k-series engine

The Honda K series
engine is a four-cylinder four-stroke engine. The K series engines are equipped with DOHC valvetrains and use roller rockers to reduce friction. The engines use a coil-on-plug, distributorless ignition system with a coil for each spark plug. This system eliminates the need for spark plug wires and distributor as well as the problems associated with them. It also allows the ECU to precisely control the ignition timing based on various sensor inputs. The cylinders have cast iron sleeves similar to the B-series engines, as opposed to the FRM cylinders found in the H-series.

Two versions of Honda's i-VTEC system can be found on K series engines; variable timing control (VTC) can be found on the intake cam of both versions. The VTEC system on engines like the K20A3 only operate on the intake cam; at low RPM only one intake valve is fully opened, the other opening just slightly to create a swirl effect in the combustion chamber for improved fuel atomization. At high RPM, both intake valves open fully to improve engine breathing. In engines such as the K20A2 found in the Acura RSX Type-S, the VTEC system operates on both the intake and exhaust valves, allowing both to benefit from multiple cam profiles.