Turbo or no....

[bayview]

turbos have nothing to do with engine life.

With proper maintenance and installation parameters the only factor affecting life is the amount of work done. Low loads lead to long life and high loads lead to more wear.

There is a direct correlation between work done and fuel used.

Diesels run at 100 HP per liter will wear sooner than an engine run at 20 HP per liter.
All the diesel myths about old engines running forever at full load arise from this simple fact. Full load on early engines was in the range of 20 HP per liter. When that same engine was boosted to 100 HP per liter AND RUN THERE . life was considerably shorter.

I strongly suspect, however that the amount of fuel used, and work done, before overhaul time was similar.

 

[sunchaser]

Deutz manufactures a range of oil cooled NA diesel engines that are well suited for marine use. n.

What are the advantages of oil cooled vs coolant cooled? I have used air cooled Deutz diesels in underground loader use. Worked fine but they proved too expensive to buy and maintain in US$ as compared to the 8-71s we alternatively used.

 

[stubones99]

Deutz manufactures a range of oil cooled NA diesel engines that are well suited for marine use. They are popular in standby applications (lifeboats, emergency gennies, large vessel thrusters, etc) because the absence of water in the cooling jacket makes for superior resistance to neglect, which is also a major worry with recreational marine engines.

They're packaged for recreational use by Vetus, and it must surely be possible to get one in your new yacht if you so desire. I put one in a Nauticat 33 once, and it was one of the sweetest running mechanically injected high speed engines I ever had the pleasure to deal with. It also has a very nice "quality feel" to it, although that's harder to define. Sadly, they're too expensive to ever become common.

Here is a self built boat by a guy named Gustav who built a steel boat with a single engine Deutz engine... What follows is the last of 6 videos about the process - his test drive.

He even has a glass floor, so he can do engine room checks from the helm, in relative quiet...

 

[koliver]

I've never had a diesel....but I'm really curious after trying to educate myself on their benefits, about turbo charging. I understand what turbocharging does.....so please don't go down that rabbit hole.....what I'd like to know is: what's the difference between a 250 ( arbitrary number) horsepower diesel that's normally aspirated and a 250 hp turbo diesel ?? Is it simply a matter of efficiency ? is a smaller engine that is turbo boosted better for weight savings.....does a turbo charger require special maintenance......are they the same in terms of reliability ? If you had access to the Fairy Godmother of Dieseldom....would you want a turbocharged or non-turbo charged engine of a given horsepower ?

( thanks, in advance for your replies, patience and understanding of my limited knowledge...)

So if you have never had a diesel.....do you have a boat? Are you thinking that you will be choosing your boat on the basis of whether it has a turbo or not?

There are few, perhaps some I don't know about, but I can't think of any, new naturally aspirated diesels. Older diesels, still very few naturals.

Turbos have been around for a long time. A friend with 1954 vintage Cats just rebuilt the turbo on one for the first time. Lots of hours on that turbo too, as his boat has always been the most used that I know. That speaks to the generally strong reliability of turbos on marine engines.

The likelihood is very small that whether or not you get turbos will be a factor in your choice of boats, especially if you are looking at newer.

 

[Hotrod]

turbos have nothing to do with engine life.

With proper maintenance and installation parameters the only factor affecting life is the amount of work done. Low loads lead to long life and high loads lead to more wear.

There is a direct correlation between work done and fuel used.

Diesels run at 100 HP per liter will wear sooner than an engine run at 20 HP per liter.
All the diesel myths about old engines running forever at full load arise from this simple fact. Full load on early engines was in the range of 20 HP per liter. When that same engine was boosted to 100 HP per liter AND RUN THERE . life was considerably shorter.

I strongly suspect, however that the amount of fuel used, and work done, before overhaul time was similar.

Sir, you might want to tell all the owners of 671tibs, with 485 hp that, turbos have nothing to do with engine Life! At 25k a Crack, for rebuilds at 2500hours.

 

[Benthic2]

I have a boat now, but it is a runabout bowrider. I will be moving up to a Trawler style boat in the near future and one of the aspects of that that I find intimidating is maintaining a diesel. My I/O is essentially a car engine and I've been running cars for ever.....there's no mystery there. I suspect if I had to, I could probably replace a gas engine for under 5 grand (but that's just a guess). Buying a boat with a diesel on its last legs, or worse yet a decent engine that I screw up from ignorance will be a major financial issue.

I'm just trying to get a better feel for them.

There's another current thread dealing with frequency of engine room checks that's not making me feel any better about this either.

I guess I didn't realize that a normally aspirated diesel was such a rarity.

I do appreciate the information that's been posted....since I know so little about them....anything is helpful.

 

[Hotrod]

I have a boat now, but it is a runabout bowrider. I will be moving up to a Trawler style boat in the near future and one of the aspects of that that I find intimidating is maintaining a diesel. My I/O is essentially a car engine and I've been running cars for ever.....there's no mystery there. I suspect if I had to, I could probably replace a gas engine for under 5 grand (but that's just a guess). Buying a boat with a diesel on its last legs, or worse yet a decent engine that I screw up from ignorance will be a major financial issue.

I'm just trying to get a better feel for them.

There's another current thread dealing with frequency of engine room checks that's not making me feel any better about this either.

I guess I didn't realize that a normally aspirated diesel was such a rarity.

I do appreciate the information that's been posted....since I know so little about them....anything is helpful.

Sir, the major reason I believe that diesel is desired over gas is, diesel is safer. There are other reasons, torque, etc, but , gasoline fumes, in confined areas blow up boats.

 

[twistedtree]

Sir, the major reason I believe that diesel is desired over gas is, diesel is safer. There are other reasons, torque, etc, but , gasoline fumes, in confined areas blow up boats.

Thats certainly an important consideration, but there are others too that are just as important.

Longevity, for example. Diesels last a lot longer than comparable powered gasers.

And operating economy. Diesel fuel has higher energy density than gas, and a diesel engine makes better use of the contained energy. The two compound to yield more power per gallon of carried fuel.

 

[bayview]

Hotrod please reread my post

 

[Henning]

@Stubones99: That's a nice boat, evidently finished to a high standard. Nice find, thanks for sharing Not one of the engines I was talking about, but still a nice one.

@Sunchaser: With oil as a cooling medium, you get lower potential for mineral deposits, zero potential for galvanic corrosion, and one less fluid to deal with. The air cooled Deutzes are great, too. I saw a few V-12s in canal ships, and they make a noise I will never forget.

I went back to look through Vetus' lineup, and all their Deutz engines seem to be water cooled now, so it must not have been as brilliant a system as I imagined. They're still naturally aspirated engines with a rock solid reputation for reliability, though.

 

[Benthic2]

Bayview....
I was confused by your post.... I took it to mean that longevity isn't effected by a turbo it is effected by how many hp/liter the engine produces.... BUT...isn't the whole point of a turbo to get more hp out of a smaller engine ? so the fact that there's a turbocharger on the engine indicates its going to be producing more hp ??? In other words, a ( these are only made up numbers....please don't jump all over me for them )..... are you saying a 6 liter normally aspirated 300 hp engine would last longer than a 4 liter turbo engine making 300 hp ?

 

[Henning]

(...)isn't the whole point of a turbo to get more hp out of a smaller engine ?(...)

It's not quite that simple. The turbo allows you to run at higher power densities, but that margin can be taken out as fuel efficiency, engine longevity or power. In smaller "high performance" engines the manufacturers tend to maximize power output, but there are other examples. I mentioned the Fiat 8281, a relatively small high speed diesel engine turbocharged to a specific output of 22-ish hp / liter. That number would surely be reachable without turbocharging, but that would be at the expense of engine longevity.

At this stage I'd drone on about medium speed marine engines and their design philosophies, but I think I've made my point as well as I can.

 

[dhays]

A pet peeve of mine also is, these new style rail engines, that require that you MUST, call manufacturer, for a PLUG IN, analysis, when the engines act up. It is no wonder that people started walking away from this life style, due to this nonsense of control, and making it difficult for self repair, and insane expense, due to having to call them for repair, and diagnosis. MaybeTed Kazisinki, the unabomber, was correct, the worst thing for mankind is technology , at least in some cases.

While there are some advantages to the electronic engines, I have been struggling with the problem that you describe for the last month. Mechanics can't diagnose the problem with my engine because they can't get the Cummins diagnostic software to run on their laptop after an update.

 

[man n black]

Manufacturers pretty well have turbos worked out.

I see no problems going with a low pressure diesel turbo motor in your boat. Sure the electronics make it more complicated but they also make your engines a helluva a lot more efficient on fuel...and after a short bit of study those systems are not so hard to grasp....

Ch

 

[CPseudonym]

Why do I get the urge to put on orange bell bottom cords, a green sweatshirt and play my Buck Trent 8-track every time I read a thread on this subject?

 

[BruceK]

Why do I get the urge to put on orange bell bottom cords, a green sweatshirt and play my Buck Trent 8-track every time I read a thread on this subject?

Classy! Back then, it was said if Weber had invented his side and down draft carburetors after we had fuel injection rather than before, it would have been hailed as a great advance in fuel delivery.
Low boost turbo cars are now approved here for newly licensed drivers.
Even so, if I don`t have turbos, that`s 2 less maintenance items.

 

[Wxx3]

I agree with all of the comments above, re how turbos can produce more power out of a small block. But let me say a few words about modern turbo charged engine longevity.

The venerable Ford Lehman 120 hp or Perkins 135 hp that were used on trawlers built in the late 70s through early 90s were generally normally aspirated (although the older Mainship 34 used a mildly turbo charged version of the Perkins) and would last many thousands of hours if limited to producing 50 hp, which is all a trawler needs to make displacement speed.

Today you have common rail turbo charged Cummins engines producing four times that hp from nearly the same displacement, the QSB 480. Not often used in trawlers but the lower 330 hp version, which is just a chip change definitely is used as RCook notes above.

The QSB5.9 engine can probably make 200+ hp continuously and last as long as a Lehman or Perkins. That is 3-4 times the continuous hp of those older engines. So what gives? How can a modern engine last the same as a 50 YO engine making four times the power. The answer is lubrication, metallurgy, design and cooling.

Lube oils are much better today than they were 50 years ago. Lubricity hasn't changed much but stability (the ability to last without breaking down), acid tolerance (less of a problem with today's low sulfur diesel) and viscosity control are much better today.

Today's engines are made with better metallurgy: the cast iron block, the cylinder coatings on some engines, bearing materials, valve and valve seat materials are all better today than they were years ago.

Design: Engines are tested at high power to failure and that info leads to design changes to bearing supports, head bolts, etc.

Cooling: The cooling system of a 480 hp engine has four times the heat rejection capability of a 120 hp engine. Just as importantly the 480 hp engine has lube oil jets that keep the bottom of the piston cool. But keeping the cooling system in top shape is a real issue for the high output engine because if something goes wrong at high power, you don't have much time to react before severe damage occurs. So raw water flow or mixer temperature alarms are essential.

So all of these changes over the last 50 years allow the same block to produce 4 times the power and last just as long. But you have to maintain them and monitor them as the margins are smaller.

David

Really well stated David, Thanks.

In fact the way you describe it, it's much like the '60s & 70's, with small displacement European engines producing far more hp per volume, but the tolerances and everything was much tighter, so they had to be well maintained.

 

[FF]

"And operating economy. Diesel fuel has higher energy density than gas, and a diesel engine makes better use of the contained energy. The two compound to yield more power per gallon of carried fuel.

With limited volume tanks the use of denser diesel will extend range before dry tanks.

Useful for offshore voyaging , less useful inshore where stale watery fuel is a bigger hassle .

Diesel does cost more per gallon to pay for the weight of fuel.

For 200 hours a year a gasoline engine would be cheaper to operate over the boats life, at 1000 hours a year diesel might be cheaper.

Mostly depending on how well the NA designed the boat with an engine swop in mind.