Turbos

I don't see what you guys are arguing about. I was taught an engine is either naturally aspiratedor charged. A charged engine has a device which increases manifold pressure and therefore oxygen content. Normally charging is achieved by an external compressor, either engine driven or electric. If the compressor is driven by a turbine powered by exhaust gasses, then it is turbo charged, and the device is called a turbocharger. Any other form of compressor is a supercharger.

So a charged engine is either supercharged, or turbo charged. Same end result, different ways of driving the compressor. Seems obvious enough to me! But I always understood the collective term to be 'charged'.
 
They're arguing because they're pedants.

None of this helps to answer or help the OP with his question though.
 
oldharry said:
I don't see what you guys are arguing about. I was taught an engine is either naturally aspiratedor charged. A charged engine has a device which increases manifold pressure and therefore oxygen content. Normally charging is achieved by an external compressor, either engine driven or electric. If the compressor is driven by a turbine powered by exhaust gasses, then it is turbo charged, and the device is called a turbocharger. Any other form of compressor is a supercharger.

So a charged engine is either supercharged, or turbo charged. Same end result, different ways of driving the compressor. Seems obvious enough to me! But I always understood the collective term to be 'charged'.
Click to expand...

As Davidj says, most of agree with Teredo on the technical point but that 100% technically correct explanation is not the same as yours.

Put simply your phrase "any other form of compressor is a supercharger" is technically incorrect as a turbo-charger is, itself, a supercharger so the technically correct sentence would be "any form of compressor is a supercharger".

And that is what we guys are arguing about! :)

Richard
 
I can't help but visualising the age curve from the other "how old are you thread" (93% here older than I am) when reading this topic. I see a handful of people who actually know what they are talking about being completely ignored by people who think they know better meanwhile other err (frankly strange) people are arguing over the definition of what the whole topic is about....

At times human behaviour is really quite odd.
 
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Beyondhelp said:
I can't help but visualising the age curve from the other "how old are you thread" when reading this topic. I see a handful of people who actually know what they are talking about being completely ignored by people who think they know better meanwhile other err (frankly strange) people are arguing over the definition of what the whole topic is about....

At times human behaviour is really quite odd.
Click to expand...

I'm bang in the middle of the major age group and I reckon I've submitted:

One post which suggests that I actually know what I'm talking about,

One post completely ignoring the other people who know what they're talking about, and

One post arguing over the definition of what the whole topic is about.

Does that mean I've a split personality? :)

Richard
 
NorthUp said:
Quote:

The worm has never come across a water cooled turbo? More wiki research required, I think!
Click to expand...

There are two common definitions for a water cooled turbo. The most common refers to cooling of the bearing housing. In an earlier post I mentioned coking, thermal degradation of the oil, ultimately leading to bearing failure. The problem was solved by introducing water cooling. Breakdown of the oil didn't occur when the engine was running but rather once a hot engine had been shut down. The thermal soak was a killer for mineral oils. A water jacket was added around the bearing housing casting. It was orientated in such a way to provide a thermal syphon without the need for flow. That, and of course the general adoption of synthetic oils, made the problem go away.

Particularly relevant to marine, a water cooled turbo also refers to adding a water jacket to the turbine housing casting. This is pretty much a metallurgists nightmare. It's almost impossible to avoid cracks due to huge changes in material section and thermal gradient. There is some legislation that requires any part of an engine to be maximum touch temperature, that, and the obvious potential fire hazard in restricted places like engine bays and so on. Another means of achieving this is to use a thermal / blanket / wrap / heat shield.

Hope this helps and is viewed by the critics as relevant to a legitimate question. Let me add that it's got nothing to do with my choice of anchor, keel or rudder configuration.
 
teredo said:
Malo., Duncan. I'm sorry, I accept that you guys seem to speak fluent Vauxhall Astra marketing-guff and do not understand plain English but this does not make you correct. That statement is COMPLETELY and UTTERLY incorrect. Why is it hard for you to look in a dictionary? Why can you not understand the basic language of English? Super = extra, additional. Are there too many syllables there for you? Charge is the fuel-air mixture taken by an engine. Is this concept understood? This "Super" and "Charger" is something that adds extra charge.

It matters not whether you power it by a turbine, a belt, a drive shaft, a divergent duct or a bloody great hamster wheel; the device is a SUPERCHARGER! That is the generic term for the device. Christ! This is so terribly, terribly basic!
If you drive it with a turbine then it is called a turbo charger or a turbo supercharger, both mean the same. If you drive it with a belt, shaft, gears it is a mechanically driven supercharger. God knows what the hamster variety is called but the electric one is - guess what???? called an electric supercharger. Go figure... But they are ALL superchargers.

All engines with forced induction are "supercharged" I do not know how you can argue against that unless you live in a different universe to the rest of us. The type of supercharging may or may not add to the understanding of the system but the way you are arguing is like saying that an Electrolux is a Hoover but not a vacuum cleaner.

Is this a forum where simple technical matters are widely ridiculed? Seems an extraordinary approach for people in a technical hobby.
Click to expand...

While it is useful to go back to the dictionary for the derivation of "made up" terms like "supercharger" used in relation to use on engines, it does not mean that your interpretation is definitive.

The whole point of language is to communicate shared meanings, which also means that definitions and meanings change over time. If it were otherwise we would not have a useful language.

So, you will not find "supercharger" as such in older dictionaries, it would only start to appear in the 1920s when the device we are talking about was invented - and the inventors needed a name which gave an accurate description. So two existing words were combined to make one word which had a shared meaning. So, for a generic word for a device compressing air into an engine "supercharger" was adequate. All such devices at the time were mechanically driven, but for some time there were alternative types of compressor so alternatives such as "centrifugal supercharger" were in use to differentiate variations on the generic term.

Later when exhaust driven compressors were invented it was clear that a new term was needed as the new devices were sufficiently different to need a new term - hence "turbocharger". Exactly the same happened in aircraft engines where we have "jets" and "turbo jets". The new terms more accurately describe the device and differentiate them by key characteristics.

So your desire to just use the generic term is nonsense as it does not give a sufficiently accurate description of the devices in question. That is why all the "user" type sources for definitions agree about the precise use of the two terms and why you are simply wrong in your assertion that your narrow definition is correct. Indeed "turbocharger" on its own is now an inadequate term to describe all the gas driven compressors in use and some qualify the term to describe different types of compressor or turbine such as "twin scroll" - just as there are various qualifying adjectives for superchargers.

So, not helpful to try and claim some form of purity by resisting the development of language.
 
"...anchor..."
Turbocharged engines, for a given horsepower, are less efficient as moorings/ anchors because they generally have less mass. ?
 
Beyondhelp said:
I own a car called a Nissan March Superturbo...

Its 1988 and has EFI, Turbo & a supercharger from factory... Its engine is 4cyl 8v 930cc. Made 110bhp stock, and just shy of 100lb/ft. People here would recognise the shape a Mk1 Nissan Micra..
Click to expand...

Awesome car! I nearly bought one, but decided not to as it was an automatic.
I bought a Startet GT Turbo instead, still plenty of fun. I did own a MK1 micra about 8 years ago, as my first car, I think there's still photos of it on the owners forum.

Back on topic, a Turbo or Supercharger (yes they are different!) done right should be absolutely fine. From the way people talk on here I imagine their engine bays must be under 5 feet of water all the time.
All modern diesels, and plenty of petrol cars are reliably clocking up hundreds of thousands of miles despite being driven through puddles, abused, neglected. The technology is pretty mature now, an engine bay on a yacht is not THAT bad an environent.
Heck one of my relatives Moody 346 has a turbo engine that's been reliable since new, assume it must be over 20 years old now.
 
Way said:
Sorry for the addition but I'm looking at re-engining so I'm doing a fair amount of research. Interesting that Bukh, who are held up as a model of successful simplicity, have a 48hp model which is Turbocharged
Click to expand...

An attempt to extend their range without having a new engine - just the same as Volvo with the 2003T. Neither gained much acceptance in the market as much better naturally aspirated engines became available with the switch from custom "marine" engines to using Japanese industrial engines as a base.
 
Personal experience: I owned a Jeep Cherokee with Iveco Turbo diesel, ran it on synthetic oil. Magnificent motor, tremendous torque. I believe the same configuration is used in marine applications. I could not do one service, and the mechanic changed the oil with standard oil. At the next oil change I put in my usual synthetic, and soon after the deposits loosened by the synthetic oil blocked the turbo oil feed. Carbon buildup choked the chambers, bending valves. Expensive. Son in law has a Volkswagen, turbo blew on us with no reason, engine oil blew into intake manifold. It could have been a runaway situation, as it was it was an expensive experience. Son owns a Nissan Micra with turbo, runs it like hell, and has not had any problems.

My conclusion: A turbo is good if you need a high power to weight ratio, and if you are going to run it hard every day, all day. If weight is not a crisis, and maintenance is less than optimal, then a turbo is, for me, too much complication and risk. It is not easily repairable at sea, even into a 'get home' configuration, and also not in remote, out of the way places. I would prefer a simple diesel like a Kubota that can be serviced by any agricultural engineer, is tolerant of bad fuel, and can shrug off indifferent or skimpy maintenance. Just my take on it.
 
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