Teardown of Toyota's Flagship Sedan (Part 1)
2.5-liter V6 engine "4GR-FSE"
A teardown analysis of the Toyota Crown Royal (a luxury sedan sold only in select Asian markets. The most recent model was launched in Japan in December 2012) was performed on November 27, 2015, by the Hiroshima Industrial Promotion Organization. This report series will examine the parts and components. Part 1 will focus on the 2.5-liter V6 4GR-FSE engine and powertrain parts. This direct-injection engine has been developed with dynamic performance, fuel economy and quiet operation in mind. It is fitted with Dual VVT-i that is capable of variable control of both intake and exhaust valve timing, and is also fitted with a dual main muffler. Part 2 of the report will focus on the chassis and Part 3 on the body.
Previous teardown reports:
4th-Generation Toyota Prius
4th-Generation Toyota Prius Teardown (Part 1)(Feb. 2016)
4th-Generation Toyota Prius Teardown (Part 2) (Mar. 2016)
4th-Generation Toyota Prius Teardown (Part 3) (Mar. 2016)
4th-Generation Toyota Prius Teardown: Photo gallery (132 parts) (Apr.2016)
4GR-FSE engine overview
The 4GR-FSE engine is a 2.5-liter V6 naturally-aspirated gasoline engine developed for rear-wheel drive luxury cars such as the Toyota Crown, Lexus GS, Lexus IS and Mark X base models. It runs on regular gasoline with a high compression ratio of 12.0, and while it adopts cylinder direct fuel injection and a simple structure, it was designed particularly with high fuel economy and silent operation in mind. The 4GR-FSE engine is equipped in the lowest-priced rear-wheel drive models in lineups from makers like Toyota and Lexus. The other three engine types, (3.5-liter V6 engine (2GR-FSE), 2.5-liter inline four-cylinder hybrid engine (2AR-FSE), 2.0-liter inline four-cylinder turbo engine (8AR-FTS)) that were added in 2015 have dual-injector systems. In contrast to that, the 4GR-FSE engine only has a single-point injection system. The key specifications of the torn-down Crown Royal car and the engine are shown below.
|Model name, grade||Crown Royal, 2.5 Royal|
|Dimensions||4895mm (L) by 1800mm (W) by 1460mm (H)|
|Valve train||V6 24-valve DOHC|
|Bore x stroke||83.0mm x 77.0mm|
|Intake system||Natural aspiration|
|Fuel type||Unleaded regular gasoline|
|Maximum torque||243Nm (24.8kgm)/4800rpm|
|Output per liter||81.2PS/liter|
|Torque per liter||9.9kgm/liter|
|Fuel economy under JC08 test cycle||11.4km/liter（2WD model）|
Engine in place shown without front bumper, grille, radiator and condenser
|Left side of the lowered engine|
Top view of the engine in place
|Rear view of the lowered engine and transmission|
|Surge tank (resin) and intake manifold||Surge tank and throttle body without the intake manifold|
The throttle body, surge tank (resin) and intake manifold are located on the top center of the V-bank. The surge tank features an ACIS (Acoustic Control Induction System) that utilizes a variable intake manifold. In order to actively utilize the pulsation effect in time with the cycles produced by the engine revolutions it has a motor-driven actuator that alters the effective intake manifold length according to the cycle of pulsation and increases torque over a broad range.
|Intake manifold (cylinder head mounting side)||Intake manifold (surge tank mounting side)|
A motor-driven swirl control valve is fitted in the intake manifold. When the amount of air induction is low when the engine has a low load state, it closes the intake air passage in the intake manifold halfway to generate tumbling motion (vertical vortices) within the cylinder.
|Cylinder head (intake port side)||Cylinder head (exhaust port side)|
The cylinder heads on the right and left sides of the V-bank have intake ports inside of it. These intake ports have two intake air passages in each cylinder. When the swirl control valve in the intake manifold closes, air flow is allowed to flow to only one of the two ports. Since the other port remains closed, a strong diagonal tumbling motion is generated which accelerates the mixing of fuel and air and vaporization of the air-fuel mixture in the cylinder.
|Cylinder head (combustion chamber)||Cylinder head and fuel injectors|
The engine has a pent-roof combustion chamber. Holes are positioned in the center of the chamber for three-prong iridium ignition plugs. There are also holes located along the periphery of the combustion chamber on the inlet port side (at the bottom of the combustion chamber in the picture) used for mounting fuel injectors that inject fuel directly into the combustion chamber. The picture on the right shows the fuel injectors attached. When the swirl control valve is closed, fuel is injected into the tumble motion that is generated in one of the two intake ports.
|Piston crown (supplied by Art Metal MFG.)||Piston, connecting rod, connecting rod cap|
The piston side of the combustion chamber has a shallow cavity in the center for homogeneous combustion of the air-fuel mixture in normal conditions and stratification combustion during cold starts. The aluminum alloy piston has a short skirt length as well as wall thickness to reduce overall weight and cost.
Fuel injection system
|Fuel injectors (supplied by Denso)||High-pressure injection pump (supplied by Denso)|
The picture to the left shows fuel injectors fitted in the cylinder head that inject fuel directly into the cylinders. Direct fuel injection cools the inlet air using latent heat from fuel vaporization. The picture on the right shows the high-pressure pump for fuel injection. Fuel injection under high pressure accelerates vaporization of fuel.
The 4GR-FSE is a DOHC engine equipped with a variable valve timing (VVT) system in the intake and exhaust camshafts that control the intake and exhaust valve timing according to the operating condition. The VVT motor and reduction gear are built into the cylinder shown at the bottom of the picture on the left. The engine has a two-stage chain drive system. A primary chain drives the intake camshafts while a secondary chain allows them to drive the exhaust camshafts.
The picture on the right shows the camshaft ladder frame that is fitted on the cylinder head. The intake and exhaust camshafts are fitted on the ladder frame. The ladder design is used to ensure high rigidity and suppress valve operation vibration.
|Cylinder block (cylinder side)
The water jacket spacer in the picture on the right is inserted into the water jacket located outside the liner.
|Water jacket spacer|
|Cylinder block (crankcase side)||Cylinder block (vehicle front side)|
The engine has a cast aluminum alloy cylinder block with cast-iron liners. A resin water jacket spacer is inserted into the water jacket to efficiently cool the top of the cylinders. Inserting a spacer half the height of the water jacket partially blocks the flow of water at the bottom of the bore, allowing the wall temperature there to rise and minimize the temperature difference with the top. This prevents bore deformation and reduces friction. The cylinder block has a long skirt that extends down to and beyond the bearing cap mounting surface that keeps the crankshaft in place to reduce operating sound and vibrations.
A die-cast aluminum oil pan that increases the rigidity of the cylinder block is used to reduce the sound and vibration of the engine. The oil filter case is built into the frontal projection of the oil pan. This structure makes it so the internal oil filter can be replaced by turning the case tip. Because the vehicle is laid out so the steering gear is snugly fit in the front bottom of the engine, a space for oil to accumulate is extended sideways at the rear of the oil pan (left end in the picture on the upper right) to retain a sufficient amount of oil in the pan. A steel cover is fitted at the bottom opening of that area.
The picture on the lower left shows the bottom of the engine without the undercover. The steering gear is located directly under the front half of the oil pan. A large oblong space is positioned in the center of the front suspension member. A horizontally long steel cover for retaining enough oil in the pan is visible.
The picture on the lower right shows the cylinder block without the oil pan. The entire crankshaft is covered by a baffle plate. An oil passage that connects to the oil filter is located in the front.
Head cover, timing chain cover
|Back of the cylinder head cover||Head cover|
The cylinder head covers and front covers of the engines on low-end cars are often made of resin to reduce weight. The Crown Royal has die-cast aluminum covers for higher rigidity to reduce operating sound and vibration. There is an oil jet for camshaft lubrication in the cylinder head cover.
|Back of the front cover (supplied by Aisin Seiki)||Front cover (supplied by Aisin Seiki)|
The oil pump and the water pump are built into the chain casing.
The exhaust system consists of two exhaust manifolds extending from the right and left banks of the V6 engine. They are each connected to the front catalytic converter, front pipes, and rear catalytic converter. The two front pipes join immediately before reaching the center muffler. The joined pipe (middle pipe) leaves the center muffler and branches into two pipes that connect to the right and left rear mufflers.
The exhaust pipes and the front pipes have a two-layer pipe structure designed to retain the heat of exhaust gas after a cold engine start and increase the efficiency of the catalytic converters. The two-layer pipe design also works as a heat shield for other parts and eliminates the need for heat shielding covers near the exhaust manifolds.
|Transmission and torque converter||Transmission (engine joint side)|
|Torque converter removed from the engine||Bottom view of the transmission in place|
The automatic transmission (A960E 6-speed AT) is supplied by Aisin AW and was developed for Toyota’s rear-wheel drive vehicles fitted with up to 3.0-liter engines. The same transmission is also used on models like the Lexus IS, Lexus GS, and Mark X.
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