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Opel launching new all-aluminum 1.0L 3-cylinder turbo for Adam; fuel economy and refinement

The new 1.0L turbo. Click to enlarge.

Opel will introduce the first in an all-new modular family of small-displacement three- and four-cylinder gasoline direct injection engines at the upcoming Frankfurt International Motor Show next month. The new three-cylinder 85 kW/115 hp, 1.0-liter turbo will be launched in the Opel Adam, coupled with an all-new six-speed gearbox.

The engine produces low-end torque of 166 N·m (122 lb-ft) all the way from 1,800 to 4,700 rpm. The 12-valve 1.0 SIDI Turbo (Spark Ignition Direct Injection) generates more torque throughout its operating range than equally powerful, higher displacement engines, while fuel efficiency is improved by 20% compared to Opel’s current 1.6-liter naturally aspirated power unit.

Technologies such as direct injection, continuously variable valve timing, and a lightweight aluminium cylinder-block are key efficiency enablers. Opel expects the new engine family to deliver CO2 emissions significantly lower than 100 g/km.

In developing this small engine, we not only set out to minimize fuel consumption and CO2 emissions, we also wanted to demonstrate that three cylinders can be just as refined as four or more. We tackled at source the balance, noise and vibration issues typical of conventional three-cylinder engines, and we’re confident customers will be pleasantly surprised by the results. This is a very lively and refined three-cylinder engine which doesn’t compromise on driving fun.

—Dr. Matthias Alt, Opel’s Chief Engineer, Small Gasoline Engines

Opel engineers started with a clean sheet of paper, which enabled the incorporation of a series of measures to eliminate the typical, “off-beat” running characteristics which have traditionally accompanied the economical driving appeal of three-cylinder engines.

The cylinder block made of high pressure die-cast aluminum is designed to reduce radiated and structure-borne engine noise, as well as reduce weight. The high-pressure fuel rail and injectors are also structurally isolated from the cylinder head to minimize the transmission of pulsing, while the fuel pump and fuel line are acoustically treated.

Another major contributor to refinement is the installation of a balance shaft in the oil sump. Driven by a chain with inverted teeth for quiet running, the counter-rotating shaft spins at crankshaft speed and is carefully mass-optimized to offset the inherent vibrations from a three cylinder operation.

The exhaust manifold is integrated inside the aluminum cylinder head, which is bolted directly to the low-inertia, water-cooled turbocharger. Click to enlarge.

Other noise attenuation measures include: acoustically-optimized covers for the top and front of the engine, the intake manifold and camshaft housings; crankshaft isolation with iron main bearing inserts; inverted teeth for camshaft drive chain; a low-hiss turbo compressor; and a lower oil pan in steel.

In bench testing at full throttle, the new engine emits lower noise levels across all engine speeds than similarly powerful gasoline turbos with 1.6-liter displacements. With its inherent refinement, the need for additional in-car sound insulation, or complex engine mountings and sub-frames, is reduced.

The exhaust manifold is integrated inside the aluminum cylinder head, which is bolted directly to the low-inertia, water-cooled turbocharger. This compact installation contributes to the delivery of a fast boost charge for strong, low-end power. The maximum torque of 166 N·m is almost 30% higher than the 1.6-liter engine generates at the same rpm.

The six-hole fuel injectors are centrally located above each piston to provide efficient combustion, and dual cam-phasing enables variable valve timing for optimum engine breathing. A twin displacement oil pump and a switchable water pump, which is disengaged when the engine coolant is cold in order to accelerate warm-up, also contribute to low fuel consumption.

New 6-speed gearbox. Click to enlarge.

New weight-saving six-speed gearbox. The 1.0 SIDI Turbo is mated to an all-new, six-speed manual gearbox specially designed for medium torque applications. With a dry weight of only 37 kilograms (82 lb), it is about 30% lighter than its current counterpart. It is also extremely compact, measuring just 375 mm along its axis.

Featuring superior shift quality, with a short lever travel and low shifting effort, the new transmission incorporates many of the refinements recently introduced on Opel’s next-generation gearboxes. These include gears with wide, asymmetrically-cut dog teeth, and triple-cone synchronizers for first/second gear, with double cones for third/fourth. Reverse gear is also synchronized.

The new gearbox will be used in a broad range of small and sub-compact Opel vehicles with engines rated at up to 220 N·m (162 lb-ft) torque. For optimum powertrain efficiency in each application, the matrix of gearing choices comprises 12 sets of gear ratios and seven final drives.

Opel plans to introduce three new engine families and 13 new engines between 2012 and 2016, plus a number of new transmissions.

The program began with the launch of the first engines in new mid-size gasoline and diesel families. These 1.6-liter turbo units are now joined by the 1.0 turbo, as the first example of a new, small displacement engine family. All will be built at GM’s new Szentgotthard plant in Hungary, where gasoline and diesel engines are produced on a shared assembly line.



Well done Opel.
Keeping up with Ford - gotta do it to stay fresh.

Gasoline cars that have < 100 gms CO2 and 115 HP are not to be sneezed at.

I wonder how many man-years of work went into this.


Three cylinder designs are inherently unbalanced and no finagling can remove it. For that range of engine size the Fiat TwinAire two cylinder all-alloy .9 and 1.0 liter engines are just inherently smoother.

Comparing them to a 50% larger engine is a gimmick. That is like comparing a 3 liter V6 to a 5 liter V8.



With a 3 cylinder engine and a 120 deg crank angle, the engine fires every 240 deg with each piston coming to top dead center every 120 deg. With a 2 cylinder inline engine, you have a choice of firing every 360 deg with the both pistons coming to top dead center at the same time or firing 180 deg and then rolling 540 deg with the pistons opposing (one up, one down). Honda did this with their 2 cylinder motorcycles. I beleive this is better for higher speed engines. However, neither choice is going to be better than a 3 cylinder inline.


This also looks really good for a PHEV sustainer engine.


I hate to see the use of a balance shaft and chain on any car since it adds weight and complexity. Seems to me making the cylinders, crank, etc., even smaller and using four holes would be best.

Since the engine is modular, I suspect they were given existing sized pistons and told to design the engine. If so, that's not a clean sheet of paper. That's a limited sheet of paper.



There are certain size ranges for efficient engine operation. You do not want to go under about 300 cc per cylinder or you start to lose much combustion heat as the combustion volume to surface area ratio decreases. However, with a small number of cylinders you also do not want to go too large per cylinder or you have balance problems. You generally will not find 3 cylinder engines more than about 0.4 liter per cylinder or four cylinder engines more than 0.65 liter per cylinder but you will have 8 liter V8s or even 28 liter V12s (Allison aircraft engine). The use of inverted tooth chains is a good thing as they are efficient, quiet, and durable and probably lighter than an equivalent timing belt.


Thanks for the info...makes sense; I understand better why the limits.

Roger Pham

Furthermore, the 3-cylinder configuration is ideal for a turbocharged engine because the turbine and compressor are having a more steady flow. 115 hp per liter is excellent power to displacement ratio.

Remove the turbo and change to Atkinson cycle and this engine should be able to develop ~60-70 hp, which is adequate for use in a full HEV with electric motor power boost. The use of 3-cylinder leave more room in the engine bay for hybrid components such as the motor, generator and power split planetary gear set. The Prius with 4-cylinder engine has a very cramped engine bay that makes it difficult to service the engine and the hybrid drive...not that the engine or the hybrid HSD needs any frequent servicing. With even more engine downsizing to 1 liter from 1.5-1.8 liter, the Prius will probably realize even higher mpg at cruise, and less wear on the hybrid battery because the engine can be used more often and depend less on the battery and motor at lower speeds.

Even the Volt and the new Cadillac PHEV will benefit from this 3-cylinder engine. 3-cylinder configuration will allow more battery capacity to be placed in the front, perhaps allowing the PHEV with a full 5-seat rating, instead of being a 4-seater with a portion of the rear bench taken by the long battery pack. Perhaps GM will learn a lesson from Ford and reduce the battery size of the Volt down to 10 kWh instead of 16, reducing cost, weight and returning cargo space and passenger space for the vehicle to be competitive with non-PHEV.

Likewise, the Ford C-Max Energi can also have its 144-hp engine downsized to a 2-cylinder 72-hp engine to increase internal space and to reduce weight, cost, and improve handling.


Don't bother removing the turbo, just use VVT on the intake to regulate the air charge and set the speed to get the desired exhaust flow.  The turbo recovers exhaust energy and recycles it to compression, or add an alternator on the turbocharger shaft to capture excess exhaust energy directly as electricity.

If you do this right with reduced geometric compression and intercooling, you may be able to reach 150 HP/liter... meaning 1 liter of engine might be plenty or even more than enough.  Turbos are tiny, and smaller engine blocks mean less-cluttered engine bays.


I like the idea that Wright aircraft had with their 3350 compound engines. The turbine is coupled back to the crank through a fluid coupling. Also, additional exhaust heat energy can be recovered using thermo-junctions to create electricity...there are still lots more power and efficient gains to be gotten from IC engines. It is a shame it takes pressure from Government to move the auto companies to action.


Those of you who think that a 3-cylinder is not refined enough should test drive a Ford car with this engine. There is really not much to complain about. Note that this engine does not have a balance shaft as the GM engine does. In contrast, a 2-cylinder engine (in a conventional drivetrain) is below my standards.


Will the next generation Volt use a 2 or 3 cyls?



I was thinking the same about using 3-cylinder Atkinson cycle engines in a full HEV/PHEV vehicles, with volume 1.0-1.5 litre (BMW already uses 1.5 L 3-cyl).
Another interesting thing would be to add the (inexpensive) Valeo electric supercharger to such engine, to boost power in charge sustaining mode, when battery (at low SOC) can only provide short bursts of power to powerful e-Motor(s). It would offer good performance for long uphills, also for fully loaded cars at higher speeds.
E-supercharger for such engine would probably need about 2kW (provided continuously by an e-motor/generator), but would add 15-20 kW to engine output.

Engine length is a limiting factor for hybrid drivetrain, as you said. Everything needs to fit between the stearing pair of wheels, as almost all hybrid drivetrains are in front of the car. So 3-cylinder layout would be preferable.

Or something even better.
What do you think of using VR3 engine, instead L3 Atkinson engine for full HEVs/PHEVs?
Say use 1/2 of narrow angle (15 degrees V configuration) VW VR6 (http://en.wikipedia.org/wiki/VR6_engine)?
It uses just one one cylinder head, with probably a more complex valvetrain.
It would shorten the L3 by about 25%, every inch counts, as cheaper (or more powerful) hybrid system can be used, or just for better serviceability.


I was pondering a turbo V-twin, with the turbocharger located between the two cylinders; it would have the virtue of being very short, needing only one crank throw.  The problem with this is that you have two blocks, two heads, and lots of coolant plumbing to assemble (which creates places for leaks).  All of that is going to run into money.


One way to reduce production cost would be with standardized models produced in very large numbers in very low production cost countries, such as China, India, Brazil etc. The approach is used with great success for car parts, ancillaries, tires etc.

Aluminum alloy blocks could be used to further reduce weight and shipping cost.

Ongoing design cost could be shared by the 20+ major electrified vehicle producers.


The drone of typical 4 cylinder engines is annoying to me. Yes, I know Honda and others make very smooth 4 cylinders. But, a recent drive in a Ford Hybrid highlighted my feelings on the subject. I simply don't like the sound and feel of 4 cylinders. I very much prefer the sound of a high performance 3 cylinder engine. Triumph motorcycles have had 3 cyl engines for many years. I've come to love them.

Years ago I owned a Geo Metro with 3 cylinders. While it was a very low tech engine and unrefined, I loved the sound of it. Especially when the muffler started failing. Quite unlike a 4 cyl with a noisy exhaust.

I guess this is a long-winded way of me saying that I'm looking forward to high performance 3 cylinder engines.

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