Nissan introducing new Micra with supercharged 3-cylinder gasoline direct injection engine; 95 gCO2/km
18 February 2011
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| The new 1.2L DIG-S engine. Click to enlarge. |
Nissan is launching a version of the Micra city car equipped with a new supercharged gasoline direct injection engine. The Direct Injection Gasoline-Supercharger (DIG-S) engine produces 72 kW (97 hp) and 142 N·m (105 lb-ft), while CO2 emissions are 95 g/km for the manual version and 115 g/km for the CVT version. Maximum speed is 180 km/h (112 mph) for the manual version. Combined cycle fuel economy figures for the manual Visia (entry-level) version is 4.1 L/100km (57 mpg US).
The DIG-S uses the Miller cycle and gasoline direct injection to raise the compression ratio to 13:1 for greater combustion efficiency and a supercharger for instant throttle response and added power. As well as delivering low CO2 emissions, the lightweight, low-friction 1,198cc three-cylinder unit produces the power expected from a conventional 1.5-liter four-cylinder engine.
Nissan is just as committed to reducing emissions from cars powered by the internal combustion engine as it is to developing new zero emission electric vehicles. The Micra DIG-S showcases how far our engineers have come.
It is clear that our new DIG-S engine offers the best solution for small cars like Micra. With instant throttle response, its performance and strong economy are a more than a match for any diesel engine with similar power outputs, but its emissions performance is much better.
We have been able to achieve this ultra low CO2 figure in a cost effective package and without the complication of particulate filters needed to clean up diesel engine emissions and which are not entirely compatible with a car that spends much of its life in the city.
—Pierre Loing, Vice President Product Strategy and Planning, Nissan International SA
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| The Micra DIG-S. Click to enlarge. |
The three-cylinder configuration gives many benefits including less weight and further reductions in friction loss, thanks to having fewer moving parts. Further gains are made thanks to the adoption of advanced engine management systems with stop/start and energy regeneration.
Equipped with the DIG-S engine, the most popular version of the Micra, the Acenta, also promises low CO2 figures: 99 g/km with a manual.
The DIG-S will be given its European debut at the Geneva Motor Show (March 3-13) with sales starting over the summer.
Europe-bound examples of the fourth generation Micra are built at an entirely new facility in India. It is also built in China, Mexico and Thailand and is sold in 160 countries around the world.
Launched late last year, the Micra is available in one body five-door body style, with three trim levels—Visia, Acenta and Tekna—and with a choice of two gasoline engines. As well as the DIG-S, there’s a normally aspirated version of the 1.2-liter engine, developing 59 kW (79 hp).
Why not do a supercharged two-cylinder engine for ~75 HP? Americans found out many years ago that ~75 HP was about right in the Geo Metro for maximum mileage and satisfactory power / acceleration. It sounds like fixes exist now for the issues that existed on the 90's era Metros.
http://1989geometro.com/geo_history.html
"In the United States a single engine was available from 1989 through 1994: a 1.0 L I3 engine. Rated at only 55 hp (41 kW), the small Suzuki-designed engine was the most fuel efficient production engine used in a GM car to date, boasting well over 45 mpg (5.3 L/100 km) in models with manual transmissions. A detuned 49 hp unit was used in the ultra-fuel-efficient XFi model, which delivered as much as 58 miles per gallon. As the 3-cylinder engines aged however, they began to become less stable and subject to vibration as well as minor deficiencies in the fuel injection system that led to decreased fuel economy. A flaw exists in Metro 3-cylinder engines equipped with an EGR valve - if the valve fails or the EGR passages become blocked, the center combustion chamber can get too hot, and over time, lose compression due to exhaust valve failure.
Customers who were surveyed stated that they wanted more power from their Metro as well as good fuel economy. In 1995, with the new Metro came a new engine: the 1.3 L I4. The new engine still had only a modest 70 hp (52 kW), but provided the extra power Metro owners wanted. That power came at the cost of some fuel efficiency, dropping the highway mileage down to around 35 mpg (6.8 L/100 km). The engine however, was not new. It was the same engine that had been in use in the Suzuki Swift (except for the GT models) for years. LSi models produced from 1995 on had the 4-cylinder engine, but the 3-cylinder was still the base power plant in the car, becoming an option for non-LSi models in 1997.
Canadian Metros had the 1.3 L engine available as an option beginning in 1993 in the 3-door GSi model, and as standard equipment in the sedan (exclusive to the Canadian market at the time: as noted in the previous paragraph, American market Metros were not available in a sedan bodystyle until 1995)."
Posted by: ejj | 18 February 2011 at 07:45 AM
Smart bit of kit, could it be mated with the Infiniti hybrid system?
Posted by: 3PeaceSweet | 18 February 2011 at 09:33 AM
Two-cylinder engines have considerably worse vibration characteristics and aren't necessarily any more efficient in this size range. The whole idea with supercharging and downsizing is that the supercharger is NOT required for most things that the driver does (because it's an efficiency-killer when it is in use) but is there to give extra power when the driver needs it. If you downsize too far, and the engine ends up having to run under boost a significant amount of the time in order for the car to get out of its own way ... that's counterproductive.
Posted by: Brian P | 18 February 2011 at 01:51 PM
No new engines need to be developed. Just make hydraulic hybrids to save energy and still have high torque for starting from stops. ..HG..
Posted by: Henry Gibson | 18 February 2011 at 02:20 PM
And what's the prime mover for that hydraulic hybrid ... A combustion engine. Better off with that engine as efficient as possible. Sheesh ...
Posted by: Brian P | 18 February 2011 at 04:54 PM
"the supercharger is NOT required for most things" - Really? I think you have this confused with a turbocharger. The supercharger is belt driven all the time, whereas the turbo only spools up when called upon. More efficient and only driven by the exhaust gas energy, not the engine torque.
Posted by: Rytooling | 18 February 2011 at 07:41 PM
Rytooling, all modern supercharger designs have a bypass valve that disengages them when the engine is running at part load. When the bypass is open, the supercharger is spinning, but not consuming significant shaft power. The bypass only closes when the driver requests close to full load. I will agree that a turbo is more efficient in most cases, but if you are using the Miller / Atkinson cycle (which this engine does), there may not be enough pressure remaining at the end of the exhaust stroke for a turbo to operate decently.
Posted by: Brian P | 18 February 2011 at 07:53 PM
The numbers are pretty impressive - I wonder how much it will cost ?
It is also a case of small cars becoming small again. This class has been slowly getting larger over the years.
It is probably good that they put a stop to it.
The problem with these cars is that they are small and cheap, and do not have the space or cost margin to allow fancy hybrid solutions (except perhaps stop/start), so the best thing may be this kind of engine development.
97 bhp and 99 gms CO2 is very impressive.
I wonder what the real world fuel consumption will be - the Fiat500 twin air is apparently nothing like as economical as the specs suggest.
Posted by: mahonj | 18 February 2011 at 11:54 PM
@mahonj: "The numbers are pretty impressive ...
97 bhp and 99 gms CO2 is very impressive.
I wonder what the real world fuel consumption will be - the Fiat500 twin air is apparently nothing like as economical as the specs suggest."
Exactly. Some cars are good, 'on paper' only.
Posted by: Pierre | 19 February 2011 at 08:01 AM
@ejj: I can't remember any owners of Suzuki Swift (of those generations)/ Geo Metro have much fond memories of those cars.
Posted by: Pierre | 19 February 2011 at 08:06 AM
Hopefully the next generation Volt will have something like this as a range extender
Posted by: 3PeaceSweet | 20 February 2011 at 03:12 AM
According to the CAR magazine of the UK, the NA version of the 3-cylinder 1.2L engine:
"the new 1.2 actually feels rough and rather restrained, and despite the kerbweight the March is pretty slow in any gear."
Hope that the supercharged one would give a better experience.
Posted by: Pierre | 20 February 2011 at 10:14 AM
Fuel economy and emissions figures are not very informative unless the test cycle is indicated.
Since the linked press release is from the European site, I would infer that the figures are based on the NEDC. The figures for the US EPA test cycle would certainly be significantly less optimistic.
I would welcome a test cycle indication in all fuel economy and emissions specifications here at GCC and all other internationally frequented publications.
Nevertheless, even for NEDC, these are good results, especially for a gasoline engine. I congratulate Nissan on their "diesel killer". ;-)
There is no scientific physical reason for a theoretical difference in efficiency between gasoline and diesel engines. Until now, diesels have generally been more efficient primarily for practical, technical, and economic reasons.
Even as so called "diesotto" and HCCI are still being developed in the laboratory, diesel and gasoline engines are already evolving convergently in production cars. In emissions, efficiency, and technical specifications, they have been gradually becoming more similar in new cars during the past decade.
Eventually the diesel vs gasoline argument will become moot. Until then, I look forward to continued improvement and technology transfer between the two.
Posted by: Fred H | 21 February 2011 at 12:41 AM
"There is no scientific physical reason for a theoretical difference in efficiency between gasoline and diesel engines."
Except for the major difference in expansion ratio.
Posted by: clett | 21 February 2011 at 01:33 AM
... and much lower pumping losses, due to unthrottled operation.
Posted by: Brian P | 21 February 2011 at 05:55 AM
There is no scientific physical reason for a difference in expansion ratio between gasoline and diesel engines. Until now, diesels have generally had higher expansion ratios primarily for practical, technical, and economic reasons.
The newest gasoline engines have expansion ratios of up to 14:1, and some newer diesel engines have an expansion ratio of 16:1. That is hardly a "major difference in expansion ratio". And if the trend continues, the gap may close, and there is no physics reason why it can not.
The same goes for pumping losses. In several Hybrid cars with gasoline engines, the engine runs nearly unthrottled most of the duty cycle. Diesels do not have "much lower pumping losses" than an unthrottled gasoline engine. There is no physics reason why a gasoline engine could not run 100% of its duty cycle completely unthrottled.
Posted by: Fred H | 22 February 2011 at 09:25 AM
Granted, if you use a variable valve timing and lift mechanism with considerable authority over the intake valve closing event. BMW Valvetronic and Fiat Multiair are like this. Neither one seems to get wonderfully spectacular fuel consumption figures. The compression ratio on a normal (premixed) gasoline engine is limited by detonation concerns at full load. If you deliberately sacrifice torque rating of the engine by deliberately ingesting less than a full charge, then yes, the expansion ratio can be bigger than the effective compression ratio (Toyota Prius does this) - it results in low specific torque output.
Mazda Sky-G has a 14:1 compression ratio and a rather diesel-like combustion chamber, and I suspect that they are injecting the fuel late, almost in diesel-like manner, but with spark ignition. Remains to be seen whether this engine will really live up to its promise; we should find out soon enough. The Fiat 500 Multiair has disappointing EPA ratings. The 1.3 Multijet diesel is still the engine of choice in that car ...
Posted by: Brian P | 22 February 2011 at 09:00 PM