Engine - K Series KV6 (Description): Description and operation

Description

General

The KV6 is of all aluminium construction, with a 90° V configuration. The KV6 uses long cylinder head bolts engaging in threads 70 mm below the mating face of the cylinder block to attach the cylinder head to the cylinder block. This ensures sufficient structural stiffness to take advantage of the compressive strength of aluminium alloy and minimise tensile loadings. There are 8 cylinder head bolts for each cylinder head, located below the camshafts.

The engine features 24 valves, sequential fuel injection, liquid cooling and is transverse mounted. It is controlled by a Siemens engine management system utilising a range of sensors to constantly monitor and optimise engine performance. ENGINE MANAGEMENT SYSTEM - SIEMENS (ALL EXCEPT NAS), DESCRIPTION AND OPERATION, Description. ENGINE MANAGEMENT SYSTEM – SIEMENS (NAS), DESCRIPTION AND OPERATION, Description.

Cylinder Block Components

The cylinder block components are described below:

Cylinder Block and Main Bearing Ladder The cylinder block is constructed of an aluminium alloy and is cast in three sections: l Cylinder block. l Main bearing ladder. l Lower crankcase extension.

For strength and rigidity, the main bearing ladder is manufactured from special alloy A357TF as used in manufacturing components in the aerospace industry. The main bearing ladder is secured to the cylinder block with 16 bolts, thus creating a very rigid crankcase 'box'. A separate outer crankcase extension adds further strength to the lower end of the cylinder block. The lower crankcase extension is sealed to the underside of the cylinder block, using jointing compound, and secured with 10 bolts. Fitted to the lower crankcase is an aluminium alloy sump.

Pistons and Cylinder Liners The aluminium alloy, thermal expansion, lightweight pistons, with semi-floating gudgeon pins, are offset to the thrust side and are carried on forged steel connecting rods. Pistons and cylinder liners are supplied in two grades, 'A' and 'B' and are also colour coded to assist identification. The pistons are marked to ensure they are correctly oriented in the cylinder liner; the 'FRONT' mark should be toward the front of the engine.

The cylinder block is fitted with 'damp' cylinder liners, the bottom stepped half of the cylinder liner being a sliding fit into the lower part of the cylinder block. The liners are sealed in the block with a bead of sealant applied around the stepped portion of the cylinder liner. The top of the cylinder liner is sealed by a multi-layer steel cylinder head gasket when the cylinder head is fitted.

The cylinder liner diameters are smaller than the big-end forging of the connecting rods and need to be removed complete with pistons and connecting rods from the cylinder block.

Connecting Rods The KV6 engine utilises forged steel H-sectioned connecting rods, with the gudgeon pin being an interference fit in the small end of the connecting rod. The big-ends are horizontally split.

Big-end bearing diametric clearance is controlled by selective bearing shells with three grades of thickness. The bigend upper and lower bearing shells are plain with locating tags.

Piston Rings Each piston is fitted with two compression rings and an oil control ring. The top compression rings are chrome-plated steel. The 2nd compression rings are chrome-plated cast iron. The oil control rings have stainless steel top and bottom rails and integral expander rings.