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Old 04-16-2017, 07:44 PM   #41
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A little geek speak: A turbo is in tech speak a "exhaust gas turbine driven centrifugal super charger".

Anything that pushes more air into the engine than it would draw on its own is a "super charger". Can be a turbo, a blower, something driven electrically, whatever.

Blowers are most commonly the roots style mechanical like used as a scavenging blower on a Detroit two stroke. On those engines it is used to push air through to get the smoke out, it does not super charge. The engine will not run without it. Strap that same blower on a Chevy car engine, now it does super charge.

Some Volvo marine engines have both a turbo and a mechanically driven blower. Both are super chargers. Blower to get low end torque, turbo takes over for higher rpm.
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Old 04-16-2017, 07:44 PM   #42
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Engines are seldom fitted with both turbo and supercharger.
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Old 04-16-2017, 07:47 PM   #43
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I wonder when the excess energy of the turbos will drive alternators, like some of the big boys do... According to what I've read, there is often much more power in the exhaust turbine to not only spin the compressor turbine and an alternator. Of course, it will be spinning fast!

Interesting note that most turbos only generate boost when operating over 100,000 RPM. IF you can hear them whistle, it's loping along and not generating much boost.
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Old 04-16-2017, 08:18 PM   #44
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Ford Lehmans. No turbo, no blower, no supercharger. And yes, not so much power. But sweet as
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Old 04-17-2017, 01:11 AM   #45
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@Ski in NC: Very well put. I'm curious, though - are you sure that a DD won't run with the blower taken off? I know for a fact that a B&W Alfa will run with the reed plates taken out of the scavenging air pump, albeit like absolute fecal matter. That one uses loop scavenging, and the DD's longitudinal scavenging scheme is even better suited to function dynamically, so I always assumed that it would run without the blower, just not very nicely.
</pedantry>

@stubones99: Interesting thought, but I somehow doubt it's going to happen. Small engines in general operate under such varying load conditions as to make it impractical, and belt driven alternators are very inexpensive and easy to deal with as long as they're not too big.
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Old 04-17-2017, 02:00 AM   #46
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Ford Lehmans. No turbo, no blower, no supercharger. And yes, not so much power. But sweet as
Yes, kinda like my sweet old dearly departed Sunbeam Tiger. No longer made darn it.
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Old 04-17-2017, 02:39 AM   #47
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Yes, kinda like my sweet old dearly departed Sunbeam Tiger. No longer made darn it.
Not sure but was the Tiger a V8, the last model development of the 4 cylinder Sunbeam Alpine? Same era as the Daimler SP250?
Compare D4 Volvo output, 300hp out of 3.75L capacity. That`s 2.5x the output, from around 40% less cubic capacity of the venerable Lehman. Turbo Volvo D4s work hard.
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Old 04-17-2017, 03:24 AM   #48
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Engines are seldom fitted with both turbo and supercharger.
True but I remember working on one back in the day with twin V16 Detroits
Not sure if I got it right but what I remember was every bank of 8 having a superchasrger and every bank of 4 having a turbocharger.
It was awesome :-)
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Old 04-17-2017, 05:27 AM   #49
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Ford Lehmans. No turbo, no blower, no supercharger. And yes, not so much power. But sweet as
Sir, I believe you are dead on, correct. When trawlers first came on the scene, early, Grand banks, marine trader, defever, all ran Lehmans 120 or 135 hp.I believe the whole concept was to push along with an easy riding hull, at 6 to 8 knots, with very low fuel consumption, and very simple maintenance. Less was considered more, which gave affordability, distance, etc.if these engines were run under load, at 1600 to 1800 rpm, and ran at 180 degrees, and serviced regularly, 10,000 hours or more were not unusual, with very modest fuel consumption. Keep the fuel clean, constantly pet the cooling system, and off you go.On the other hand, the velvet drive, was a little different story, but not terrible, in my opinion.
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Old 04-17-2017, 05:34 AM   #50
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"On the other hand, the velvet drive, was a little different story, but not terrible, in my opinion."

A Twin Disc cold have been fitted , but the boats cost would have been higher.
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Old 04-17-2017, 06:04 AM   #51
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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.
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Old 04-17-2017, 08:00 AM   #52
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@stubones99: Interesting thought, but I somehow doubt it's going to happen. Small engines in general operate under such varying load conditions as to make it impractical, and belt driven alternators are very inexpensive and easy to deal with as long as they're not too big.[/QUOTE]

Wartsila and some other vendor collaborated on a solution for large container ships that no longer needs to run another APU or genset. Of course, this is a much larger scale than trawlers, but the article I read said that almost all turbos had much more power than the compressor needed.

I would never suggest a belt drive on a turbo shaft since the small pulley would be turning as much as 130,000 RPM and I don't think they make rubber belts that could stand the centrifugal force of having to change directions that fast without flinging rubber in all directions. It would either have to have a step down gear train or build the alternator around the center part of the shaft between the hot side and the compressor side, with windings to run at that speed. You might want to put an explosion proof wrap around it, just in case... No telling what a rare earth magnet would do if spun off the shaft at 130,000 RPM.

Dealing with the variable speeds is a fairly easy device. In the voltage regulator, you take whatever voltage coming off the windings and make it what you need for your systems. It might be 500v or 30v, who knows.

The one thing it will need is a speed sensor, since putting too much load on the turbo when it is idling will stall it, overheating one side of the turbo and never letting it get to speed to operate. So it should only work while the turbo is loaded and generating boost.

I'll try to find the article and post a link to that on here.

stu
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Old 04-17-2017, 08:33 AM   #53
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@stubones99:

I think you misunderstand me. I would never suggest driving a rubber belt of any kind off a turbo. Allow me to rephrase:

Varying load conditions on small / short haul engines pose a challenge because exhaust turbine driven power generation would only be available at higher load levels. Thus, development of such technology for small / recreational engines is unlikely, especially since our existing solution of crankshaft driven rubber belts solves the problem so cheaply and easily up to ~2 kW.
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Old 04-17-2017, 08:58 AM   #54
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Here is a link, and I was wrong... it was Mitsubishi

https://www.vesselfinder.com/news/52...ry-Award-Video
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Old 04-17-2017, 09:56 AM   #55
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Interesting. That does at least provide some packaging benefits over Wärtsilä's system, which uses an entirely separate turbine for electricity generation.

I wonder how this scales down? I suppose it might find a niche in short-haul applications in combination with a clutchable PTO generator, although it would make for a relatively expensive system...

Cool stuffs :-)
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Old 04-17-2017, 10:11 AM   #56
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turbo powered generator

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Interesting. That does at least provide some packaging benefits over Wärtsilä's system, which uses an entirely separate turbine for electricity generation.

I wonder how this scales down? I suppose it might find a niche in short-haul applications in combination with a clutchable PTO generator, although it would make for a relatively expensive system...

Assuming the generator is actually an alternator, it could vary the excitation current to the stator and vary the load on the turbo drive. zero excitation current = zero load.

The coolest thing is using the generator as a motor, spinning up the turbo before the engine runs, providing boost early and lowering emissions. That makes it more of an electric supercharger, which converts to turbo + generator once the engine is under load.

If you're doing the motor thing, it can't be an alternator, but milling the shaft to hold rare earth magnets for the generator would be a simple thing. It will be a few years til we see something like that in marine engines though.

What I'd like to see is the flywheel generator / starter, so you do without the starter Bendix. I've heard several boaters trying to start already running engines and that's not a good sound. On the other hand, any problem with a flywheel generator / starter means you have to drop the transmission to get to the flywheel. I wonder what the stats are between the separate starter, integrated flywheel starter are in real life. I've not heard of a hybrid car with a starter problem yet.
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Old 04-17-2017, 10:23 AM   #57
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130,000rpm is the realm of tiny car turbos. They are made tiny so that they spool very quickly, try to avoid turbo "lag". Larger turbos spin much slower, not sure of exact numbers. And you can design a turbine with small blades on a larger diameter wheel to get whatever rpm you desire, suitable for direct drive on a generator, certainly do-able.

From an above post, the Detroits often had blowers and turbos. Both are not superchargers. The blowers are scavenging blowers, doing the get the smoke out thing for starting and light load ops. Once on load, the turbos not only supercharge but take over the scavenging duty also. Some have bypass valves that open up around the blower, so while it remains spinning, at least some air is vented around it to reduce parasitic loads.

A similar two stroke, the larger EMD engines common in loco's and tugboats, some have a turbo that is geared and clutched to the crankshaft. As engine starts, turbo is mechanically driven to scavange. Once under load, turbo gets driven by exhaust and an over-run clutch opens up to disconnect drive from crank.

I like the idea of a exhaust turbine being used for other useful work, be it gennie or going back to the crank. On small engines not really worth it. On freighters, heck yea.

This was done in the 40's and 50's on big recip aero engines. Called turbo/compound or something like that. Exhaust turbines geared to crank, supercharging done with gear driven centrifugal blower. Later (??) evolved to the turbos we are now familiar with. Tech faded as the gas turbine jet, turbofan and turbo props got developed and retired the big recips.
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Old 04-17-2017, 11:15 AM   #58
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Let's talk recreational marine diesels for a brief moment where there are few if any options to avoid a turbo if you are considering a new to 15 year old engine. Theory, trucks, dozers buses, freighters etc are one thing but a newer Mainship, GB, DeFever, Nordhavn etc quite another.

Over a very long period of time and having spent lots of money on engine related maintenance, not one red cent has been spent on turbo repair. Some argue that turbos wear out engines. Hah, in my low boost 200 hour a year usage the boat, base engine and gel coat will outlive many attentive owners.

I do know those who run their diesels at high RPMs and over propped. They are oblivious to soot on the transom and even desultory ER checks. These owners are boat yard and rebuild shop dreams and don't mind paying to play.
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Old 04-17-2017, 11:38 AM   #59
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"newer Mainship, GB, DeFever, Nordhavn etc quite another."

All these boats need about 100 - 150HP engines to operate properly if displacement boats.

Car diesels are tiny and their service life stinks in a marine HD application.

A truck engine of about 350-400 CI would be grand but many are turboed to please both the air police and owners that want hill climbing ability. Cost and complexity to no purpose.

The cruising low speed market is way to small to have an engine created and millions spent for Tier whatever for the air police.

Best we can do is use one of the 4 engines mentioned and set it up right for the boats requirements.

For many boats , esp at 200 hours a year , a modern gasoline engine could be best choice. Esp if we finally get rid of the ethanol in the gasoline.
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Old 04-17-2017, 11:43 AM   #60
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Let's talk recreational marine diesels for a brief moment where there are few if any options to avoid a turbo if you are considering a new to 15 year old engine. (...)
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.
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