Ski King Engine Size

Designs for inboard or outboard power

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scscott
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Ski King Engine Size

Postby scscott » Tue Aug 29, 2017 8:58 am

I am new to building a boat and I was looking at building the Ski King and wanted to have a gas engine vs a diesel. I was noticing that engines lower than 100hp appear to be diesel. The site says that the HP should be between 50-100hp. Is this a restriction due to weight or speed concerns?

Does anyone have ideas of where i can get an inboard gas engine to fit within the ski king range? The MerCruiser 4.3L starts at 135hp for their gas engine.

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Bill Edmundson
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Re: Ski King Engine Size

Postby Bill Edmundson » Tue Aug 29, 2017 9:38 am

scscott

I think the 135hp would be fine.

Does anyone remember what Dwain Colton (Skiiiiii Kiiiinnnngggg) is running? I'm thinking it's a small block V8.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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PeterG
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Re: Ski King Engine Size

Postby PeterG » Tue Aug 29, 2017 11:40 am

Looking at engine options, the GM 3.0L four cylinder like that used for the Mercruiser 135hp is a great choice for the Ski King. It is a marine engine as designed, with the RPM and torque range you would want for this boat. It is rated up to 140hp which would still be OK for this design. The Gray Marine Fireball 90hp was listed at about 460 lbs and the GM 3.0l 140hp is listed at about 450 lbs decked out for inboard use (transmissions not included here). You get an extra 50hp with the 3.0L for the same weight, sounds like a great choice. You can build this boat to the longer length (extend 10% longer by spacing frames further apart) to increase displacement slightly and have more room between the frames for the engine. I would be cautious about higher horsepower, it means more weight and can have squirrelly stability at high speeds.
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scscott
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Location: Chicago, IL

Re: Ski King Engine Size

Postby scscott » Tue Aug 29, 2017 11:57 am

Peter G,

Thanks for the input. The stock 15' is about as long as I can go. So if i read that correctly you said the Mercruiser 135hp 4.3L would be a good choice or the GM 3.0L four cylinder.

Thanks

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Mr Hot Rod
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Re: Ski King Engine Size

Postby Mr Hot Rod » Tue Aug 29, 2017 1:47 pm

Bill Edmundson wrote:Does anyone remember what Dwain Colton (Skiiiiii Kiiiinnnngggg) is running? I'm thinking it's a small block V8.

Here's some info about Dwain's 283 CID V8 :

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From the Customer Photos - Archives :


    Image
    Ski King wrote:I just finished it after months of chasing parts and completely rebuilding it. It is now .060 over 283 (292cu.in.) and has run for about 30 minutes (cam break in). When I finish the deck it'll go in the boat and then see if it "floats" HA!!!..Dwain

    Source : SKI KING by Dwain Colton, Portland, OR (5-08)

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PeterG
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Re: Ski King Engine Size

Postby PeterG » Tue Aug 29, 2017 7:54 pm

Scscott, I would shy away from the 4.3L v6 as it's rated for 220hp it's probably too much for the Ski King. I say that in spite of Dwain's setup with the V8. The 3.0L four cylinder is rated for 140 hp and would be the better choice. But that's your choice to make :-)
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

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Bill Edmundson
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Re: Ski King Engine Size

Postby Bill Edmundson » Wed Aug 30, 2017 5:15 am

scscott

There is a tradeoff here. Performance is a function of boat weight / HP. The 4 cylinder is obviously lighter than the 6 cylinder.

I put a diesel in the Tahoe. I planned on a 160 hp. It only turned 3400 rpm. We couldn't work out the gears and prop combination. The sales guy recommended the 125 HP. It turns 3900 rpm and the gear & prop worked out fine. The 125 HP is 300# lighter. Performance numbers for the boat are almost the same. It saved me a lot of money and uses less fuel.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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