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Did You Know?
The Northstar engine was ranked as one of the 10 best engines in North America by Ward's Auto World, consecutively for the year 1995, 1996, and 1997.
It was the year 1990, and good old America was once again under threat from the expanding prowess of Germany and Japan. Both had been steadily taking over the world and already; their troops had established camps on American shores. Whether or not USA would fall prey to this seemingly unstoppable duo, it was up to General Motors (GM) to decide!

In the war waged for the domination of the world of automobiles, the legendary all-American automobile giant GM took up the challenge of defending the American four-wheeler realm. Their answer to the technological war-cries of the east was the Northstar engine. Touted as GM's most complex and advanced engine architecture ever, the Northstar engine has had a long run of almost 17 years, during which it has become a milestone in American automobile development. In the following sections, we shall learn more about the historic Northstar engine.

History of the Northstar Engine

General Motor's Cadillac division of cars has always been associated with luxury and class. Since GM's purchase of the company in 1909, Cadillac, through continuous technological advancements, has managed to establish itself as one of America's most respected premier luxury car brands.

In the late 1980s, German competitors such as BMW and Mercedes-Benz started vying for the large American four-wheeler market. At the same time, Japanese rivals Toyota and Nissan sent forth their luxury brands Lexus and Infinity to heat up the competition. All these cars came armed to the hilt with such exciting features that were never before seen on American soil.

Among the most alluring of these was the new-generation dual overhead cam V8 engine, which was a direct challenge to the aluminum HT Overhead Valve (OHV) V8 that the Cadillac was using at the time. No matter how one looked at it, Cadillac's engine simply was no match to the European and Japanese models, and soon, GM started losing its precious luxury market share. Soon, it became a do or die situation for them.

The engineers at GM were faced with the daunting task of completely overhauling the luxury Cadillac brand. They prepared a checklist of changes which they decided to incorporate into new models. This included sophisticated suspensions, brakes, steering, and most importantly, a brand new high-tech engine with all the features that the competition was offering, and more. They decided to name this engine the Northstar engine, and the supporting system of steering brakes and suspension the Northstar system.

Northstar Engine Specifications and Features

The Northstar engine made its debut in the year 1992 on the Cadillac Allanté, which was a two-seater roadster that GM pitted against the sports cars from Germany and Japan. It featured a highly complex design and advanced features, which GM hoped would be the game changer for them.

The Northstar engine comprises a cast aluminum 90° V8 block, with a 102 mm bore spacing split into unitary upper and lower halves. It is capable of producing 300 hp, and has an engine displacement of 4565 cc. The lower crank case assembly supports the crankshaft without the conventional main bearing caps. Under this, the oil gallery is located which can typically hold 7.5 - 8 quartz of oil.

This is an interference engine having bronze pin bushings and free-floating pins. The cylinder liners are cast-iron, while the pistons are made of cast-aluminum. There are a total of 4 valves per cylinder. The cast-aluminum cylinder heads use dual overhead cams driven by the maintenance-free cam-drive chain case. They act directly on hydraulic lifters at the ends of the valves, and are fed via a lubrication passage drilled lengthwise through the cylinder head.

The intake valve is angled at 25°, and the exhaust is canted to 7°. Platinum-tipped spark plugs are mounted at the center. To reduce the weight, the cam covers are made up of magnesium.

The induction system comprises 8 thermoplastic tubes which are used for sequential fuel injection. The firing of the spark plugs, along with the delicate fuel-injection timing, is controlled by the powertrain control module (PCM). The PCM also controls the 4T80-E transmission.

One of the most advertised features of the Northstar engine was what GM called its 'limp-home' mode. This mode was basically a fail-safe, in which the engine could be run even in the absence of a coolant for a limited amount of time. It worked by switching cylinder banks supplying fuel to them alternately, which allowed the inactive bank to be air-cooled. This technique, coupled with the engine's all-aluminum construction and large oil capacity, enables the engine to maintain safe running temperatures for up to a distance of about 100 miles, without any significant damage.

A rather quirky feature on some Northstar-equipped cars was a liquid-cooled alternator which GM claimed would prolong its life. It was used in the Seville, DeVille, and Eldorado models of Cadillac, but was discontinued in 2001 in favor of an air-cooled setup, owing to complaints of leaks.

In the later years, more developments were made to the original Northstar design. These included a direct coil-on-plug ignition system, variable valve timing (VVT) which could vary intake by up to 40° and exhaust by 50°. VVT was designed for the longitudinal LH2 version of the Northstar, and due to packaging issues, wasn't used on the transverse front-wheel drive engines.

The Northstar Series of Engines

The Northstar engine was originally designed for the Cadillac. However, in its 17-year long tenure, it found home in other cars as well. Many revisions were made to the original design in order to make it compatible to different models.

Cadillac Allanté, released in mid 1992, was the first car to house a Northstar engine. It also introduced the Northstar system comprising traction control, adaptive suspension, and anti-lock braking system (ABS). The Northstar engine in the Allanté and many of its subsequent versions required premium grade gasoline. In 1993, it was used in the Cadillac Seville and Eldorado. This original Northstar engine, known as the L37, was a 4.6 lt 32-valve dual overhead cam all-aluminum V8 engine, outputting 295 hp.

In 1994, another version, the LD8, was released. It had a different cam profile and a lower peak horsepower rating of 270 hp. However, it managed to have an improved throttle response and increased torque output in the lower rpm range.

The L37 4.6 lt V8 was again updated in 1995, and it now had a slightly improved power rating of 300 hp. Similarly, the 4.6 lt LD8 too received a 5 hp push, bringing its overall power output to 275 hp. These two versions continued to be used in different Cadillac models for almost a decade.

For a long time, the Northstar engine graced only the Cadillac, until it was finally adopted in the Pontiac Bonneville in 2004, and later in the Buick Lucerne in 2006. Also, a 4.0 lt L47 V8 version was used in the Oldsmobile Arora, while a 3.5 lt LX5 V6 was used in the Oldsmobile Intrigue. Towards the end of 2003, the engine received a forged steel crankshaft. A V12 version was planned for the Escalade, but due to the new CAFE standards, the idea had to be discarded.

The Northstar was originally designed for front-wheel drive vehicles. However, in 2004, it was modified for the rear-wheel and all-wheel drive STS, SRX, and XLR models of Cadillac. The rear-wheel drive engine, known as the RWD(LH2) Northstar, had a power output of 320 hp and a torque of 315 lb-ft.

In 2005, Cadillac received a much-needed upgrade, with a 4.4 lt supercharged (LC3) Northstar V8 engine, and a brand new hydra-matic six-speed automatic transmission system. The power output of the new engine was 469 hp at 6000 rpm, with a torque of 439lbs-ft at 3900 rpm. These were the highest figures that the Cadillac had ever produced. This engine was featured in the 2006-2009 Cadillac STS-V, and a slightly scaled 443 hp version was used in the 2006-2009 Cadillac XLR-V

Though the L37 and LD8 engines made it on the Cadillac DTS and CTS, released in 2010, in July the same year, GM decided to cease production of the Northstar engine altogether. Newer Cadillac models, like the CTS-V, feature the small-block OHV engine, which is a much simpler design in comparison to the Northstar.

Common Problems

Beyond a doubt, the Northstar engines were a technological masterpiece when they were first released. They created a hype in the market, and the sales of Cadillac rose subsequently. However, no technology is perfect, and over the years, GM's customers realized that there were several chinks in the Northstar's armor.

In the original Northstar V-8 of 1994-1999, oil leakage was a common issue. This problem occurred due to the seating of the oil-seal within the aluminum block. However, Cadillac fans dismissed this problem, arguing that it wasn't uncommon for high performance engines to use greater amounts of oil. GM later was able to fix this issue by developing a rear oil-seal that pressed into the block. However, it could only be removed or replaced by using a special service tool.

Another common problem was that of the head gasket blowup. Burning of oil caused a buildup of debris in the engine, because of which, the engine would overheat and the gasket would blow up. GM developed a cleaning kit to solve this issue.

When it was first introduced, the Northstar engine was a quantum leap forward for GM. This highly advanced engine enabled GM to take on the European and Japanese rivals, and though it has had a bumpy ride from start to finish, it shall always be remembered as one of the benchmark designs of the American automotive industry.