Impeller pick help

« **on:** July 29, 2014, 07:59:02 PM »

Hello guys have a 1976 hawaiian Mini day 21' built a 545 Stroker full roller all forged aluminum heads and 1000 cfm carb over transom headers. 125 hp shot of NOS looking for a all around impeller berk pump needs a rebuild so need ideas. Running a JC A with place diverter should I be running a AA with this heavy boat? Spinning the A at 5400 now thanks

« **Reply #1 on:** July 29, 2014, 08:04:15 PM »

Where does your motor make its power? If your spinning 5400rpm now going to a bigger impeller is going to knock that down to probably 5000rpm. Impeller needs to match your motors power band.

« **Reply #2 on:** July 29, 2014, 08:09:23 PM »

Haven't had it on the dyno but should be around 550 before nos 11:1 compression mild port and polish I know the heavy hull is holding me back

« **Reply #3 on:** July 29, 2014, 08:17:30 PM »

Before and after pics

« **Reply #4 on:** July 29, 2014, 08:32:47 PM »

Well, how much HP is part of the equation, but where it makes it is also very key.
That being said, your in uncharted waters will your hull modifications. Jet boats are weight sensitive and it looks like your baby's got a pretty heavy booty on her. May I ask what the idea behind the mods were?

« **Reply #5 on:** July 29, 2014, 08:38:52 PM »

Set back pump and motor over a foot, rides much better and added more room for interior. Not a great idea for performance but glad I did it made the boat more family friendly and plus no one else has a custom swim step like mine

« **Reply #6 on:** July 29, 2014, 09:02:36 PM »

A couple things kind of jump out at me. 545 ci, 11-1, 1000 cfm carb, should do 550 hp easy, but you say it's only spinning a worn out pump to 5400rpm. What is your cam? I would suspect you would be getting some slippage from that pump allowing the motor to spin higher than 5400 rpm. I think I would tighten the pump up and see how it does with the A. Maybe add an inducer to help get it to launch, but if you can't get past 5400rpm with that motor, I don't think a AA is going to do you any favors.

« **Reply #7 on:** July 29, 2014, 09:04:53 PM »

I am intrigued by what you did. I'd love to see that in person and take a ride in it.

« **Reply #8 on:** July 29, 2014, 09:14:35 PM »

This is my cam card running hydraulic roller, I don't think the pump is loose it just is making a bearing whine at idle like you said if it was loose I figure it would pull to the rev limiter. I do have a XS loader but no inducer. Thanks for the help

« **Reply #9 on:** July 29, 2014, 09:18:44 PM »

May have cruise down south and have you check her out

« **Reply #10 on:** July 29, 2014, 09:20:41 PM »

« **Reply #11 on:** July 29, 2014, 09:24:22 PM »

Where are the motor pics.. Love the paint how does it tow did you have to scoot the axles back

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« **Reply #12 on:** July 29, 2014, 09:24:50 PM »

With all that junk in her trunk

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« **Reply #13 on:** July 29, 2014, 09:33:10 PM »

Tows easy, I did pull axels back to match. Pics prior to swapping to OT bassets

« **Reply #14 on:** July 29, 2014, 09:35:05 PM »

At speed

« **Reply #15 on:** July 29, 2014, 09:44:39 PM »

Looks like you ain't afraid to jump in to a project got any pics of the boat on the trailer finished

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« **Reply #16 on:** July 29, 2014, 09:47:11 PM »

From the looks of it the motor stayed put and just the pump moved back

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« **Reply #17 on:** July 29, 2014, 09:51:23 PM »

Here you go, no motor pushed back over a foot kept the same bellhousing. Made U shaped back seat instead of rear facing buckets

« **Reply #18 on:** July 29, 2014, 10:43:12 PM »

Have you hit it with the nitrous yet? That 125 shot should get you to your peek RPMs +50 to 100 more. Tighten up the pump and see what happens. I would start with a B. JMO

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« **Reply #19 on:** July 30, 2014, 02:19:22 AM »

Needs a bigger cam and needs to be solid roller not hyd... If you cut the impeller to a (b) it will turn 5800-6000..

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just re-read for what you have in the motor you are just about right,,, what do you want the boat to do? its a cruiser with a hot rod motor in it....you are using race gas? 11.1 comp? what kind of heads? cant tell by pics

the real

? is what do you want out of the boat and motor?

just trying to help
ralph

« **Reply #20 on:** July 30, 2014, 06:57:53 AM »

I have used the spray brings it up to 5500. Ralph I'm running edelbrock 6066 heads. Run 93 most of the time when pulling kids on the tube or just family time. Run 100 and bump timing up when it's time to play with nos. needs to be a cruiser most of the time but still want to be able to have some hot runs. 90% of the time I'm at 3000 rpm thanks for the help guys

« **Reply #21 on:** July 30, 2014, 07:30:46 AM »

your compression is closer to 11.5, be very care full with the tune

i have the same motor but 502 ci, victor intake 1150 dominator and custom solid roller cam, im at 10.8 cr. i turn a tight pump with an A 5700 depending on tune up.. your motor is giving that A cut all it can... do you want to go faster? putting a B cut in will give you more top end and less for pulling the tubes... and drink fuel like crazy..

Brad's motor is a 514 with 12.5 comp and i think he pulled 700hp on the dyno at 6k rpm's

so it is all about what you want the motor and boat to do?

if you ask me leave it alone and put a bigger shot of no2 on it when you want more....
hope this helps
ralph

« **Reply #22 on:** July 30, 2014, 07:55:38 AM »

Custom SRP pistons and cc'd the heads so I know I'm right at 11:1 but still am careful with tune have way too much $$ in the motor to pop a hole in a piston! Thanks Ralph info helps just didn't know if I was missing anything sticking with the A happy with the performance it has now but this is my first jet, hooked for sure gotta love 70's hot rods

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« **Reply #23 on:** July 30, 2014, 08:06:34 AM »

Oh yeah get a stud girdle on that valve train

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« **Reply #24 on:** July 30, 2014, 08:34:28 AM »

Ahhhhhhhh! now I see your problem! That's a FORD!

Poor thing is doing all it can to act like a real motor.

Just kidding, I agree with Ralph, it will never be a race boat. Make the motor happy, keep it in it's operating window and enjoy it. If that's 45mph or 85mph @5500rpm then that's what she's got to give.
I admire your willingness to do it different, your own way. I like that swim step feature you built. It's the play boat that roar's.

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