Engine: Description and Operation

CYLINDER BLOCK
The cylinder block is made of heat treated aluminum with cast-in-place iron liners. The block is a closed deck design with the right bank forward. To provide high rigidity and improved NVH, the block has cast-in contours and ribs, along with powdered metal 6 bolt main caps (4 vertical, 2 horizontal), with a die cast aluminum structural beam windage tray mounted to the main caps.
The block design allows coolant flow between the cylinder bores and an internal coolant by-pass to a dual poppet inlet thermostat.

CRANKSHAFT
The crankshaft is constructed of a forged micro alloy steel. The six throw, nine counterweight crankshaft is supported by four select fit main bearings with the number three serving as the thrust washer location. The select fit identification markings will be on the rear side of the number nine (rear-most) counterweight. The six separate connecting rod throws are an even-firing design which reduces torque fluctuations while a vibration damper is used to control torsional vibration.
The crankshaft oil seals are an one piece design. The front seal is retained by the timing chain cover, and the rear seal in a housing that attaches to the cylinder block.

PISTONS AND CONNECTING RODS
The pistons are made of a high strength aluminum alloy with an anodized top ring groove and crown. Piston skirts are coated with a solid lubricant for scuff resistance. The connecting rods are made of powdered metal with a "fractured cap" design. The connecting rod attaches to the piston with a full floating pin retained by lock rings.

CYLINDER HEADS
The cylinder heads are made of an aluminum alloy. The cylinder head features four valves per cylinder with pressed in powdered metal valve guides. The cylinder heads provide enclosures for the timing chain drive, necessitating a unique right and left cylinder head.

TIMING DRIVE SYSTEM
The timing drive system has been designed to provide quiet performance and reliability to support a NON free wheeling engine. The system consists of a primary and secondary chain drive.
The primary timing chain drive uses a single, double-flexure, inverted tooth type chain. The primary chain drives both of the intake camshafts directly from a sprocket mounted on the crankshaft. In addition, the water pump is driven by the "back side" of the primary chain, necessitating the double flexure type chain.
The chain is controlled by three fixed chain guides, and a pivoting tensioner arm. These guides utilize low friction and long wearing nylon plastic wear faces. To tension the primary chain, a fully automatic spring loaded, engine oil-fed, hydraulic tensioner is used. The tensioner is mounted in the right cylinder head with the plunger contacting the pivoting tensioner arm. A mechanical ratchet mechanism inside the tensioner prevents excessive chain slack upon engine start-up as the chain wears. The tensioner is designed with an internal oil reservoir to assure noise-free performance, even during engine start-up before oil pressure reaches the tensioner.
To reduce engine NVH and timing chain loads a camshaft damper is used. This damper mounts to the right intake camshaft sprocket. The damper utilizes a synthetic rubber elastomer to provide damping, similar to a crankshaft damper.
For lubrication the primary chain utilizes oil leakage from the front of the oil pump. This oil spills on the crankshaft sprocket, which is then carried by the chain throughout the primary drive.
The secondary timing chain drive system uses two conventional roller-type chains, one at each cylinder bank. The purpose of the secondary chain is to provide a mechanical driven connection between the intake and exhaust camshafts. The intake camshafts drive the exhaust camshafts. The sprockets for both intake and exhaust camshafts are a press-fit and are only serviced as an assembly with the camshafts.
To tension the secondary chain a spring-loaded, hydraulic tensioner is used at each bank and attaches to each cylinder head between the intake and exhaust camshafts. The tensioner incorporates upper and lower chain guide faces. The lower guide face is attached directly to the tensioners hydraulic plunger. Also, the tensioner uses an internal oil reservoir design to prevent engine start-up noise. The secondary chains are lubricated via an oil passage through the upper guide face on each tensioner.

CAMSHAFTS
The assembled fabricated camshafts are composed of five bearing journals machined into a hollow steel tube. Six steel lobes, a secondary timing drive sprocket, and a primary sprocket/thrust flange are pressed onto the camshaft tube using a unique assembly process. Camshaft end play is controlled by the primary camshaft sprocket attachment flange on the intake camshafts and by a thrust flange on the exhaust camshafts.

ROCKER ARMS
The rocker arms are composed of steel stampings with an integral roller bearing. The rocker arms incorporate a 0.5 mm (0.0197 inch) oil hole in the lash adjuster socket for roller/camshaft lobe lubrication.

VALVES
The valves are made of heat resistant steel, and have chrome plated stems to prevent scuffing. The four valves per cylinder are actuated by roller rocker arms, which pivot on stationary lash adjusters. All valves use three bead lock keepers to retain springs and to promote valve rotation.

VALVE SPRINGS
The valve springs are made from high strength, chrome-silicon steel. The springs are common for intake and exhaust applications. The valve spring seat is integral with the valve stem seal, which incorporates a garter spring to maintain consistent lubrication control to the valve stem.

INTAKE MANIFOLD
The intake manifold is made of a composite material and features a compact, low rumble design that maximizes engine performance while minimizing induction noise. The air plenum chambers absorb air pulsations created during each cylinder's intake stroke. The plenum chambers are connected to maximize low RPM torque.

EXHAUST MANIFOLD
The exhaust manifolds are a log style design and made of cast nodular iron. The outlets are designed for V-band clamp attachment of close coupled catalytic converters.

ENGINE LUBRICATION
The lubrication system is a full-flow filtration, pressure feed type. The oil pump body is mounted to the engine block. The pump inner rotor is driven by the crankshaft. A structural windage tray is used to increase power by minimizing oil windage at high engine RPM.


























ENGINE LUBRICATION SYSTEM
The lubrication system is a full flow filtration pressure feed type. Oil from the oil pan is pumped by a geroter type oil pump directly, coupled to the crankshaft. Oil pressure is controlled by a relief valve, mounted inside the oil pump housing.