Repowering 45 Novi

Discussion in 'Diesel Engines' started by Greg Phillips, Feb 15, 2019.

  1. Greg Phillips
    Joined: Feb 2019
    Posts: 2
    Likes: 0, Points: 1
    Location: Block island

    Greg Phillips New Member

    I am repowering a 45 ft Atkinson Novi fishing boat. The current motor is a 6v92 and I am thinking of a c15 or a 3406 B. The cooling system is closed with keel coolers and the exhaust system is dry stacked. I have plenty of extra room as I am also rebuilding the cabin and engine hatch. Any thoughts on those motors as good or bad would be helpful. I am searching around for low hour truck motors and old farm pump motors that are remaned. The price difference is huge. I am new to the keel cooler dry stack setup so any advice and description of what components I will require if I go with a truck motor would be helpful.

    Reason for repower is the current motor has 30-40 thousand hrs and 9900 on this rebuild. I plan to fish the boat offshore and travel to Florida for winter fish season. Also the boat is under powered and not near max hull speed. The gear in the boat was replaced two years ago and is a twin disc 5091 2.95:1. If I move up to 450-500 hp will this gear be able to handle the increased torque? Shaft is 2.5 and prop is 32 x 32”. Thank you!
     
  2. Lepke
    Joined: Sep 2015
    Posts: 81
    Likes: 6, Points: 8, Legacy Rep: 10
    Location: Oregon to Alaska

    Lepke Junior Member

    Twin disk 5091 isn't rated for that much hp, especially continuous. See table.
    Truck engines are derated compared to the same engine in marine use. Usually the cam, injectors and pistons are different. Sometimes other things. You'll need a marine exhaust manifold or the engine room will get excessively hot. Especially in Florida. And the truck circulation pump may not be enough for the keel coolers. I think the 3406C is a better engine. Loggers around here are getting a million miles between rebuilds on C engines. A lot tougher life than over the road trucks.
    There are companies that buy and sell used marine engines. No idea who on the East Coast, but try ebay and places that do rebuilds. You ought to look at a 8v92 as a replacement. Everything would be the same except for being a little longer. With a different engine brand everything changes in the engine room. Because marine commercial users are under Tier regulations, many good Detroits are being pulled.
     

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  3. Greg Phillips
    Joined: Feb 2019
    Posts: 2
    Likes: 0, Points: 1
    Location: Block island

    Greg Phillips New Member

    Thanks I am talking with a number of places about both 3406b and 3406c. The twin disc is a 2.95:1 which is rated slightly higher and I don’t plan on running high rpm ever. The marine exhaust manifold is a must I agree and I have switched from looking at industrial and truck motors. I appreciate the input
     
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