Cummins Marine is amazing

[jddaniel]

Got a boat with twin 370hp Cummins 903ci V8 diesels (former tugboat engines), and was thinking about re-powering. Not that the 903 V8s were a problem, just thinking about size-reduction and maintenance concerns later (903s are HUGE, duh). I find it amazing (or maybe I should expect) that Cummins Marine offers a 360ci I-6 (B5. 9 series) that puts out the same HP as the old 903ci V-8! Now I'm sure, I've got to think about some torque loss, cut down prop size or gear reduction or something, but the engine size reduction and less moving parts thing really sounds good. Anyone with any Cummins Marine re-power stories, lets hear 'em...



Awesome$$,



JD

 

[R.E. Miller]

Alright, tall tales here we go...

I am not going to say who, because this is the internet, but a major cummins service and sales center told me and a few of the Mason Dixon members about a boat that they re-powered. I cannot imagine what this thing weighed, or how many pounds of fuel flowed through the lines when it was wide open. The story is that the boat was originally powered by three 8V-71's turbo or not, I don't know. The cummins place installed 4, yes 4, cummins diesels of which I cannot remember what model ISX, or something all rated at enormous HP #'s. They said that the owner could control the tide levels and times with the new set-up just by bliping the throttles while in the marina he he... just to have that kind of cash



Russell

 

[Ray Torresdal]

903 vs. B5.9

I know nothing about marine applications. That out of the way, my thoughts. In truck applications the 903 was governed at 2800 rpm. I don't know what the marine B5. 9 is governed at, but I doubt much higher. I very seriously doubt you will have to change gearing, unless it would be to gear the prop faster/engine rpm. I also wouldn't be too surprised if the B5. 9 was close enough to the 903 in torque #'s. The 903 I drove needed a 13 speed, instead of the 10, but did a pretty good job. It got good fuel mileage for it's time. Good luck! Ray

 

[gatoram]

I'm not sure about a re-power, but Cummins marine is a fine way to go. I bought a new 1990 26' Shamrock with a 210 hp 6bt(turbo-no aftercooler) 1:1 transmission. I put over 6500 hours on that engine with no major problems. Repowered it in '98 with a new 210 - the only difference a Hurth transmission with a 1. 23:1 ratio turning a 4 blade 17"x17". I cruise 21-22 knots and consistently burn 3 gph. The boat weighs 7500#. I haven't researched it lately, but they had the 6bta up to 330 hp. Thru the repower( I did my own at a local yard) Cummins SE was exceptionally helpful in every aspect. They even manufactured special mounts for the transmission end on a Friday afternoon-I had them Monday morning unpainted but ready to go. Hope this helps you.



Tom p. s. i make a good part of my living with this cummins and it works

 

[tgbol]

When I worked for the Harbor Dept they obtained a small tug boat for moving work barges and pilings around the harbor. The boat was close to 50 years old at the time. It had a Detroit Diesel 6-110. Repowered it with a 5. 9 6bta. More than twice the power. really worked great.

 

[Don M]

JD,

While the marine re-power is a good idea and might seem easier and cheaper at first you may end up with troubles over the long haul.

The main thing I see wrong is the Diamond 370HP marine engine is rated for that power rating for 1 out of 8 hours of use.

After which you have to reduce power output and the engine rpm by 200. It is a great little engine for recreational purposes though. If you are going for that type of use it may be ok.

The big 903's can produce the 370HP all day and night and not suffer like the 5. 9.



Further the 370HP Diamond is for a maximum of 300 hours per year of use.



Trying to make up the torque loss might hurt in the long run as well. The 903's really make the torque to drive the screws.



Don~

 

[Sled Puller]

Check with www.enterpriseengine.com about Cummins marine engines, what they are cabable of power wise, and how long they will live.

370hp is just a factory starting point.





What would the weight savings be over the big engine?

And what are your plans going to be for your boat? A pleasure boat is not near as stressful as a tug pushing around tons of weight all day long.

Just the same, I have more power right now than maybe90% of the semis on the road, but I don't think I could haul 80,000 pounds.

Do you think the 903s were overkill, or is that big of an engine needed?



Gene

 

[jddaniel]

Thanks for the informative replies. Yeah its definitely recreational, they're pushing a 65-foot aluminum houseboat. And yes, the 903s were probably overkill for this application, even though its a big boat, its fairly light, and shallow draft. True, the 903s are probably never working near their rated capacity to move this thing. Aside from some obvious benefits like space, weight, fuel savings, a 370B would probably be a bit much as well, probably a lower rated B series would be better and still have plenty of power to push it around.

The previous owner had his own marine towing company, and I believe he just had some spare 903s out of a workboat, and replaced the original gas I/Os with the 903s, then sort of homemade-engineered his own version of a nozzle rudder/drive, works pretty good along with bow thrusters helping in docking and tight quarters.



Thanks



JD

 

[Sled Puller]

Twin 903's in a 65 foot Houseboat?



Holy Cow!



Turn those babys up and lets go offshore racing!!!!

 

[jddaniel]

Exactly, I like that thought! Yeah these things are incredible at WOT, kind of like a caged tiger, except the cage feels like a wet paper sack, scared to think of the potential they have!



Yet another project, these babies deserve a proper home!