The Quest for Power

TECHNOLOGY
The Quest for Power

Using a supercharged engine enabled engine design requirements for big power in a lightweight, compact package to be met. Aside from minor differences in the engine unit, and intake and exhaust systems tailored for street use to ensure noise and emissions standards are met, the 200 PS supercharged engine of the Ninja H2 is essentially the same as the over 300 PS engine of the closed-course Ninja H2R, delivering an intense acceleration unlike anything you can experience on a naturally aspirated bike. Designed in-house, the immense potential of the highly compact, highly efficient, supercharged 998 cm3 In-Line Four engine is a testament to the technology possessed by the KHI Group.

In-House-Designed Supercharger

The supercharger used in the Ninja H2 was designed by Kawasaki motorcycle engine designers with assistance from other companies within the KHI Group, namely the Gas Turbine & Machinery Company, Aerospace Company, and Corporate Technology Division. Designing the supercharger in-house allowed it to be developed to perfectly match the engine characteristics of the Ninja H2. The highly efficient, motorcycle-specific supercharger was the key to achieving the maximum power and the intense acceleration that engineers wanted to offer.

Planetary Gear

The supercharger is driven by a planetary gear train, which runs off the crankshaft. Designing the gear train using technology from Kawasaki’s Aerospace Company resulted in a very compact unit, with minimal power loss. The gear train increases the impeller speed to 9.2x the crank speed (via a 1.15x step gear and 8x planetary gear). This means that at maximum engine speed (approximately 14,000 min-1), the impeller shaft is spinning at almost 130,000 min-1. Mounted in a thrust bearing structure, the impeller shaft floats on a film of oil.

Impeller

The impeller is formed from a forged aluminium block using a 5-axis CNC machining centre to ensure high precision and high durability. ⌀69 mm in diameter, it features 6 blades at the tip, expanding to 12 blades at the base. Grooves etched into the blade surfaces help direct the airflow. The impeller’s pumping capacity is over 200 litres/second (at atmospheric pressure), with intake air reaching speeds of up to 100 m/s. After passing through the supercharger, air pressure is increased to as much as 2.4 times atmospheric pressure.

Power Unit Designed to Withstand 300 PS Output

The Ninja H2 power unit is loaded with technology developed specifically for this supercharged engine. In order to accommodate the higher air pressure from the supercharger as well as ensure a high reliability with the over 300 PS output of the closed-course Ninja H2R, the whole engine was designed to be able to handle stresses 1.5x to 2x greater than on a naturally aspirated litre-class engine. In fact, aside from its camshafts, head gaskets and clutch, the engine unit is exactly the same as the unit on the Ninja H2R.

Combustion Chamber Design

Combustion chamber design eliminates the squish area. Small engines use the squish to generate turbulence that helps promote more thorough fuel-air mixing. However, for a large high-output engine, preventing engine knock was a more important factor: best performance was obtained with a controlled combustion. The combustion chamber is formed by machining; precise control of the chamber volume also helps prevent engine knock.
Compared to a naturally aspirated litre-bike, the compression ratio is relatively low at 8.5:1—but ideal when combined with the high-pressure air used in the supercharged engine.

Pistons

The combustion chamber design is complemented by a flat piston crown design. Its shape, inspired by the pistons used in the 18-cylinder Green Gas Engine developed by Kawasaki’s Gas Turbine & Machinery Company, also contributes to the engine’s anti-knock performance.

Dog-Ring Transmission

To facilitate smooth, quick shifting, a dog-ring type transmission was selected. This is the kind of transmission commonly found in MotoGP or Formula 1, and was developed with feedback from the Kawasaki Racing Team. Unlike a standard motorcycle transmission in which shift forks slide the gears into position, with a dog-ring transmission the gears all stay in place. Only the dog rings move, sliding into position to engage the desired gear.
A contactless-type quick shifter (a first for a Kawasaki motorcycle) is also fit standard.

Ram Air Intake

Air supplied to the supercharger enters via a single Ram Air intake in the left side of the upper cowl. The total frontal area is approximately 6,500 mm2, about 3x the area of the supercharger entrance.
The Ram Air duct was designed to route fresh air to the supercharger in as straight a line as possible. Its shape was derived to match the impeller characteristics, further contributing to the engine’s high output. For optimum efficiency for the 200 PS engine, the air cleaner is positioned directly before the supercharger.

Aluminium Intake Chamber

The large 6-litre intake chamber is ideally shaped for high efficiency and high engine output. Being constructed of highly rigid aluminium offers two advantages: 1) aluminium offers excellent surface heat dissipation, helping to keep the intake air cool; 2) the rigid structure helps to ensure airtight performance with the supercharged air pressure (approximately 2 atm).
Inside the intake chamber, the top injectors spray fuel onto stainless steel nets positioned over the intake funnels (patent pending). This promotes a more uniform fuel-air mixture, and fuel misting, which helps cool the mixture.

Intake & Exhaust Ports

The intake ports are polished to ensure smooth flow and minimise resistance.
Straight exhaust ports—one for each exhaust valve—do not converge in the cylinder head. The straight-line design enables the most efficient egress of air from the combustion chamber, while contributing to efficient chamber filling.
Cam profiles were optimised for the 200 PS engine and are tuned to offer strong low-speed torque. Compared to naturally aspirated litre-class supersport models, lift is lower (reduced valve spring load allowed mechanical loss to be significantly reduced) and the overlap is narrower.

Exhaust System

Entrance to the header pipes is ovular to match the dual exhaust ports per cylinder. Partly formed by hydroforming, each header pipe tapers from an ovular to a ⌀45 mm round cross-section. The collector pipes are also hydroformed. For the ideal exhaust pressure, all four header pipes are connected.
The exhaust system also includes a compact under-engine pre-chamber, with a double-wall construction for high rigidity. This construction helps reduce radiating noise and exhaust noise.
The right-side single silencer ensures that noise and exhaust gas emissions meet market regulations.

Oil Jets

To keep the engine compact and simple, a single lubrication system provides cooling oil for the engine components, supercharger and transmission. Oil jets lubricate the supercharger chain at the contact points where the chain meets the upper and lower gears. In addition, the supercharger drive train’s lower gear has an oil passage.
Inside the engine, there are two oil jets per cylinder to ensure the hot pistons are effectively cooled.
Transmission oil jets (first use in a Kawasaki motorcycle) enable a compact transmission with high durability.

Bodywork

Compact side cowls and under cowls were designed to assist with heat dissipation. The engine is almost exposed, making it easy for air to escape (so that fresh, cool air can enter). An overall chassis CFD analysis and wind tunnel testing further aided in creating a design that directs air into the radiator and then helps draw heat out of the engine space. The radiator offers superior cooling performance because it flows approximately 1.5x more air than other bikes.

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