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Old 14-10-2005, 09:22   #1

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Anyone Running a Turbocharged Engine?

If so, what do you think?

How old is it?
Had any problems?

I would like to power my WestSail with a dimensionally smaller size engine (like Yanmar 4JH series), but I would have to go with a turbo to get the HP I need.

I know turbos got a bad rap in the 80's with autos, but local diesel mechanics say the modern ones are very reliable and low maintenance. They say the main thing to watch for is ensuring they get enough good air flow as they need more than the naturally aspirated diesels.

What do y'all think?


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Old 14-10-2005, 10:23   #2
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I have a 75 hp 4JTseries. I attended a seminar and the yanmar trained technician said that:

1. If the engine has been sitting for more than 48 hrs you should pre lube the engine by cranking the engine with the stop buttom pushed and the water intake close until the low pressure alarm/light goes out. Make sure that you open the water intake before you start the engine.

2. You should let the engine "cool off" at idlle for a few minutes before turning it off . This will reduce the oil temparature and protect moving parts (like the turbo charge) when warm oil goes down to the sump when the engine is off.

This is the area were Porche and SAAB ended up with damaged turbo chargers. The owners will be racing on the interstate at a zillion mpg, open the garage door, park ther car and tun the engine off. I have heard that this practice cost someone around $10k fora turbo charge.


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Old 14-10-2005, 11:46   #3
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Turbochargers on Deisel engine are very reliable today and actually have been for some time. Diesel/turbo combinations are very different in reliability than the petrol engine. This is due to the turbos not having to work so hot and spin so fast as in Petrol engine. There are really only two negative aspects with a Deisel Turbo. It can get clogged with carbon soot and may need a clean somewhere in it's life. And, it is a major wear device, when compared to the longevity of the rest of the engine. In saying that, it will still last for many many hrs before repairs are required. PROVIDING you adhere to a few very basic BUT important rules. Ensure you use a very good oil. Ensure you carry out reqular filter changes.
Now as to letting the engine cool down before shut down. It's not actually the engine cooling down part that is the issue. The Turbo is fair screaming around in rotation. Small Petrol turbos can exeed 250,000RPM. A Deisel is no where near that, usually due to the fact that a Deisel turbo is often bigger in Diameter. But they are still honking along and take some time to come to a compleate stop. The Turbo has no contact bearing. It relies on a film of oil to keep the shaft from touching the outer bearing surface. Two special high temp seals maintain the pressure and so the spinning part of the turbo floating. If the oil pressure stops, the shaft "crashes" into the bearing surface and major damage results. So you can do two things. Let the engine idle for two minutes to ensure the turbo is at minimum speed and the turbo housing is as cool as it can be. OR, a very cool little device is available. It is a Cartridge that goes beside the Oil filter and is plumbed into the turbo's oil feed line. It is a sprung loaded piston device. When the engine is started, it is charged with oil and the spring/plunger is pushed back and maintained in position by the oil pressure. When the engine is shut down, Oil is still pumped under pressure to the turbo as the spring pushes the plunger back down and the turbo gets a lovely cooling bath of oil for a couple of minutes.
Now about the Air supply. Yes they do need more air than that of the SAME naturaly Apserated engine. But if you are coming down in size of engine and keeping the same HP, then the air required will be similar. The one thing with a Deisel, HP is the result of a set measure of fuel and air burned. So ruffly within reason, a 100HP Turbo engine will use the same air and fuel quantity as a 100HP NA engine. The difference being, the NA engine will be bigger in physical size.

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Old 14-10-2005, 16:09   #4
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Clean oil

The key to longevity of turbochargers is clean oil. If you change your oil regularly, they will last a long time. If you don't the engine makes a nice anchor (one time use). Modern turbos are susuptable to fouling (coking) and failure is not far behind.
By the way, what is the point of running a turbo when a naturally aspirated engine of the same horsepower is available for the same money and will probably fit in the same space.

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Old 14-10-2005, 16:24   #5
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As Wheels said, one of the major turbocharger longevity issues is allowing the turbocharger to cool down. As he stated, the shaft that connects the two parts of the turbocharger (turbine and compressor) floats on a cushion of oil. If you just shut the down, the heat in the turbine just burns the oil surroundig the shaft (coking). This results in in a build up on the shaft and eventually a failure of the turbo. This failure can take several forms. If you're lucky, the shaft only breaks, you notice and shut the engine down. Only need a new turbo. If not, the compressor wheel fails too, the bits get sucked into the engine and rebuild/new engine time.

But, with the advent of the newer oils this is minimized. I, and most Porsche Turbo enthusiast, use synthetic oils. Its major benefit is that it resist thermal breakdown a lot better than dino oil (conventional oils). So as well as the 2-3 minute cool down, use a good systhetic. Your turbo will last you much longer!

My turbo is in my Porsche 930. 3.3 liter, Kokeln intercooler and turbocharger. It puts out about 480 rear wheel horsepower at 5300 RPM. I have had it running for about 5 years, no problems. No tickets either! Hey wait, this isn't!??

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Old 14-10-2005, 16:38   #6
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There is a very big difference between a turbo charged diesel engine on an automobile, a truck or even a power boat. Sailboats often operate for long periods of time at engine speeds that are less than optimum for the turbine.

In talking to local mechanics there seemed to be a universal agreement that turbo-charged engines should only be used as a last resort on sailboats and that reliabilty has not been that great on turbos primarily due the the use patterns of sailors and since few sailors take the time to take the necessary precautions that are required to maintain the reliability of a turbo.

A Westsail is probably the worst applications. Turbos do best when there horsepower is more critical than torque, but boats like the Westsail really need a lot of torque and horsepower is less important.

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Old 14-10-2005, 16:55   #7
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Learning curve,
I don't see the need to go to a TD power plant. You should be able to make hull speed with 50ish Hp. Are you running an extra large alternator? SeaFrost or Gurnert fridge? Engine CAT pump for the water maker?
I'd think the 4JH4 56hp would be ideal. If you need a little extra the Westerbeke 64A, which is a derated 82B engine.
A turbo does add complexity and maintainance as temperatures are critical esepecialy during cool down. Keeping a turbo engine on boost requires higher speed, both RPM and hull.
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Old 15-10-2005, 05:52   #8

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Westerbeke 64A

I am not dead set on a turbo charged engine. I would rather go with a naturally aspirated engine. But part of this question is that I am trying to MAKE SPACE in the engine room. So I am trying to find a suitable representative of an engine and explore options.

Calculations show that I need about 60hp minimum.

In my search, most of the popular brand of engines in the 60-100hp range for naturally aspirated are usually 5 cylinders. This is a bit dimensionally longer of an engine than I would prefer. The size of a 4 cylinder is what I would prefer.

Yanmar doesnt have one.
Volvo's are big.

The Westerbeke 64A looks the best right now. It is just a bit larger than the Yanmar 4JH, 4 cylinders, low-rpm.

I am just trying to get opinions on t/c diesels.

Anyone run a Westerbeke 64A?
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Old 15-10-2005, 11:33   #9
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Firstly,let me say, I'd not select a turbocharged engine as an auxillary engine. There ARE Many complexities associated with it.

BUT, Diesel engines that operate within a narrow range are absolutely IDEAL for a turbocharger. The turbine side of the turbocharger is sized and internally engineered to take a certain velocity and volume of exhaust gasses and with this flow spin another vane that compresses air. This air is in turn fed back into the engine to increase the amount of air and fuel combusted by the engine. These turbines have a somewhat narrow band of optimal operation. These narrow bands are expressed as compressor maps for a particular compressor/turbine combination. The more narrow the operational band, the easier it is to select an optimal turbocharger. In diesel, boat operation, we are generally less concerned with acceleration or torque over a wide RPM range. We are mostly interested in maximizing power at an optimal propellor range at a given RPM. This is a WHOLE lot easier than the issues we have to contend with in autos.

I would be concerned about many small diesel service folks. They don't see them very often, so they may not be a awaire of current issues. I have seen a large marine diesel mechanic do complete injector service on a set of large diesels, when in reality it was a stuck pop-off valve.

But.... Thats another story
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Old 15-10-2005, 17:26   #10
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How heavy is your boat....

Your website on the Westsail 42 does not give any details on how heavy you expect the boat to end up but if we work with 30,000 lb and a waterline length of 36' for a heavy boat...
A 60 hp diesel should give around 50 shaft hp but the maximum continuous use rating (if we assume 80%) would be around 40 shaft hp.
My reference to Gerr's propellor handbook suggests that you could expect around 7 kts on a good day.
If you used a 50 hp engine instead then you might work with 30 continuous shaft hp and you might expect 6.3 kts on a good day.
If you used a 80 hp engine then you might think about 7.4 kts on a good day.
This is following the formulas in the book. My calculations should always be treated as suspect.
In practice you may find that with a heavy boat you will frequently be motoring or motorsailing in light weather.
Your decision is as to whether the cost and difficulty of the larger engine is worth the extra knot in extra speed that you might get.
I have read some reports that suggest that a feathering propellor can provide some real benefits.
More experienced cruisers may care to comment on this.
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Old 15-10-2005, 19:47   #11

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."Rule of thumb says 1hp per 500lbs of displacement. A calculator I found says 32,000lbs of displacement with 40 feet of waterline will need about 63 horses to drive it up to a hull speed of 8.5 knots."

My calculations are using 32,000 lbs displacement and approx 40' waterline (it probably is less).

I will definately be using a feathered prop. I have a Max-Prop on my sloop and I will never go back to a fixed pitch prop (backing ability is greatly improved).

And, I am not looking to plow as fast as I can through the water in order to get back to the yacht club to get first drinks <g>. I would be happy with a nice steady 6-8 knots under motor.

My displacement sloop, which as 23 LWL, was repowered with a Yanmar 3GM, up from a Volvo MD7A. This was a bit TOO much power. We had to pitch the max-prop back 4 degrees. Still, we have enough power to push the boat beyond hull speed (about 5.5-6.0 knots). But, the helm gets a little crazy, and we start burning more fuel. I really dont care to do that. I might have gone one size smaller in prop had I known
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Old 15-10-2005, 20:03   #12

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Strygaldwir once whispered in the wind:
In diesel, boat operation, we are generally less concerned with acceleration or torque over a wide RPM range. We are mostly interested in maximizing power at an optimal propellor range at a given RPM. This is a WHOLE lot easier than the issues we have to contend with in autos.

I would be concerned about many small diesel service folks. They don't see them very often, so they may not be a awaire of current issues. I have seen a large marine diesel mechanic do complete injector service on a set of large diesels, when in reality it was a stuck pop-off valve.

What you are saying makes some sense. I am a bit mechanically inclined. Be it diesel or gasoline. Turbos are foreign to me, however.

I know what you mean about marine diesel mechanics. My wife works at a boatyard, and has she got stories about "contract" diesel mechanics.
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Old 20-10-2005, 16:34   #13
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Turbo Diesel

We've had a larger Yanmar Turbo Diesel for 7 full seasons which has run very reliably so far (knock on teak). The only two problems: i) you should have a remote relay for the starter to avoid an intermittant problem with the voltage drop on the solenoid from the "switch" harness to the engine; and ii) watch the return lines for the fuel if the continue to use the non-rated fuel lines.

Other than those two easily fixable problems, it's a great engine.

I think should run it at 75-80% of maximum RPM's to avoid problems -- nursing it along isn't doing any favors unless you're in long-distance (fuel conservation) mode.

Therein lies the problem. If you oversize the engine, you're really not doing yourself any favors.

IF your cruising displacement for the Westsail 42 is 32,000#, then it's about the same as our J/160 (53'). I don't know how easily driven the hull is, but that might become an issue.

Beyond that: JEFFH -- what's the torque is less important than HP about?
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Old 20-10-2005, 16:47   #14
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That voltage drop seems to be a common problem on Yanmars with a long harness run. I have it on my GM30F. Most people think it's a defective switch but it's not.
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Old 21-10-2005, 04:14   #15
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Torque vs Horesepower

The key to turning a propeller is not nominal horsepower rating, but the amount of torque applied to the shaft- and delivered to the prop.

Basically: Torque defines how MUCH Work and engine does; whereas Horsepower defines how FAST it does the work. Engine horsepower is most relevant to how well the engine performs at high speed, while its torque rating is most relevant to lower speeds experienced on sailboats. This is because maximum horsepower is achieved at higher rpm levels (often in the 5,000- to 6,000rpm range) while maximum torque is achieved at lower rpm levels (often between 200 and 3,500 rpm).

Torque (TQ) is a static measurement of rotational Force; whereas Power (HP) is a measurement (actually, it's calculated) of Work (Ft./Lbs) performed over Time (seconds). A given HP at a given RPM will always result in a given TQ figure. If two engines have the same HP at the same RPM, they will (by definition) have the same TQ.

One Foot/Pound (Ft/Lb) is the amount is the amount of Work required to lift a 1 Pound weight a distance o 1 Foot.

One Horsepower (HP) is 550 Ft/Lb of Work in one Second, or 33,000 Ft/Lb. per Minute.


Torque (TQ) = (5,252 x HP) RPM

Horsepower (HP) = (TQ x RPM) 5252

*1. Perhaps one of our Engineering types could explain the mathematical development of these principles (radians & all that).


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