and over the transum. I think on the 454 I should go to headers for better breathing.
Any input would be greatly appreciated thanks:D
 

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jetboataholic
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Pictures would be great!:)bulb
 

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mo balls than $cents$
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WELCOME TO THE SITE!

match the impellor to the peak hp of the motor. 12je pumps are tuff to keep fed at higher mph, so you're gonna need to buy a bolt on shoe/rideplate kit to keep it fed. if your motor will make say 750hp at 6500, run a impellor that'll allow the motor to reach that rpm level. i've built and ran a few 12je's that were fast, i stuck 900hp to my 12je in the taylor sj i had and it took a berk a cut to keep it held to 6700-6800rpms;) you're gonna need a a-cut i'd bet for starters. if its too much impellor, you can cut it down, but it takes a biggg hp motor to turn a aa cut over 6000rpms.
 

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Discussion Starter #7
WELCOME TO THE SITE!

match the impellor to the peak hp of the motor. 12je pumps are tuff to keep fed at higher mph, so you're gonna need to buy a bolt on shoe/rideplate kit to keep it fed. if your motor will make say 750hp at 6500, run a impellor that'll allow the motor to reach that rpm level. i've built and ran a few 12je's that were fast, i stuck 900hp to my 12je in the taylor sj i had and it took a berk a cut to keep it held to 6700-6800rpms;) you're gonna need a a-cut i'd bet for starters. if its too much impellor, you can cut it down, but it takes a biggg hp motor to turn a aa cut over 6000rpms.

Thanks, its hard to find anyone in appleton wisonsin that knows anything about jetboats. I'll ask about a jetboat and they will say do you mean a jet ski and then I just hang up the phone.
The best guesstimits on the engine right now is around 800 to 850 hp. I've been told to start with a aa cut and go from there. The transum and runners for the engine where just redone before I got the boat.
I'm new to jets so I'm guessing that by shoe/rideplate you are refering to the scope that bolts in place of the weed guard on the intake.
I've looked a alot of the pics on this site and others and I always see the tall intakes but not very many blown engines. Is there a reason for this or is building a blown engine not a good fit for a jet boat.

thanks again its nice to be able to have some of my questions answered:)
 

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mo balls than $cents$
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Thanks, its hard to find anyone in appleton wisonsin that knows anything about jetboats. I'll ask about a jetboat and they will say do you mean a jet ski and then I just hang up the phone.
The best guesstimits on the engine right now is around 800 to 850 hp. I've been told to start with a aa cut and go from there. The transum and runners for the engine where just redone before I got the boat.
I'm new to jets so I'm guessing that by shoe/rideplate you are refering to the scope that bolts in place of the weed guard on the intake.
I've looked a alot of the pics on this site and others and I always see the tall intakes but not very many blown engines. Is there a reason for this or is building a blown engine not a good fit for a jet boat.

thanks again its nice to be able to have some of my questions answered:)
what bolts in place of the stock rock grate is called a loader, you're gonna need a proloader or the ss, depends on where you buy it.

this is the shoe/ride plate kits i've used in the past with good luck. keep in mind its a universal kit and there's alot of work to get it tuned right across all the different brand of hulls.

http://www.hi-techperformance.com/images/E_Series_Shoe_2315.jpg

http://www.hi-techperformance.com/images/3e-sho~1.jpg
 

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Just Me
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did that boat originally have an olds motor in it? If it did, i think the guy selling it said the pump had just been rebuilt. Not that i've been looking for boats around the midwest ;)
 

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mo balls than $cents$
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Problem Child, if that Cobra Jet is anything at all like the other common 16 foot jet hulls, with a "deep-entry bow",it is not a good hull to be putting big power into. Please post some pics of the hull, particularly a side view on trailer that shows the bow and the bottom shape. The last guy who had a 16 foot jet project that he dumped a hi-po small block into(against advice) found out quickly it was not a good idea.

EDIT: Found a couple of pics HERE. If the pics at top are what you have, you have the hull design I was referring to.
 

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Discussion Starter #12
did that boat originally have an olds motor in it? If it did, i think the guy selling it said the pump had just been rebuilt. Not that i've been looking for boats around the midwest ;)
No it had 396 bb chevy in it. I got the boat about 4 years ago for $200.00 I painted it for my buddy and then he lost interest in it so he gave it to me for the cost of the paint, which I had purchesed for well $200, but now I have to sand the base clear off so I can gell coat it. from the rub rail down and then I'm going to do the upper in base clear and right know I have about four colors in the design I can up with. The dash was full of holes from gauges, a radio and switches. So I had a piece of brushed stainless laser cut to fit over the dash and I will mountthe gauges in a row just under the dash or in a cluster on top of the dash not sure which yet. I'm having the whole wiring harness made and enclosed in a full breaded wrap from front to back. The engine harnes will be made by the same company and there will be a bulk head connector between the engine a main harness. I hate messy wires.;)
 

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Discussion Starter #13
Problem Child, if that Cobra Jet is anything at all like the other common 16 foot jet hulls, with a "deep-entry bow",it is not a good hull to be putting big power into. Please post some pics of the hull, particularly a side view on trailer that shows the bow and the bottom shape. The last guy who had a 16 foot jet project that he dumped a hi-po small block into(against advice) found out quickly it was not a good idea.

EDIT: Found a couple of pics HERE. If the pics at top are what you have, you have the hull design I was referring to.
Well this is good timing to get that info because I'm just starting on it.
This would have a big block so worse yet.
That sucks:)st:mad::mad::mad::mad::mad::mad::mad::mad: I was hoping that wouldn't be the case but ya the hull design matches the top set of pics. I was starting to wonder why I've never seen that design in pics before.
So whats the deal with that design. Not strong enough, bad handling?
With that said I sould start looking for a differnt hull?
I will still post some pics to verify but that is the design.

Thanks for the heads up though.:)bulb
 

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Your not that far from the Lake Shawano crew. Head up to the Shake the lake bash next weekend. http://www.performanceboats.com//showthread.php?t=2420 http://www.youtube.com/watch?v=kWofytcsC3k
I grew up on washington lake just down the channel from shawano lake. That is where I feel in love with jet boats. I remember seeing the eliminators on the lake.

Thanks I will try to make it this year if not then next year for sure.

Just wondering was shake the lake held down by oshkosh before?
I thought I heard its was and the oshkosh got a little salty with the noise and they stop doing it?
Just wondering.
 

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Discussion Starter #20
So would I be save in putting around 450 hp in this hull and staying with the a-cut aluminum impeller and then finding a better hull to build the blown motor for.

Thanks again for everyones help you guys saved me alot of wasted time and money,:D
 
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