CAT 3126 marine

[Mark Rinker]

Anyone know about marine CAT 3126s - rated at 375hp? Common thought in marine circles is to leave them set/propped at factory spec, but hey...thats no fun if there is efficiency and MORE POWER to be gained.

Any insight, experiences appreciated.

[EdHale]

I don't know anything about this particular engine Mark, but I do know a bit about boats. The last new one I bought and still have btw, was over propped from the factory. I don't know if it was intentional or someone on the line just grabbed the wrong prop, but it was over propped from the correct pitch of 19-21" to 25".

The way to determine the correct prop pitch for any boat is to load the boat up to the loading, fuel/water/food/passengers, that you normally have when under way. If the engine will turn max rpm at wide open throttle, then the boat is propped correct. If you can't get max rpm for your engine then the pitch needs to be reduced or increased if you hit your rev limiter. Keep in mind if you have the boat loaded lighter, even with the correct prop pitch you have the potential to hit the rev limiter.

This is the true test of the correct prop for any boat.

[Mark Rinker]

Hey Ed - we are having Georgia weather up here this winter! My boat could still be sitting in the slip we hauled her out of - not frozen in the marina...at the end of January...in Minnesota?

My engines seem to be running fine - very consistant power, temp, fuel consumption from port to starboard (they pull from separate tanks). The RPM test you mention is within 50rpm of loaded 2800 rpm target, so I think the props were matched well from the factory.

My goal is to find any fuel consumption efficiencies possible - through re-propping, tuning, etc. There is a 425hp version of my engine available from CAT, that involves different injectors, turbo, and fuel rate. That would be a fun mod to investigate, matched to the right props to put the power down.

I can't completely describe the feeling of rolling both of the throttles to WOT on this boat from a dead stop. It takes a few seconds for the turbos to spool, but since they breath through a huge oiled gauze style filter, the whine is very noticable and pleasant. At about 1500rpm, the bow rise stops, and the whole boat rises about 12" up out of the water - so as you come up on plane your visual perspective changes as speed increases. Its like riding on top of a motorhome through a sea of water moguls that flatten out under 26K# plowing along happily at 24 cruise; 32mph tops.

Fun stuff.

[EdHale]

This isn't typical weather for us Mark. I have moved from Georgia to 65 miles south of Birmingham, AL, but regardless it is 68 degrees here right now. I have the windows open. Imagine that on January 31.

It sounds like your boat is pretty well dialed in now, but most of us understand the desire to tweak it a bit. It sounds like a sweet ride and I know what you mean about the sound and the joy of cruising along under twin diesel power.

I will be going back to Panama City, FL this summer. This will be my second summer as a volunteer at a State Park in the area. I get to use my Masters license while there however, driving a shuttle boat out to one of the barrier islands. I might as well make a few bucks while there an it is something I enjoy doing - driving a boat and getting paid for it.

[Mark Rinker]

My plans, exactly. Just a few years behind you. About to take my passion for diesels and apply it to marine engines for the next chapter of MRE. Looking forward to getting off the road - someday.

[a5150nut]

My plans, exactly. Just a few years behind you. About to take my passion for diesels and apply it to marine engines for the next chapter of MRE. Looking forward to getting off the road - someday.

Sounds like MRE Barge & Tug Service in the works.

[Mark Rinker]

Sounds like MRE Barge & Tug Service in the works.

Hey that has a nice ring to it!

[a5150nut]

Might sound good to you. But I bet Mama would throw you overboard when you start hanging old tire off the rails!

[Mark Rinker]

LOL - it would be fun to see how much one could push/tow. It has 22"/23p props... :eek:

Seriously I am considering going back to school for marine diesel tech. Take all of the experiences here, and apply them to some large boat maintanence/performance tuning.

[More Power]

Anyone know about marine CAT 3126s - rated at 375hp? Common thought in marine circles is to leave them set/propped at factory spec, but hey...thats no fun if there is efficiency and MORE POWER to be gained.

Any insight, experiences appreciated.

DOn't know much about the marine Cat, but I spoke to a GM special projects tech in early 1996 who reported that they had assembled a 3500 series pickup with a 3126 as a test vehicle. It was rumored at the time that GM might go with the Cat to replace the 6.5 as an HD alternative to the PSD/ISB Cummins. I even did a story about all this for TDP - with pics. But... 1996 was the year that the Duramax was conceptualized. The rest, as they say, is history...

[Mark Rinker]

HOLY HANNA...that thing must have had some mega-suspension. The 3126 must weigh 2x of a bigblock.

[rustyk]

Dry weight is a bit less than 1600 lbs, so it's somewhat reasonable. Somewhat...