The Toyota Motor Corporation G-family engine is a family of straight-6 piston engines produced from 1979 to 2008. It is notable in that only a single displacement, 1988 cc, was produced in this series. Initially belt-driven OHC non-interference engines (except the VVT-i version which is an interference engine), multivalve DOHC (except the 1G-EU SOHC 12 valve engine) and variable valve timing were added later during the production run. The 1G-GEU was Toyota's first mass produced 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. This engine was designed around the new LASRE technology for lighter weight – such as sintered hollow camshafts. These engines were used as a lower-displacement alternative to the more upmarket M family and JZ family straight-sixes. For ten months (in 1967-1968), Toyota also offered Hino's GR100 engine as the "Toyota G" in the shortlived Briska light truck.

G (Hino GR100)

After Toyota's takeover of Hino Motors in 1967, the Briska one-tonne truck was sold with Toyota badging for ten months. The engine code was changed from Hino's "GR100" to "G" for these cars. The engine is a 1251 cc watercooled OHV inline-four with distant Renault origins and was originally developed by Hino for their Contessa passenger car. Bore and stroke are 71 x, maximum power 63 PS at 5500 rpm. Hino's earlier models had a variety of power outputs ranging from 52 to 65 PS. Apart from its name, this engine is unrelated to the later series of Toyota G engines.

1G

Since just one displacement was offered, all G-family engines are marked 1G and share the same "square" 75 mm bore and stroke. Applications:

1G-E

The export-spec two-valve 1G-E had no emissions controls and were used in commercial vehicles and for a few export markets, mostly southeast Asia. Typical specifications:

1G-EU

The Japan-spec 1G-EU was produced from 1979 through 1988. This and the 1G-E are the only two-valve SOHC members of the family. Output was 105-125 hp at 5400 rpm and 157-172 Nm at 4400 rpm.

1G-FE

The DOHC 1G-FE uses a narrow valve angle and other fuel economy optimizations. It was introduced in 1988, it features a cast iron block with aluminum cylinder head and uses the slave cam system. Output was 135 PS at 5,600 rpm and 176 Nm at 4,400 rpm. In 1998 VVT-i was added, which bumped output to 160 PS at 6,200 rpm and 200 Nm at 4,400 rpm for the Altezza/IS 200. Production of this engine family ceased in 2008 after the discontinuation of the Crown Sedan mild hybrid. Applications:

1G-GEU

The 24-valve DOHC 1G-GEU was intended for high performance and featured a pent-roof combustion chamber. Introduced in August 1982 and produced through 1986, mostly for the Japanese market, it 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. Output was 140-160 PS at 6,200 rpm and 162-181 Nm at 5,600 rpm. 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. Applications:

1G-GE

The 1G-GE replaced the 1G-GEU in 1988. It was detuned from 160 PS to 150 PS and served the same cars as 1G-GEU did. Torque was 18.6 kgm at 5600 rpm. It was produced for the Supra GA70 until 1993.

1G-GTE

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 PS at 6200 rpm and 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 the 280 PS 1JZ-GTE on most Toyota cars. Applications:

1G-GP/GPE

The 1G-GP and 1G-GPE was an LPG version of the 1G-GE engine. Output is 110 PS at 5600 rpm and torque is 15.5 kgm at 2400 rpm. Applications:

1G-GZE

The 1G-GZE was a supercharged version produced from 1986 until 1992. Output is 170 PS at 6,000 rpm and 226 Nm at 3,600 rpm. Like the turbo, it was a 24-valve DOHC 6-cylinder engine but featured a distributorless ignition system (DIS). The 1G-GZE was mated only with automatic gearboxes. In August 1991 it was replaced with the 1JZ-GE on the Mark II/Chaser/Cresta, while serving on the Crown until 1992. Applications: