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Engineering at Work in Cadillac's Northstar V8
Chalsma, Jennifer K.. Machine Design. Cleveland: Jun 11, 1992. Vol. 64, Iss. 11; p. 30 (4 pages)
Abstract (Document Summary)
The 1993 Allante is the first Cadillac equipped with General Motors' new 32-valve Northstar engine. The 4.6 Northstar engine is the product of an intensive, 4-year development process. The result is a 90 degree V8 engine that delivers a peak output of 290 hp at 5,600 rpm and 290 lb-ft of torque at 4,400 rpm, powering the Allante from zero to 60 mph in 6.9 seconds and to a top speed of 150 mph. The Northstar engine requires no maintenance for 100,000 miles, except for fluids and filters, and it is so quiet that designers had to install an interlock that prevents a driver from inadvertently turning the starter when the engine is running. The engine block is a 3-piece assembly consisting of the upper cylinder block, lower crankcase with integral main bearing caps, and oil manifold plate. The 4T80-E transmission is electronically controlled for increased reliability and smooth shifting. It does not use a throttle valve cable, vacuum modulator, or governor.
Full Text (610 words)
Copyright Penton Publishing Jun 11, 1992
Since its introduction in 1987, the Allante has been a showcase for automotive technology at Cadillac. It was the first Cadillac with four-wheel antilock brakes as standard equipment, the first to offer traction control, the first with speed-dependent damping, and the first front-wheel-drive vehicle with a 200hp V8 engine. Now the 1993 Allante is is the first Cadillac equipped with GM's new 32-valve Northstar engine.
This 4.6-liter power plant is the product of an intensive, four-year development process. Engine design was carried out with concurrent-engineering practices involving cross-functional design teams, customer groups, suppliers, and manufacturing engineers. The result is a 90deg V8 engine that delivers a peak output of 290 hp at 5,600 rpm and 290 lb-ft of torque at 4,400 rpm, powering the Allante from 0 to 60 mph in 6.9 seconds and to a top speed of 150 mph.
In addition to performance, Cadillac's goals for the engine were quality, reliability, durability, and smooth and quiet operation. These aims were met so successfully that the engine requires a maintenance for 100,000 miles, except for fluids and filters, and it is so quiet that designers had to install an interlock that prevents a driver from inadvertently turning the stater when the engine is running.
ENGINE BLOCK
The aluminum block is a three-piece assembly consisting of the upper cylinder block, lower crankcase with intergral main bearing caps, and oil manifold plate. The lower crankcase assembly uses a four-bolt, main-bearing attachment and surrounds the crankshaft for improved rigidity, resulting in reduced noise. This type of assembly is usually found only in high-performance racing cars. To help eliminate the problems of differential thermal expansion between the iron crankshaft and aluminum block, the main bearings are 4-mm thick and steel-backed.
Using aluminum for the block keeps the mass low--weight without accessories totals 403.9 lb --and provides a more balanced front-to-rear weight distribution. Iron cylinder-bore liners are cast directly into the block to improve rigidity and decrease the chance that the liners will ship or creep. To further improve rigidity, the engine is designed with only four "T" joints, where multiple planes meet. The 1992 Allante engine, by contrast, has 18.
IGNITION SYSTEM
The Northstar is the first Cadillac engine equipped with a distributorless, direct-ignition system made of four separate coils with no moving parts. It is designed to provide spark delivery at up to 7,000 rpm without any loss of spark as is typical in a conventional coil/distributor system. It also uses 25% less voltage than a conventional distributor.
Spark delivery is determined by a relutor ring cast directly on the crankshaft. The reluctor provides information on the rotational orientation and speed of the crankshaft. In operation, when there is a break in the magnetic field between the reluctor ring and position sensors located in the crankcase, a signal is sent to deliver spark. Reliability of the system is enhanced because the sensors are loicated internally and are less prone to failure from dirt and oxidation. Dual-tipped platinum spark plugs that do not have to be changed for 100,000 miles complete the system.
The unique 1-2-7-3-4-5-6-8 firing order was chosen to reduce torsional vibration and front main-bearing stress, and to minimize overall noise.
A small starter located in the V of the block saves exterior space and is protected from road splash and environment. To service it, a technician need only remove the four bolts holding the fluid-induction system.
Because the engine is mounted transversely in the vechicle and most of the accessories mount toward the front of the vehicle, or left side of the engine, the right bank of cylinders is staggered forward to provide additional space for accessories on the left.
Chalsma, Jennifer K.. Machine Design. Cleveland: Jun 11, 1992. Vol. 64, Iss. 11; p. 30 (4 pages)
Abstract (Document Summary)
The 1993 Allante is the first Cadillac equipped with General Motors' new 32-valve Northstar engine. The 4.6 Northstar engine is the product of an intensive, 4-year development process. The result is a 90 degree V8 engine that delivers a peak output of 290 hp at 5,600 rpm and 290 lb-ft of torque at 4,400 rpm, powering the Allante from zero to 60 mph in 6.9 seconds and to a top speed of 150 mph. The Northstar engine requires no maintenance for 100,000 miles, except for fluids and filters, and it is so quiet that designers had to install an interlock that prevents a driver from inadvertently turning the starter when the engine is running. The engine block is a 3-piece assembly consisting of the upper cylinder block, lower crankcase with integral main bearing caps, and oil manifold plate. The 4T80-E transmission is electronically controlled for increased reliability and smooth shifting. It does not use a throttle valve cable, vacuum modulator, or governor.
Full Text (610 words)
Copyright Penton Publishing Jun 11, 1992
Since its introduction in 1987, the Allante has been a showcase for automotive technology at Cadillac. It was the first Cadillac with four-wheel antilock brakes as standard equipment, the first to offer traction control, the first with speed-dependent damping, and the first front-wheel-drive vehicle with a 200hp V8 engine. Now the 1993 Allante is is the first Cadillac equipped with GM's new 32-valve Northstar engine.
This 4.6-liter power plant is the product of an intensive, four-year development process. Engine design was carried out with concurrent-engineering practices involving cross-functional design teams, customer groups, suppliers, and manufacturing engineers. The result is a 90deg V8 engine that delivers a peak output of 290 hp at 5,600 rpm and 290 lb-ft of torque at 4,400 rpm, powering the Allante from 0 to 60 mph in 6.9 seconds and to a top speed of 150 mph.
In addition to performance, Cadillac's goals for the engine were quality, reliability, durability, and smooth and quiet operation. These aims were met so successfully that the engine requires a maintenance for 100,000 miles, except for fluids and filters, and it is so quiet that designers had to install an interlock that prevents a driver from inadvertently turning the stater when the engine is running.
ENGINE BLOCK
The aluminum block is a three-piece assembly consisting of the upper cylinder block, lower crankcase with intergral main bearing caps, and oil manifold plate. The lower crankcase assembly uses a four-bolt, main-bearing attachment and surrounds the crankshaft for improved rigidity, resulting in reduced noise. This type of assembly is usually found only in high-performance racing cars. To help eliminate the problems of differential thermal expansion between the iron crankshaft and aluminum block, the main bearings are 4-mm thick and steel-backed.
Using aluminum for the block keeps the mass low--weight without accessories totals 403.9 lb --and provides a more balanced front-to-rear weight distribution. Iron cylinder-bore liners are cast directly into the block to improve rigidity and decrease the chance that the liners will ship or creep. To further improve rigidity, the engine is designed with only four "T" joints, where multiple planes meet. The 1992 Allante engine, by contrast, has 18.
IGNITION SYSTEM
The Northstar is the first Cadillac engine equipped with a distributorless, direct-ignition system made of four separate coils with no moving parts. It is designed to provide spark delivery at up to 7,000 rpm without any loss of spark as is typical in a conventional coil/distributor system. It also uses 25% less voltage than a conventional distributor.
Spark delivery is determined by a relutor ring cast directly on the crankshaft. The reluctor provides information on the rotational orientation and speed of the crankshaft. In operation, when there is a break in the magnetic field between the reluctor ring and position sensors located in the crankcase, a signal is sent to deliver spark. Reliability of the system is enhanced because the sensors are loicated internally and are less prone to failure from dirt and oxidation. Dual-tipped platinum spark plugs that do not have to be changed for 100,000 miles complete the system.
The unique 1-2-7-3-4-5-6-8 firing order was chosen to reduce torsional vibration and front main-bearing stress, and to minimize overall noise.
A small starter located in the V of the block saves exterior space and is protected from road splash and environment. To service it, a technician need only remove the four bolts holding the fluid-induction system.
Because the engine is mounted transversely in the vechicle and most of the accessories mount toward the front of the vehicle, or left side of the engine, the right bank of cylinders is staggered forward to provide additional space for accessories on the left.