Northstar Engines and System Technical Discussion Discussion, cool Northstar info. in Cadillac Engine Discussion; Engineering at Work in Cadillac's Northstar V8
Chalsma, Jennifer K.. Machine Design . Cleveland: Jun 11, 1992. Vol. 64, Iss. ...
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.
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.
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.
Intake manifold wins top prize at auto division's 24th Annual Awards Banquet
J Eddy. Plastics Engineering. Brookfield Center: Dec 1994. Vol. 50, Iss. 12; p. 18 (2 pages)
The thermoplastic air intake manifold for the 1995 GM Cadillac Northstar V-8 engine won the Grand Award at the SPE Automotive Division's 24th Anual Automotive Awards Banquet, held 3 November 1994 in Detroit, Michigan, USA. The Grand Award recognizes the most innovative use of plastics in an automotive application of the model year 1995. Designed and produced by Freudenberg-NOK's Plastic Products Division, the Northstar component is said to be the most complex automotive plastic intake manifold currently in production. The manifold is made of BASF's glass fiber reinforced Ultramid nylon 6/6, which is specially formulated to resist engine temperatures and attack from oil, fuel, and underhood fluids. Other award-winning components are briefly described.
Pennington, J N. Modern Metals (USA). Vol. 47, no. 4, pp. 56, 58-61. May 1992
Design of the North Star 4.6 l, 290 hp engine is freely derived from racing practice: four chain-driven overhead camshafts; four valves/cylinder; a two-piece, short-skirt block; and light alloys throughout. The Northstar contains more Al, 59 lb in the upper casting and 21 lb in the lower, compared to a total of 47 lb for the older design.
Wrigley, A. American Metal Market. Vol. 103, no. 75, pp. 8. 19 Apr. 1995
General Motors Corp. is seriously considering converting a major component, the lower crankcase, of its 4.6-liter Cadillac Northstar V-8 engine to magnesium from aluminum. Such a move would save 7 lb or more per engine and provide a new application for Mg die-casting material worth at least 7.5 million lb gross annually) 9% of the current total annual die-castings market for primary Mg in North America. However, the growing price difference between Mg and Al looms as a potential obstacle to these plans, according to GM sources in Detroit, Michigan, USA.
Wrigley, A. American Metal Market (USA). Vol. 107, no. 41, pp. 5. 3 Mar. 1999
After considering other materials, General Motors Corp has decided to continue using Mg cam covers on its 4.6-liter Northstar V-8 engines. It expects to use between 400 000-500 000 of the lightweight covers on those engines in the 2000 model run starting in summer 1999. GM considered switching to molded plastic or cast aluminum units because of the high cost of Mg. But the weight-savings, dimensional stability and sound-damping properties of the cast Mg units decided the issue in Mg's favor.