 While today some engines rely on a single camshaft per cylinder bank, which is known as a "single overhead camshaft" (SOHC), most modern engines are driven by a two camshafts per cylinder bank arrangement (one camshaft for the intake valves and another for the exhaust valves); such camshaft arrangement is known as a "double" or "dual overhead cam" (DOHC), thus, a V engine, which has two separate cylinder banks, may have four camshafts (colloquially known as a "quad-cam engine").More unusual is the "modern" W engine (also known as a 'VV' engine to distinguish itself from the pre-war W engines) that has "four" cylinder banks arranged in a "W" pattern with two pairs narrowly arranged with a 15-degree separation.Even when there are four cylinder banks (that would normally require a total of eight individual camshafts), the narrow-angle design allows the use of just four camshafts in total.