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Super Fuzzy Moderator
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This article appeared on SailNet in 2001. Not much I've found that updates it so its my starting point.

How do people feel about Turbo Diesels today ? Are the pros and cons mentioned in the article still valid ?

I confess I have been quite negative re TDs not realising that in a sailing boat they are most likely to be very low boost and not the high boost intercooled type found in autos.

This is quote from the original article......I don't know who posed the original question...indeed I don't even know who Tom Wood is.

"Turbo Diesels
<hr style="color: rgb(209, 209, 225);" size="1"> <!-- / icon and title --> <!-- message --> <!-- eWebEditPro 1.8.0.2 -->I am currently replacing a diesel engine in a 41-foot sailboat. I would like your opinion on a turbo versus a non-turbo version of the same engine?
Tom Wood responds:
There are turbo chargers and then there are turbo chargers, so the answer depends on whether the engine in question has just a little blower to aid combustion, or whether it has a great big, intercooled, aggressive ram charger.

Consider that one of Yanmar's most popular sailboat engines, the 4JH series of four-cylinder diesels—all of which have a displacement of 1.817 cubic inches—comes in five flavors. They make five models on the same block with the 51-hp 4JH2-BE model being the only one naturally aspirated. Next up, the 4JH2-TE at 63 hp has a puny little blower that hardly qualifies as a real turbo charger, but is effective in getting almost 25 percent more power out of the same engine. From there we go up to the 4JH2-HTBE at 76 hp, the 4JH2-DTBE at 88 hp, and the 4JH2-UTE at 100 hp, all magically pulled out of the same little four cylinders. How do they do it? By increasing blower speed, intercooling the turbo to withstand the heat, and increasing air intake and exhaust port size to carry the combustion through the engine more efficiently.
Many years ago, turbos were finicky, hard to find repair parts or mechanics for, and generally enjoyed a bad reputation. Today, even some of their severest critics like me, have one in their own boat. Why? Turbos have become more reliable, and companies like Yanmar have offered better warranties and parts supplies.
The main advantage is, of course, more power when you need it without adding a great deal of weight to the boat by using a larger engine. Instead of using a six cylinder engine weighing 500 pounds more, a sailor can get 80 or 100 hp out of the same lightweight four cylinders. Except for the minor drawbacks of a high-pitched whine at high rpms on the aggressive turbos, and a tendency to lope, or hunt, at idle, from an operator's standpoint there will be very little difference.
So, what are the disadvantages? The bigger the turbo, the bigger the price tag—both for original installation and for repairs if they break. Installation costs can really soar with the big turbo since they may have larger water inlet sizes or exhausts or may need larger mufflers, strainers, and other parts. Naturally aspirated engines obviously use less fuel because they have less power.
Turbos add another piece to the maintenance schema on board. Since they sit as a bridge between the exhaust and intake sides of the airflow, the exhaust side tends to carbon up, especially if the engine is idled a good deal, is lugged by an mis-pitched prop, or is run at light loading (read charging batteries, refrigerator, or watermaker). This carbon needs to be removed periodically (Yanmar suggests every 50 to 200 hours, depending on the fluid used) in a painful process of injecting either water or expensive turbo cleaning fluid into the air intake while the engine is being run across the water at top speed. If a blob of carbon breaks loose, it can hit the high-speed blades of the "fan" causing a very expensive-sounding clank—and the sound is not deceptive, because replacing an aggressive, intercooled turbo is a big job.
So, you can see, I've not given up my bias against turbos on boats entirely, only modified it a bit. The small, non-intercooled turbos have become reliable enough that I can live with one in my basement. If I felt I needed more power than was available in a naturally aspirated or small blower, I'd go on up to a large displacement engine before I'd go the aggressive-intercooler route. But this is only my opinion, and I note that Sue & Larry installed a 100-hp Yanmar on Serengeti. "


Peoples....what are your thoughts ?
 

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I shy away from them (on sailboats) too, but would not necessarily disqualify a desirable boat due to a turbo engine. Especially one with a low-boost version. I could live with it if adequately/properly heat shielded.

Also, there's boost and then there's boost. Our 31 footer has a naturally aspirated 3 cylinder 27 hp Yanmar. My brothers 31 footer has a 6 cylinder Yanmar turbo that puts out 440 hp. Now that's some boost!!;)
 

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Turbo diesels are good in the right application, unfortunately I do not think sail boats or any displacement boat are the correct application for such an engine, particularly when boost and electronic controls are applied to give a normally aspirated version two or three more powerful variant. Buy the norammly aspriated version, carefully maintained, it will last a long, long time......
 

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The information is not "out of date" but I there are a few points that I disagree on. The real advances recently have been in the fuel injection, not on the turbo side (it is somewhat effected). In the automotive world, variable vane or geometry turbos are becoming common and they are a different beast but most boats still use fixed blades. In my opinion, a moderately sized turbo makes a lot of sense on just about any diesel engine. Really large turbos will have too much lag and produce a lot of boost on the top end which increases cylinder pressures to undesirable levels. A moderately sized turbo will do a really good job of providing the necessary air to the cylinder.

The first place that I would disagree is on fuel consumption. If you look at a thermodynamic diagram, the biggest loss for turbodiesels is that they do not fully expand the gases in the combustion chamber (you would need infinite stroke). This means that the gases exiting the cylinder are still hot and can be used to power a thermodynamic device (turbo). By having a turbo, you ensure that you have enough air to fully burn the fuel in the combustion chamber and you can get more power out of a smaller displacement. Done properly, you will get better fuel economy out of a slightly smaller turbocharged engine versus a naturally aspirated one.

The other place that I would disagree is the carbon buildup. The exhaust needs to mix with something to lead to a really bad buildup and it is usually water or oil. A turbo will not introduce either of these to the exhaust stream (it has a problem if it is introducing oil). On an engine with a large laggy turbo, you can get a puff of smoke on throttling up but the engine tends to be less sooty in general than a naturally aspirated one due to improved airflow. I have never seen any exhaust tubing clogged due to having a turbo but I have seen plenty of piping clogged due to things like crankcase breathers being plumbed in.

In my opinion, turbos have made such large improvements for diesel engines (this is especially true for OTR engines). I have worked on a lot of both and the turbocharged engines do not give me any more problems than the naturally aspirated ones.
 

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. If I felt I needed more power than was available in a naturally aspirated or small blower, I'd go on up to a large displacement engine before I'd go the aggressive-intercooler route. But this is only my opinion, and I note that Sue & Larry installed a 100-hp Yanmar on Serengeti. "


Peoples....what are your thoughts ?
I have the same engine (and boat as Serengeti). All the pro's and cons you mention are real. It is expensive to maintain.
 

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Courtney the Dancer
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I agree with Klem's post with the exception that I still prefer a naturally aspirated small diesel. In larger diesels, such as OTR trucks turbos make much more sense where they need to generate 4-500hp with a minimum amount of weight. On most small (40' +- ) sailboats the weight savings is not a significant factor, and reliability is higher on the list of priorities. Turbos turn at up to about 75,000 rpm ( IIRC) and need a high volume of oil to lubricate the bearings and for cooling. While they are basically a simple device, they are an additional complication that is really not needed on a small, displacement style hull. In keeping with the KISS principle I would choose a NA engine over a turbo, but would not reject a boat strictly on that basis alone.
 

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Super Fuzzy Moderator
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Discussion Starter #7
I have the same engine (and boat as Serengeti). All the pro's and cons you mention are real. It is expensive to maintain.
I'm assuming that means this particular engine is of the high boost, inter cooler variety ?
 

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4Jh2 - ute, on the Peterson 46. There is a very hot whatchamacallit on the end of the grey noisy, smelly bit and it makes a whirring sound over 2700 revs. The autostream thingamejig spins around a lot and we get plastered to the back rail.

It was on the boat and I agree exactly with JRD's last comment.
 

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Super Fuzzy Moderator
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Discussion Starter #9
4Jh2 - ute, on the Peterson 46. There is a very hot whatchamacallit on the end of the grey noisy, smelly bit and it makes a whirring sound over 2700 revs. The autostream thingamejig spins around a lot and we get plastered to the back rail.

It was on the boat and I agree exactly with JRD's last comment.

Oh I do like it when I find someone who is seemingly as mechanically inept as moi !!

2700rpm ? Holy crap....our red noisy smelly thing would have conniptions if we even approached 2700rpm.

Then again slow measured progress is our way, the only way to get plastered on the Womboat is with me and the Wombet over dinner and a bottle or so of vino. :)
 

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Telstar 28
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Oh I do like it when I find someone who is seemingly as mechanically inept as moi !!
Is that even possible??? :D :laugher

2700rpm ? Holy crap....our red noisy smelly thing would have conniptions if we even approached 2700rpm.

Then again slow measured progress is our way, the only way to get plastered on the Womboat is with me and the Wombet over dinner and a bottle or so of vino. :)
Personally, I prefer to keep the engines on a boat as simple as possible. The less complicated they are, the less likely they are to fail or need very expensive repairs. Given the usage of an engine on a well-found sailboat, having a turbo really doesn't make much sense... this does not necessarily apply to motorsailers, which have a different purpose and usage by design.
 

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My 2 cents. I been hired to move boats that have turbos, but turbos make me nervous. There are lots of things that can be fixed underway on a naturally aspirated diesel. But, I have never been on a boat that had a spare turbo on board in case of a break down. Not being a diesel mechanic, I don't know that I would try to replace one underway, because looking at it, it looks to be major surgery.
 

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Sunsets and Warm Beer....
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I could see them being very helpful... I would think that they would also give you a very long service life being that they aren't spooled up beyond belief like there OTR counterparts. My 04 VW GLI had a 1.8T in it with a chip to increase boost to around 14 to 18 PSI. Needless to say that car has seen three turbo's simply because of the abuse and miles. A sailboat that's not motored for thousands of miles and never raced port to port, via power, i'd think it's a great option.
 

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Provided you are not pushing the stock parameters, a turbo should have approximately the same overhaul life as the engine. In OTR trucks, most turbos spin up to 125,000 rpm and almost all last a full rebuild without problems.

For people who are concerned about a turbo failing them, they are quite easy to check. You take off the hose coming from your air filter and grab the turbine wheel and try to shake it. If there is significant play in there, your turbo is getting near the end of its life. Like a jet engine, they are incredibly simple devices and will run for a very long time. Personally, I have never felt the need to carry a spare turbo but if you did, they would be relatively easy to change (a lot easier than a piston which I know some people to carry) since it is just 4 hoses/manifolds and possibly a boost line depending on the engine.

It is true that KISS would say a turbo is not good. However, I feel that common rail injection and other things like that violate this principal much worse.
 

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Telstar 28
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Klem—

I can't think of any small sailboat diesels that use common rail injection off the top of my head. That's usually a feature on bigger diesels...
 

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Courtney the Dancer
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Turbos are very reliable, but do add another level of things that could go wrong. While marine use usually eliminates one big killer of turbos, dirty air (sandblasting), there are still several things that can cause failure. My son has a Yanmar with a turbo and while the PO was in the Bahamas the seal(s) let go allowing oil to enter the intake and exhaust. Fortunately they shut the engine down before all the oil was gone which would have destroyed the engine. Most of the turbo failures that I have personally experienced have been similar to this, the internal seals will start leaking, usually on the exhaust side (hot) causing a lot of smoke and sometimes damage to the bearings due to lack of lubrication. The other failures have been from faulty or plugged air cleaners allowing dust and sand to destroy the actual vanes, but that was with construction equipment in very dirty conditions, not likely on a boat. Although reliable, I know a lot of pilots that won't have a plane with a turbo engine because they don't want to have to worry about it. I don't either.
 

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Airplanes go up where the air is thin, so it can be a good idea to have a turbo on a piston-powered airplane -- especially since it can help you get up higher over weather. (I'm with jrd on that though.) People with planes also like to go fast. Operating effectively in thinner air helps you go really fast.

In a sailboat you are at sea level (except for our freshwater friends) where the air is pretty thick. Speed-wise, you can only go a few knots. What's the point in adding complexity to solve a problem that doesn't exist?

My thoughts anyway. I wouldn't discount a sailboat that had a turbo, but I wouldn't go out of my way to get one.

(I'm not a mechanic nor do I play one on TV.)

Regards,
Brad
 

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I shy away from them (on sailboats) too, but would not necessarily disqualify a desirable boat due to a turbo engine. Especially one with a low-boost version. I could live with it if adequately/properly heat shielded.

Also, there's boost and then there's boost. Our 31 footer has a naturally aspirated 3 cylinder 27 hp Yanmar. My brothers 31 footer has a 6 cylinder Yanmar turbo that puts out 440 hp. Now that's some boost!!;)
That is how I feel, exactly. I have the 4JH3e, no turbo.

Brian
 

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On a boat there seems to be a little upside that comes with a huge downside. On an airplane -- as Bene says -- they're especially useful as at altitude the air is thinner and the turbo brings in all this compressed air so that the engine can perform as though at sea level.

But even on an aircraft engine that has to pass an annual engine exam, a turbo life is dramatically shorter -- something like 30% shorter. As JRD says, the seals start leaking, and bearings are stressed, gaskets get leaky.... I would think that the carbon build-up would be the least of your worries.

They need to make a marine engine that runs on vodka tonics.
 

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Francophobe
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I can run on vodka but I am not sharing with an engine!:D
 
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