Looking for real-world experience with Detroit Diesel 8V-92 DDEC III (760 HP) for long-range cruising

[JL#1]

Hi all,

We’re seriously considering a yacht that checks nearly every box for us — layout, build quality, condition — but it’s powered by twin Detroit Diesel 8V-92TA DDEC III engines (760 HP, 1250 operating hours). Before we go further, I’d love to hear from anyone with direct experience running or maintaining these engines in a marine application.

Our cruising plans are to run the boat from Alaska down to Mexico, spending long periods aboard and typically cruising slow and steady in the 8–10 knot range. We’re not in a hurry and value reliability and range over speed.

Our only prior diesel experience was with Cummins QSBs (on our previous boat), so these older two-stroke Detroits are new territory for us. I’ve done a fair bit of reading and understand the basics — they’re not as fuel-efficient as modern 4-strokes, can be prone to wet-stacking if under-loaded, and need diligent maintenance. That said, we’re trying to figure out if these engines are a deal breaker or simply a quirk we can manage with proper care.

A few specific questions for anyone familiar with this setup:

• How do these engines behave when run at lower RPMs for extended periods (8–10 knots cruise)?
• What kind of fuel burn and RPM have you seen in real-world cruising conditions?
• Have you run them long distances at modest speeds — if so, how did they hold up?
• Any common failure points or maintenance headaches specific to the DDEC III version (electronics, injectors, cooling systems, etc.)?
• Are parts and support still reasonably available?
• How concerned should we be about the DDEC electronics in terms of reliability and future serviceability?
• If you were us — looking at a boat you otherwise love — would the 8V-92s stop you, or would you go ahead with eyes open and a good maintenance plan?

We’re not opposed to a higher fuel burn if everything else about the boat works for us — we just want to go in with realistic expectations and understand any potential long-term limitations of these engines for slow-speed cruising.

Any insights, stories, or hard data from owners or mechanics would be hugely appreciated.

Thanks in advance for your time and experience — we’ve learned a lot from this forum and value the collective wisdom here.

Justin

 

[PierreR]

I have no direct experience with the 92 series Detroit's but I have experience with the 71 and 53 series. In the last century Detroit was the higher end premium engines for power and longevity. Modern 4 stoke engines beat them hands down now.
If the engines are up to temperature you will likely have few problems with wet stacking. At 8-10 knots that should be no problem 6-7 knots you might have issues. At 8-10 knots they will use about 10-15% more fuel that a 4 cycle diesel. Clean fuel, good anitfreeze and regular oil changes are key.
They are sensitive to exhaust back pressure and are therefore have louder exhaust and a 4 cycle. They are prone to small oil leaks from the many gaskets.

At 1,250 hours and clean bill of health now, is certainly not a deal breaker in my opinion.

 

[tiltrider1]

My advice is search YouTube. Lots of videos regarding damaged dd8v-92’s due to heat issues. All of these are due to a lack of adequate maintenance. This will give you an idea of what level of maintenance is required.

I think highly of the Detroit 2 stroke engines. Some are more bulletproof than others but all are good engines if you understand the correct level of maintenance.

 

[Ken E.]

Your question needs to be answered by a user of DDEC Detroits with high horsepower. I've had 8V71'S but they were low horsepower naturals. They were good running slow, got reasonable fuel economy, didn't smoke and leaked oil like crazy.

There are thousands of Detroits world wide in lower horsepowers in work boats that are run slow daily with no adverse effects. But they're not DDEC 8V92'S. If I were you you, I'd seek out a 2-cycle Detroit mechanic and pose your questions to him, although such mechanics are becoming hard to find, at least in the PNW.

 

[JL#1]

Thanks for everyones replies and feedback so far! It's noted.

 

[sunchaser]

Do you have any information on how the previous owner(s) used these diesels as far as %load?

Secondly, maintenance records are vital as to current health. The Seattle area is blessed with some good 92 series mechanics. Any chance you could talk with the previous maintenance people?

Lastly, what vessel are the 92s in?

 

[JL#1]

Do you have any information on how the previous owner(s) used these diesels as far as %load?

Secondly, maintenance records are vital as to current health. The Seattle area is blessed with some good 92 series mechanics. Any chance you could talk with the previous maintenance people?

Lastly, what vessel are the 92s in?

I've been advised that load % and more info can be pulled by a mechanic with the DDEC programming via the controllers, currently I don't know?

The current owner has owned it since 2007, and had a major health issue in 2022 that impacts his memory, so info is somewhat limited and what is available may not be accurate.

I've asked what exists for maintenance records and have obtained some info but my understanding is it was maintained by various mechanics. I'll ask to see if anyone who historically maintained it I could connect with.

In a 64' pilothouse motor yacht, semi planing hull, about 80,000lb dry weight.

 

[kapnd]

Sunchaser’s question above needs an answer!
High hp DD motors at 1250 hours could be pretty tapped out if they were run hard.
If it were my decision, I’d be moving on to something with more modern design power.

 

[Taras]

That would be an engine that would make me pass on purchasing that vessel. Everyone has an opinion, but watching my friends DDEC's constantly break, massive fuel consumption, oil leaks, time to major overhaul is short, loud, etc..... if you're looking for a trawler, this is not a trawler motor.

 

[Mako]

@JL#1, I'm like @Ken above that I ran 6-71N's. They were amazing engines, but honestly I'll never own another boat with Jimmies, as we have now entered another millennium with more modern choices.

I've read all sorts of cautions about the -92 series especially with the highly tweaked engines like your TAs. I would recommend you reach out to Lepke here on the TF as he's extremely experienced with the Detroits.

BTW, if you really love the boat, and wish to keep it "forever" then you could switch those beasts out for a couple of 4-71Ns and run your boat like a Hatteras LRC at a stately 8 knots

BTW, are there a JL#2 and #3?

 

[JL#1]

@JL#1, I'm like @Ken above that I ran 6-71N's. They were amazing engines, but honestly I'll never own another boat with Jimmies, as we have now entered another millennium with more modern choices.

I've read all sorts of cautions about the -92 series especially with the highly tweaked engines like your TAs. I would recommend you reach out to Lepke here on the TF as he's extremely experienced with the Detroits.

BTW, if you really love the boat, and wish to keep it "forever" then you could switch those beasts out for a couple of 4-71Ns and run your boat like a Hatteras LRC at a stately 8 knots

BTW, are there a JL#2 and #3?

Thanks! Don't love it that much to bite off engine swaps.

Lol, no, only a #1

 

[mmullins]

Well, you can grab a cold one and watch old episodes of "In Too Deep" on YouTube. I'm pretty sure Gus is running 8V92'S in his old Broward. As for me, I just bought (July 2025) a 53' Hatteras with 6V92's. I don't have any complaints so far. But, I've only put about 500 miles on her.

 

[man n black]

FWIW and I know I'm not comparing apples to apples here....

One of my very good friends runs a 6V92 turbocharged mill in his Bluebird motorcoach that he just finished overhauling. He loves it. He does say though that to make good climbing / pulling power in PNW mountain passes he cannot start from dead stopped and must get a run at it...stating they the 6V makes its power at higher RPMs than other diesels of the same slightly later timeframe. He also says he watches temps very closely.

He however is an expert regular mechanic with the tools, knowhow and has strong local support from a Detroit specialist.

Good luck in your search!

Ch

 

[mmullins]

FWIW and I know I'm not comparing apples to apples here....

One of my very good friends runs a 6V92 turbocharged mill in his Bluebird motorcoach that he just finished overhauling. He loves it. He does say though that to make good climbing / pulling power in PNW mountain passes he cannot start from dead stopped and must get a run at it...stating they the 6V makes its power at higher RPMs than other diesels of the same slightly later timeframe. He also says he watches temps very closely.

He however is an expert regular mechanic with the tools, knowhow and has strong local support from a Detroit specialist.

Good luck in your search!

Ch

USCG uses Detroit 6V92's in their 47' Motor Lifeboat to this day. They must be semi dependable.

 

[JL#1]

FWIW and I know I'm not comparing apples to apples here....

One of my very good friends runs a 6V92 turbocharged mill in his Bluebird motorcoach that he just finished overhauling. He loves it. He does say though that to make good climbing / pulling power in PNW mountain passes he cannot start from dead stopped and must get a run at it...stating they the 6V makes its power at higher RPMs than other diesels of the same slightly later timeframe. He also says he watches temps very closely.

He however is an expert regular mechanic with the tools, knowhow and has strong local support from a Detroit specialist.

Good luck in your search!

Ch

Thanks! Appreciate the response.

 

[JL#1]

USCG uses Detroit 6V92's in their 47' Motor Lifeboat to this day. They must be semi dependable

Well, you can grab a cold one and watch old episodes of "In Too Deep" on YouTube. I'm pretty sure Gus is running 8V92'S in his old Broward. As for me, I just bought (July 2025) a 53' Hatteras with 6V92's. I don't have any complaints so far. But, I've only put about 500 miles on her.

Thanks! I have watched lots of his videos, they are pretty great! I believe he has the 12V-92's. Congrats on your Hatteras purchase, hope you've been enjoying!

 

[mmullins]

Thanks! I have watched lots of his videos, they are pretty great! I believe he has the 12V-92's. Congrats on your Hatteras purchase, hope you've been enjoying!

More holes, more money! LOL! Since I rarely exceed hull speed, I'm looking for that elusive Detroit 4V92. LOL!

 

[JL#1]

More holes, more money! LOL! Since I rarely exceed hull speed, I'm looking for that elusive Detroit 4V92. LOL!

Haha, good luck with your search

 

[Dockmaster]

Not many Trawler's with these engines I suspect. Here's the same response I gave you on another forum where you posted same question:

I had 1993 era 12v92 DDEC in my boat. I did a top end on one and a major on the other. All of the mechanical engine parts were readily available (pistons, heads, bearings, etc.). The DDEC parts are a whole different issue. The parts have not been manufactured by Sturdy (OEM) for a long time. When (not if) you need a part your options are limited. You can send the component to Sturdy and they may be able to repair it. Or you can try to find used parts from places like EBay.
The other challenge is finding someone to work on the DDEC items. There are very few of these folks left. And if you have an issue in Alaska or Mexico you’ll be flying someone in if you can find someone willing to travel.
I don’t recall if the DDEC III version made the switch to 24v components or still have the 12v components. Mine had the 12v components which creates even more hassles. 24v starters and alternators with 12v DDEC components means you have converters and more potential failure points.
I wouldn’t buy a boat with those engines but to each his own.

 

[Dockmaster]

USCG uses Detroit 6V92's in their 47' Motor Lifeboat to this day. They must be semi dependable.

There is a reason the USCG issued a large Service Life Extension Program (SLEP) contract on these boats starting back in 2019. It includes repowering and getting rid of the 6V92's

 

[JL#1]

Not many Trawler's with these engines I suspect. Here's the same response I gave you on another forum where you posted same question:

I had 1993 era 12v92 DDEC in my boat. I did a top end on one and a major on the other. All of the mechanical engine parts were readily available (pistons, heads, bearings, etc.). The DDEC parts are a whole different issue. The parts have not been manufactured by Sturdy (OEM) for a long time. When (not if) you need a part your options are limited. You can send the component to Sturdy and they may be able to repair it. Or you can try to find used parts from places like EBay.
The other challenge is finding someone to work on the DDEC items. There are very few of these folks left. And if you have an issue in Alaska or Mexico you’ll be flying someone in if you can find someone willing to travel.
I don’t recall if the DDEC III version made the switch to 24v components or still have the 12v components. Mine had the 12v components which creates even more hassles. 24v starters and alternators with 12v DDEC components means you have converters and more potential failure points.
I wouldn’t buy a boat with those engines but to each his own.

Thanks! I just read it and replied, appreciate the insight!

 

[John Walsh]

Although we ended up buying a trawler with Perkins, we had planned on getting a boat with Detroits. I did a great bit of research on running the engines at lower RPM. 8-92 have a bad reputation when pumped to 500 Hp or higher. A mechanic a Johnson and Towers suggested switching to continuous duty injectors and running wide open.

 

[RonR]

While not the same boat. I ran a pair of 750hp 8V-92 TA’s in a 50’ Sport fisher for a few years.
Boat weight was around 55,000.
At 12knots we would see 10.5 gallons per hour, 1.2nm/gallon. If I ran much slower they would like to soot up. Given this boat had huge props & could top out at 30mph.
Detroit’s are on the loud side, they smoke on start up, they smoke at idling. They often leak oil. They require oil changes more often than other brands. And one must always use the recommended 2-stroke oil. But with that being said, they were always reliable.
Parts are getting a little more difficult to obtain, but not impossible or vastly expensive.
If I was going to do it again, I would hire the best surveyor I could find that specialized in wiring (Global Marine, Aaron Wilson). Really need to check the ECM harness & grounds for corrosion. Make a habit of insuring your temp sensors are working correctly. Make a habit of clean fuel, clean filters. Make a habit of servicing your heat exchangers. If you hate the DDEC setup, you can swap back to mechanical. But you need injectors, pumps and controls. Prob set ya back 7-10k.
For the right boat at the right price I would do it again. I kind of love the sound!

 

[Hobbit]

Hi all,

We’re seriously considering a yacht that checks nearly every box for us — layout, build quality, condition — but it’s powered by twin Detroit Diesel 8V-92TA DDEC III engines (760 HP, 1250 operating hours). Before we go further, I’d love to hear from anyone with direct experience running or maintaining these engines in a marine application.

Our cruising plans are to run the boat from Alaska down to Mexico, spending long periods aboard and typically cruising slow and steady in the 8–10 knot range. We’re not in a hurry and value reliability and range over speed.

Our only prior diesel experience was with Cummins QSBs (on our previous boat), so these older two-stroke Detroits are new territory for us. I’ve done a fair bit of reading and understand the basics — they’re not as fuel-efficient as modern 4-strokes, can be prone to wet-stacking if under-loaded, and need diligent maintenance. That said, we’re trying to figure out if these engines are a deal breaker or simply a quirk we can manage with proper care.

A few specific questions for anyone familiar with this setup:

• How do these engines behave when run at lower RPMs for extended periods (8–10 knots cruise)?
• What kind of fuel burn and RPM have you seen in real-world cruising conditions?
• Have you run them long distances at modest speeds — if so, how did they hold up?
• Any common failure points or maintenance headaches specific to the DDEC III version (electronics, injectors, cooling systems, etc.)?
• Are parts and support still reasonably available?
• How concerned should we be about the DDEC electronics in terms of reliability and future serviceability?
• If you were us — looking at a boat you otherwise love — would the 8V-92s stop you, or would you go ahead with eyes open and a good maintenance plan?

We’re not opposed to a higher fuel burn if everything else about the boat works for us — we just want to go in with realistic expectations and understand any potential long-term limitations of these engines for slow-speed cruising.

Any insights, stories, or hard data from owners or mechanics would be hugely appreciated.

Thanks in advance for your time and experience — we’ve learned a lot from this forum and value the collective wisdom here.

Justin

I had a 50’ wood boat with 8V71 natural for 8 years. At 8kts it’s 4.5 USGPH @ 1400 rpm. 9kts 1600to 1700rpm 9 GPH. It’s was good for us at the time a bit loud or current boat is 7ft longer 5’ wider and burns 4 USGPH at 8 kts single Cat D333 1968 and is quieter. 92 series are turbo a little quieter but thirsty. 2 would be a deal breaker for me all you need is one. IMHO no problems in 23 years of cruising PNW I like the prop protection from a full keel as well.

 

[Dswizzler]

Not sure what kinda boat you are looking at with these motors, I’ve run from SanFrancisco to to the Panama Canal, over the last ten years with a pair of those motors in a 58ft Vantare. The beauty of they motors is you can Always find the parts and so one to work on them. Currently setting at about 4800 hours, the boat had 1800 hours on it when I bought it. I’d say jump in with both feet. 80,000 pound of boat at 7 knots gets me about 1.1-1.2/miles a gallon. PM me if you have additional questions. Currently sitting in Barra De Navidad , Mexico.

 

[Dswizzler]

Not sure what kinda boat you are looking at with these motors, I’ve run from SanFrancisco to to the Panama Canal, over the last ten years with a pair of those motors in a 58ft Vantare. The beauty of they motors is you can Always find the parts and so one to work on them. Currently setting at about 4800 hours, the boat had 1800 hours on it when I bought it. I’d say jump in with both feet. 80,000 pound of boat at 7 knots gets me about 1.1-1.2/miles a gallon. PM me if you have additional questions. Currently sitting in Barra De Navidad , Mexico.

 

[Dockmaster]

Not sure what kinda boat you are looking at with these motors, I’ve run from SanFrancisco to to the Panama Canal, over the last ten years with a pair of those motors in a 58ft Vantare. The beauty of they motors is you can Always find the parts and so one to work on them. Currently setting at about 4800 hours, the boat had 1800 hours on it when I bought it. I’d say jump in with both feet. 80,000 pound of boat at 7 knots gets me about 1.1-1.2/miles a gallon. PM me if you have additional questions. Currently sitting in Barra De Navidad , Mexico.

Are you saying you have no problem finding parts and service techs for DDEC versions of the 8v92’s? And rated at 760 hp? Or do you have mechanical versions of the 8v92?

 

[Comodave]

USCG uses Detroit 6V92's in their 47' Motor Lifeboat to this day. They must be semi dependable.

Not so much anymore.

The original engines in the U.S. Coast Guard's 47-foot MLB were twin Detroit Diesel 6V92TA engines, each producing
435
hp. The Coast Guard has since upgraded many of these vessels with twin Cummins QSC8.3-M engines, which provide
530
hp each, for a combined horsepower of
1060
hp. These newer engines are part of a service life extension project that aims to improve performance and fuel efficiency.

 

[Dswizzler]

Are you saying you have no problem finding parts and service techs for DDEC versions of the 8v92’s? And rated at 760 hp? Or do you have mechanical versions of the 8v92?

Did a major overhaul on one motor, in place back 2011, but since then no major repairs needed. Yes, hoses, heat exchangers, starters have needed repair or replacement, but nothing has stopped us from running. Mechanics, I have found in California, Mexico, El Salvador and Panama. Some learned from their fathers. Yes they leak oil, but they run all day. Our longest run was 96 hours from the Mexican southern border to Manzanillo, Mx. we typically run between 6-8 knots at around 950 rpms. That is the sweet spot getting us 1.1-1.2 miles per nm. They burn typically a total of 6-7 gallons per hour total, so 3.5 per motor, with a single turbo.

About every 20-30 hours we blow out the turbo, running the boat at WOT which is 1900 rpm, we are over propped. That burn rate is about 65 gph, I like to go slow and enjoy the ride.

 

[jskoda]

I am currently running 8V92 s @750 hp on a 65' Motoryacht weighing in at 120k. I have zero issue with this boat at 2000 miles engines have about 7000 hours. I previously had 6v92s and did the Loop in that boat. When I was looking for a new boat I specifically looked for Detroit Diesels. They are simple and are reliable. They have never let me down.