ENGINE UNIT

Cylinder Head

1. The cylinder head sub-assembly structure has been simplified by separating the camshaft housing sub-assembly (cam journal portion) from the cylinder head sub-assembly.

2. The cylinder head sub-assembly, which is made of aluminum, contains a pentroof-type combustion chamber. The spark plug is located in the center of the combustion chamber in order to improve the engine's anti-knocking performance.

3. The angle of the intake and exhaust valves is narrowed and set at 29° to permit a compact cylinder head sub-assembly.

4. Thin-electrode type spark plugs with a 12 mm (0.472 in.) diameter threaded base are used in order to make it possible to increase the diameter of the intake and exhaust valves.

5. A taper squish combustion chamber is used to improve anti-knocking performance and intake efficiency. In addition, engine performance and fuel economy have been improved.

   

   *1	Intake Valve	*2	Spark Plug Hole
   *3	Exhaust Valve	*4	Camshaft Housing Sub-assembly
   *a	Intake Side	*b	Exhaust Side
   *c	View from Bottom Side	*d	A-A Cross Section
   *e	Taper Squish	*f	29°

6. A Siamese type intake port is used to reduce the overall surface area of the intake port walls. This prevents the fuel from adhering to the intake port walls, thus reducing HC exhaust emissions.

   

   *a

   Siamese Type Intake Port

   *b

   Independent Type Intake Port (Reference)

Cylinder Block

1. An aluminum cylinder block sub-assembly with a 7 mm (0.276 in.) distance between the cylinder bores is used to achieve a compact and lightweight configuration.

2. An oil separator is provided in the blowby gas passage inside the cylinder block sub-assembly. This separates the engine oil from the blowby gas in order to reduce the degradation and consumption of volume of the engine oil.

3. A spiny type liner, which has an irregularly shaped outer casting surface, is used to enhance the adhesion between the liners and the aluminum of the cylinder block sub-assembly. The enhanced adhesion helps heat dissipation, resulting in a lower overall temperature and reduced heat deformation of the cylinder bores. A cylinder block sub-assembly with this type of liner cannot be rebored.

   

   *1	Oil Separator	*2	Cylinder Block Sub-assembly
   *3	Spiny Type Liner (Irregularly shaped outer casting surface of liner)	*4	Oil Separator Cover (No. 1 Ventilation Case)

4. Through the use of an offset crankshaft, the centerline of the cylinder bores is shifted 8 mm (0.315 in.) towards the intake in relation to the crankshaft center. Thus, the side force (thrust) applied to the cylinder wall is reduced when maximum combustion pressure is applied, which contributes to fuel economy.

   

   *a	Bore Centerline	*b	Crankshaft Centerline
   *c	Maximum Pressure	*d	Offset Crankshaft
   *e	Non-offset Crankshaft	-	-

Oil Pan

1. The stiffening crankcase assembly is made of aluminum alloy.

2. The No. 2 oil pan sub-assembly is made of steel.

3. The oil pump assembly is installed in the stiffening crankcase assembly to make the engine compact.

4. To improve serviceability, the stiffening crankcase assembly has been designed so that it can be removed without removing the No. 2 oil pan sub-assembly and the oil pump assembly.

5. The air conditioning compressor brackets are integrated into the stiffening crankcase assembly.

   

   *1	Stiffening Crankcase Assembly	*2	Oil Pump Assembly
   *3	No. 2 Oil Pan Sub-assembly	-	-

Timing Chain or Belt Cover

1. An aluminum die-cast timing chain or belt cover sub-assembly is used.

2. The timing chain or belt cover sub-assembly has an integrated construction including parts of the cooling system (engine water pump assembly and water passage). Thus, the number of parts has been reduced for weight reduction.

3. An oil passage is provided on the timing chain or belt cover sub-assembly to simplify the lubrication system.

4. The timing chain oil jet is provided in the timing chain or belt cover sub-assembly.

   

   *1	Timing Chain or Belt Cover Sub-assembly	*2	Water Pump Gasket
   *3	Engine Water Pump Assembly	-	-
   *a	Water Pump Volute Chamber	*b	Water Passage
   *c	Oil Passage	*d	Timing Chain Oil Jet
   *e	View from A	-	-

Timing Chain and Chain Tensioner

1. A chain sub-assembly with an 8 mm (0.315 in.) pitch is used to make the engine more compact.

2. The No. 1 chain tensioner assembly uses a spring and oil pressure to maintain proper chain tension at all times.

3. The No. 1 chain tensioner assembly suppresses noise generated by the chain sub-assembly.

4. The No. 1 chain tensioner assembly is a ratchet type tensioner with a non-return mechanism.

5. To achieve excellent serviceability, the No. 1 chain tensioner assembly is constructed so that it can be removed and installed from the outside of the timing chain or belt cover sub-assembly.

   

   *1	Chain Sub-assembly	*2	No. 2 Chain Vibration Damper
   *3	No. 1 Chain Vibration Damper	*4	No. 2 Chain Sub-assembly
   *5	Chain Tensioner Slipper	*6	No. 1 Chain Tensioner Assembly

Valve Mechanism

1. This engine uses a Dual Variable Valve Timing-intelligent (Dual VVT-i) system which controls the intake camshaft (camshaft) and exhaust camshaft (No. 2 camshaft) to provide optimal valve timing according to driving conditions. With this, lower fuel consumption, higher engine performance, and reduced exhaust emissions have been achieved.

2. The intake camshaft (camshaft) and exhaust camshaft (No. 2 camshaft) are driven by a chain sub-assembly.

3. The intake camshaft (camshaft) and exhaust camshaft (No. 2 camshaft) are made of cast iron alloy.

4. Together with the use of the No. 1 valve rocker arm sub-assembly, the cam profile has been designed with an indented R (radius). This results in increased valve lift when the valve begins to open and finishes closing, helping to achieve enhanced output performance.

5. An inner compression spring, whose upper portion is shaped like a beehive, is used to reduce inertial mass. As a result, the load on the inner compression spring and friction are reduced.

   

   *1	Camshaft Timing Exhaust Gear Assembly	*2	Exhaust Camshaft (No. 2 Camshaft)
   *3	Intake Camshaft (Camshaft)	*4	Camshaft Timing Gear Assembly
   *5	No. 1 Valve Rocker Arm Sub-assembly	*6	Valve Lash Adjuster Assembly
   *7	Valve Stem Cap	*8	Valve Spring Retainer Lock
   *9	Valve Spring Retainer	*10	Valve Stem Oil Seal or O Ring
   *11	Valve Spring Seat	*12	Valve
   *13	Inner Compression Spring	-	-
   *a	Cam with Indented R	*b	Indented R Portion of Cam (Profile)
   	Lift amount increased		Beehive

   Figure 1. Valve Timing

   

   *a	VVT-i Operation Range (Intake)	*b	VVT-i Operation Range (Exhaust)
   *c	TDC	*d	BDC
   	Exhaust Valve Opening Angle		Intake Valve Opening Angle

Valve Rocker Arm

1. This engine uses No. 1 valve rocker arm sub-assemblies with built-in needle bearings. This reduces the friction that occurs between the cams and the areas (No. 1 valve rocker arm sub-assembly) that push the valves down, thus improving fuel economy.

   

   *1	Valve Lash Adjuster Assembly	*2	No. 1 Valve Rocker Arm Sub-assembly
   *3	Needle Bearing	-	-

Valve Lash Adjuster

1. Valve lash adjuster assemblies, which maintain a constant zero valve clearance through the use of oil pressure and spring force, are used.

2. The valve lash adjuster assemblies, which are located at the fulcrum of the No. 1 valve rocker arm sub-assemblies, consist primarily of a plunger, a plunger spring, a check ball, and a check ball spring.

3. Engine oil supplied by the cylinder head sub-assembly and the built-in spring actuate the valve lash adjuster assembly. The oil pressure and the spring force that act on the plunger push the No. 1 valve rocker arm sub-assembly against the cam, adjusting the valve clearance created during the opening and closing of the valve. As a result, engine noise has been reduced.

   

   *1	Cam	*2	No. 1 Valve Rocker Arm Sub-assembly
   *3	Oil Passage	*4	Plunger
   *5	Oil Hole	*6	Plunger Spring
   *7	Check Ball Spring	*8	Check Ball
   *a	Valve Lash Adjuster Assembly Cross Section	-	-

   Tech Tips

   Valve clearance adjustment is not necessary because a valve lash adjuster assembly is used.

VVT-i Controller

1. A VVT-i controller (camshaft timing gear assembly or camshaft timing exhaust gear assembly) consists of a housing driven by the chain sub-assembly and a vane coupled with the intake camshaft (camshaft) or exhaust camshaft (No. 2 camshaft).

2. Both the camshaft timing gear assembly and camshaft timing exhaust gear assembly have a 4-blade vane.

3. The oil pressure sent from the advanced or retarded side path at the intake camshaft (camshaft) and exhaust camshaft (No. 2 camshaft) causes rotation in the camshaft timing gear assembly vane circumferential direction to vary the intake and exhaust valve timing continuously.

4. When the engine is stopped, a lock pin locks the intake camshaft (camshaft) at the most retarded position and the exhaust camshaft (No. 2 camshaft) at the most advanced position, to ensure that the engine starts properly.

5. An advance assist spring is provided on the exhaust side camshaft timing gear assembly. This spring applies torque in the advance direction when the engine is stopped, thus ensuring the engagement of the lock pin.

   Figure 2. Intake Side

   

   *1	Vane (Fixed on Camshaft)	*2	Sprocket
   *3	Housing	*4	Lock Pin
   *5	Intake Camshaft (Camshaft)	-	-
   *a	At a Stop	*b	In Operation
   	Oil Pressure	-	-

   Figure 3. Exhaust Side

   

   *1	Advance Assist Spring	*2	Lock Pin
   *3	Housing	*4	Vane (Fixed on No. 2 Camshaft)
   *5	Sprocket	*6	Exhaust Camshaft (No. 2 Camshaft)

Piston

1. The pistons are made of aluminum alloy to allow them to be compact and lightweight.

2. The piston head portion uses a taper squish shape to achieve fuel combustion efficiency.

3. Full floating type piston pins are used.

4. The piston skirt is coated with resin to reduce friction losses.

5. Low-tension piston rings are used to reduce friction and achieve excellent fuel economy.

6. Narrow-width piston rings are used to reduce weight and friction.

7. The oil ring is a 3-piece type, and use of the oil ring contributes higher reliability and lower friction.

8. A Physical Vapor Deposition (PVD) coating has been applied to the surface of the No. 1 compression ring and oil ring, in order to improve wear resistance.

   

   *1	No. 1 Compression Ring	*2	No. 2 Compression Ring
   *3	Oil Ring	-	-
   *a	Taper Squish Shape	*b	Resin Coating
   *c	PVD Coating	-	-

Connecting Rod and Connecting Rod Bearing

1. The connecting rod sub-assemblies are made of high-strength steel for weight reduction.

2. Plastic region tightening bolts are used.

3. The width of the connecting rod bearings have been optimized to reduce friction.

4. The lining surface of the connecting rod bearings are micro-grooved to provide an optimal amount of oil clearance. As a result, cold-engine cranking performance has been improved and engine vibration has been reduced.

   

   *1	Connecting Rod Sub-assembly	*2	Plastic Region Tightening Bolt
   *3	Connecting Rod Bearing	-	-
   *a	Micro-grooved	-	-

Crankshaft and Bearing

1. The crankshaft has 5 main journals and 8 balance weights.

2. The pins and journals have been machined with increased precision and the surface roughness has been minimized to reduce friction.

3. All pins and journal fillets have been hardened to improve their strength.

   

   *1	Journal Fillet	*2	Oil Hole
   *3	No. 5 Journal	*4	No. 1 Journal
   *5	Balance Weight	*6	Pin Fillet

4. The width of the crankshaft bearings has been optimized to reduce friction.

5. An oil groove is provided on each crankshaft bearing (upper main bearing). The oil groove is deep at the center and is shallow at the edges to reduce the amount of oil that will leak from the crankshaft bearing. As a result, the size of the oil pump has been reduced, minimizing friction.

6. The lining surface of the crankshaft bearings are micro-grooved to provide an optimal amount of oil clearance. As a result, cold-engine cranking performance has been improved and engine vibration has been reduced.

   

   *1	Upper Main Bearing (Crankshaft Bearing)	*2	Lower Main Bearing (Crankshaft Bearing)
   *a	Micro-grooved	*b	Center
   *c	Edge	*d	Oil Groove Depth

V-ribbed Belt

1. Accessory components are driven by a serpentine belt consisting of a single V-ribbed belt (fan and generator V belt). This reduces the overall engine length, weight and number of engine parts.

   

   *1	Generator Pulley	*2	Supercharger Pulley
   *3	Air Conditioning Compressor Pulley	*4	Crankshaft Pulley
   *5	Water Pump Pulley	-	-

Engine Mount

1. The engine is supported by 3 mountings. A hydraulic mounting is used for the engine mounting insulator sub-assembly RH to reduce vibration and noise.

   

   *1	Engine Mounting Insulator Sub-assembly RH	*2	Engine Mounting Insulator LH
   *3	Engine Moving Control Rod	-	-