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Old 21-06-2010, 09:50   #1
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Repowering a Skookum 53

This forum is a wonderful place to get all kinds of insight. I recently pulled the plywood overhead off of the troll pit and took it to some friends to have a new one built out of Aluminum, and as these things go I had a glass man look at some delaminated glass on my troll pit and ended up cutting out the after section of it, and will be coming back with new plywood & glass. On to the point, while I was at it I found an Isuzu that will fit into my engine compartment and I am in the process of removing the Detroit 471 & replacing it with a 6 BD 1 turbo Isuzu. I have a Twin Disc 506 reduction gear, but the Isuzu comes with a Borg Warner, I am wondering if I should just rebuild the Twin, or do the same with the Borg and install it ? All engines are working as are the reduction gears, the engine change decision, arises from fuel economy, hp & engineering consistency I have an Isuzu gen set.. I have not yet started the change out, I am still waiting for the Isuzu to arrive from Ballard, and I am hoping to sell the 471 locally and get the buyer to help remove it. All input is welcome.
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Old 21-06-2010, 18:14   #2
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Install the engine with what comes on it.

Why you would want to use an old reduction gear is beyond me.
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Old 21-06-2010, 19:54   #3
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Twin Disc has a reputation around here as being near bullet proof, Borg Warner not so much.
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Old 21-06-2010, 20:14   #4
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Will they interchange or will you need an adapter?
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Old 22-06-2010, 02:25   #5
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Quote:
Originally Posted by captain58sailin View Post
Twin Disc has a reputation everywhere as being near bullet proof, Borg Warner not so much.
I have to agree
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Old 22-06-2010, 07:02   #6
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I believe that I can use the plate that is on the back of the 471, if need be I can use the plate of the 471 as a template and engineer a new plate with the bolt pattern of the Isuzu and the Twin Disc.
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Old 22-06-2010, 18:54   #7
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Seems like an awful lot of work.

IS there a dampner plate that will fit the Isuzu?
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Old 22-06-2010, 19:37   #8
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Have installed 5 different Isuzu engines all WITH Twin Discs transmissions.
All WITHOUT turbos. Surprised that you would need 185 hp ( which you get from a turbo driven 6 BD 1 Isuzu) for a 53ft Skookum which @ 37tons only needs 120HP to cruise at 8 knots.

Think about a naturally aspirated diesel - just one issue with turbos is the need to run them at a high RPM to get the output = Noise!
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Old 22-06-2010, 21:20   #9
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The information I have is that the rated is 140 hp for this unit, and no I don't need the power. If I can take the turbo out of the equation, without hindering the performance, then I probably will. I will not be running anywhere near maximum output of the Isuzu, @ 1500 RPM, I will have all the push I need, and my fuel consumption will be half of what it is now. I spoke with some transmission guys in San Francisco and they were telling me that there are 5 different SAE transmission housings and that if I were adapting down to a smaller housing it was no problem, adapting up is a different story, I don't have the engine on the ground yet to make that determination. Thanks for all the good input, it is really good to get some different perspectives. I will keep you all posted as things progress.
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