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Northstar engine series

Development and features

The Northstar's design was initiated as a response to the advanced dual overhead cam V8 engines introduced by European and Japanese competitors of Cadillac in the late 1980s. At that time, Cadillac was using the aluminum HT Overhead Valve (OHV) V8 which had been pushed hastily into production after the failure of the V8-6-4 of 1981.

Cadillac was developing new models like the Allant and updated Eldorado and Seville STS which they hoped would compete against the best from BMW, Mercedes-Benz, Lexus, and Infiniti. They developed a laundry list of items that must be included in these new models, including sophisticated steering, braking, and suspension technologies, which became known as the Northstar System. One key element was a high-tech V8 engine with all of the features and performance of the competitors' offerings.

The "Northstar" V8, as it was then known, was an evolution of the Lotus-designed Chevrolet LT5 all-aluminum DOHC 32-valve V8 used in the Corvette ZR-1. Archrival Ford Motor Company was developing a similar engine at that time as well, and Ford's Modular engine would precede the Northstar into production with its introduction on the 1991 Lincoln Town Car. Both continue in production at 4.6 L of displacement.

Capable of producing 300 hp (224 kW) out of its 4565 cc displacement, the Northstar featured a cast aluminum 90 V8 block with 102 mm (4 in) 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 silicon gasket forms the oil gallery under this. A typical oil change used 7.58 quarts of oil.

Cast-iron cylinder liners were specified and the forged aluminum pistons included valve clearance. Northstar is an interference engine, with bronze pin bushings and free-floating piston pins used.

Cast aluminum cylinder heads were used featuring 4 valves per cylinder. The heads used dual overhead cams which are 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.

Eight thermoplastic tubes were used in the induction system, leading to sequential fuel injection. The engine used a distributorless ignition system with a waste spark setup. The PCM controls spark and fuel injection timing as well as the shift points for the new 4T80-E transmission.

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 100 mi (161 km) without damage.

Another unusual feature of some Northstar-equipped cars is a liquid-cooled alternator used on Cadillac's Seville, DeVille, and Eldorado. The liquid-cooling helped prolong the life of the alternator in these electronic-laden models, though GM reverted to a traditional air-cooled setup for 2001 to eliminate potential leak points and extraneous tubing.

All engines of this family share the same Northstar bellhousing pattern.

Later developments included direct coil-on-plug ignition, and variable valve timing, which can vary intake by up to 40 and the exhaust by up to 50. VVT was devised for the longitudinal LH2 version, and has not, to date, been used on the transverse front wheel drive engines due to packaging considerations.

Northstar series

The engine was introduced in mid-1992 in the 1993 Cadillac Allant and continues to be used in most Cadillac models. The original Northstar Allant also introduced the Northstar System which included traction control, adaptive suspension, and antilock brakes. Early Northstar required premium grade gasoline to run safely.

The Northstar was sold exclusively by Cadillac for over a decade before being introduced in the 2004 Pontiac Bonneville and 2006 Buick Lucerne. However, the 4.0L L47 V8 variant was used in the Oldsmobile Aurora and the 3.5L LX5 V6 in the Oldsmobile Intrigue. The engine received a forged steel crankshaft in October 2003. Cadillac had planned to introduce a V12 Northstar this decade, likely for use in the Escalade, but economics and new CAFE standards have killed this idea.

Most Northstar engines produce 275 hp (205 kW) to 315 hp (235 kW). The engines were revised for 2000 with coil-on-plug ignition and roller follower valvegear for improved fuel economy and reduced emissions. Though power output did not change, this update eliminated the need for premium fuel.

All but the supercharged Northstar displace 4.6 L (279 cu in) with a 93 mm (3.7 in) bore and 84 mm (3.3 in) stroke. For better head gasket sealing between cylinders, the supercharged version is de-bored to 91 mm (3.6 in) for a total displacement of 4.4 L (266 cu in) . The block is said[who?] to be capable of expansion up to 5.4 L, though no such engine has been produced.

The Northstar was on the Ward's 10 Best Engines list for 1995, 1996, and 1997.

The Northstar System was Cadillac's trademarked name for a package of automobile performance features. Introduced in mid 1992 on the 1993 Cadillac Allant and later on that year's Seville and Eldorado, the Northstar name continues in use to this day.

The Northstar System included the following components:

L37 high-output 300 hp (224 kW) and 295 ftlbf (400 Nm)

LD8 high-torque 275 hp (205 kW) and 300 ftlbf (407 Nm)

GM 4T80-E 4-speed automatic transmission

Road Sensing Suspension

RSS was available in both standard and CV-RSS (continuously-variable) systems. It monitored damping rates of the shock absorbers every 15 milliseconds, selecting between two settings.

4-wheel disc brakes with Bosch antilock brakes

Magnasteer speed-variable power steering

Magnasteer combines conventional hydraulic power steering and magnetized "doughnuts" mounted around the output shaft, which stiffen the steering as vehicle speed increases.

The latest versions of the Northstar engine include the 4.6L 320 hp (239 kW) and 315 lbft (427 Nm) LH2 which began in 2004, and supercharged 4.4L 469 hp (350 kW) LC3 created for the STS-V which are detailed below.

General Motors employed a continuously variable system for the Cadillac Northstar System, VVT (Variable Valve Timing). The Northstar VVT provides a continuously variable system throughout the RPM range, increasing fuel economy. GM engines use the double overhead cam, varying both intake and exhaust for better performance.

L37

The L37 (VIN "9") was the original Northstar. It is tuned for responsiveness and power, while the later LD8 is designed for more sedate use. The L37 code has been used on all high-output transverse Northstars, even as the exact engine specifications evolved. Its displacement is 4600cc flat the compression ratio for the L37 is 10:1, shared with the LD8.

The original L37 was specified at 290 hp (216 kW), but 1993 production examples were rated at 295 hp (220 kW). The engine topped out at 300 hp (224 kW) from 1996 through 2004 on the STS, DTS and ETC models, making these some of the most powerful domestic front wheel drive cars ever built, the most powerful title still belonging to the 1970 Cadillac Eldorado 500 cu in (8.2 L) with 400 hp (298 kW) (although the latter's rating is in the older SAE gross horsepower system, figured without accessories or muffler, where the current engine outputs are as-installed, net ratings). For 2005 the high output Northstar became Northstar NHP, and was downrated to 290 horsepower (220 kW) under the new SAE certified horsepower rating system. In 2006, the updated DTS "Performance Package" model got a slight bump to 292 hp (218 kW). Vehicles using the L37 include:

Year

Model

Power

Torque

1993

Cadillac Allant

295 hp (220 kW) @ 5600 rpm

290 lbft (393 Nm) @ 4400 rpm

1993-1994

Cadillac Eldorado ETC

295 hp (220 kW) @ 5600 rpm

290 lbft (393 Nm) @ 4400 rpm

19952002

Cadillac Eldorado ETC

300 hp (224 kW) @ 6000 rpm

295 lbft (400 Nm) @ 4400 rpm

1993

Cadillac Seville STS

295 hp (220 kW) @ 5600 rpm

290 lbft (393 Nm) @ 4400 rpm

19942004

Cadillac Seville STS

300 hp (224 kW) @ 6000 rpm

295 lbft (400 Nm) @ 4400 rpm

19962004

Cadillac DeVille Concours/DTS

300 hp (224 kW) @ 6000 rpm

295 lbft (400 Nm) @ 4400 rpm

2005

Cadillac DeVille DTS

290 hp (216 kW) @ 5600 rpm

285 lbft (386 Nm) @ 4400 rpm

2006resent

Cadillac DTS Performance

292 hp (218 kW) @ 6300 rpm

288 lbft (390 Nm) @ 4500 rpm

2008-present

Buick Lucerne Super

292 hp (218 kW) @ 6300 rpm

288 lbft (390 Nm) @ 4500 rpm

LD8

The LD8 (VIN "Y") is a transverse V8 for front-wheel drive cars. Introduced in 1994, it is designed to provide more torque than the high-revving L37. The LD8 code has been used on all torque-tuned transverse Northstars, even as the exact engine specifications evolved. Compression ratio is 10:1.

The 1998 revision is quieter than previous Northstar engines, due to hydraulic engine mounts, and performs better due to a tuned intake system.

Most LD8 Northstars are rated at 275 hp (205 kW) and 300 lbft (407 Nm).

Year

Model

Power

Torque

1994

Cadillac Eldorado

270 hp (201 kW)

300 lbft (407 Nm)

19952001

Cadillac Eldorado

275 hp (205 kW) @ 5750 rpm

300 lbft (407 Nm)

2002

Cadillac Eldorado

275 hp (205 kW) @ 5600 rpm

300 lbft (407 Nm) @ 4000 rpm

1994

Cadillac Seville SLS

270 hp (201 kW)

300 lbft (407 Nm)

19952001

Cadillac Seville SLS

275 hp (205 kW)

300 lbft (407 Nm)

20022004

Cadillac Seville SLS

275 hp (205 kW)

300 lbft (407 Nm)

1994

Cadillac DeVille Concours

270 hp (201 kW)

300 lbft (407 Nm)

1995

Cadillac DeVille Concours

275 hp (205 kW) @ 5750 rpm

300 lbft (407 Nm)

19962001

Cadillac DeVille

275 hp (205 kW) @ 5750 rpm

300 lbft (407 Nm) @ 4000 rpm

20022005

Cadillac DeVille

275 hp (205 kW) @ 5600 rpm

300 lbft (407 Nm) @ 4000 rpm

2006resent

Cadillac DTS

275 hp (205 kW) @ 6000 rpm

295 lbft (400 Nm) @ 4400 rpm

20042005

Pontiac Bonneville GXP

275 hp (205 kW) @ 5600 rpm

300 lbft (407 Nm) @ 4000 rpm

20062007

Buick Lucerne CXS

275 hp (205 kW) @ 6000 rpm

295 lbft (400 Nm) @ 4400 rpm

LH2

The Northstar was designed originally for transverse front-wheel drive applications. It was modified substantially in 2004 for longitudinal rear- and all-wheel drive use in the SRX and XLR, as well as receiving continuously variable valve timing on both intake and exhaust sides. The RWD (LH2) Northstar produces 320 hp (239 kW) and 315 lbft (427 Nm). An increased compression ratio of 10.5:1 enables most of the increase in power from the L37 and LD8 Northstars.

Year

Model

Power

Torque

20042009

Cadillac SRX

320 hp (239 kW) @ 6400 rpm

315 lbft (427 Nm) @ 4400 rpm

20042009

Cadillac XLR

320 hp (239 kW) @ 6400 rpm

310 lbft (420 Nm) @ 4400 rpm

2004resent

Cadillac STS

320 hp (239 kW) @ 6400 rpm

315 lbft (427 Nm) @ 4400 rpm

Supercharged LC3

A 4.4 L (266 cu in) supercharged Northstar is used in the 2006 Cadillac STS-V and Cadillac XLR-V. The bore was reduced for increased strength and improved head gasket sealing. Variable valve timing is used on both the intake and exhaust sides. The STS-V engine produces 469 hp (350 kW) at 6400 rpm and 439 lbft (595 Nm) at 3900 rpm with 9:1 compression and the XLR-V engine produces 443 hp (330 kW) at 6400 rpm and 414 lbft (561 Nm) at 3900 rpm.

Year

Model

Power

Torque

20062009

Cadillac STS-V

469 hp (350 kW) @ 6400 rpm

439 lbft (595 Nm) @ 3900 rpm

20062009

Cadillac XLR-V

443 hp (330 kW) @ 6400 rpm

414 lbft (561 Nm) @ 3900 rpm

L47

A L47 inside an Aurora's engine bay

The L47 Aurora engine was a special V8 designed for the Oldsmobile Aurora, based on the Northstar engine. It is a DOHC 3,995 cc (3.995 L; 243.8 cu in) V8 which produced 250 horsepower (186 kW) and 260 ftlb (353 Nm) of torque. The bore is 87 mm (3.4 in) and the stroke is 84 mm (3.3 in). The L47 has a 10.3:1 compression ratio and uses premium fuel.

An early version or prototype of this engine was used in the 2nd generation Oldsmobile Aerotech.

Although most of the Northstar's features, including the coolant loss system, remained intact, the decreased bore increased weight unacceptably. To reduce it, Oldsmobile used a one-piece glass-filled thermoplastic intake manifold and simplified AC Rochester sequential fuel injection. A new die-cast structural aluminum oil pan incorporated baffling to reduce oil starvation in hard driving. A starter interlock prevents the starter from engaging if the quiet L47 is already running.

A highly modified 650 hp (485 kW) version of this engine was used by General Motors racing division initially for Indy Racing League competition starting in 1995, then was later used in the Cadillac Northstar LMP program in 2000. Both engines retained the 4.0 L capacity, but the Northstar LMP version was twin-turbocharged.

The Aurora was also used in the Shelby Series 1 car.

The Aurora engine was introduced in 1994 for the 1995 model year, and General Motors has not used this engine since the demise of the marque in 2004.

Year

Model

Power

Torque

19952003

Oldsmobile Aurora

250 hp (186 kW) @ 5600 rpm

260 lbft (353 Nm) @ 4400 rpm

LX5 (Shortstar)

A "Shortstar" LX5 inside an Intrigue's engine bay

The LX5 V6 is a DOHC engine from Oldsmobile, introduced in 1999 with the Oldsmobile Intrigue. It was produced by the Premium engine group at GM and was thus called the Premium V6, or PV6, while it was being developed. It is based on the L47 Aurora V8, which is itself based on the Northstar engine, so engineers called it the Short North, though Oldsmobile fans have taken to calling it the Shortstar.

It is not a simple cut-down V8. Although it has a 90 vee-angle like the Northstar and Aurora, the engine block was engineered from scratch, so bore centers are different. It has chain-driven dual overhead cams and 4 valves per cylinder, but is an even-firing design with a split-pin crankshaft similar to the modern GM 3800 engines. The LX5 displaced 3,473 cc (3.473 L; 211.9 cu in) and produced 215 hp (160 kW) @ 5,600 rpm and 230 ftlb (312 Nm) @ 4,400 rpm. Bore is 89.5 mm (3.52 in) and stroke is 92 mm (3.6 in). Compression ratio is 9.3:1.

The cost of building this engine was high, and it was not used in many vehicles. It was said at the time that a family of premium V6s would follow, with displacements ranging from 3.3 L to 3.7 L, but only the LX5 was ever produced.

The LX5 was entirely different from any other V6 in the GM inventory - the only other DOHC V6 engines offered by GM were the Chevrolet Twin Dual Cam produced from 1991-1997 and the Cadillac/Holden HFV6 available from 2004 to the present day. These three designs are completely unrelated and oddly enough leave two gaps in 1998 and 2003 where no DOHC V6 was available from GM. This contrasts starkly with competitors practices of evolving engineering over multiple, continuously improving designs.

As with the Aurora V8, production stopped with the demise of Oldsmobile.

Year

Model

Power

Torque

19992002

Oldsmobile Intrigue

215 hp (160 kW) @ 5600 rpm

230 lbft (312 Nm) @ 4400 rpm

20012002

Oldsmobile Aurora

215 hp (160 kW) @ 5600 rpm

230 lbft (312 Nm) @ 4400 rpm

The 3.5L LX5 was on the Ward's 10 Best Engines list for 1999 and 2000.

See also

GM 60-degree DOHC V6 engine

GM High Feature engine

Cadillac V8 engine

GM Ultra Engine

List of GM engines

Notes

^ http://74.125.47.132/search?q=cache:6nj6yREp_4wJ:www.ehow.com/facts_5467367_northstar-engine-information.html+LT5+northstar&cd=10&hl=en&ct=clnk&gl=us

^ Weitzman, Larry (2001).The Aurora by Oldsmobile (2001), Better in every respect. Autochannel. Retrieved on June 28, 2009.

References

Frank Markus. "1993 Technical Highlights". Car and Driver (October 1992): 5960. 

"Technical Highlights". Car and Driver (October 1993): 115. 

Joel D. Pietrangelo. "Northstar is heart of Allante re-do for '93 - V-8 engine, General Motors' Cadillac Motor Car Div.'s new model roadster". Ward's Auto World (February 1992). 

External links

Northstar engine - official website

Technical article from AutoSpeed

Ward's article

GM Premium V Performance Discussion Forums

Categories: Cadillac engines | GM engines | Automotive technology tradenamesHidden categories: All articles with specifically-marked weasel-worded phrases | Articles with specifically-marked weasel-worded phrases from September 2008
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