feature of the M102 engine introduced in 1980, which together with the crossflow head design promoted greater efficiency over the M115 engine it replaced. MG The MG factory in Abingdon-on-Thames produced a Twin-Cam variant of the pushrod MGA 1600 MkI MG MGA line from 1958 to 1960. The original push rod 1588 cc cast iron block was crowned with a cast aluminum twin cam cylinder head which included one inlet and exhaust valve each, per cylinder. This configuration enabled a cross flow "hemi head" circulation within the combustion chamber, that enabled improved breathing (volumetric efficiency) as well as utilization of enlarged valves and domed pistons. Early versions proved fragile on the street and in competition due to pre-ignition (detonation), and oil loss, which led to decreasing the compression ratio from 9.1. to 8.3 with redesigned pistons. It was a successful update but sales dropped off so rapidly the company halted Twin Cam production and used the matching chassis for some MGAs, with push rod engines, known as the MGA 1600 MkI and MkII DeLuxe models. Mitsubishi Mitsubishi produced several hemi engines including the 'Orion', 'Astron', and 'Saturn' units. Nissan Nissan's Z, VG (SOHC version only) and VQ engines use hemispherical combustion chambers. The Z and VG are true hemispherical while the VQ uses a compound pent-roof shape. Porsche Porsche has made extensive use of hemi-head engines, including the air-cooled flat-6 engine in Porsche 911 models from 1963 to 1999. The 1973 2.7 L version generated 56 hp per naturally aspirated litre of piston displacement. Toyota Toyota Motor Corporation's V family of engines were a longitudinally mounted V8 engine design. They were used from the 1960s through the 1990s. The V family engine was used in the prestigious Toyota Century. Toyota had worked with Yamaha to produce the first Japanese full aluminum alloy block engine. The V Family is often referred to as the Toyota HEMI as the engine features a similar cylinder head design to those found on the Chrysler's Hemi, even though most of the engine design is completely different. The V 2.6L engine was first used in the Crown Eight from 1964 to 1967 as part of the second generation Crown range. Thereafter the Crown Eight was replaced by the upmarket Toyota Century. The 3V, 4V and 5V engines were used in the Toyota Century up until 1997 when it got a complete redesign and gained the 5.0