The Toyota Motor Corporation G-family engine is a family of straight-6 piston engines produced from 1979 to 2006. It is notable in that only a single displacement, 2.0 L (1,988 cc), was produced in this series. All were belt-driven OHC non-interference engines (except the VVT-i version in the IS200 which is an interference engine), with multivalve DOHC (except the 1G-EU SOHC 12 valve engine) and even variable valve timing added later. The 1G-GEU was Toyota's first four-valve twincam engine. A prototype version of the 1G-GEU called the LASREα–X, featuring twin turbos, variable valve timing and intake as well as variable displacement, was fitted to the Toyota FX-1 show car at the 1983 Tokyo Motor Show. It showcased a number of technologies which were later to become commonplace.
These engines were used as a lower-displacement alternative to the more upmarket M family and JZ family straight-sixes.
Since just one displacement was offered, all G-family engines are marked 1G and share the same "square" 75 mm (2.95 in) bore and stroke.
Toyota Celica Supra
The Japan-spec 1G-EU was produced from 1979 through 1988. This is the only two-valve SOHC member of the family. Output was 105-125 hp (78-93 kW) at 5,400 rpm and 116–127 lb·ft (157-172 Nm) at 4,400 rpm.
The DOHC 1G-FE uses a narrow valve angle and other fuel economy optimizations. It was introduced in 1988. Output was 135 hp (101 kW) at 5,600 rpm and 130 lb·ft (176 Nm) at 4,400 rpm. In 1998 VVT-i was added, which bumped output to 160 hp (119 kW) at 6,200 rpm and 148 lb·ft (200 Nm) at 4,400 rpm for the Altezza/IS 200. With the end of the first generation Lexus IS this engine ceased production in 2005.
Toyota Altezza/Lexus IS 200
Toyota Mark II
The 24-valve DOHC 1G-GEU was intended for high performance and featured a pentroof combustion chamber.Introduced in August 1982 and produced through 1986, mostly for the Japanese market, output was 140-160 hp (104-119 kW) at 6,200 rpm and 120–134 lb·ft (162-181 Nm) at 5,600 rpm. This was Toyota's first multi-valve twincam engine to make it to the market, and won the "JSME Medal for New Technology" (Japan Society of Mechanical Engineers) in 1982. To minimize the downsides of a multi-valve setup, the 1G-GEU was also equipped with T-VIS (Toyota Variable Induction System), increasing low to mid-engine speed torque. Like all following twin cam Toyotas, it used a timing belt rather than chain, for less noise and lower maintenance requirements. In August 1983, the fuel injection system was changed to EFI-D, which measures the pressure in the intake manifold to determine the proper air-fuel mixture.
Aug 1981–1985 Celica XX GA61
Aug 1982–? Toyota Chaser/Mark II/Cresta
Aug 1983–? Toyota Crown
Feb 1983–? Toyota Soarer
The 1G-GE replaced the 1G-GEU in 1988. It was detuned from 160 hp down to 150 hp and served the same cars as 1G-GEU did. It was produced for the Supra GA70 until 1993.
The 24-valve DOHC 1G-GTE added two CT-12 turbochargers to the versatile motor. There were 3 generations of this engine both air-to-air and air-to-water intercoolers were used, pushing output from 185 to 210 hp (138 to 157 kW) at 6200 rpm and 173 to 203 lb·ft (234 to 275 Nm) at 3800 rpm using the air-to-air over the air-to-water. This was the most powerful engine of the whole G family. In May 1991 it was replaced with >280 hp 1JZ-GE on most Toyota cars. Spinning a bearing is a high risk in these engines if maintenance such as regular oil changes are not done due to oil starving in this engine.
1986–1992 Supra MK3 (chassis code GA70, JDM only)
1988–1992 Mark II/Chaser/Cresta (chassis code GX81)
1986–1991 Soarer (chassis code GZ20)
The 1G-GPE was an LPG version of the 1G-GE engine. Output is 81 kW (110 PS) at 5600 rpm and torque is 152 N·m (15.5 kg·m) at 2400 rpm.
Toyota Crown Comfort
The 1G-GZE was a supercharged version produced from 1986 till 1992. Output was 168 hp (125 kW) at 6000 rpm and 167 lb·ft (226 Nm) at 3600 rpm. Like the turbo, it was a 24-valve DOHC engine but featured a distributorless ignition system (DIS). 1G-GZE was mated only with automatic gearboxes. In August 1991 it was replaced with 1JZ-GE on the Mark II/Chaser/Cresta, while serving on the Crown until 1992.