Toyota made the last engine in the GR family lineup to power their Lexus vehicles. These engines are the collective effort of the previous models before it; they combined some elements and features from those early versions and integrated them here. And that engine is the Toyota 8GR. So, today, let’s talk about the engine’s design, issues, applications, aftermarket support, issues, reliability, and many more.
The Toyota 8GR engine is modeled on the latest release of the 2GR-FSE engine. It has two versions, the 8GR-FKS and 8GR-FXS, 8GR-FKS being the basic model of the 8GR. The key features of its inspiration model 2GR-FKS were kept and integrated into the 8GR engine. Toyota 8GR engine is the analog of the 2GR-FKS engine.
Like the 2GR-FKS engine, 8GR engines received Toyota’s latest advanced technology in that period which includes the reversibility from the Otto cycle to Atkinson cycle for a better fuel economy. That kind of improvement is shared on both the 2GR-FKS and 8GR using the VVT-iW (Variable Valve Timing – Intelligent Wide) on the intake camshaft. At the same time, the exhaust camshaft also uses variable valve timing (VVT-i). 8GR engines are equipped with Distributorless Direct Ignition System (DIS) coil-on-plug ignition system, Electronic Throttle Control System (ETCS-i), and Acoustic Control Induction System.
Like the 2GR-FKS engine, 8GR machines have a combined port fuel injection (Toyota’s D-4S) and direct injection, which works simultaneously. The exhaust manifold is already integrated into the cylinder heads, and the exhaust gas valve (EGR) circuit is cooled.
Engine Specifications and Design:
- Production Run: 2017 – Present
- Cylinder Head Material: Aluminum
- Cylinder Block Material: Aluminum
- Configuration: V6
- Bore: 94 mm
- Stroke: 83 mm
- Valvetrain: DOHC with four valves per cylinder
- Displacement: 3.5 L (3456 cc)
- Compression Ratio: 11.8
- Weight: 370 lbs.
- Max HP: 311 HP at 6,600 RPM
- Max Torque: 280 lb-ft at 4,800 RPM
Modeled from 2GR-FKS, 8GR engines are designed for longitudinal layout and have an open-deck type cast-Aluminum alloy cylinder block; it has spiny cast-iron cylinder liners cast into the block material. These uneven surfaces increase the adhesion between the Aluminum cylinder block and the cylinder liners. The engine cylinder banks have a 60-degree angle inclination in V arrangement.
There are inclined coolant channels drilled in between the cylinders. Spacers in the water jackets are also installed along with the mentioned channels to allow a more intensive coolant circulation near the cylinder top, which improves a more uniform thermal load and improves heat dissipation.
The 8GR has a bore of 94 mm and a stroke of 83 mm. Its crankshaft is made from forged steel supported by four journals and five balance weights held by individual main bearing caps. 8GR’s connecting rods are forged that used Aluminum bearings, whereas the bearings for the crankshaft are also made from Aluminum, like the bearings in the connecting rod.
The cylinder wall lining surface is micro-grooved for the optimum distance designated for the oil clearance, which reduces the engine vibration and significantly improving the cold-engine cranking performance. The engine’s connecting rods and caps were made from high-strength steel and nutless-type tightening bolts to reduce weight.
The 8GR engine has compact T-shaped Aluminum pistons that feature polymer-coated skirts to reduce friction; Alumite coating for the top piston ring to enhance wear resistance; and they are connected to the connecting rods with fully floating pins.
The piston walls are sloped, which distributes the load to the piston pin at the expansion stroke. Piston crowns, like the 2GR-FKS, have a tapered-squish design to reduce engine knocking and improve the engine’s thermal efficiency; the squish angle is designed to allow better ventilation due to enhanced airflow, improve flame travel, and promote swirls. The cylinder block utilizes piston oil jets on the right bank and left center of the block to provide lubrication and regulate the temperature of the pistons.
In addition to that, the oil sump is comprised of a massive upper part and stamped steel lower sump; the oil level sensor is installed on the crankcase.
The cylinder head is divided into three-part separate housings: the valve cover, camshaft housing sub-assembly, and cylinder head sub-assembly, all of which are made from Aluminum alloy.
The two camshafts are installed in different housings, mounted on the cylinder heads that make the design and manufacturing more simple. The intake camshaft is equipped with VVT-it for a smoother valve timing change according to different driving conditions and VVT-i on the exhaust camshaft and is made from cast-iron and chain-driven. The main timing chain drives the intake camshafts, and through the secondary chains, the exhaust camshafts are guided by the intake camshafts.
The 8GR engine also has steel-laminate type head gaskets between the cylinder heads and banks to enhance durability and sealing performance; it also used a shim about the cylinder bore of the gasket. It has taken an influence from the 1GR in its siamese type intake ports to reduce wall wetting and hydrocarbon emissions due to the reduced overall surface area of the port walls. The engine’s exhaust manifold is installed into the cylinder heads, and there are roller rockers and valve adjusters in the valve mechanism.
Roller rockers arms drive the valves with built-in needle bearings and a unique cam profile design to increase the valve lift versus the traditional shim-less lifter type of the first generation 2GRs; it also reduces the friction between the camshafts and the roller rocker arms. At the same time, this increases the overall cylinder head height to cater to a slightly taller rocker system.
The 8GR engine has a plastic variable-length intake manifold driven by an Acoustic Control Induction System that chooses the proper length of the opening and closing of the intake air control valve depending on the driving conditions based on RPM.
The rated output of the 8GR engine is 311 HP at 6,600 RPM and 2,800 RPM at 4,800 RPM.
There is only one known application of the 8GR-FKS engine as a stock which is the Lexus LS 350.
Another version of the 8GR engine is the 8GR-FXS which is also a 3.5 L engine. It holds the same bore and stroke dimension, but a higher compression ratio of 13 and is used mainly for hybrid vehicle applications, including on-demand Atkinson cycle. The rated output of the 8GR-FXS is 295 HP at 6,600 RPM and a torque of 260 lb-ft at 5,100 RPM.
The 2017 Lexus LC 500h, 2017 Lexus LS 500h, and 2018 Toyota Crown are some of the applications of the Toyota 8GR-FXS engine.
Engine Tuning, Upgrades, and Modifications
8GR engine, like its brother 2GR-FKS, is not the best platform for naturally-aspirated tuning, and fortunately, there is a supercharger available for this engine. However, if you want to tune it this way, you need to buy pistons that can fit a 12.0 compression ratio – if you own an 8GR-FKS, pair it with a performance camshaft and cold air intake; do some head porting and polish, 3-1 headers, performance exhaust system, and tune the ECU. These upgrades can help you reach at least 330 HP.
Another option is to buy a TRD or HKS supercharger kit, bolt it in the stock internals and get around 350 HP. Luckily, 8GR stock internals is pretty reliable so that you can remain that way, but longevity is a factor. Moving on, If 350 HP is not enough, you may opt to increase the boost pressure to the maximum point by having a more powerful supercharger, 500 cc/min fuel injectors, pistons fitted to at least 13 compression ratio, and an ECU upgrade.
Problems Surrounding 8GR Engines:
Like most engines we have today, 8GR is not an exemption to the consequences of age and mileage as it can also experience having common issues. Though it is not generally an engine design flaw, it still remained a mind bug for you as an owner to know the issue last minute.
So, these problems we will mention here are addressed to weigh the reliability and overall toughness of the engine under tremendous usage. Some issues may be more common than others; we still want to make a prudent reminder for you to understand some problems with the engine.
First is the oil leakage. Engine oil leaks come from different areas of the engine for various reasons also. However, in 8GR engines, leaks have something to do with the oil tube in the VVT-i lubrication system and other GR engines, especially the 1GR, 2GR, and 3GR. The VVT-i line is made from iron and rubber hose that feeds the oil, and the material itself, such as the rubber, is highly susceptible to wear-out breakage down the line and might be the primary cause of the leak. Good thing that Toyota already solved this issue, even on the 2GR ones in 2010, and replaced the hose with a metal one. You might notice a minor leak due to some oil drops on the ground or produce some smoke; more significant leaks leading to rapid oil loss that plummets the oil pressure and creates a more prominent smoke.
Another issue that might arise is the noise coming from the engine, which is also caused by many factors. But, as for the 2GR, 3GR, and 8GR engines, this problem might be due to an idler pulley. You can hear an annoying squeaking sound from the engine bay. Take note that the idler pulley is situated between the cover plates. The plate outside the pulley goes to the engine; the plate inside is our target, which is the extra one, must be installed to secure the elimination of the squeaking sound.
The last issue hanging in the engine is the water pump failure. 8GR and the whole GR engine family weak point is also in this department, as a member of the same engine family. Keep in mind that water pumps are a standard maintenance item and must be replaced periodically. Water pumps are vital to the engine performance as they cool down or regulate the operating engine temperature to avoid overheating and other heat-related issues.
So, with that being said, a faulty water pump is highly detrimental to the engine, considering that it involves coolant circulation. This issue happens due to the normal wear and tear of the water pump commonly occurring in unpredictable times, as it can happen anytime, especially on older models.
8GR engines are the modified version of the 7GR engine and the last of the old 2GR-FKS installment, technically speaking, for its architecture and features. It definitely deserves a ballot for its excellent applications and potential. It is a technologically advanced, innovative, but powerful engine; added to its arsenal is the switch of the Otto-Atkinson cycle that makes the fuel consumption better than its competitors.
8GR engines are huge contributors to the advancement of the automotive industry, collectively with other automakers, for they powered different vehicles as well. With proper care, maintenance, and periodic checking, this engine can provide you long years of service that can top 250,000 miles. Don’t forget to use high-quality engine oil, gasoline and schedule the replacement accordingly and timely, especially the water pump.
I hope that this simple discussion about the 8GR engine helped you understand its design, applications, power, tuning potential, issues, reliability, and overall impact on the automotive industry and community.