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SoCowifornia

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diesel jet boat
« on: July 21, 2017, 10:32:12 AM »
Anyone out there have any experience with a cummins 6bt in a jet? would like to know reasons why not to, and if it could work, how would you set it up. Advice and comments appreciated. I've seen a 5.9 in just about everything, but cant find a jet boat example.
  • Boat #1: 1976 tahiti
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shield3

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Re: diesel jet boat
« Reply #1 on: July 21, 2017, 11:48:54 AM »
Here's someone that did it

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mash on it

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Re: diesel jet boat
« Reply #2 on: July 21, 2017, 02:52:54 PM »
Here's someone that did it

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I would assume that a jet boat would not have the engine mounted backwards, run through a transmission and a Casale v-drive gear box.

Ya that ones a v-drive and a 4bt...not a 6bt.

Not knowing much about 6bt's, I believe they are governed at 4000 rpm. Even a AA American turbine impeller only requires 259 hp and 339 lb/ft of torque @4K, yeah, easy for a 6bt. but thats the end of the 6bt.  (Thanks Tom at JBP) http://www.jetboatperformance.biz/pages/calculator.html

FYI, 4000 rpm, is about 38mph on my barge. (AT AA Impeller, 21' Eliminator Day Cruiser luxo-barge)

80% thrust is cruise speed. 80%=3200 rpm, is ~28 mph, and barely on plane, in my junk.

A 6bt is about 900 lbs. 454 with iron heads and alum intake is 575-600 ish.

In reality, it needs a gear box to work the 6bt. That's  even MORE weight.

Could it work? Absolutely. Practical? Not so much.

A 3-fiddy-chebby would make a 6bt look silly on the water.

Thats all I got.

Dan'l



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CJ/RR 212...under construction  "Pistol Annie"

SoCowifornia

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Re: diesel jet boat
« Reply #3 on: July 23, 2017, 09:00:05 AM »
It would definitely be a disappointment, to do all the work installing the cummins an go so slow!, reason for wanting to do the project is that I have several 5.9's in my shop, as well as several running in trucks and equipment, and they are just so reliable. I'm absolutely fed up with the unreliability of my current 460.
  • Boat #1: 1976 tahiti
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Spectra12

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Re: diesel jet boat
« Reply #4 on: July 23, 2017, 09:09:43 AM »
It'll work in a v drive with a tranny. I believe the one pictured is behind a three speed. On a jet diesels don't spin fast enough. I know someone that put a 6.0 powerstroke on a berkeley and it was a waste of time. Cool setup but not a runner for sure.


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connorstexas

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Re: diesel jet boat
« Reply #5 on: July 24, 2017, 12:17:03 AM »
need an overdrive of some sort. diesels dont like over 3500 rpm unlike big blocks. has all the torque in the world but need to get that prop/get spinning upwards of 5-6k... just my 2 cents


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