Chipping up a Cummins 5.9L 230hp engine to 380hp

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Mar 20, 2017
Vessel Name
Hayley Rose
Vessel Make
North Pacific Trawler 43'
Has anyone had any experience with "chipping" up a cummins 5.9L 230hp QSB engine from 230-380hp? According to the engine specs it's a doable feature of the engine. iThere are things that have to be done, you have to have a larger: shaft, strainer, and RACORs and a heavier duty transmission. Then at the time of the upgrade, you adjust the pitch on the prop. The 230 block and the 380 block are exactly the same and has the same CPL#. So, mostly it's an electronic upgrade with a prop adjustment. Theoretically, I have confirmation it can be done. I'm just wondering who's physically done it and how did it work out? Did it affect your engine dependability or longevity?
Thanks for the input.
I haven't done it, but I had an extensive conversation with Tony Athens, the owner of a Cummins dealership in Oxnard, Ca, about it. He did say that it was a simple chip upgrade, but at a cost commensurate with Cummins pricing among the various models.

In that case I was considering buying a new boat, a Mainship 34T, that was offered with the 380 hp engine, but starting out with a lower horsepower version to see how it would work and if I needed more I would ust do the chip upgrade. I ended up buying the boat with a Yanmar 370 hp engine which was about $10,000 cheaper.

If you were to do it, I think I would follow the same approach: set up the transmission and prop shaft to deal with the maximum hp/torque output. Then select the prop to match the hp version that you start with. Then if you need to change, it will at worst only be a pitch change.

Note that the lower hp versions are rated at 2,600 rpm and the 380 hp version is rated at 3,000. Since the increased hp lets the engine turn the prop faster until it peaks out, you should only have to make minor prop changes if at all. A little work with boatdiesel's prop calculator will tell you how much if any.

In so far as engine longevity, it is related to how much horsepower you really use. That engine is probably good to 250 hp continuous, no matter which version you have.

MD. I have the same boat as you, mine is powered with QSB 330. After more than 6000 miles, I have found, that I never use that HP. Wide open with a clean bottom it will make 12 knots, burning 16+ gph. I run it at that speed to check cooling, vibration and so far for short periods of time. The rpms I use for the most part are, 1250 1450 1600 and 1800. 1800 will get you 8 knots. It seems like a lot of work for very little return. If it were me and it was nagging at me to get more hp, I would just do the chip and run it. After some testing, you would see if having the prop reworked was necessary. The shaft size on the 330 hp, is 55 mm. Might be the same on the 230 engine. Doing everything you mentioned, I am guessing you would be spending 15-20k. Hope this helps, Dan
Does the 230 have an after cooler? I thought not. The reason the lesser HP 5.9s are so nice is no after cooler. From the frying pan into the fire with this one change alone.

Then all the other marinization parts and pieces to extract an additional 75% power have to be added in. Sounds like a daunting task for a go slow by design boat.
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We have a 2009 230 HO. It does have an after cooler. The Cummins Diamond series 220 does not have an aftercooler. We have several friends who alo own the H-38 with the 380 and the 480 (3400rpm). It is the same block. But for the bigger engines in addition to the changes mentioned above, believe that the turbo is different. My friends with the higher output engines almost never use the extra power becasue of the fuel burn. At 6.5 kt we burn 2 gph. at 7.2 we burn 3 gph. at 8kt we burn about 4 gph. at our WOT 9.2 kt we burn 11.2 gph. I have heard that this boat at 16 kt would burn 26 gph.

But for what it's worth, i just got off a delivery on a 84' "trawler" from Nassau to Melbourne FL that boat burns 156 gph at high cruise 16kt... Filled up in Ft. Pierce, almost 3,000 gallons.
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