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Old 9th July 2013, 14:11   #1
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Default Low compression ratio diesels coming up

>>>

An article in the latest edition of The Economist ( the Babbage blog on technology) describes the latest innovation in diesel engine technology (low compression ratio engines by that maverick Mazda, and by Mitsubishi); all copyrights acknowledged. All emphases in the article below are mine.

Quote:
" NOT to belittle the success Tesla Motors has had with its Model S luxury electric car—outselling its petrol-powered equivalents since being launched last year—the prospects for battery-powered vehicles generally may never shine quite as bright again. Babbage believes their day in the sun is about to be eclipsed by, wait for it, the diesel engine.

Surely not that dirty, noisy, smelly, lumbering lump of a motor that was difficult to start in the winter? Certainly not. A whole new generation of sprightly diesels—developed over the past few years—bear no resemblance to your father’s clattering, oil-burner of an Oldsmobile. It is no exaggeration to say that, with its reputation for unreliability and anaemic performance, the Olds 4.3-litre diesel from the late 1970s single-handedly destroyed the reputation of diesel engines in America for decades to come. Quite possibly, it also contributed to Oldsmobile’s own demise.

Later this year, Americans will get their first chance to experience what a really advanced diesel is like—and why Europeans opt for diesels over hybrids, plug-in electrics and even petrol-powered cars. The leader of the new pack is the Mazda 6, completely redesigned for 2014, with the choice of either a 2.5-litre four-cylinder petrol engine or a 2.2-litre turbo-charged diesel. The diesel has 30% better fuel economy and provides oodles more pulling power. Good as the petrol version is, motorists who choose it over the diesel will miss out on a lot.

Mazda is not the only motor manufacturer with an advanced diesel in the works. Among others, Mitsubishi Motors has been selling cars with a new generation of 1.8-litre and 2.2-litre diesel engines in Europe since 2010. Hedging its bets on hybrids, Toyota has also been testing several radically new diesel designs.

What marks this latest generation of diesel engines from even their “common-rail” predecessors of the late 1990s, let alone their belching ancestors from the 1970s, is the use of a surprisingly low compression ratio of around 14-to-1 rather than the more usual 16-to-1 or higher. The reduction in cylinder pressure may sound marginal, but it gives rise to a virtuous cycle of beneficial effects unavailable before.

For a start, the lower cylinder pressure reduces thermal and mechanical stresses in the engine. As a result, the heavy cast-iron block traditionally needed to stop a diesel ripping itself apart can be replaced with a lighter aluminium casting. That trims 25kg (55lb) off the block of the new Mazda diesel. Lower cylinder pressures mean that pistons, rings, valves, crankshaft and other engine parts can also be made 25% lighter. And because they are weighed down less by a lump of an engine, the vehicle's brakes, suspension components and bodywork do not need to be quite so rugged either. All these weight savings translate into greater efficiency. According to Ricardo, an engineering consultancy, every 10% reduction in a family car’s weight boosts its fuel economy by more than 4%.

Another benefit of lower cylinder pressure is that.....
Read the rest of the article by clicking the link here : http://www.economist.com/blogs/babbage/2013/07/diesels


The spirit of Rudolf Diesel is alive and kicking!

Regards
issigonis

Last edited by Rehaan : 9th July 2013 at 18:18. Reason: Quoting only a section of the write-up, and leaving the link for those who wish to read further. Thanks.
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Old 9th July 2013, 14:36   #2
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Default re: Low compression ratio diesels coming up

And so, the auto industry observers, reviewers are still on the payrolls of the oil companies. Fossil fuels and clean, leave alone Diesel, come on. I would have almost bought in to this article, if not for that disclaimer. That was the give away.
Not dwelling in to technical details, I'm finding it hard to push behind me, the Tesla Vs NYT episode and Tesla Vs BBC drama.
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Old 9th July 2013, 14:42   #3
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Default re: Low compression ratio diesels coming up

I dream of a day when petrol is no longer desirable and passenger cars use only diesel as fuel. It is the petrol engines that have to be taxed; the prices of diesel engines should be brought down to encourage efficiency and a lower carbon footprint.
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Old 9th July 2013, 14:44   #4
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Default re: Low compression ratio diesels coming up

Quote:
Originally Posted by Mudhalaipatti View Post
And so, the auto industry observers, reviewers are still on the payrolls of the oil companies. Fossil fuels and clean, leave alone Diesel, come on. I would have almost bought in to this article, if not for that disclaimer. That was the give away.
Not dwelling in to technical details, I'm finding it hard to push behind me, the Tesla Vs NYT episode and Tesla Vs BBC drama.
>>>

Please explain : disclaimer? giveaway?

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Old 9th July 2013, 16:05   #5
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Default re: Low compression ratio diesels coming up

Quote:
Originally Posted by issigonis View Post
the urea-injection system, with its tank that has to be refilled every six months or so, is no longer required.
What is an Urea injection system? Refilled in 6 months? Which diesels are we talking about here?
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Old 9th July 2013, 16:13   #6
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Default re: Low compression ratio diesels coming up

So the classic low end torque of the diesel engine will also vanish!!!
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Old 9th July 2013, 16:14   #7
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Default re: Low compression ratio diesels coming up

Quote:
Originally Posted by issigonis View Post
>>>

Please explain : disclaimer? giveaway?

Regards
issigonis
"NOT to belittle the success Tesla Motors has had with its Model S luxury electric car"

"Their big advantage will be that they will come with none of the range anxiety and recharging difficulties to worry about"

To boast about a new technology or innovation is another thing. But to discredit a segment altogether is, for me, wishful thinking.

Further this article is focused on North America. Do people really car bout their fuel bills there ? Duh number one.
Why compare this with hybrid and electric cars, in the first place. A comparison with petrol would be apt and that was supposed to be the USP of this article. But then the not so subtle nudge against electric cars didn't go unnoticed.
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Old 9th July 2013, 16:52   #8
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Default re: Low compression ratio diesels coming up

Revintup to answer your question-

In 2010 or so I saw this on Melbourne City Buses and the diesel Mazda CX 7 crossover; they had a small tank filled with a bluish liquid that ran through the cat con and absorbed the carbon particles or something like that. Every service this liquid had to be replenished/changed like engine oil.

Last edited by KMT : 9th July 2013 at 16:54. Reason: provide reference to question
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Old 9th July 2013, 18:46   #9
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Default re: Low compression ratio diesels coming up

Quote:
Originally Posted by Mudhalaipatti View Post
"NOT to belittle the success Tesla Motors has had with its Model S luxury electric car"

"Their big advantage will be that they will come with none of the range anxiety and recharging difficulties to worry about"

To boast about a new technology or innovation is another thing. But to discredit a segment altogether is, for me, wishful thinking.

Further this article is focused on North America. Do people really car bout their fuel bills there ? Duh number one.
Why compare this with hybrid and electric cars, in the first place. A comparison with petrol would be apt and that was supposed to be the USP of this article. But then the not so subtle nudge against electric cars didn't go unnoticed.
The range is a problem in any electric car, forget the Tesla bashing episodes, the fact is that Tesla themselves highlight the number of charging points available in a geography because it takes a lot longer to charge up than fill up a an empty fuel tank.

The diesels have progressed, the fact is that most people still refer to the diesels in old Ambys here and the Oldsmobile in USA. The fact is that 50 state clean diesel as they are called are reliable and non-polluting. The urea tank can be refilled for around 40USD.

Tesla is still in infancy, and 100k for a car is still not mass market. The Mazda will allow for owners to experience power with significantly better range. I don't see how that is not progress but EV bashing. People will care about fuel bills anywhere, the reason why downsizing and turbocharging is gaining ground, Ford EcoBoost engines for example, is because the fuel price pinch is felt everywhere.
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Old 11th July 2013, 21:03   #10
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Default Re: Low compression ratio diesels coming up

Quote:
Originally Posted by Mudhalaipatti View Post
I would have almost bought in to this article, if not for that disclaimer. That was the give away.
Nothing in the automotive space is cast in stone until the actual technology has reached the customer from the manufacturer. And even then, it is possible there would be differing points of view.

This is just a teaser of what MAY be and at the end of the day is just an opinion. Way too preliminary to even think of “buying into”, unless one is agreeable with the probability of a miss being as good as a mile.

The operative words in the article give it away too easily.

Quote:
Babbage believes …..


Babbage fully expects….
There are many such articles around. Whether they are red herrings only time will tell.

Last edited by VeyronSuperSprt : 11th July 2013 at 21:04.
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Old 11th July 2013, 21:20   #11
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Default Re: Low compression ratio diesels coming up

Check out
http://www.mazda.com/mazdaspirit/sky...kyactiv-d.html
rather than the babbage article!

Any further developements on the Miller Cycle?

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Old 11th July 2013, 21:23   #12
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Default Re: Low compression ratio diesels coming up

The Skyactiv is a gasoline engine, is it not? Read about it a while back. Some good tech in there.

Edit: Skyactiv 'G' is what I was talking about, apparently. Didn't know they had a Diesel engine with similar tech too.

Last edited by pranavt : 11th July 2013 at 21:24. Reason: Updating post
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Old 11th July 2013, 21:27   #13
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Default Re: Low compression ratio diesels coming up

Quote:

Mazda’s new “Skyactiv-D” engine winds up to 5,200 revolutions per minute, a figure previously unheard of among road-going diesels.
Babbage hasn't obviously heard of the humble Rapid TDI, a diesel which also revs very smoothly upto 5200 revolutions per minute.
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Old 12th July 2013, 07:05   #14
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Default Re: Low compression ratio diesels coming up

I didn't fully understand, what exactly is enhanced /changed (if any) so that the compression ratio is found out that it can be reduced? Is it only the "piezoelectric fuel injectors with multiple nozzles, which can spray fuel in whatever pattern best suits the operating conditions. Also, because the valves on modern engines have variable lift and timing, the exhaust valves can be left slightly open as the engine is coughing and spluttering during a particularly cold start" that has enabled to experiment lower compression ratios?

So, was it mostly for starting that the comp ratio kept higher earlier?

Quote:
Originally Posted by KMT View Post
In 2010 or so I saw this on Melbourne City Buses and the diesel Mazda CX 7 crossover; they had a small tank filled with a bluish liquid that ran through the cat con and absorbed the carbon particles or something like that. Every service this liquid had to be replenished/changed like engine oil.
Why don't we in India have to change this? Do we not need urea to mask the NOx here? Is it just that our emission norms are not that strict?

Last edited by thoma : 12th July 2013 at 07:08.
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Old 12th July 2013, 08:13   #15
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Default Re: Low compression ratio diesels coming up

Well, i am confused. As far as i understand, fuel efficiency is directly proportional to compression ratio. That is primarily the reason why diesel with a higher CR deliver better efficiency. So when you decrease the CR, wont the fuel efficiency decrease.

Or do they mean that this decrease is masked by the increase due to weight reduction.?Enlight me please.
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