Hyundai Kappa engine

The Kappa engine series are gasoline powered, all-aluminum block and utilizes a 16-valve design with DOHC as opposed to the 12-valve design SOHC of its Epsilon engine family predecessor.

Main improvement is adding VTVT (variable valve timing) to the engine.

1.0 L (G3LA)

2021 Hyundai Grand i10 Nios 1.0 engine

The 998 cc (1.0 L) three-cylinder engine makes 69 PS (51 kW; 68 hp) at 6,200 rpm and 9.7 kg⋅m (70 lb⋅ft; 95 N⋅m) of torque at 3,500 rpm.

1.2 L (G4LA)

2021 Hyundai Grand i10 sedan 1.2 engine

The 1,197 cc (1.2 L) is a destroked variant of the Kappa II G4LA engine produced in India to circumvent the 1,200 cc tax bracket. It is a four-cylinder engine making 83 PS (82 hp; 61 kW) at 6,300 rpm and 11.6–12 kg⋅m (84–87 lb⋅ft; 114–118 N⋅m) of torque at 4,200 rpm. Since 2020, it is also known as the Smartstream G1.2 engine.[5]

1.25 L (G4LA)

2012 Kia Picanto 1.25-litre Kappa II engine

The 1,248 cc (1.25 L) is the European version. It is a four-cylinder engine making 86 PS (63 kW; 85 hp) at 6,000 rpm and 12.3 kg⋅m (89 lb⋅ft; 121 N⋅m) of torque at 4,000 rpm.

1.4 L (G4LC)

2019 Kia Soluto 1.4-litre Kappa II engine

The 1,368 cc (1.4 L) version adds Dual-CVVT and VIS, the engine makes 95–100 PS (70–74 kW; 94–99 hp) at 6,000 rpm and 13.5–13.7 kg⋅m (98–99 lb⋅ft; 132–134 N⋅m) of torque at 4,000 rpm.

Announced in 2016 and intended for use in Hybrid applications, main improvements are utilizing Atkinson cycle, higher compression ratio, cooler EGR system and higher pressure fuel system.

Developed at a cost of $421 million over a period of 48 months, the Kappa project was aimed at increasing fuel economy while ensuring compliance to stringent EURO-4 emission regulations. The newest versions of Kappa engine family comply with Euro-6DTemp regulations.

The engine block is made from high pressure die-cast aluminum which results in considerable weight savings - the entire engine with a manual gearbox only weighs 82.4 kg (182 lb). The 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 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. A highly sophisticated process of Physical Vapor Deposition (PVD) is used to apply an ultra-thin layer of Chromium nitride to the piston’s oil ring. Chromium Nitride-coated piston rings using PVD is an innovative technology borrowed from the Hyundai Tau engine introduced earlier. Friction between the oil ring and cylinder wall has been further minimized by reducing the oil ring tension. The Kappa engine 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 mi (160,000 km). For ignition, the Kappa engine 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. The long reach spark plug (M12 thread) also enabled engineers to enlarge the valve diameter for increased airflow and combustion efficiency. A lightweight, heat-resistant engineering plastic was used for the intake manifold. The fuel delivery pipe assembly is a returnless type (to eliminate evaporative fuel emissions) and is made of SUS (steel use stainless) with a specially designed inner structure for the reduction of pulsation noise.

The valvetrain features a number of innovations: friction reducing roller swing arm, hydraulic lash adjusters which ensure proper clearances between the valve stem and roller swing arm, which significantly reduce valve tapping noise. The valve springs feature a beehive shape and smaller retainer. The reduced weight and spring load further help lower friction and improve fuel economy. The valvetrain is driven by a silent-type, maintenance free steel timing chain that replaces a roller-type timing chain: The optimized design greatly reduces impact forces and noise when the gear tooth and chain engage.

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. This offset minimizes the lateral force created by the rotating piston & rod assembly (known, and audible, as "piston slap" at its extreme). The net effect is an improvement in fuel consumption and a reduction in noise, vibration and harshness - it should also help with engine longevity since reduced lateral force will equal reduced bore wear.

Engine management is provided by two 16-bit 32 MHz microprocessors which control and monitor ignition timing, idle speed, knocking and emissions.

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