Holden L98 ‘Generation IV’ V8 engine (2006-10)

Introduction

Produced by General Motors at its plant in Silao, Mexico, the L98 was a 6.0-litre pushrod V8 petrol engine that was unique to Holden vehicles. The L98 was first introduced in the VZ Ute SS Thunder before its more widespread application throughout Holden’s VE and WM Commodore ranges. From January 2009 to September 2010, the L98 was only offered in VE Commodore and VE Sportwagon models with manual transmissions since models with automatic transmissions had the L76 engine with its cylinder deactivation technology (GM’s Active Fuel Management’, or AFM).

The differences between the L76 and L98 engines were:

• The L98 engine omitted the AFM hardware of the L76 engine; and,
• The L98 engine produced an additional 10kW for a maximum of 270kW due to its high-flow exhaust system with dual 2 ¼ inch pipes and four outlets.

L98 block

Based on the 6.0-litre LS2 engine which featured in HSV’s models, the 6.0-litre L98 replaced the 5.7-litre LS1. Like the LS1, the L98 engine had a deep-skirt, aluminium cylinder block that was cast from 319-T5 aluminium and contained gray-iron cylinder bore liners that were centrifugally-cast. Furthermore, a die-cast valley cover and upper deck rails connected the cylinder banks for greater rigidity.

Although the 92.0 mm stroke was unchanged, the L98 engine had 101.6 mm bores (compared to 99.0 mm for the LS1) which increased the engine’s capacity to 5967 cc.

L98 internals

Like the LS1, the L98 engine had

• A nodular iron crankshaft that was held in place by five main bearings with six bolts per bearing cap (four vertical and two horizontal);
• Sintered, forged and cracked PF1159M steel connecting rods which had cracked’ big ends; and,
• Pistons made from cast eutectic aluminium.

For the L98, however, changes included flat-top pistons and a higher compression ratio of 10.4:1 (up from 10.1:1).

L98 cylinder head and camshaft

In keeping with the engine’s greater capacity, the L98 engine had new high-flow cylinder heads. The single, in-block camshaft continued to be produced from steel billet, was rifle-drilled and had induction-hardened lobes. For the L98, the camshaft sensor was repositioned.

L98 valvetrain

Similarly, the L98 engine had two stainless steel valves per cylinder (one intake and one exhaust) that were actuated by cast steel, needle bearing roller rocker arms which had a ratio of 1.7:1. For the L98 engine, changes included larger 55.0 mm intake valves and 40.4 mm exhaust valves, though hydraulic roller lifters continued to be used.

L98 lubrication

For the L98 engine, the oil pan was redesigned with cast baffling to reduce mass and improve oil control; the bat wings’ of the LS1 oil pan were also omitted. The L98 engine continued to use a gerotor oil pump though, in common with the L76, special oil galleries were introduced for the AFM system.

L98 injection and ignition

Like its predecessor, the L98 engine had electronic, sequential port fuel injection (SFI) and each cylinder had its own injector to meter fuel. Furthermore, each cylinder had its own ignition coil, coil driver assembly and short plug wire that connected to the spark plug. The L98 engine, however, introduced more efficient ignition coils

The L98 engine had electronic throttle control and a larger, 90 mm single-blade throttle body. For the L98, the new E38 powertrain control module (PCM) included electronic throttle control functions, such that a separate module was no longer required; the PCM was also updated for the external knock sensors.