Supercharger question

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OKELLY

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« on: July 26, 2016, 08:23:19 PM »
Who thinks a Stock Hardin marine motor will handle a 6-71 blower at low boost? Not sure if it's got forged Pistons or what it really even has strength wise or not. Don't know much about Hardin marine so any info would be awesome! Or someone who has some decent input. 😎👍


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jyeager

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« Reply #1 on: July 26, 2016, 08:36:13 PM »
Maybe................ i personally would spend the money and set it up right. JMO
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GT Jets

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« Reply #2 on: July 26, 2016, 08:55:48 PM »
I put several 6-71 blowers on 330 hp Mercruiser 454 engines,  the problem is, on a jet,  it's hard to keep the rpm in check. With an I/O, you just go up a prop,  the rpm still need to stay under 5k on stock guts.

JMO.

GT
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

OKELLY

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« Reply #3 on: July 26, 2016, 09:13:37 PM »
On those 330 hp they handled? Or were they just ticking time bombs? Yea I get you when you say keep her under 5k. Just a little to much stress with high rpm. Also benefits. What you think. Worth it?


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OKELLY

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« Reply #4 on: July 26, 2016, 09:15:04 PM »
Also what was the boost you ran?


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GT Jets

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« Reply #5 on: July 26, 2016, 09:22:02 PM »
Also what was the boost you ran?


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5lbs on most,  ran one at eight but it had a bottom end done.

These were Bravo I outdrive boats.

There was a few I remember,  a 75mph Wellcraft Nova 23'.

The other was a 25' Baja, don't remember the performance.

GT
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

OKELLY

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« Reply #6 on: July 26, 2016, 09:31:05 PM »
Ok awesome!! I really appreciate all of that. Im just in a little carribean and she moves decent already but bigger and better and a little more speed is always better. 😈


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Flusher

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« Reply #7 on: July 27, 2016, 06:48:22 PM »
Which 6-71 are you talking about?  There are two different GMC 6-71's, a large and a small case, not to mention, several aftermarket cases and rotors.

Have the rotors been "stripped"?  This means that the tips of the rotors have been machined for seals to tighten the clearance between the rotors and the case.  A "stripped" blower will have less internal leakage and generate more heat.

What drive ratio will this setup include, or are you on your own for the drive?

If you can resist temptation and keep the boost to a reasonable amount, there is no reason you couldn't successfully run a blower.  As long as you keep it out of detonation, the greatest loads on the pistons and rods will be at TDC on the intake stroke.

Lastly, your engine needs to be in sound condition before you undertake such an endeavour.

A couple things that might scare you away.  1.) It takes a lot of power to drive a blower.  The crankshaft should be double-keyed and you don't want to run a cast hub damper.  2.) I would consider opening the ring gap to compensate for the addition heat and expansion.

Good luck,

Joe
"I want to roll with my brother Joe" - Joe Bateman - January 29, 1950 ~ November 27, 2013

 


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