Manifold and exhaust system - K Series KV6 (Description): Description and operation

Description

Inlet Manifolds

The inlet manifold on the KV6 engine is located on the top of the engine, between the cylinder banks. The manifolds direct intake air into the cylinders where it is mixed with fuel delivered by the injectors prior to ignition in the cylinders. The inlet manifold comprises left and right hand cast aluminium inlet manifolds and a plastic moulded inlet manifold chamber.

Two handed aluminium inlet manifolds are secured to the cylinder heads using fourteen bolts and sealed with one piece composite gaskets. Three injectors, which are sealed with 'O' rings, are located in each manifold and are retained in position by the fuel rail. The fuel rails are secured to each manifold using two bolts. A coolant outlet is located in the left hand end of each manifold and a vacuum take-off point is located on the left hand manifold. Three 'O' rings and three moulded seals provide the seal between the inlet manifolds and the inlet manifold chamber.

Inlet Manifold Chamber

The inlet manifold chamber is a one piece plastic moulding which is fitted on the inlet manifolds and secured with four bolts. Three 'O' rings and three moulded seals locate in recesses and seal between the inlet manifold chamber and the inlet manifolds.

The inlet manifold chamber features a single throttle body which feeds into a 'Y' piece, which separates into two secondary pipes. The secondary pipes connect to two main plenums, one for each bank of cylinders. At the closed end of the plenums is a balance valve which is operated by an electric motor. This valve enables the two plenums to be connected together.

From the two plenums, the primary tract length to the cylinder head face is approximately 500 mm. Each of these tracts has a side junction with a power valve leading to a short inlet tract plenum, approximately 350 mm from the cylinder head. Each power valve is connected to a link rod which is operated by a single electric motor.

Exhaust Manifolds (All Except NAS)

Two handed, steel fabricated exhaust manifolds are fitted. Each manifold has three branches which merge into one flanged outlet. Each manifold is sealed to the cylinder head with a composite gasket. Four studs in each cylinder head locate each manifold which is secured with nuts.

A starter catalyst is fitted to each manifold at the point where the three branches merge. Each manifold also has a HO2S located upstream of the pre-catalyst. Refer to the Emissions section for details of catalyst and HO2S operation. EMISSION CONTROL - K SERIES KV6, DESCRIPTION AND OPERATION, Description.

Exhaust System (All Except NAS)

The exhaust system comprises three major parts; a front pipe assembly incorporating a catalytic converter, an intermediate pipe assembly and a tail silencer.

Front Pipe Assembly The front pipe is connected to the flanged connections of the left and right hand exhaust manifolds. The front pipe locates on two studs on each manifold and is secured with nuts. A bracket near the front flange is secured to a gearbox attachment bolt. The two manifold pipes merge into an integral flexible pipe which in turn connects with the catalytic converter. The flexible pipe is formed into a concertina shape which is protected by a metal shroud. The flexible pipe allows for ease of exhaust system alignment and also absorbs engine vibrations.

A further pipe section from the catalytic converter is terminated by a flanged connection with captive studs. This pipe section also has a threaded port which provides for the location of the post catalyst HO2S. Refer to the Emissions section for details of catalyst and HO2S operation. EMISSION CONTROL - K SERIES KV6, DESCRIPTION AND OPERATION, Description.

CAUTION: Ensure the exhaust system is free from leaks. Exhaust gas leaks upstream of the catalytic converter could cause internal damage to the catalytic converter.