Horsepower upgrade, 2003, 41DA, 3126 CATs

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by JMS23, Oct 11, 2018.

  1. JMS23

    JMS23 New Member

    Nov 20, 2017
    Rochester hills, michigan
    2003 410SDA Searay Sundancer,
    3126 CAT x 2, at 350 hp ea
    i know this item has been discussed in the past, but i wanted to see if there are any new technical reasons i should not upgrade my 350hp, 2003, 3126 CATS to either the 385 hp or the 425 hp option on the engine. numerous friends now have the 42DA and 44DA with the 485hp Cummins and unfortunately i cannot keep up with them when we cruise together. i am not concerned with fuel economy, we boaters in Michigan are lucky to put 75 hours per season.
  2. fwebster

    fwebster Well-Known Member TECHNICAL Contributor PLATINUM Sponsor

    Oct 6, 2006
    Middle Tennessee ; Panama City Beach, FL
    1996 450DA
    3116 Caterpillars
    I've commented on this before, but I am told t hat you cannot upgrade the 350hp 3126 to 420 hp without changing the fuel pump and injectors and reprogramming the ECM. You will have to get the cost and estimated labor from Caterpillar, but I'd guess $this would be roughly $15K.

    You can have the pump reset to get to 385 hp for some labor expense only. However, you will be adding only 35 hp and at normal cruise that is more like 30 hp at cruise speed which is going to leave you 85 hp short of the power your friends have and you still cannot run with them.

    You are burning 10-15 gph less fuel than the Cummins boats and I'd tell your friends to slow down The fun is in the getting there; not in the destination.

    Don't fix what isn't broken..........
    techmitch and dtfeld like this.
  3. dtfeld

    dtfeld Water Contrails GOLD Sponsor

    Jun 5, 2016
    Milton, GA
    410 Sundancer
    Axiom 12 MFD
    Cat 3126 V-Drives
    Also, as you increase to HP, you also increase the wear/tear on the internal components. This would likely result in higher MX cost and a lower expected life of the engines.

    Another consideration is what transmissions and props you have. HSW800IV is likely whats in the boat, and they are right at the max hp these transmissions can handle. And getting that extra hp through the props and into the water will require at a minimum tweaking the props or outright replacement. These two items could easily double the cost of this project. At that price, your probably 1/3-1/2 the cost difference between what you have and a 2005-2007 420/440. and the upgrade might be a better option.

    And as frank pointed out, your very unlikely to be able to keep up with them, as looking at a boat speed calculator online, I think you'll only pick up 1-2 kts/hr at cruise RPM.
  4. JMS23

    JMS23 New Member

    Nov 20, 2017
    Rochester hills, michigan
    2003 410SDA Searay Sundancer,
    3126 CAT x 2, at 350 hp ea
    thanks for all the info. unfortunately i don't care for the cockpit layout of the newer 42-44 so that is not an option i would consider. i am getting an opinion and costs from our local CAT rep here in the great lakes area this week. i will let you know how the conversation goes.
  5. Riptide III

    Riptide III Active Member

    Dec 8, 2007
    Dartmouth MA
    1997 Sea Ray 400DA
    Cat 3116 TA
    1994 Sea Ray Laguna CC Twin 135 Mercs
    Steels hit on a good point. I believe (according to a local diesel shop) Sea Ray changed out the transmissions when they went from the 3116 to the 3126 because of the power rating. I don't know what the tranny in the 3126 is rated for but I think that is the first nut I would crack. That would be easy for you to find out and possibly save you and some other people some time.

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