GM 6.0 Liter V8 Small Block L98 Engine

The 6.0L L98 engine debuted in the 2006 Holden Commodore VZ Ute, and was eventually used in several other Holden-specific applications. It is extremely similar to the the 6.0L LS2 engine that debuted in the 2005 Chevrolet Corvette C6, and the 6.0L L76 engine used in many trucks and sedans, featuring an all-aluminum construction.

The L98 engine is a derivative of the 6.0L L76, which, itself, is a modified version of the 6.0L LS2 engine. The key difference between the L98 and L76 is the removal of the displacement on demand, or active fuel management system from the L76. It is otherwise identical to the L98 V8 engine. As such the power figures are very similar with the L98 producing 362 horsepower and 391 pound-feet of torque.

Engine highlights include:

• Cylinder block: the L98 cylinder block shares two key design elements with GM’s original small-block V8: a 90-degree cylinder angle and 4.400-inch bore centers. The bore and stroke dimensions are: 4.00-inch (101.6 mm) bore x 3.62-inch (92 mm) stroke.
• Oiling System: the oiling system is a lightly-tweaked version of what was seen in the Gen III engines. The oil pump is still driven by the crankshaft. However, the addition of active fuel management used in the L76 required a redesign of the oil galleries to maintain adequate oil pressure throughout the engine as various cylinders were deactivated and reactivated in use. Even though the L98 removes the AFM, the oiling system is otherwise identical.
• Rotating assembly and windage tray: within the Gen IV block is a durable rotating assembly that includes a steel crankshaft and 6.098-inch-long, powder-metal connecting rods, as well as hypereutectic cast aluminum-alloy pistons. The pistons have a flat top design, and the piston rings have been redesigned to have less friction.
  The crankshaft in the Gen IV small block is located with grey iron main caps, comparable to what was found in the Gen III engines.
• PCV System: the positive crankcase ventilation system design of the L98 is common to the L76 and LS2 engines. Instead of pulling crankcase gases and engine oil blow-by from the valve cover, the system, instead, had its pickup in the valley cover, in between the cylinder banks, beneath the intake manifold. This designed system is better able to capture built up crankcase gases, rather than capture excess oil moving around the valvetrain, reducing possible oil consumption issues noted on some Gen III LS engines.
• Camshaft Design: also rotating inside the engine block is a hydraulic roller-lifter camshaft, however, like the L76, the L98 features a notably less aggressive camshaft than the LS2 engine, a consequence of having to work with the special AFM lifter setup.
  • The L98 camshaft’s specifications lift include: 0.478/0.466-intake/exhaust lift, 196/208-crank angle degrees intake/exhaust duration at 0.050 tappet lift and 116-degree cam angle lobe separation.
• Cylinder Head Design: the L98 cylinder heads are otherwise identical to what was featured in the L76 engine, and are denoted by their “823” casting number. They are aluminum, and feature rectangular intake ports common with LS3 V8, D-shaped exhaust ports and have a 70cc combustion chamber.
  • Steel intake and exhaust valves are used in the aluminum alloy heads, and they measure 2.165-inch (55.0mm) intake and 1.59-inch (40.4mm) in diameter. The valves are held at 15 degrees intake/15 degrees exhaust angles.
  • Valvetrain components include beehive valve springs and roller-pivot rocker arms with a 1.7 ratio – the amount of movement on the valve side of the rocker arm in comparison with the pushrod side.
  • Pushrod design is common to the Gen III engine, and they measure 7.385-inches long.
• Fuel Injection System: sequential port-fuel injection is utilized on all Gen IV engines. Port-fuel injection places the injectors on a fuel rail mounted the intake manifold. From there, the injectors spray fuel into the intake ports, just ahead of the combustion chamber. The fuel then mixes with incoming air before going through the combustion cycle. L98 injectors are common with the L76 and are rated at 42 lb/hr @ 58 psi.
  • The L98 utilizes a conventional in-tank fuel pump, with an in-line fuel filter.
• Active Fuel Management: the key difference between the L98 and the L76 is that Holden removed the AFM system from the L76 to create the L98.
• Exhaust Manifolds: the Gen IV manifolds weigh 1/3^rd less than the Gen III manifolds, a function of reduced wall thickness, from 4mm to 3mm. GM claims they also offer a four percent improvement in flow.
• Intake Manifold and Electronic Throttle: all Gen IV engines now feature electronic throttle control, which allows for the deletion of an idle-air control motor. The throttle body into the intake manifold measures 90mm (3.55-inches) in diamter. The manifold design used on later L98 engines is common to what is found on the LS3 V8 engine.
• Cooling System: the Gen IV cooling system sees just a light tweak compared to the Gen III engines with a redesigned water pump that is both lighter than the Gen III setup as well as less likely to leak with age, a somewhat common issue with Gen III blocks.
• Ignition System: the Gen IV has a more efficient coil-near-plug ignition system with redesigned coil packs.
• Unlike some early LS2 engines that use the older 24-tooth reluctor wheel, all L98 engines use the newer 58-tooth setup, which provided more accurate crank position data to the ECU. This system would go on to be standard equipment on all LS-based small block engines after LS2.
• E38 Engine Controller: operation and performance of the Gen IV is overseen by several different ECMs depending on the model year and crank reluctor wheel setup on the engine. Most L98 engines use an engine controller marked as E38.

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Other members of the Gen IV Small Block engine family include:

• Naturally-aspirated 6.0L V8 L76
• Naturally-aspirated 6.0L V8 L77
• Naturally-aspirated 5.3L V8 LS4
• Naturally-aspirated 7.0L V8 LS7
• Naturally-aspirated 6.2L V8 LS3
• Naturally-aspirated 6.2L V8 L99
• Supercharged 6.2L V8 LS9
• Supercharged 6.2L V8 LSA

Gen IV Vortec motors for pickup trucks, consisted of the following engines:

• 6.0L V8 LY6
• 6.0L V8 L96
• 6.0L V8 LFA
• 6.0L V8 LZ1
• 4.8L V8 LY2
• 4.8L V8 L20
• 5.3L V8 LMF
• 5.3L V8 LH6
• 5.3L V8 LC9
• 5.3L V8 LY5
• 5.3L V8 LMG
• 5.3L V8 LH8
• 5.3L V8 LH9
• 6.2L V8 L92