the Northstar System. Central to it was a high-tech V8 with the performance and sophistication to compete with an ever-expanding list of imported challengers. Capable of producing out of its displacement, the Northstar featured a cast aluminum 90° V8 block with bore spacing split into unitary upper and lower halves. The lower crankcase assembly supported the crankshaft without conventional main bearing caps. An oil manifold plate with an integrated silicone gasket forms the oil gallery under this. A typical oil change used of oil. GM specified cast-iron cylinder liners and the cast aluminum pistons included valve clearance. Northstar is an interference engine: the valves will strike the pistons if they lose timing. It has bronze piston pin bushings and free-floating piston pins. GM used cast aluminum cylinder heads featuring 4 valves per cylinder. The heads used dual overhead cams driven through the "maintenance-free" cam-drive chain case. The cams act directly on hydraulic lifters on the ends of the valves and are fed with a lubrication passage drilled through the cylinder head lengthwise. The intake valves are inclined at 25°, while the exhaust valves are canted to 7° with center-mounted platinum-tipped spark plugs. The cam covers are magnesium for light weight and sound damping. Sequential fuel injection was delivered via eight thermoplastic tubes. Ignition was distributorless, with a waste spark setup. The powertrain control module (PCM) controlled spark and fuel injection timing as well as the shift points for the new four-speed, transverse GM 4T80 transmission. All engines of this family share the same Northstar bellhousing pattern. One notable feature advertised at the time was the "limp home" fail-safe mode, which allowed the engine to continue running for a limited time without any coolant. Supplying fuel to only one cylinder bank in turn, the engine would "air cool" the inactive bank. This technique, combined with its all-aluminum construction and large oil capacity, allows the engine to maintain safe temperatures, allowing a Northstar-equipped car to be driven with no coolant for about without damage. Another unusual feature of some heavily electronic-laden Northstar-equipped cars such as the Seville, DeVille, and Eldorado is a liquid-cooled alternator. Although this was intended to prolong alternator life, GM reverted to a traditional air-cooled setup for 2001 to eliminate potential leak points and extraneous tubing. Later developments included direct coil-on-plug ignition, roller lifters, and variable valve timing, which can vary intake by up to 40° and the exhaust