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Hyundai’s New Kappa Gasoline Engine; Focus on Lightweighting and Friction Reduction

Hyundai’s Kappa engine. Click to enlarge.

Hyundai has unveiled its newly-developed Kappa gasoline engine in two variants: a 1.2-liter version for India, and two 1.25-liter versions for Europe and the rest of the world. The first car to have the Kappa engine installed will be the i10, produced at Hyundai Motor Co.’s Indian subsidiary in Chennai. Hyundai will also apply the engine in its i20 A- and B-segment cars, with a Kappa-engined i20 to be revealed at the Paris auto show this fall.

Hyundai’s i10 minicar with a 1.25-liter Kappa engine carries a fuel economy rating of 5.0L/100km (47 mpg US) in the European combined test cycle, with CO2 emissions of 119 g/km. The Euro-4 compliant, inline four-cylinder engines produce 57-59 kW (76-79 hp) of power and torque of 112-118 Nm (82-87 lb-ft).

Cutaway of the i10 with Kappa. Click to enlarge.

Kappa adopts a number of weight- and friction-reducing technologies to achieve its fuel economy. The engine block is made from high pressure die-cast aluminum which results in considerable weight savings. At 82.4 kg (182 lbs) (1.2L engine with manual gearbox), Kappa is the lightest in its class among leading European and Japanese-made engines (using the same measuring criteria across the competitive set), according to Hyundai.

Kappa’s main block features a ladder frame construction for structural stiffness while its cylinders are fitted with cast-iron liners for improved abrasion durability. Additional weight was shaved off by integrating the engine support bracket with the timing chain cover.

The offset crankshaft helps reduce side forces. Click to enlarge.

According to Hyundai, the most significant engineering innovation applied in the Kappa is the offset crankshaft, an engineering concept first adopted in the Gamma engine introduced last year.

Unlike a conventional engine where the centerline of the cylinder bore is in perfect vertical alignment with the rotating axis of the crankshaft, the Kappa’s centerline is offset by a small distance. By creating this offset distance, engineers have succeeded in minimizing the side force created by the pistons. The net effect is an improvement in fuel consumption and a reduction in noise, vibration and harshness.

Engineers also devised an innovative piston concept to reduce piston mass. The shape of the piston skirt was optimized to reduce its size while the compression height of the piston was also reduced, resulting in weight savings. The optimized piston skirt is also treated with Molybdenum Disulfide (MoS2), a special anti-friction coating.

Physical Vapor Deposition (PVD) is used to apply an ultra-thin layer of chromium nitride (CrN) to the piston’s oil ring. CrN ensures high wear resistance and a low friction coefficient. CrN-coated piston rings using PVD is a technology borrowed from the Tau V8 engine that Hyundai introduced earlier this year.

Friction between the oil ring and cylinder wall has been further minimized by reducing the oil ring tension. The smaller mass and special surface treatment of the piston skirt and oil rings yielded additional savings in fuel consumption.

Kappa is the first Hyundai engine to be fitted with an accessory drive belt which does not require a mechanical auto-tensioning adjustment device, reducing the hardware and further lowering weight and cost. Because it is designed to maintain an ideal tension setting, the belt runs quieter and with proper preventative maintenance and care, the belt will last 100,000 miles.

Kappa uses a new, longer reach spark plug which enabled engineers to enlarge the size of the water jacket to promote more efficient engine cooling around the critically important spark plug and exhaust port area. Cooler operation also prevents engine knocking.

The long reach spark plug (M12 thread) also enabled engineers to enlarge the valve diameter for increased airflow and combustion efficiency.

Kappa’s valvetrain features a roller swing arm to lower friction in the valvetrain. Hydraulic lash adjusters ensure zero clearance between the valve stem and roller swing arm, eliminating valve tapping noise.

A new valve spring features an innovative beehive shape and smaller retainer. Its reduced weight and spring load help lower friction and improve fuel economy. Kappa’s valvetrain is driven by a silent-type steel timing chain that replaces a roller-type timing chain.

A lightweight, heat-resistant engineering plastic was specified for the intake manifold. This reduces cost and weight and yields an overall performance improvement.

Kappa is the eleventh in Hyundai’s series of gasoline engines. Annual output from the Chennai plant is forecast to reach 250,000 units per year. With the newly-constructed No. 2 Kappa engine plant, HMI will have a total engine manufacturing capacity of 570,000 units per year, including the existing 320,000 units-per-year No. 1 Epsilon and Alpha engine plant. The Kappa engine plant began production today (15 July).

Hyundai Motor India (HMI) launched the i10 in October 2007 and has sold 184,465 units as of the end of June, one of HMI’s best sellers.



The offset crankshaft design was also employed in the
3-cylinder, 1-litre engine of the Honda Insight hybrid car, and many other energy saving ideas as well.


Very clever engineering, but they need to develop a light weight 3 cylinder 900cc turbo diesel too.


Will Hyundai use these more efficient lighter, smaller ICE in their future PHEVs?


I'm not seeing the innovation here - the GEO Metro came out 10+ years ago.

Alex Kovnat

We note ejj's reference to the Chevrolet Geo Metro.

Unfortunately you wouldn't be allowed to produce that same car today, because since the 1990's crashworthiness (for example, side impact) standards have become more stringent. And be prepared for more bad news: While the powers-that-be are demanding more and more miles per gallon, they are also demanding 2X or more roof crush strength.

Ironically, its perfectly legal to risk bashing in your skull riding a motorcycle, but not legal to undertake the relatively lesser risk of driving a car like the 1990's Geo Metro.

I like the i10 with the Kappa engine. I think its cute! But one of the disadvantages to a car as small as the i10 is, if you demand hybrid electric operation where are you going to put the battery pack and other add-ons required for that kind of car? Remember, the Prius is not that little a car.

Nonetheless, I think the i10 should be available to those who want one.

I believe that if the auto-haters will be a little less shrill, perhaps we can accept a few compromises. Since a car like the i10 will be mainly a commuter car, perhaps we can accept a lesser degree of crashworthiness than we would demand from a car that's likely to be used for transporting children.

Once again, what the hell does crashworthiness have to do with the size of the vehicle??


The space frame design with plastic body panels is a strong, light and crash worthy design. You can make a car roomy, light and safe, it is a matter of good engineering.

With hybrid turbo compounding and heat recovery, a 1.2l engine could power a 4 door sedan and get 60 mpg. The technology is here now, all we have to do is do it.


Alas, there's no way you can build a 76-79 bhp turbodiesel this light because the basic design of a diesel engine requires a much stronger engine block than a gasoline engine. That's why Honda's 2.2-liter i-DTEC engine rated at 150 bhp (SAE 08/04 net) weighs as much as the 2.4-liter K24 engine rated at 190 bhp (SAE 08/04 net).


I've got an '88 Ford Festiva similar to the Geo Metro when feather footed, got as high as 53MPG on the flat & 47MPG in the mountains. I thought as ejj, that the small cars of the late 80's & 90's got the best MPG.

But I've read feather footing reports that Toyota Yaris owners have gotten 48MPG, & Honda Fit owners have gotten 45MPG(one owner AVERAGES 48MPG).

I took my wife's 2008 Hyundai Accent for 3 feather footing day trips & got 41.5, 42.6, & 45.1 MPG. Were these trips on some flat highway, no hills & ideal temperatures? From sea level I traveled over 1400, 3000, 4000, & 5500 foot mountain passes, to 101 degree E.Washington, & to Mt. Rainier.

All three cars are 20+% heavier than Geo Metro & Festiva with lots of airbags & far better crash worthiness. Plus, traffic is much heavier & traffic lights more numerous now than 20 years ago.

Sure, these newer cars won't get such high MPG in commuter traffic. But, still people are driving way too aggressively & too fast to get the new & downwardly revised EPA economy numbers. Then pretend racer Eddy complains that his car is defective because he can't get 45MPG at 80MPG dodging in & out of traffic. What magic does Eddy believe?


The 1NZ-FXE in the Prius & the original 1NZ-FE in Yaris and Echo from 1997 incorporate the offset crankshaft. This is mature technology today. No mention of double VVT camming either. Toyota's 1SR-FE family have this too.

I thought there was an effort by all manufacturers to eliminate the serpentine belt with seperately driven pumps ?

Fiat's 900cc parallel twin is now the gold standard of small engines with the turbo version at 105Hp.

Engines are not the real problem. The real problem is the transmission systems which are still from the 20th Century. They force us to use 4 cylinder engines. Completely decoupled engines as found in the VOLT will eventually allow the development of single cylinder engines whose sole purpose will be to generate power. Bottom end torque, the 6 spd, the mechanical CVT and the Dual clutch will be history. Their place subsumed by an electronic inverter and AC induction motor combination.

Then series hybrids don't actually need a battery. The inclusion of a battery is merely a variant on the architecture put in place by the manufacturers. Bob Lutz has said as much that a batteryfree VOLT is a possibility. I think they are searching for a lower price point where most of the advantages of full hybridisation can be obtained.


Im cazzy about your tech

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