1G engine series consists of four types of 2-liter, in-line, 6-cylinder gasoline engines for passenger cars, with different performance characteristics to meet diversified market demands. These engines are already put into mass production.The original engine - 1G-EU - is a compact and light weight 2-valve OHC engine with the maximum power 77 kW/5200 rpm. The 1G-GEU is a 4-valve DOHC engine developed on the basis of the 1G-EU engine, with a higher performance and a higher power of 103 kW/6200 rpm. The 1G-GZEU is a mechanical supercharging type engine based on the 1G-GEU, with a remarkably improved performance in the low and medium engine speed ranges, and the highest power of 110 kW/6000 rpm. The 1G-GTEI! is a turbocharging type engine also based on the 1G-GEU, with a markedly improved performance in the medium and high speed ranges, and the high power of 136 kW/6200 rpm.A number of new technologies were introduced on development of these engines. Major technological innovations include Toyota variable induction system, Roots-type supercharging system and twin turbocharging system, which are effective not only for the improvement of performance but also for the enhancement of response. Two mass dampers are also installed at the crankshaft pulley in order to reduce the vibration of crankshaft, and to increase the engine rotation speed capability.