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  • #124396

    alan neuman
    Participant
    Vessel Name: blue dolphin
    Engines: Cummings 5.9
    Location: New York
    Country: USA

    hello my 2013 tiara 36 open with Cummings 5.9 at 380 hp .Is it possible to increase to the 425hp and will I increase my speed is it worth to do cost v speed and fuel consumption Please let me know thank you and happy holiday

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  • #124521

    JimmyK
    Participant
    Vessel Name: Incognito
    Engines: 2 x 6BTA 370s
    Location: Boston
    Country: US

    I looked into this a little and it appears that the 330/355/380 are all the same and can be up/down-rated via software.  425 is a different CPL.  I think the turbo is different, not sure if anything else is.  So I don’t think Steve is correct when he says you can re-program to get to 425?  I believe you would need to make additional changes.  Hopefully someone can chime in with the list of differences and then you can determine whether the cost/effort is worth it for the very small increase in HP…my guess would be no but it would be nice to have the info laid out.

    1 user thanked author for this post.
    #124506

    JimmyK
    Participant
    Vessel Name: Incognito
    Engines: 2 x 6BTA 370s
    Location: Boston
    Country: US

    Good answer Steve…but is the only difference between the 380 & 425 programming?  No other differences in the motors?

    It would be easy & cheap enough to add a little pitch to the props so long as you’re not overloading the engines.

    #124399

    Steve Lewis
    Participant
    Vessel Name: Just Us
    Engines: Cummins 480CE
    Location: Marblehead, OH
    Country: USA

    Some thoughts………

    Happy Holidays!

    Re-programming the engine to a 425 alone will not get you a faster boat. You still have the same gear and propeller pitch. Propellers move boats, engines just turn them. There is a great article in the Tony’ Tips section that explains this.

    https://www.sbmar.com/featured-article/propellers-move-boats-engines-just-turn-them/

    Look at what Tiara does to the gear ratio and the prop pitch on the boats from the factory outfitted with the 380 vs the 425. I attached the Tiara performance reports and it shows that they come from the factory with different gear ratios and prop pitch.

    The 380 has a 2.04 ratio and 23×30 prop
    The 425 has a 1.96 ratio and 23×31 prop

    That is how Tiara makes the 425 equipped boat go faster. Since the 425 has 1 to 2 GPH more fuel burn at 2400+ rpm there is more power to turn the gear and prop. Thus the higher speed.

    Compare them at 2400 and 2600rpm. See the higher fuel burn on the 425 that is then transmitted through the bigger gear and prop. That is what gets the boat moving fast. Not just the added HP, its the HP+Gear+Prop.

    The easy way to get your boat to go faster in its “As Is” setup is to carry less weight. Like fuel load. You can pick up 1 to 2 mph by carrying a lighter load of fuel. We have a different boat but we have the same fuel capacity. 400gallons. I notice that when we run “light” 150gal or less we move along at about 1.5mph faster with a 1 to 2 GPH lower fuel burn.

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