Toyota 1GR: Everything You Need To Know

Toyota introduced its GR generation in 2002 as a designated replacement for the previous 3.4 L 5VZ-FE Engines. And the family was represented by none other than the 1GR or commonly known as 1GR-FE. 1GR-FE is a member of the GR Family along with the 3.5 L 2GR, 3.0 L 3GR, 2.5L 4GR, and specially designed engines 5GR-FE, 4.0 L 6GR, 3.5 L 7GR for the Chinese market.

1GR-FE is a 4.0 L, water-cooled naturally aspirated engine produced since 2002 and first became available in Australia in the Toyota 120 Series LandCruiser Prado, but eventually installed in the Toyota MK7 Hilux; this engine is a successful hit, especially for the Toyota off-roads. The early version of the 1GR-FE comprises a heavy crankshaft, heavy pistons, and a single VVT-i system on the intake camshafts. In 2009, newly modified 1GRs equipped with a dual VVT-i variable valve timing system on the intake and exhaust were introduced to replace the initial launch of the 1GR. In addition, Toyota improved its cylinder head, lighter pistons, lower compression ratio, updated cooling system, and modified intake ports and cylinder sleeves.

And with that, we will take a detailed discussion regarding the 1GR engine.

Engine Specifications and Design:

  • Production Run: 2002 – Present
  • Cylinder Block Material: Aluminum
  • Cylinder Head Material: Aluminum
  • Configuration: V6
  • Bore: 94 mm
  • Stroke: 95 mm
  • Valvetrain: DOHC 4 Valves per Cylinder
  • Displacement: 4.0 L (3,956 cc)
  • Compression Ratio: 10 and 10.4 (Dual VVTi)
  • Weight: 336 lbs.
  • Max HP: 285 HP at 5,600 RPM (Dual VVT-i)
  • Max Torque: 289 lb-ft at 4,400 RPM

Toyota 1GR engine’s design is made for longitudinal mounting in Rear Wheel Drive and Four- Wheel Drive pickup applications. It has six cylinders enclosed in a colossal Aluminum 60-degree V-arrangement block with cast-iron sleeves. It has a bore and stroke of 94 mm x m5 mm, respectively, resulting in a 3956 cc capacity. The output is produced initially rated as 236 HP at 5,200 RPM, with 266 lb-ft of torque at 4,400 RPM when it is tuned for 87-octane, and 240 HP at 5,200 RPM with 278 lb-ft of torque 3,700 RPM when tuned for 91-octane. This engine is equipped with Toyota’s VVT-i, variable valve timing technology on the intake side, and has a compression ratio of 10.

Toyota released an updated version of the 1GR engine that features Dual VVT-i, which is integrating the variable timing technology both on the intake and exhaust, which increased the output to 270 HP at 5,600 RPM and 278 lb-ft of torque at 4,400 RPM on 87 octane.

Inside the block, the 1GR engine features spiny type cylinder liners made from a cast-iron cast into the block; this atypical surface improves the adhesion between the Aluminum cylinder block and the liners, resulting in better heat dissipation and reduced heat deformation of the cylinder bores. So, in the event of cylinder wall damage, the overall cylinder block must be replaced. This engine has Aluminum alloy pistons along with a taper-squish combustion chamber design to improve the intake and fuel efficiency while also improving the engine’s performance and anti-knocking properties. It adopted a siamese-type intake port to prevent fuel from abiding by those walls due to the port wall’s reduced surface area; dual VVT-i engines have a higher compression ratio due to an optimized piston shape.

The 1GR is also equipped with a high-temperature plastic insulator that significantly increases the rigidity of the block. This protection fills the empty space between the block materials and the outer portion of the cylinders, which is common to open deck engines. In addition, there are two passages for each bank that sums into four. This keeps the combustion chamber temperatures more uniform and reduces cylinder hot-spotting. Added to that, jacket spacers are added to the water jacket that draws coolant above the cylinder bore and prevents the water flow in the middle and under the water jacket for more uniform temperature distribution. That results in lower oil viscosity and reducing friction between bore walls and pistons.

Its crankshaft is forged steel with four journals and nine balance weights for the VVT-i; five balance weight crankshafts for dual VVT-i engine and were optimally placed to reduce vibration and noise. 1GR uses forged high-strength steel connecting rods and caps with Aluminum bearings; used nutless-type plastic region tightening bolts; and to reduce friction, the piston skirt is coated with resin. The top piston ring groove is coated with anodic oxide to enhance rust and wear resistance. Oil-cooling jets were installed under the pistons to minimize heat accumulation in the piston.

1GR cylinder heads are made from Aluminum with steel laminate-type head gaskets; double overhead cast-iron camshafts with four valves per cylinder. Toyota added a shim about the cylinder bore to increase the sealing surface for improved durability. In addition, dual VVT-i engines used roller rocker arms with built-in needle bearings to reduce the friction between the roller rocker arms and camshafts.

Initial 1GR engine variants with single VVT-i features Toyota’s Acoustic Control Induction System. This system is made of a bulkhead that bisects the intake manifold into two sections and an intake air control valve to control the length of effectivity. When the engine operates at mid-level RPM conditions under high load, an actuator closes the intake air control valve to enhance the effective length of the intake manifold; other operating conditions open up the intake air control valve to reduce the effective length of the intake manifold.

Applications of 1GR with VVT-i 

  • 2002 – 2009 Toyota 4Runner/ Hilux Surf
  • 2007 – 2011 Toyota Land Cruiser
  • 2002 – 2009 Toyota Land Cruiser Prado
  • 2004 – 2015 Toyota Tacoma
  • 2005 – 2006 Toyota Tundra
  • 2005 – 2015 Toyota Fortuner
  • 2006 – 2009 Toyota FJ Cruiser
  • 2009 – Present Toyota Land Cruiser 70
  • 2015 – Present Toyota Hilux

With Dual VVT-i

  • 2009 -Present Toyota 4Runner
  • 2009 – 2017 Toyota FJ Cruiser
  • 2011 – 2014 Toyota Tundra
  • 2012 – Present Toyota Land Cruiser
  • 2012 – Present Lexus GX 400
  • 2015 – Present Toyota Fortuner
  • 2009 – Present Toyota Land Cruiser Prado

Engine Tuning, Upgrades, and Modifications

Like the other carmakers, Toyota has their in-house line of performance kits, and for them, it is called TRD or Toyota Racing Development.

I mentioned the TRD company because they are the ones that make supercharger kits, intercoolers, ECU, and other aftermarket parts for GR engines; these aftermarkets are designed out of the Eaton M90.

So, to install a supercharger for your 1GR engine, take note that you need a lower compression ratio. To attain that, you need to buy forged pistons, Carillo connecting rods, and a thicker cylinder head gasket. You will also need a TRD intake system and a 3-1 design headers kit. Install these performance parts on the single VVT-i, and it can develop 320 HP and 370 lb-ft of torque; some head porting and polish can be pushed to 350 HP.

Common Problems

Here we will discuss some common issues for the 1GR-FE or simply 1GR engine. Of course, this is not occurring at all machines, for there is only a tiny percentage that affects these problems; however, this is still useful to give you some heads-up.

First is the occurrence of overheat since there are reports that the first 1GR-FE motors suffered from blown head gaskets; the head gasket conceals the engine block and cylinder heads. If gaskets are faulty, seals for the cylinders and oil, coolant leaks might be affected by this. Misfires, coolant loss, and white smoke coming from the exhaust are some things that might indicate this issue. Many 1GR original head gaskets last around 250,000 miles.

Next is Water Pump Problems. This is like the prelude of the head gasket problem; the lack of coolant flow can, indeed, lead to overheating and escalating to head gasket problems. Water pumps are vital parts of the engine as they provide the cooling process of the engine. With that, they are highly subjected to wear and tear with years of use and improper maintenance. You might need to replace the water pump if you can see coolant stains or actual coolant leaks near the drain holes. This might appear at around 150,000 miles.

Another issue is the ignition coil. Premature ignition coil failures do happen, and gladly, they don’t happen that much. But this component is also a victim of the standard wear and tear, which means replacements are common. However, some ignition coils last a lifetime. Some indicators that the ignition coil is failing are rough idling, loss of power, stuttered acceleration, and misfirings.

There is also a ticking noise for the 1GR engine but don’t worry, that is absolutely normal as it only emphasizes that the gasoline steam ventilation system is functional; that noise also accompanies injectors operation.

Summary

1GR engines are highly reliable engines and durable too. We cannot question its longevity as it still remains in production today – even having a few minor updates from time to time. Yes, for sure, this engine is quite underwhelming for a modern engine for such a large engine displacement, but that comes with a benefit we mentioned above. Though it has some issues such as head gasket problems and weak water pumps, thin cylinder walls make it impossible to bore the block; and are not suitable for a work truck or a big SUV. However, this engine can last a lifetime with proper maintenance, high-quality engine oil, and fuel.

I hope that this discussion helped you to understand 1GR or 1GR-FE engines more. Its engine design, power output, problems and issues, tuning, and overall impact on the community and the automotive industry.

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