Cummins Repower: Removing TWO DETROIT DIESEL 12V-71 Engines! [Ep. 142]

In this episode, "Cummins Repower: Removing TWO DETROIT DIESEL 12V-71 Engines!" we're diving into some serious engine action!
We're yanking out not one, but two mighty Detroit Diesel 12V-71 engines and making room for a slick new Cummins upgrade.
These Detroit Diesel beasts are known for their power and toughness, but even legends need a makeover sometimes. Watch as we tackle this engine swap with a mix of humor, expertise, and plenty of grease.
If you're into engines or just love a good transformation story, this series is packed with cool insights and handy tips. Buckle up, it's going to be a wild ride! So don't forget to subscribe and hit that bell button so you don't miss any steps of this engine repower.
➡️To see where it all began - check out this playlist: • A SUPERYACHT ROMANCE -...
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[@sethbarnes7608]

Ahhh, the good ol' Detroit diesel. If there isn't any oil under it, there's no oil in it!😂

[@OnboardTangaroa]

And there was plenty of oil under them. That will be in the next video. Thanks for watching!

[@ryanehlis426]

The 12v 71 Detroit is such a cool engine, back in the day that was the ultimate big boy power plant in a semi tractor 😊

[@OnboardTangaroa]

They are for sure. Unfortunately time has caught up with them. They have had a seriously long run though.

[@crankycrow7371]

The Detroit's are 3 times better than any Cummins . I have been running 71 series Detroits in my commercial fishing boat for 38 years and they will outlast 3 Cummins engines of the same power . when the Cummins of the fleet are tied to the wharf for repairs the Detroits are out making money .

[@OnboardTangaroa]

Unfortunately the term "better" is subjective. Compared to the Cummins we have going in I have no doubt that the Detroits would last longer and due to the mechanical nature of the Detroits and lack of an injection pump it would take a lot to strand one. Sadly this is not the only thing to measure worth by. For starters the Cummins 6.7's weigh 3000 lbs less per engine. Thats 6000 lbs less weight to have to push. Secondly, fuel consumption is at least 25% better than the Detroits. That gives us roughly 1500nm more range with our capacity. It also saves around $2800 in fuel between fill ups. As a fisherman surely you can appreciate the additional profits gained by spending 25% less on fuel not to mention the added benefit of being able to stay out fishing longer. On your comment about the Detroits outlasting 3 Cummins engines of the same power my question would be whether those engines were of the same displacement class or if they were smaller displacement engines being pushed harder. Nice and slow running with low load on any engine will make it last exponentially longer. While I am not a big fanboy of either engine as both have there merits I am sure there are just as many Cummins owners that would refute your claims as there are Detroit owners that would support them. Glad they have worked well for you for 38 years. For this application they are the wrong engine though.

[@crankycrow7371]

@@OnboardTangaroa tell me after 15 thousand hours which engine is cheaper to run , the cummins will need to be replaced and the Detroits are only at half there life . i never had one go less than thirty thousand hours with proper oil change periods . But the cummins is a much better than a Cat . The Volvos seem to be holding up not bad but parts are hard to get and expensive . Good luck with the cummins electronics and the cheap plastic hose clamps but they do run very clean .

[@OnboardTangaroa]

I would wager after 15 thousand hours the These Cummins will still average massively cheaper than the Detroit in fuel and oil alone. This is especially true seeing as the QSB's run in our application (low load, low rpm) are seeing 25,000+ hours when properly maintained. Even then they would not need to be replaced, only overhauled. I will admit they do not tolerate poor maintenance as well as the Detroits but that is another story altogether. I am building these as custom units so there are no plastic hose clamps or cheap anything for that matter. I would have liked to have kept the Detroits and tried some efficiency upgrades but there were just too many variables that influenced the decision. Funny enough the Detroits actually ran pretty clean themselves (on the exhaust side) except that they were never run hard enough on this boat to clean out the stacks properly so if we ever bumped them up they would smoke for a bit. They did sound pretty awesome at full song though. Take care.

[@bugsternc]

@@OnboardTangaroa Hello, great job getting these two monsters out. For the little history of the engines, let me tell you those of my old Grand Banks 50 Europa, the same boat was marketed with Caterpillar V8s for the American market and Cummins 6BTA 5.9L or Ford Lehman 120hp for the European market, for a identical speed of 8 knots, 10 maximum......only the consumption changed...... For your boat, you could even have fitted 6BTAs, I don't think you would have seen a big difference. Anyway, I can't wait to see what happens next.... good luck to you both Stephane

[@OnboardTangaroa]

Thanks Stephane! We are pretty excited. Our power demands are pretty low at our cruise speed of 9 knots. It think its going to work out pretty well. Take care!

[@Rs500ybd]

Fantastic Big Efforts deserve Reward I Hope you enjoyed your Pub..

[@OnboardTangaroa]

Thanks! We did indeed enjoy our pub afternoon. Thanks for watching!

[@jeremystory6981]

Amazing effort,, you can't stop no matter what's in your way well then from both of you

[@OnboardTangaroa]

Thanks! It has been quite the yard visit this time around. Keeping motivated is always a challenge.

[@arczealdesigns9512]

That was awesome! Great work! You guys earned that night at the pub!

[@OnboardTangaroa]

Oh yes indeed we did. We are glad you enjoyed the video.

[@killerkane1957]

Just stumbled across your channel. I’m sure you know what you are doing. I’m seriously questioning the engine swap. The Detroits are simply the best in my experience. Never in water but I’ve pumped a lot of it. With Detroit. Great work and I’m sure things will be fine. Cummins will move your boat just like they would pump my water.

[@OnboardTangaroa]

There are several things that make the Detroits reliable. That is especially true with the ones we had onboard as they were the least powerful of all of the 12v-71 engines. Those things will run till they had no fuel left. Unfortunately there are things that make them very unsuitable for our purposes. The main one being a severe reduction to our range with several other smaller gripes. Unfortunately the bad outweighed the good in our case. The Detroits 12v-71's have had a good long run but as with everything over time and technology has made them obsolete. Electronic engines these days are starting to lose the stigma of being unreliable. The new line up of common rail engines are rivaling or exceeding the longevity of even the old greats. They do have their own little issues to be aware of but proper maintenance negates those issues. Thanks for watching!

[@killerkane1957]

@@OnboardTangaroa Very well stated and explained! I’m a very bristly Texas rancher. Old as water. Electronics?? What is that? Common rail? Lol! I get it and understand. I will go so far as to agree. But. At the same time, I’m just an old fool stuck in 1969. Sail on sailor!

[@OnboardTangaroa]

Lol, I started my career on mechanical diesels. I know the feeling. I can't say I didn't have my reservations going with the electronic engines. The more I have worked on them the more confident I have become with them. They really are pretty simple. Thanks for watching and take care!

[@johnbowen2963]

O YERRRRRR SCREAMING JIMMMMYS . GOTA LOVE EM

[@OnboardTangaroa]

I both love them and hate them.

[@mrmiscast]

Looking good... What a job... Can't wait til the next video...

[@OnboardTangaroa]

It was definitely a lot of metal to move. Thanks for watching!

[@JustinTurnerman]

Nice work. Now to put it all back to together 💪

[@OnboardTangaroa]

That's the plan! In progress.

[@johnschieffelin3226]

Amazing. Heavy duty stuff for sure.

[@OnboardTangaroa]

Yes indeed!

[@rhare7353]

You now have the ideal time to build the wine cellar that you always wanted...

[@OnboardTangaroa]

Oh, now there is an idea!

[@scottyvallance]

Amazing! Well done.

[@OnboardTangaroa]

Thank you! Slowly getting there.

[@claudeross126]

So much respect for both of you.

[@OnboardTangaroa]

Thanks! We may get ourselves into more than we should sometimes😂. Thanks for watching!

[@justnsaliga8518]

I wish i could buy those Detroit's though

[@OnboardTangaroa]

They are on Ebay!

[@olof.aolsson8441]

Is it a Steel hull? If it is, why not cut a hole in The side of The hull instead?

[@OnboardTangaroa]

Infinitely easier to go through the top on this boat. The hatches were already there. The hull is aluminum and easy enough to cut into but I would never compromise the hull by cutting into it. I'm sure it could be rebuilt strong enough but in my experience you always see where the holes are cut through hull sides, especially on this boat as it is bare aluminum with no filler or paint. Take care!

[@jakleo337]

Driptroit diesels. The joke is if you put a picture of a DD on the wall there would be oil on the floor underneath it in the morning.

[@OnboardTangaroa]

I had not heard that one before. Thanks for the laugh!

[@boatlover2296]

They really don’t look that bad

[@OnboardTangaroa]

They don't look bad and they run well but that is not the only reason we are swapping them out. There are no service records at all on these motors and they have been neglected for far too long. I would want to overhaul them before I would trust them and we are just not willing to put that money into engines that are unsuitable for the purpose we need. The new engines will increase our range massively and will be much easier to maintain.

[@yamahagriz8820]

Congrats! Huge Milestone!

[@OnboardTangaroa]

Thanks! It feels pretty good.

[@brucebrown5863]

That was exciting, it went well.

[@OnboardTangaroa]

Lol, as good as I could have hoped for.

[@Adam-en4zm]

Very impressive work guys, glad nobody died! Hope the repower is going well.

[@OnboardTangaroa]

Thanks! We are slowly powering through.

[@Adam-en4zm]

@@OnboardTangaroa You know why I love your channel? Every time I think I'm in too deep on my boat project (like my in-situ genset rebuild), I can see how I'm actually just playing in the kiddie pool. You guys are crazy talented and hustlers for sure. Are you guys working jobs at the same time as doing all this, or is it full time work?

[@OnboardTangaroa]

We look forward to having the big project list shrink for sure. Glad you are enjoying the videos. Between Janis and I we have a lot of built up experience. We are not perfect and may not always do things correctly but we try our best. We are off work while in the yard but have full time jobs otherwise which we are needing to get back to for sure.

[@Adam-en4zm]

@@OnboardTangaroa You guys have a crazy amount of talent between you two. I suppose years of working on charter boats is great experience, and it doesn't hurt to have your background in performance cars. Nobody is perfect, the good mechanic is always learning. Crazy that you're both doing this kind of refit while working full time. Super impressive. Looking forward to seeing those Cummins in place!

[@hansh8071]

Keep rolling, troopers 😁 grtzcfrom Holland

[@OnboardTangaroa]

Oh man, we are pushing. Hard to keep motivated for sure but we will get there. Thanks for watching!

[@chuckfountain620]

Good job. ❤

[@OnboardTangaroa]

Thanks!

[@getongab]

I would trade any POS modern diesel engine for any Detroit engine.

[@OnboardTangaroa]

You are welcome to do so. Thanks for watching.

[@adamlivelife2608]

Modern engines are better when deleted and that you can do when you swap engines into old vehicles or boats etc 😎 I would have went with CAT engine myself 🤔🤔

[@OnboardTangaroa]

So much better not having to worry about the same things the OEM's have to worry about. Cats are good but its just so easy to get parts for the Cummins and I get pretty deep discounting through my business.

[@adamlivelife2608]

@@OnboardTangaroa makes sense more parts and repairs Cummins dealers are everywhere. I would Love to have enough money to do something like this. I live in the lift lock city on the Trent Severn Water way, I believe the max boat size is 80ft. I would not need a big boat though a 40ft do well good 😎

[@OnboardTangaroa]

A 40 footer up there would be perfect! I had to google the waterway. What a beautiful area.

[@arthurcitron9774]

Spot on!👊🏻🇺🇸

[@OnboardTangaroa]

Thanks! Now to get them sold. Take care!

[@SuperJlonergan]

awesome your mom helping you so much

[@OnboardTangaroa]

Thanks for watching, although Janis is not my mom. She is my lovely wife of 22 years. I may look young but I'm closing on 50 years on this earth.

[@faxmactory]

Bro i was thinking it, you said it!

[@OnboardTangaroa]

Le sigh.

[@troyturner-ve1zj]

So big! I guess back in the day those were the power option or screaming Jimmy’s

[@OnboardTangaroa]

These are the screaming Jimmy's. Back when fuel was cheap they were certainly the way to go.

[@troyturner-ve1zj]

@@OnboardTangaroa lol I thought they were Detroit’s! Well then that explains the bilges, Definitely Jimmy was in there with his twin brother

[@OnboardTangaroa]

Lol, had to carry a spare few liters of oil on every trip we took and we used them! Lets just say the bilge was well lubricated.

[@rogerreed905]

Great effort team . . 👋💐🍻🇳🇿twa

[@OnboardTangaroa]

Thanks! Its been a ride so far. Take care.

[@justnsaliga8518]

Mistake replacing those detroits.... Fuel savings yes.... Longevity is important should have gone from all mechanical 2 stroke to all mechanical 4 stroke and you would have seen similar if not the same fuel savings and more power. Did you look at Cummins VTA 903 T repower? That would be the best upfit in this case....

[@OnboardTangaroa]

I respectfully disagree. Fuel range was only one of a few reasons we chose the 6.7. Another main reason we went with the electronic engines was because of the ability of common rail injection to reduce noise levels drastically. A third reason is ease of sourcing parts. The fourth reason is the ability of the common rail engine to run cleanly even at low loads. As for longevity, the 6.7 marine diesels are having no problems reaching 20,000+ hours in our application if they are run like we will be running them and are properly maintained. Save the electronics which I am good with they are actually very simple engines. Sure, the big diesels can be in frame rebuilt but 20,000 hours is a long way off and these engines are actually fairly easy to remove if needed. The days of needing 10+ liter engines in this range of boats has passed. For an example, one of the yachts I used to be engineer on was a 120ft aluminum Palmer Johnson ketch with a beam of 26ft and 185 gross tons. It is powered by a single 650hp Volvo D-16 which is a 16L engine (was an MTU at the time I worked aboard but similar specs). I crossed both the Atlantic and Pacific oceans multiple times on that boat and have been in some pretty gnarly weather. Power was never a problem and we were never near WOT. Now if we go back to Tangaroa at 78ft LOA with a 17ft beam we are 85 gross tons. We are using two 6.7L engines rated at around 300 hp each and will likely spend 99 percent of their time between 1600 and 1800 rpm and 50hp each. My experience tells me this will be way more than necessary. I did not look into any other engines as these checked every box I required. Don't get me wrong, I respect the capabilities and reliability of the older mechanical diesels but I have been working specifically with electronic engines for over 13 years now and while the electronics were pretty crap at first they have become pretty reliable these days and I have the experience to diagnose and repair them if required. Thanks for watching!

[@jeremystory6981]

I see the reasons why a pretty good choice you got the money and time to do it,,, you sound like you're familiar with what you're going to be working this one probably the best thing you can do,, I don't even know when it's getting hard to find parts for those things spare motors

[@OnboardTangaroa]

I do have a love for the electronic engines. Seeing as the Cummins engines are still in production today It will be a long time before parts will become hard to find. Thanks for watching!

[@fstlnj29]

Those things are big! The replacements will be nice!

[@OnboardTangaroa]

Thanks for watching! They are indeed huge. basically like taking two large sedans out of the engine room. Can't wait to finish up the repower.

[@SolarBurrito]

How heavy are they each?

[@OnboardTangaroa]

They are 4500 lbs a piece. Definitely enough to make a bad day if something went sideways!

[@camojoe83]

What you asking out of those motors and gearsets?

[@OnboardTangaroa]

Do you mean asking price for the old motors or how much power we are asking from the new motors? We are asking $10,000 for each of the Detriot engine/gearbox combo. Power requirements for the new engines are roughy 250HP per engine.

[@camojoe83]

@@OnboardTangaroa that's the info I was looking for. Not a terrible price, but not exactly worth the drive from Ohio, either... 12v Detroits are fun to play with. You could run a whole commercial capacity mobile sawmill off a pair like that. One for electric and one hydraulic. If you're a maniac, you can direct drive the head saw and shredder with em and use the front drives for hydraulics. Never lived till you got a v12 rattler at the edge of the ketchup all day spinning a tub grinder faster than 2 loaders can keep it fed. Good times.

[@OnboardTangaroa]

That would make for a good video! Wish we could have kept them but they are just a poor match for the kind of cruising we will be doing.

[@robertusa1234]

The old motors. They’re a market for them. Don’t just send them to the scrap yards.

[@OnboardTangaroa]

We are trying to sell them for sure. I know there are lots of people out there that use them and love them but so far no luck selling them. If anything we will part them out but I would obviously prefer to sell them complete.

[@dadejazzba402]

So what's in the future for those engines?

[@OnboardTangaroa]

We would love to sell them to someone who could use them but those people are getting harder to find. No bites yet.

[@larryskeeper1197]

@@OnboardTangaroa That's a real shame.

[@OnboardTangaroa]

It is indeed. I would love to see Portia and Stella continue on.

[@73Datsun180B]

@@OnboardTangaroa I would buy both if shipping to NZ wasn't so horrendous!

[@ruxoneto6560]

@@OnboardTangaroa where are engine located & price ? N.a. or turbo.

[@markhuston9250]

Fabulous video…….now that was the real thing! 👍🏼

[@OnboardTangaroa]

Glad you enjoyed it! It went as smooth as could be expected. Now the work begins.

[@RodHinman-zr6ps]

But only ice half the fuel

[@OnboardTangaroa]

Exactly! Thanks for watching!

[@donmunro144]

No better place for a Detroit than on a boat. They make one hell of an anchor.

[@OnboardTangaroa]

Seems like either people are hardcore for them or hardcore against them.

[@cornnutzgazpacho-libre3555]

AMAZING! good job U2. Now, what happens with the old engines? You were saying that you didn't have a rear boat anchor.

[@OnboardTangaroa]

At 4500lbs each they would make great anchors 😂. We are hoping that we can sell them complete to someone who can use them but sadly no bites yet.

[@camojoe83]

What you asking out of them and the geqrsets?

[@user-oj1ri5ld3x]

How many hours were on those engine's were they ever overhauled in the past

[@OnboardTangaroa]

No idea and no idea. That is one of the main reasons for the repower. The engines have no hour meters and there are zero service records on them. I vaguely recall that when we were looking at the boat to purchase we were told one of the engines had been rebuilt at some point but that's about it.

[@camojoe83]

Dumping the screamin jimmys for cummins, huh? Idk about that, bro. Sounds like something a dodge fanboi would do.

[@OnboardTangaroa]

Well seeing as I have never owned any diesel vehicles or diesel engines other than the Detroits that are coming out and the Cummins that are going in I doubt I have any fanboi attributes. On the flip side, ignoring the benefits of over 60 years of technological advancement sounds like something a Detroit fanboi would do.

[@sethbarnes7608]

So I've heard of the great loop, but what is this cruise you guys wanna do? It sounds totally fun!

[@OnboardTangaroa]

It should be a great experience. Traveling a northern route from Canada to Japan should allow us to see some pretty cool places we have never seen before. We are pretty excited. Thanks for watching!

[@mikedobbs1575]

Nobody died! 👍

[@OnboardTangaroa]

😂So far so good. Thanks for watching.

[@mikedobbs1575]

@@OnboardTangaroa Well just keep doing what your doing and i will.

[@OnboardTangaroa]

Yes sir!

[@camojoe83]

I can tell by the first 30 seconds of the video that only one of you will complete the sushi run.

[@OnboardTangaroa]

Well, we have made it through 22 years of marriage without killing each other. I think we can make it through this😁.

[@melclark1066]

One of the messiest engine rooms I have ever seen.

[@OnboardTangaroa]

Not for too much longer. I have been removing old abandoned wiring and other nasty for a while now. Tangaroa is 50+ years old with many years of neglect before we purchased her. This repower has given us a somewhat clean slate down there to work with.