When it comes to the United States in recent years, excellent engine, and that the most value overemphasize say is common NORTHSTAR Polaris, the engine is now generally mounted on a common premium brand Cadillac all models. Americans are not good at doing engine, it is an indisputable fact. When the Japanese, Germans spend heavily in research engine technology, burning oil does not blink Americans still pursuing spacious and comfortable enjoyment, American carmakers not to focus on the development of engines, engine technology makes the United States lags behind Japan, Europe and other counterparts. But the emergence of Polaris engines changed this situation, it is no exaggeration to say that the United States Northstar engine engine industry has epoch-making significance.
1, resulting in the development process
Northstar engine was first unveiled in 1993 Cadillac Allante, Eldorado and Seville STS three cars on, because it is a large displacement V8 engine, so basically used outside of the Cadillac luxury brand, then this Polaris V8 codenamed L37, displacement of 4.6 liters. Then Polaris virtue of their excellent liter power and excellent fuel consumption and reliable performance make Mercedes-Benz and BMW are the same displacement engine in the US market to shame.
In 1994, L37 Northstar V8 engine celebrates its latest version LD8. LD8 biggest change over the re-create the cam shape, reducing the power, but it improved low speed torque, is more suitable for such use SUV SRX. In 1995, the first generation L37 Polaris 4.6 liters V8 engine is adjusted to 300. The LD8 version of the Polaris also rose to 275. That is to say to the 95-year, 4.6-liter Northstar engine has two versions, namely 275 and 300. It is worth mentioning, both the L37 and LD8 Northstar has been in use to this day, the current Cadillac DTS is to use the L37, the latest flagship Buick Lucerne cars use LD8.
time to 2004, there has been code-named Polaris LH2 engine on the Cadillac XLR sports car and luxury SUV SRX, the 2005 Cadillac STS also spend LH2. LH2 using VVT variable valve timing technology, which although in Japanese, German car already commonplace, but in the US the engine is a breakthrough. In addition, LH2 also brought new ETC electronic throttle control technology. Other Polaris engines gradually equipped with ETC. Polaris entire family present total of 4 engines, namely 4.4LV8 (LC3), 4.6LV8 (L37), 4.6LV8 (LD8) and 4.6LV8VVT (LH2). Polaris Polaris the V8 engine features generally made from aluminum die-casting, after 2000, common aluminum alloy in order to reduce porosity occurs during the forming process, using a new high pressure casting process, improving performance. In the year 2000, Polaris engine compression ratio of 10.3: 1, to the years after 2000 changed 10: 1. Double camshaft per cylinder, four-valve, the camshaft chain drive taken, Polaris engine intake manifold 66 is made of a thermoplastic nylon, but it can not receive heat from the engine pass over at the same time cooling the intake air the impact, thereby maintaining good working conditions. Polaris using a common SFI (sequential fuel injection) fuel injection sequential manner into the cylinder, intake and exhaust cam position is controlled by the inductor, so as to accurately fit in and out of the gas cylinder.
Polaris also a feature that the engine can continue to run when all coolant are unavailable. When the computer detects the condition of the engine is overheating, it will temporarily stop half-cylinder operation, which can reduce the temperature of the whole engine, in order to allow the vehicle to continue driving, but GM warned that this situation is also up not only with more than 50 miles. Polaris Cadillac DeVille and Seville in the body is also equipped with a liquid-cooled AC motor due to excessive Cadillac body electronic parts has increased the burden on the power system, so by way of a liquid-cooled to ensure operation of the generator. But in 2001, GM re-use air-cooled AC motor, the purpose is to prevent leakage of liquid cooling brought about. ArcticStar engine now represents the highest technology US engine technology, the engine has been sold with the introduction of the SRX and XLR came to China, I hope that through this article, to give readers more clear understanding of Polaris engines.
2, and the history of technology explain
A brand has features different from other brands, wanted this feature for a long time only to hold, the best approach is to rely on leading-edge technology. Like the public
have the best FSI and TDI technology, Toyota has interpreted superb VVT-I technology like GM also has a world-renowned best engine assembly – Polaris Series engine.
1996 North star 32valve v8 engine
Northstar engine was first unveiled at the 1993 Cadillac Allante, Eldorado and Seville STS these three car , codenamed L37. It is precisely because it has had a large displacement V8 features, so almost all are arranged in a Cadillac on this luxury brand. In 1994, L37 Northstar V8 engine improvements ushered in by an updated version LD8. The biggest change is LD8 redesigned cam curve, part of engine power is reduced, but improved torque at low engine speed, thus LD8 more suitable for heavier SUV SRX such use. In 1995, two generations of Polaris engine L37 and LD8 are respectively, after tuning the output adjusted to 300 horsepower and 275. Since then, both on Polaris engine has not changed, it has been used up to now. The
In 2004, the supercar XLR Cadillac and luxurious SUV-SRX
2004 years Cadillac XLR configuration Northstar-V8 engine there has been code-namedPolaris LH2 engine, the 2005 Cadillac STS also appeared this Polaris LH2 engine. The new LH2 uses VVT variable valve engine for the first time in history, the United States applied timing technology. This technique allows the intake valve and a valve opening and closing time are independently controlled, from low to high speed by adjustment between the operation of opening and closing the valve to ensure that the most appropriate time, with precise control of fuel injection, increased more efficiently gasoline combustion efficiency of the cylinder, so that to improve performance, but also improves the cleanliness of engine exhaust. In addition, also brings new LH2 of the ETC (electronic throttle control technology) systems, this system replaces the mechanical transmission between the accelerator pedal and the accelerator. By accelerator pedal position sensor, engine control sensors, automatic cruise command, antiskid control gear change, and recording the energy emitted by the engine control module commands sent to the engine throttle control unit, to change the size of the throttle. The system helps to minimize fuel consumption, while ensuring powerful, direct response, and is conducive to the discharge of clean. After LH2, L37 and LD8 also fielded the ETC control unit.
LC3 engine
LC3 supercharged engine configuration and cooling system
[123 ] in addition to LH2, and then the Cadillac V-series specially developed for the new sports sedan 4.4L displacement, code-named Polaris LC3 V8 supercharged engine, this engine provides dynamic performance comparable to the car, loaded on the STS-V and XLR-V on. At this point, the whole family present, Polaris total of 4 engines, namely 4.6L V8 (L37), 4.6L V8 (LD8), 4.6L V8VVT (LH2) and 4.4L V8 (LC3).
The General Characteristics
Polaris engine:
V8 engine Polaris all made of aluminum alloy engine block off the manufacturing process using casting technology by the year 2000, in order to solve the group GM in the pores of the aluminum alloy cold forming process appears, it uses a new high pressure casting process, aluminum alloy part the engine is reducedPores, improved engine performance. In addition, in the year 2000, Northstar engine compression ratio of 10.3: 1, to the post-2000 into a 10: 1 to accommodate dual camshafts per cylinder, four-valve, chain driven camshaft design. Finally, Polaris engine intake manifold 66 is made of a thermoplastic nylon, the intake manifold can be made of this material it will not be over the influence of the heat engine transmitted at the same time cooling the intake air, thereby maintaining good engine into the atmosphere.
In addition to the above, there is a feature Polaris engine, the engine can continue to run is when all coolant fail, this is called “Limp home” mode. In this mode, the computer detects when the engine is overheating situation, it will temporarily stop running half of the cylinder, so that we can reduce the temperature of the entire engine, in order to allow the vehicle to continue driving, but GM Group added a remark: only travel 50 miles in this case the most vehicles.
Polaris fifth member of the family:
At present, a member of the family inside the latest Polaris engine is accompanied by the introduction of the concept car with CIEN the North star XV12 concept engine. This engine is a cylinder using a 60 degree angle, all-aluminum double overhead camshaft (DOHC), single-cylinder four-valve design V12 engine displacement of 7.5 liters. Capable of outputting 750 horsepower and 450 lb / ft of torque, but the volume is the same compact to a V8 engine.
Thomas Stephens, vice president of General Motors Corporation Powertrain The engine’s design, said: “Despite the power of General Motors assembly products is very large, but so far we have not been developed V12 engine, which is our North star XV12 engine is exploring a field. our car with other products on the market, distinguished senior automotive important point is the powertrain, and uses advanced technology to meet the XV12 engine most of shape V8 engine requirements and fuel economy standards, which makes GM a matter of course in a leadership position in this area. at the same time, this engine also inherited ourSome design tradition. “
project manager GM Northstar North star XV12 engine, engineer Steve Kowalk said:” The shape is probably one of the biggest challenges we face as we start to want to make the V12 and V8 same outer shape size of the engine. We try to reduce the volume of the engine, so that it can be applied to as many types of cars being. At the same time, we have to maximize the engine displacement, and to make use of ‘variable displacement’ technology, enable it to provide the power needed at any time. The thickness of the cylinder wall will be reduced to 7 mm, and using a rear cam drive, so that the volume more compact, lower hood. “
XV12 engine
North star XV12 engine relative to other Polaris engine uses advanced technologies, including :.
l “variable displacement” technology
The engine may be closed by a valve the cylinder is stopped. Close to the cylinder side of the cylinder is only applicable, so that when the cylinder deactivation side, this engine with a six-cylinder inline engine identical. system shutdown and reactivation of very short response time, oil and valve arrangement enables the system consisting of the solenoid valve which activates at 6000 revolutions / minute and off.
2. petrol injection
[ 123] a direct injection gasoline combustion system uses this engine is given a higher power and fuel economy, while reducing emissions of hydrocarbons emissions. similar techniques may be found in the mass of the engine FSI to.
3. the variable intake manifold art
North s tar XV12 engine redesign of the variable three sections of the primary and secondary intake manifold such that the engine output torque curve is more gradual. It usesA simple, compact and reliable design. The electric actuator of the variable intake valve driving manifold speed change faster than conventional pneumatic actuators. After
4. The rear timing chain
In the rear of this engine, there is a subsidiary member can drive the engine transmission chain portion, with the engine running with the timing chain. This reduces the number of accessory parts front of the engine, to shorten the overall length of the engine and reduce the height of the front end of the engine to achieve higher volume and shape requirements.
5.36000 miles drain intervals
In order to reduce the cost of the environment and the user’s stress. North star XV12 engine oil change intervals of 36,000 miles in the design, which is to improve the oil sensor and the monitor, to reduce oil consumption, to improve the cooling performance of the oil tank and the expansion of volume is achieved by.
In general, the engine represents the highest level Polaris engine manufactured in North America. In German, Japanese engine manufacturers have been introducing more and more economic and environmentally friendly engine, while in North America, there is a higher power toward the North Star at goal.