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Increase HP on 150 hp turbo 4BT Cummnins.

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  • boatworkfl
    replied
    You need to contact Cummins for advice on upping the engine HP.
    It usually entails injectors-the turbo- and possibly exhaust, maybe more.

    Leave a comment:


  • TenMile
    replied
    I have the 3388 with the 4BTA 250 HP Engines. The manual states the engines can run 1 hour for every 8 at WOT (3000 RPMs) and run constant at 80% - 2600 RPM's. When we cruise on plane we will generally run the engines at 2500RPMs which will cruise us at roughly 17-18kts. At WOT I've hit 23kts but only ever do that for a short run to ensure I can hit WOT. Mine do have the turbos and the aftercooler. Aftercooler is another maintenance item that requires removal, cleaning, grease and zincs.

    With either engine, if you cruise at hull speed, fuel consumption is roughly 3 gallons per hour (total). On our longer trips we average 4-5 GPH combining hull speed and planing. I believe the engines max out at 9 GPH each at 3000 RPMs.

    Keep the cooling system clean and flushed. Watch your temperatures and change your oil regularly and these engines will treat you well.

    Leave a comment:


  • fishexit
    replied
    Bought a 1995 3988 with Hino 310hp 6 cyl thinking I would like to have the extra hp just in case needed. In order to run at blowout rpms boat has to run at speeds on SF Bay hull was not really designed for, just not as comfortable wise. Wished I would have gotten a 6 cyl 250hp instead that way less speed for running engine up for 10 -15 Minutes. Just thinking out loud.

    Louis and Roxie

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  • Ruffryder
    replied
    4BT @WOT minimum rated RPM 2800, minimum prop targeting RPM 2900

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  • hodaka
    replied
    Cpt.Blair, about your questions to me, let me divide them into two parts. First, about my personal cruise and WOT speeds. My wife and I choose to cruise at 6-7 knots, which is usually about 1100 rpm. Why? Because we like to go "slow" and look around and cruise for at least weeks and sometimes months at a time -- easier to look about at the scenery and it's quieter at low rpms. Other may like faster, its all good. Of course, to make slack times at rapids, or in the case of medical urgency, or whatever, it's nice to have some zip. At such low rpms like around 1100 rpm, the consensus wisdom is every day or so, run the 4bt engines at higher rpm for maybe 10-15 minutes, which I do, usually running at 2300 rpm, more or less for about 15 minutes.

    Second, about max rpms, and what is it? The Bayliner Owners Manual I have says "The diesel engine should be able to come up to 3000 rpm on a normally loaded boat." The Manual suggests trying different props if can't get to 3000 rpm. For my boat, neither the previous owner of 19 years, nor I, have ever used 3000 rpm -- max rpm for us is about 2500-2550, and that very sparingly Maximum engine longevity is our objective, and the 4bt's are great and reliable. Wonderful engine. As is the bigger cousin - the 6bt's -- which is the same engine with 2 more cylinders basically.

    When I'm running my 3388 for 15 minutes or so every now and then at around 2400 rpm, and assuming no current or wind and flat water, and with trim tabs all the way down, my recollection is the speed is about 13 knots, possibly 14 knots at 2600 rpm according to the previous owner. You also get lots more noise, but all boats seem that way to me when running at or near max rpm. The Cummins engines of that vintage are no worse in my opinion than the other engines of, say, the 1990's.

    A minor point -- check the internet for max rpm on the marine Cummins 4bt. My recollection is that there are time limits for running at or near the highest rpms, and at some point at a lower rpm (say 2400 rpm, not sure about that at all, check it out) the engine is rated to run constantly at that lower rpm. Again, not sure, check it out. For me that is never an issue, as almost always we cruise slowly at 6-7 knots.

    An aside. At one point I briefly looked into the opposite of what you are doing -- I made inquiries whether I could reduce the hp of each 4bt engine to maybe 100hp or even 75hp, by taking off the turbos, etc. Knowledgeable folks said don't bother -- the engines are set up for 150hp, it would cost lots of money to properly set them up for, say, 100 hp, even assuming it could be done. Might need different injector pump, many other issues, not worth it, I was told. Good advice, I think.

    Tony Athens views are well worth following, he knows his stuff backwards and forwards. Thanks for including his comments above, and good luck to you with whatever boat you end up with.

    Leave a comment:


  • CPT.BLAIR
    replied
    Hodaka, I am in the middle of purchasing the 3388. I will not be able to sea trial as vessel is being purchased as is,"that's another story". Can you share what your cruise and WOT speeds are?

    Yes, Tony was helpful. Here was his response.

    If you are buying a vessel with 4BT150’s, then that is what you are “stuck with”, in so many words.. You cannot up-rate the HP, just trust me on that.

    So, if the current engines DO NOT meet you need for speed, then you need to rethink the purchase………………

    But here is a caveat……………….If the vessel is fast enough at 100% WOT , loaded up the way you are going to use it WEIGHT WISE, and can make an accurate 2800 RPM or make even a tad more that that, then IMO, you could redo the cooling system on the engine and a few other things to make it reliable to cruise at 2800 RPM for many hours at at time going from Point A to Point B…

    The engine is unbelievably solid inside ( shares the same base “lower end” as a 480 QSB 5.9) and it very hard to break from over stressing the components.. But you do have to do some major upgrades to the cooling system along a few other things..

    Tony

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  • hodaka
    replied
    Agree Tony Athens would be knowledgeable. I see you have a1996 Bayliner 3388 with the 150hp versions of the 4BT, same as mine. The 250hp versions have an aftercooler added, I believe. That makes an already tight space even tighter. I think Bayliner used 3 different injection pumps on the engines for the 1996-2001 production of 3388’s. My 1996 3388 has Lucas Cav pumps, The answer to your Q may depend on the pump used, not sure. Good luck.

    Leave a comment:


  • Uncle_Bob
    replied
    That's a question for Tony Athens https://www.sbmar.com/contact-us/

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  • CPT.BLAIR
    started a topic Increase HP on 150 hp turbo 4BT Cummnins.

    Increase HP on 150 hp turbo 4BT Cummnins.

    I know there are a bunch of ways to get more HP out of the 4BT. Some guys are getting 300-400hp in there trucks. And there is the 250HP version. My question is. Has anyone had any luck with increasing the HP on the 150 version and use in the marine application? Say something as simple as turning up the fuel? I am not looking for massive gains. But to see if it is possible to get a safe 30-50 hp increase.

    Thanks,
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