Toyota 1G: Everything You Need To Know

Before 2JZ engines, there were 1JZ engines, and before 1JZ, there were 1G engines. And yes, that is true that the 1G engine is the Vito Corleone of the JZ engine or simply the Godfather of those engines. In the 1980s, these engines are the crazes, and Toyota has the automotive duel with Nissan, and there’s no doubt that due to that, we have the modern engines today.

1G engines only offered a single displacement capacity of 2.0 L. 1G-GE is Toyota and Yamaha’s first engine collaboration and Japan’s first twin-turbo production engine; the GTE being the first twin-cam twin-turbo production engine.

The Toyota 1G engine has several modifications, and each modification varies on the integrated technology and updates; these serialized engines somehow created 1G variants that we used and continue to use up until today even its production halt in 2005, namely: 1G, 1G-EU, 1G-FE, 1G-GEU, 1G-GE, 1G-GTE, and 1G-GZE.

So today, we will talk about the 1G engine’s design, power, applications, issues, problems, aftermarket support, maintenance, and overall impact on the industry and community.

Engine Specifications and Design:

  • Production Run: 1988 – 2005
  • Cylinder Head Material: Aluminum
  • Cylinder Block Material: Cast-iron
  • Configuration: Straight-six
  • Bore: 75 mm
  • Stroke: 75 mm
  • Valvetrain: SOHC with two valves per cylinder and DOHC with four valves per cylinder
  • Displacement: 2.0 L (1988 cc)
  • Compression Ratio: 8.8 (1G), 9.2 (1G-GEU), 8.5 (1G-GTE), 8 (1G-GZE), 9.6 (1G-FE), and 9.5 (1G-GE)
  • Weight: 400 lbs.
  • Max HP: 210 HP at 6,200 RPM (1G-GTE)
  • Max Torque: 206 lb-ft at 3,800 RPM

Toyota 1G engine is a fixed 2.0 L naturally-aspirated, straight-six petrol engine from the G-family by Toyota. Toyota 1G engines boast features that are ahead of their time during its initial release. Some of the 1G engine characteristics are Aluminum cylinder heads with four valves per cylinder, cast-iron cylinder blocks, and a single overhead camshaft but was later upgraded to dual overhead camshafts driven by a belt. In addition, engines were equipped with the EFI technology or the Electronic Fuel Injection and VVT-i later on.

The cylinder block of the 1G engine has a bore of 75 mm to square it with the 75 mm stroke. It is made from cast iron with a monoblock specially cast structure that utilizes the seven-bearing support system; the crankshaft has seven journals. The pistons are made from cast Aluminum and are paired with two compression rings and a single oil ring.

All of the Toyota engines carry the same bore and stroke, displacement, and a 1G mark.

Applications of the 1G Engine:

  • Toyota Soarer
  • Toyota Celica Supra
  • Toyota Crown
  • Toyota Cressida/Mark II/Cresta/Chaser
  • Toyota Altezza
  • Lexus IS200

The initial version of the 1G engine with a SOHC cylinder head is the Japan spec 1G-EU which was produced in 1979 – 1988. This engine and the 1G-E are the only two-valve SOHC member of the 1G. It has 125 HP at 5,400 RPM and 127 lb-ft of torque at 4,400 RPM. However, the 1G-E engine is the export spec two-valve engine, delivered in Southeast Asian markets. 1G-Es has no emission controls and are most common in commercial vehicles. Therefore, 1G-E has a lower power output of 107 HP at 5,000 RPM and 119 lb-ft of torque.

In 1988 Toyota introduced the 1G-FE engine optimized for a better fuel economy and a narrow valve angle. As we mentioned earlier, it has a cast-iron block and an Aluminum cylinder head. This engine produces 133 HP at 5,600 RPM and 130 lb-ft of torque at 4,400 RPM. Later on, in 1998, ten years after its launch, Toyota integrated the VVT-i system, which ramps up the power output to 158 HP at 6,2000 RPM and 148 lb-ft of torque at 4,400 RPM for the IS 200 and Toyota Altezza.

Applications of the 1G-FE Engine:

  • Toyota Crown
  • Toyota Chaser
  • Toyota Mark II
  • Toyota Mark II Blit
  • Toyota Cresta
  • Toyota Altezza
  • Lexus IS200

1G family will not be complete without the performance variants gracing under the hood. And in the early 1980s, August 1982 to be exact, Toyota introduced, in the Japanese market, the high-performance 24-valve Double Overhead camshaft 1G-GEU engine. This engine featured a pent-roof combustion chamber which allows a faster burning time of the air-fuel mixture. This is Toyota’s first-ever multi-valve twin-cam machine to hit the market and even won JSME’s Medal for New Technology in 1982. It is equipped with T-VIS (Toyota Variable Induction System) that increases the speed-torque from low to mid-range engine speeds. For the succeeding Toyota twin cams, Toyota used a timing belt instead of a chain to lessen the noise and lower maintenance requirements. After one year, in August 1983, EFI-D replaced the fuel injection system to determine the appropriate air-fuel mixture by measuring the intake manifold’s pressure. This engine produces 158 HP at 6,200 RPM and 133 lb-ft of torque at 5,600 RPM.

1G-GE replaced the 1G-GEU engine in 1988 with a lower power output of 150 HP and placed to the cars same as 1G-GEU. It was created for Supra GA70 up until 1993.

Applications of the 1G-GEU Engine:

  • 1981 – 1985 Celica X GA61
  • 1982 Toyota Chaser/Cresta/Mark II
  • 1983 Toyota Crown
  • 1983 Toyota Soarer

The most powerful engine in the G family is the 1G-GTE which is introduced in 1986. This engine is a 24 valve DOHC with two CT-12 turbochargers to top it off. There are three generations of this engine that used both air-to-water and an air-to-air intercooler. It also has a varying power output ranging from 182 to 207 HP at 6,200 RPM and 173 to 203 lb-ft of torque at 3,800 RPM by using the air-to-air over the air-to-water. In May 1991, 1JZ-GTE replaced the 1G-GTE on most Toyota cars.

Applications of the 1G-GTE Engine:

  • 1986 – 1992 Supra MK3
  • 1986 – 1992 Mark II/Cresta/Chaser
  • 1986 – 1991 Soarer

A supercharged version was also released under the 1G-GZE name. This version is a 24-valve DOHC produced from 1986 to 1991 and carried most of the characteristics of the 1G-GTE engine. It features a distributor-less ignition system (DIS) and is only paired with automatic gearboxes. In August 1991, 1JZ-GE replaced the 1G-GZE on the Mark II, Chaser, and Cresta and serving up until 1992 in Toyota Crown.

Engine Tuning, Upgrades, and Modifications:

Upgrading 1G engines is not practical most of the time because that is where 2JZ-GTEs were created for; a more powerful 1G engine. However, if you opt to do some upgrades, consider putting some upgraded parts for the 1G-GTE, if you have a 1G-GTE block, and buy some performance parts such as a front intercooler, boost controller, blow-off valve, cat-back exhaust system, Walbro fuel pump, and an ECU. Maximum boost pressure will increase up to 15-17 psi and get 300 horsepower on a stock turbo and stock pistons. However, you need to change the stock internals or turbo for better results because internals and turbo of this kind do not produce more power, so you may buy a single turbo kit like Garrett GT28 or GT3, head gaskets, forged pistons, and do some head porting.

Problems Surrounding 1G Engine:

As much as we wanted to keep the pristine conditions of our cared engines, we cannot escape the truth behind all of them that there will come a time some issues or problems might occur due to years of usage or unplanned troubles. Coming from decades ago engine production, this engine definitely has its problems sorted out through the owner’s experience. This is just a precautionary list for you to be ready if ever you opt to buy this engine:

The first is excessive oil consumption; excessive oil consumption corresponds to loose piston rings and valve stem seals. This is due to the age of the engine. These issues can be easily resolved by replacing the old piston rings and valve stem seals.

Excessive oil consumption might also be a direct result of oil leakage, and oil leak is a common problem for the 1G engines. This immediate issue must be resolved because, if neglected, it can result in a far worse engine situation, as the engine overheats due to improper lubrication inside the engine. This problem is also the main driver of engine failure. You might need to change the oil pressure sensor for this and check where the leak is coming from. Don’t forget always to check the oil pressure, but if the sensor is not functional, replace it.

Next is the rough idling. Rough idling happens when fuel is burned at an inconsistent rate, and you can notice it while running if it becomes worse. This is caused by faulty or wrongly installed spark plugs and wires. Try checking those and check the throttle valve, idle control valve, and throttle position sensor, which might need some cleaning.


1G engines are one of the most iconic engines, especially in the competitive 80s era of machines. This was when most of the grandfathers of our modern engine originated from; if they are not for them, this engine will not be here with us. So with this technology and pioneer innovations that Toyota made, they have given us a reliable and continues to do so with the 1G line of the family. It is the first twin-cam and twin-turbo engine in the 80s. Though it has some problems and issues, it can withstand 200,00 miles with proper maintenance and care.

I hope you understand the 1G engine with this simple guide and helped you to understand the 1G engine’s engine design, power, torque, applications, aftermarket support, and overall impact in the automotive industry.

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