Toyota GR engines have many versions under their belt, and one of those is the 2.5 L 4GR-FSE engine, an engine that complements the 3GR but of a smaller capacity. It was produced in 2003 to replace the famous and legendary 1JZ-GE engine.
This 4GR-FSE engine features a single-point direct injection technology that, in contrast to the lowest priced rear-wheel-drive models in the lineup from Toyota and Lexus makers, has a dual injector system. The other engine types are the: 3.5 L V6 engine 2GR-FSE, 2.0 L inline-four-cylinder turbo, and 2.5 L inline-four hybrid engine.
So today, we will talk about the Toyota 4GR-FSE engine. Its engine design, power, torque, capabilities, features, and overall impact on the automotive industry and community.
Engine Specifications and Design
- Production Run: 2003 – Present
- Cylinder Head Material: Aluminum
- Cylinder Block Material: Aluminum
- Configuration: V6
- Bore: 83 mm
- Stroke: 77 mm
- Valvetrain: DOHC 4 Valves Per Cylinder
- Displacement: 2.5 L (2499 cc)
- Compression Ratio: 12.0
- Weight: 397 lbs.
- Max HP: 215 HP at 6,400 RPM
- Max Torque: 192 lb-ft at 3,800 RPM
Toyota 4GR or the 4GR-FE is a 2.5 L V6 naturally-aspirated gasoline engine designed and developed for rear-wheel-drive primarily luxury cars such as the Toyota Crown, Lexus IS, Lexus GS, and Mark X models; as well as Lexus vehicles with an index of 250, as well as for some other Toyota cars.
This engine is similar to 3GR-FE with a smaller displacement but higher compression ratio and some mechanical revision.
The engine block of the 4GR-FE is made from cast Aluminum alloy and gave the nod to 3GR’s 60-degree V angle on the cylinder banks, as well as integrating the spiny type cast-iron cylinder liners.
This external casting has atypical surfaces to enhance further the adhesion between the Aluminum cylinder block and the liners. It is inserted with resin water jacket spacer in the water jacket to cool the temperature down on top of the cylinders efficiently, prevent bore deformation, and reduce friction.
A long skirt extends down to the bearing cap mounting surface of the cylinder block to keep the crankshaft in place that helps reduce excessive vibrations and silent operation.
4GR-FSE has a forged steel crankshaft, with a 77 mm-long stoke, the reduced bore diameter of 88 mm for a 2,500 cc capacity; to go with hyper eutectic alloy pistons for tighter skirt clearances and sintered forged steel connecting rods.
The firing order for the 4GR-FSE engine is 1-2-3-4-5-6.
The piston design is carefully detailed by having different specific shapes for both the left and right banks and having intake ports in the V banks inside of it that have two intake air passages in each cylinder.
The pistons have a shallow cavity in the center for homogenous combustion of the air-fuel mix in both stratification combustion during cold starts and normal conditions.
Integrating it with a product like hyper eutectic pistons, other than adding strength, also improves the resistance to seizures and scuffs, which are mainly operated under cooler temperatures.
Toyota 4GR-FSE cylinder heads are identical with the 3GR-FSE in which the two heads were divided at the cam journals.
Both are DOHC heads equipped with variable valve timing systems (Dual VVT-i) on the intake and exhaust camshafts; the intake system uses variable-length intake manifold ACIS (Acoustic Control Induction System).
ACIS controls the length of the intake valves depending on the driving conditions and RPM range. 4GR uses the same camshafts as 3GR, which are made of alloyed cast-iron and have induction hardened cams.
It uses a two-stage chain system comprised of a primary chain that allows the crankshaft to drive both the right and left intake camshafts and a secondary chain that helps the intake camshafts to move the exhaust camshafts. Both the timing chains were made of high-strength single-row roller chains and compact sprockets.
The 4GR-FSE engine has a pent-roof combustion chamber, and holes are drilled and positioned in the chamber’s center for three-prong iridium ignition valves.
There are also holes situated along with the peripherals of the combustion chamber on the intake port side used for mounting fuel injectors that inject fuel directly into the combustion chamber.
Fuel injectors are mounted and directed on top of the cylinder head, synchronized with the piston position. The fuel from the tank pump is sent to the high-pressure pump, then to the under pressure into the fuel rail, and eventually into the cylinder by injectors.
The shape of the intake ports is also essential as it promotes the propagation of reverse swirls in the cylinder.
Fuel pressure sensors are installed in the Fuel rail to provide feedback and a mechanical pressure valve. Fuel rails are made of Aluminum alloy. In addition to the platinum electrode contact, Toyota added iridium spark plugs with two side electrodes.
Stratified combustion mode is when the injection comes at the end of the compression stroke, which is common during cold starts to accelerate catalyst warm-up. The fuel, which is actively dispersed and vaporized, is reflected from the recess of the piston heading straight to the spark plugs.
Even though the mixture in the whole cylinder is lean, however, the mixture is rich enough to be re-ignited by spark and fire the remaining mixture volume in the spark plug area.
A lean mixture in the remaining volume has a lesser penchant for detonation, which allows increasing the compression ratio and an increase in the engine power output. This is due to the evaporation of injected fuel-air charge in the cylinder, and it is cooled further to reduce the possibility of engine knocking.
Applications of the 4GR-FSE Engine:
- 2003 Toyota Crown Royal and Athlete (GRS180/181 for Japan)
- 2004 Toyota Mark X (GRX120/125 for Japan)
- 2005 – 2013 Lexus IS 250 (GSE20/25)
- 2008 Toyota Crown Royal and Athlete (GRS200/201 for Japan)
- 2009 – 2015 Lexus IS 250C (GSE20)
- 2012 – 2015 Lexus GS 250
- 2012 – 2018 Toyota Crown Royal for Japan
- 2013 – 2015 Lexus IS 250
Engine Tuning, Upgrades, and Modifications
With much consideration, always keep in mind that 4GR engine design is not meant to run fast and powerful, especially for performance-based kind of builds, but it is primarily made for leisure driving.
But if you want to increase the power of the 4GR-FSE engine, one good process is to buy a supercharger kit that the ARMA Company manufactures. You can install this kit on the stock internals, and you have a maximum boost pressure at seven psi. As a result, you can get around 310 HP and 280 lb-ft of torque.
Problems Surrounding 4GR-FSE Engine
4GR-FSE engine origins are much like the 3GRs, so they share most of the issues and problems. Therefore, this is not a comprehensive list of engine issues but more of a preventive caution for you to watch if you experience or own a 4GR-FSE engine.
The first and the most known problem is the oil leak. An oil leak in the 4GR engine is due to the breakage of the rubber section of the oil tube in the VVT-i lubrication system.
This breakage is the leading cause of a rapid oil loss in the engine; oil starvation may lead to severe engine damage – camshaft beds and crankshaft bearings. However, oil loss can only be determined when the oil pressure warning indicator lights up.
This issue so big and endangering to the vehicles, Toyota announced a recall service campaign.
Another common and the weakest point problem of the 4GR engine is the water pump leaks and noise. This consumable has a service of around 30,000 miles.
Water pumps are vital for engine operation as it provides the coolant circulation and problems such as this restrict the proper coolant flow that will create a ripple that results in overheating. Again, normal wear and tear is the primary suspect of this.
Another problem to consider is the noise that comes from the engine. This issue might be due to an idler pulley. You can hear an annoying squeaking sound from the engine bay.
Last is the Water Pump Failure. 4GR’s weak point is also on this department, and as a member of the same family, this issue might also haunt other GR engines. This issue is detrimental to the engine, considering that it involves coolant circulation.
This happens due to the normal wear and tear of the water pump commonly occurring in unpredictable times, as it can happen anytime. Well, if the pump fails, it should have been taken care of imminently to avoid overheating due to lack of coolant flow.
4GR-FSE direct injection engine has been innovated to pair with the dynamic performance, fuel economy, and smooth operation. It is fitted with a dual VVT-i that is equipped with variable valve control technology in both intake and exhaust valves and is also fitted with a dual main muffler.
Toyota 4GR-FSE engine is designed to capture comfort and leisure in one machine. It has a 2.5 L displacement which is powerful enough for everyday driving. But don’t be so assertive in bringing in more power in this machine as it is not designed for such purposes.
However, this engine has a good fuel economy, and apart from excellent combustion, the technology is at par with its competitors. Overall, it’s a solid engine for a lightweight one.
However, some minor issues and the problem cannot detest the reputation of this engine.
I hope this simple guide can help you understand 4GR-FSE engines more by discussing a detailed rundown above.