Richard Halls thread in "Diesel a bad buy" makes a valid point in suggesting that emission reducing multi valve engines require to operate at higher rpm's to extract the best from the torque and power curves.
reflecting also on threads from HJ and indeed other contributors, on the need to to let turbochargers idle after high engine rpm/constant speed driving in order to stop the carborizing of oil in the turbo's bearings.
Is this a "eureka" moment for the supercharger?
Plus points:
No turbo lag
A flat torque curve over a wide rpm range.
No problems with carburized bearings
Higher torque and HP values for a specific engine.
Arguably, lower emissions.
Minus
Cost, I guess.
Regards,
Julian
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Without being too cynical Julian, its not the Eureka moment if the M-B superchargers are anything to adopt as a benchmark.
All the motoring correspondants agree that they are rough! My experiences are admittedly limitted but I am happy enough with the Turbo thank you.
regards
Simon
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Fossil burning fuels with or withour turbo's, superchargers should be thing of the past. Our focus should be on alternative renewable energy such as hydrogen. Once again I wish our motoring future was planned by engineers and scientists without the hidden agenda's that politicians and business have.
Eleanor
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I saw a program the other day about hydrogen powered engines/cars.
There was some german woman, representative of the Govt. green bits, extolling the virtues of this. Cleaner, available, etc. etc.
It then went across to some other german woman, representative of the Govt. not-so-green bits, pointing out that whilst using it was cleaner, producing it was a very mucky and polluting business. Net loss for the environment.
Green-girlie retaliated with a claim that moreinvestment would mean much cleaner production.
Now admitedly my German is about as good as my scientific knowledge, but that, rightly or wrongly, was the gist of it.
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Eleanor,
Completely agree regarding politicinas versus engineers, and basically alos with your view on the future, but how does your environmental viewpoint sit with your present situation - looking to buy a Bentley Turbo R ?!!
Regards, Adam
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Actually, nuclear power has no real waste disposal problem. It's just the anti-nuclear power brigade who object to every method put forward, on principle.
Provide me a nice house in Caithness with a big enough estate (including a 5-mile straight for Toad) and a suitable income, and you can bury it all in the rocks below my land; and I'll tap the decay heat to keep warm. And put up frightful signs to frighten off ramblers, too!
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Eleanor..Hydrogen is the new Green word..only problem is by the time you have produced a gallon of the stuff you have spent the entire GNP of some small countries...
Lets stick to what we know...
Yes i do work in the oil industry..but that does not make me biased...?
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Mmmmm. Do the following words mean anything to you?
R101
Hindenburg?
Oh, the humanity...
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Yes ...so does three mile island ,Chernobyl & the Tory Canyon, however your point is what.?
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Sorry, GC, that remark was meant to be tongue-in-cheek.
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O Thats all right then...
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Simon,
Oh dear, have I got something to look forward to? It seems smooth as a babys bottom at the moment.
Perhaps Shorrocks or Rootes then! Are these companies or designs still in operation? I remember the Commer 2 stroke truck with the Rootes supercharger in the late 1950's, they had a very characteristic exhast note.
Cheers,
Julian.
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Problem with superchargers is that they take power directly from the engine, wheres turbos use what is otherwise wasted energy. Hence they are not as economical.
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Try telling that to any Volkswagen Owner who is unlucky enough to own a G-Lader Supercharger fitted G40 or G60 engine with a knackered G-Lader.
Wonderful motas and they sound odd but fantastic. However, the G-Lader needs an overhaul every 40,000 miles at around £300 and a new one costs close to £1500 I think.
That sort of shot the G40 Polo, G60 Golf (Import only), G60 Corrado and G60 Rallye in the foot - although I would have one anyday! Dead easy to tune and go like stink. Also drink like stink I'm afraid.
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Julian. The Commer two stroke engine which as you say had a brilliant exhaust note that could be heard miles away wasn't a Rootes designed engine,
It was designated as the TS3 and was a three cylinder horizontally opposed engine with 6 pistons. It was always said the that the TS was for Tiller Stevens which was a marine engine manufacturer on the south coast.
I'm not sure that it was a supercharger which was fitted. it was always referred to as a blower and I believe it used to blow the exhaust gases away whereas isn't a true supercharger on the inlet side.
I think I still have literature on this engine and will try to find.
But do you remember the most amazing sound of all. The Foden two stroke diesel of the 50s??
Alvin
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I've got a Foden 2 stroke supercharged marine diesel in a barn. 4.2 litre I think. Aluminium block. It's a mark three and therefore has separate cylinder heads. Great machines. Went on forever. You can get a working one attached to a generator from Harry Pound in Portsmouth for about £1000. (mine is knackered as the heads are missing)
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richard turpin wrote:
>
> I've got a Foden 2 stroke supercharged marine diesel in a
> barn.
And how fast will the barn go when it's at full revs, Richard?
(how do you register a barn for road use?)
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Nothing to do with cars or trucks but with all the comments about 2 stroke diesel engines and blowers etc, I thought I would put in my two penneth worth.
B&W marine diesel, 8 cylinder double acting two stroke with rootes blower:
3 pistons per cylinder
2 lenghths of stroke per cylinder
3 different sizes of bore per cylinder
1 piston with a hole in it for one of the other pistons to run through.
Bore as I recall 548mm, 550mm and 552mm, strokes (and most unsure here) but about 1200mm and 600mm.
Engine speed 110rpm max
Used to catch fire every day at about 17:00. This was when the 2nd engineer had gone on shift and had wound down the cylinder lubrication to save oil. When we went down we put it up to stop the fires. The blower used to run at about 10psi as I recall. Maybe some old Blue Funnel engineers who read this will put me right on these figures.
Bill
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Aha! the Foden 2 stroke must be the one I was thinking of earlier. I thought it was also used in ERFs, but I am perhaps wrong on that. Sounded amazing anyway. I quite like the idea of a Foden powered generator, but I don't really need one.
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This has been discussed before, but to recap:
The perception seems to be that hydrogen appears miraculously in cylinders.
However, the fact is that to have a "green" cycle, i.e. splitting water into hydrogen and oxygen, the energy to produce hydrogen must come from a "green" source.
With current technology this means hydro-electric or nuclear.
So there is a stark choice between CO2 emissions and the greenhouse effect; hydro-electric which comes down to tidal power with the loss of coastline and land for pumped storage inland sites; or nuclear with waste disposal problems.
As the saying goes, there is no such thing as a free lunch.
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Brian..
You ommited a third "Green" source....Sun..The UAE has 364 days every year ( it rained last year) with an average of 11 1/2 hours every day,However being an oil exporter this may take some time to happen, but when it happens they will be shipping this stuff all over the place.
GC.
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Boot an XJR8 or XKR8 and besides picking up speed fairly quickly you hear a wonderful whine from the Eaton supercharger as you guzzle gas at the rate of about 10mpg.
HJ
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Tomo
I'm with you there, I think that some of the hysteria comes from reading too many sci-fi stories as children. I sail on the Blackwater past Bradwell NPS and it does not worry me one bit.
With regard to disposal, I believe that once Earth to orbit gets a bit more reliable we will simply send anything that can't be stored or recycled on Earth off to burn up in the Sun.
Must be better than having fossil fuel power stations producing eight million tons of CO2 each per annum! And then they complain about cars with CO2 output measured in grams!
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Guy L,
Seems the consensus view is a thumbs down for superchargers!
You clearly have some practical and detailed knowledge of them, so thought I would ask you to expand, myself being one of those MB owners with a K suffix, and now a little concerned about what lies ahead!
Why in your experience do they knacker at such low milages? Is it maybe high rotor tip speeds and swept area?
Is the compromise of a compact unit imposing the need for higher rotor speeds?
Would some imaginative design work coupled with the use of wear resisting materials (ceramics perhaps) or easy modular part replacement maintenance improve the package?
Is the G Lader product more maitenance sensitive?
Would synthetic oil improve compressor life?
Cheers,
Julian
I can imagine positively charged engines with smaller capacities as another aid to reduce emissions, though I sympathise with your views on simplicitythat you have referred to in previous posts.
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Alvin
Rootes was the name for the type of supercharger/blower fitted to these engines, they consisted of two rotors each with three lobes and they intermeshed in a precision machined housing. Your right in that its job was to provide positive displacement of the exhaust gas rather than increase the air charge density during induction.
I wonder why the blown 2 stroke is no longer popular? probably power output and emissions, if I have to guess. I discovered, looking in an old textbook, that GM also made a blown 2 stroke diesel, and it was used as a crawler power unit amongst other things in the 50's
Regards,
Julian
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Julian.
GM 2 Stroke engines are the back bone of the oil industry, we have appox 150 operating in the middle east and russia. Simple to work on ...NO ELECTRONICS....and the sun and moon may vary..but not a GM 2 stroke... You can still buy them reconditioned from the USA with a 2 year warranty...try that with some of the new diesel engines of today.?
GC
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GC,
Noting that you have links with the oil industry, (your note to Eleanor C) amusingly, I found the reference to the GM 2 stroke in the book "Know Your Tractor" published by Shell in 1955. I trained as an Agricultural Engineer in the early 60's and purchased this book at the time. I can believe the reliability of the 2 stroke Diesel, but given comments by previous contributors wonder how reliable the blower is?
Regards,
Julian
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J L .
Blowers are not problematic with these type of engines as they are basicaly used to scavenge the burnt gasses from the combustion chamber , the system should run at about 7 psi.
The main fall from grace is that they are not so fuel efficient as four strokes ( this of course does not really effect the oil industry ) and the emission outputs are less than favourable .One other thing with the GM Detroit Diesel is you can also fit a turbocharger before the blower to increase HP, but then you have to fit a throttle delay ( again no electronics ) using lub oil pressure to prevent the rack opening to soon and creating thick black smoke when the throttle is opened.As to the different types of engine configuration a 2 cylinder 71 series uses the same liners,pistons & rings as the 3-71 , 4-71 , 6-71 ,8V-71 , 12V-71 & 16V-71 , likewise heads are interchangeable with 4-71 , 8V-71 & 16V-71 so you can immagine the benifits of stocking spare parts in remote locations.
GC
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