Considering Repowering Again

The different DDC HP numbers are SAE flywheel HP and propeller shaft HP.
It's the same engine.
IMO, the C32s will fit. In a lower HP config & tune, could also near last forever.

That would surprise me.

Time to crawl in with a c32 (or 3412) somewhere with measuring tape in hand. Having worked around both engines with out a tape in hand, IMO the low profile 12V92TA and straight ZF clutch was still taller.
The DDC blowers protrude up from the airbox about the same as Cats aftercooler.
Take a C-32 with a down angle propeller shaft and I think you could lay a bunk above it for the in-laws.
Less the oil filters, fuel filters, black boxes and junk that can be remotely mounted, both blocks and exhaust manifolds are about the same width,, IMO with out a tape in my hand..

The DDCs could not use a down angle clutch because of all the junk on the block sides below the exhaust manifolds. The Cat just has a starter down there.

The Cat heat exchanger does eat up some room. No reason it could not be lowered some. Down angle clutch will really help here also.

You have turbo, blowers, more cam shafts than Carter has pills and inter gears wizzing all over those DDC engines. Plus, because of the open exhaust for the Detroits, near wide open exhaust. Then old freaking motor mounts. No telling where your noise is coming from now.
IMO (again), with some work, maybe a muffler upgrade, you should be quieter.

I'm sorry your at the far corner of the country from me.
I luv working on these projects. A few under my belt. None this large, but all fun and working very well.

The CAT C18 engines are known to be noisier than the rest, that particular model only. Even with a good Marine Exhaust or Centek muffler system. But your DD’s were not quiet engines so it may be a wash.

The other alternative is the derated MTU 10V2000M86, probably the best package/power for the Donzi 54 , would have a higher upside on resale too.

I remember working with a pair of C32-1652s in a Hat 72. I did not think it was that loud.
Muffler to below hull outlet. Idle bleeder out the stern.

It’s the straight inline C18 that is the loud one, common knowledge on the SF circuit. Unique sound because of its firing order.

But again , the 2-stroke Detroit’s have their own bark.

Mans will just hum...a bit more expensive, but I think everyone will agree that its a very quiet motor.

Some of the new V8 Man's would be a good choice. MAN also has HP levels to bridge the gap between the C18's and C32's as far as HP goes. They are indeed quieter than the cats. The C18's, while they are noisy, they are definitely not as noisy as a set of 12v92 TA's. The C18's are bulletproof motors and MUCH more fuel efficient than the C32's, by a LONG shot. Quite honestly, you rebuilt the DDEC's, finding parts for them is still possible, run them until you have a failure, OR until you have a buyer willing to pay good money for them, it's not like you're going to get a ton of money selling the 12v92's.

Heras a snapshot of the 12V-92TA:


1040 is the shaft horsepower. There was an 110hp DDEC Version at the end of the production run.

The big benefit you will get is a tremendous weight savings:
12V-92TA = 5,861 lbs. dry
CAT C18 = 4,101 lbs. dry
MAN V8-1200 = 4,278 lbs. dry. They also have a de-rated 1000hp version that is 3,925 lbs. if you don't need to go above 1000hp.

The weight savings is a great trade-off to add a SeaKeeper and still be less than the overall Detroit Diesel engine package weight.

If you're happy with the performance with the current 12v92's, you'll be ecstatic with the C18's. 85 GPH (both) at 80% load, and my guess between the weight savings, extra HP and etc is that you'll pick up 3 knots at cruise and top speed.

My input is simple. If it ain't broke, don't fix it.

You could easily spend a lot of money to get a boat to perform just as it does today. That's pretty much best case. Worst case is you spend a lot of money and struggle to get it right and performing as it does today.

I had a Detroit Diesel 12V-92TA spec sheet as well, maybe a little older, it may have also included the large factory gearbox in the 5,861 lbs.

The CAT C32 weighs 6,780 lbs. and is too much iron in my opinion. The MTU 10V2000M86 at 5,082 lbs. gives you 1360 hp and would get you to 35 Knots if speed was on your mind.

If you are keeping the boat for the next 5 - 10 years, I would go with the repower and enjoy the benefits.