|2008 Northstar 4.4L V8 SC ( LC3 )
|Premium V 4.4L SC V-8
|4371cc ( 267 ci )
|Engine Orientation: L=Longitudinal T=Transverse
|dual overhead camshafts
|Valves per cylinder:
|Performance Build Center, Wixom, MI
|roller follower with hydraulic lash adjusters
|Bore x stroke:
|91 x 84 mm
|Bore Center: (mm)
|Bore Area: ( cm2 ) ( total engine bore area )
|Premium Fuel Required
|Horsepower: hp ( kw )
|469 hp ( 349 kw ) @ 6400 rpm SAE CERTIFIED POWER
|443 hp ( 330 kw ) @ 6400 rpm SAE CERTIFIED POWER
|Torque: lb-ft. ( Nm )
|439 lb-ft ( 595 Nm ) @ 3900 rpm SAE CERTIFIED POWER
|414 lb-ft ( 561 Nm ) @ 3900 rpm SAE CERTIFIED POWER
|Fuel shut off:
|Engine Mass: ( kg/lbs ) engine plant as shipped
|BIN 5 / EURO 4 compliant
|Close-coupled catalytic converters
|EGR and A.I.R. not required
|Block: ( upper )
|sand cast 319 T 7 aluminum
|Block: ( lower )
|319 T 7 semi permanent mold cast aluminum alloy
|Supercharger / Intake:
|GM patented integral design
|GM specific helical Roots rotor set, cast aluminum case
|Four laminova style intercoolers
|cast nodular iron
|Forged steel with rolled fillets
|cast nodular iron
|powder metal with heat treatment
|Intake and exhaust variable valve timing
|Piston oil spray cooling
|Polished exhaust ports
|Platinum tip spark plugs
|secondary throat cut inlet ports
Powertrain Text for the 2008 LC3 V8:
The Northstar V8 was launched in the 1993 Cadillac Allante, the first all-American dual-overhead cam aluminum V8 passenger car engine. Sixteen patents protected its advanced technologies; seven more have been granted since. In 1994, the original Northstar (RPO L37) was joined by a second version (LD8), both displacing 4.6L. In 2006, the extensively redesigned Northstar 4.4L V8 supercharged VVT (RPO LC3) was developed from the 4.6L. It is the standard engine in the high-performance XLR-V roadster and STS-V sedan.
Exceptional smoothness, refinement and drivability were the targets for the 469-hp supercharged Northstar V8, which features an all-new aluminum block design and the most power output for any production Cadillac to date. To ensure tight tolerances and strength, the block of the 4.4L is sand-cast, compared to the die-cast block of the 4.6L. The deck of the new block is semi-closed, meaning that the ends of the cylinder head decks of each bank are connected to each other by trusses. An open deck block, such as the 4.6L by comparison, has cylinder banks that protrude outward from the main body of the block. The trusses add rigidity to the block and cylinders.
The engine shares about half of its components with the naturally aspirated 4.6L Northstar variant, and it is also a naturally balanced 90-degree V8 with continuously variable valve timing.
The Roots-type supercharger was chosen for its combination of instant response and low parasitic losses. A Roots-type supercharger uses two “twisted” helical rotors that compress intake air and force it into the intake of the engine. The new larger rotor set is exclusive to the Northstar V8 SC. The supercharger is driven by a belt from the crankshaft pulley.
The supercharger rotor housing is integrated to the intake manifold in a unique and GM patented one-piece casting, which saves space and improves the flow of the intake charge. The manifold/housing module also contains four high efficiency water-to-air intercoolers that cool the charge after the supercharger compresses the air. These Laminova™ intercoolers are tubes with very fine external fins that provide for both heat transfer and damping pressure pulses from the supercharger to reduce noise.
Introduced for the 2005 4.6L Northstar V8, variable valve timing (VVT) uses continuously variable vane-type cam phasers on all four camshafts. These hydraulically controlled phasers vary the duration that the valves are open in relation to the intake and exhaust cycles of the engine, depending on engine speed and load. The intake valves are timed independently of the exhaust valves with the Northstar VVT system. The timing for the 4.4L supercharged engine is specific to optimize the boost provided by the supercharger.
Supercharged engines typically require slightly lower compression ratios than do naturally aspirated engines to compensate for boosted operation. The compression ratio of the 4.4L supercharged V8 is reduced to 9.0:1, compared to 10.5:1 for the naturally aspirated 4.6L engine in rear-drive applications. To improve fuel efficiency for the supercharged engine, the displacement was reduced from 4.6L to 4.4L by reducing the cylinder bore diameter from 93mm to 91mm. The new 4.4L engine carries over the 84mm stroke of the 4.6L engine. The new block is designed for the slightly smaller cylinders, taking advantage of extra structure to improve strength and rigidity. The smaller diameter pistons are also stronger, as are the connecting rods. The wrist pin bushings are also enlarged for greater strength. Overall, half of the parts for the supercharged engine are new compared with the 4.6L engine.
Further enhancements for the supercharged engine include a lubrication system modified for oil cooling jets that target the underside of the pistons. This cools the piston crowns, allowing more spark advance to increase engine output. To handle the extra heat generated by boosting the 4.4L supercharged engine, the water jacket in the block has been modified for more efficient flow of coolant. To ensure that the greater combustion chamber pressures are contained, the head gaskets are advanced multi-layer steel (MLS). The layers are coated to ensure sealing even the smallest of pores in the aluminum.
Electronic “drive-by-wire” throttle eliminates a mechanical link between the accelerator pedal and throttle plate. The 4.4L supercharged V8 has no throttle cable; instead, a potentiometer at the pedal measures pedal angle and sends a signal to the engine control module (ECM); the ECM then directs an electric motor to open the throttle at the appropriate rate and angle. Electronic Throttle Control (ETC) is integrated with the ECM, which uses data from multiple sources, including the transmission’s shift patterns and traction at the drive wheels, in determining how far to open the throttle. With this data, the 4.4L supercharged V8 effectively anticipates the driver’s demands, whether it’s a slow-speed parking maneuver or wide-open throttle operation on the open road, and responds appropriately. ETC delivers outstanding throttle response and greater reliability than a mechanical connection. Cruise control electronics are integrated in the throttle, reducing the amount of wiring required, further improving reliability and simplifying engine assembly. To control the complex flow of information from the ETC sensors, as well as the advanced variable valve timing system, the latest generation of engine control processors, E67, is used.
Other development specific to the supercharged engine was extensive flow and noise tuning. The intake system uses quarter-wave tuners to reduce noise without affecting airflow. The air cleaner itself is optimized for better flow, and the mass airflow sensor is also a minimally restrictive design. To increase exhaust flow, the exhaust ports in the cylinder heads are polished by a special process that forces an abrasive compound through the passages, called “extrude-honed”. The surfaces of the ports emerge shiny and smooth, reducing surface drag and improving flow. The valve seats are composed of an advanced copper-infiltrated material, which transfers the heat to the cooler cylinder head evenly. This allows the valves to withstand the higher thermal loading that supercharging produces.