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81-624: All Prizms were built at NUMMI (New United Motor Manufacturing, Inc.), a joint venture company between Toyota and General Motors in Fremont, California . The NUMMI plant at Fremont had manufactured the Prizm's predecessor, the Chevrolet Nova , and would later manufacture the Pontiac Vibe , one of its replacements. Production of the newly-rebadged Chevrolet Prizm began in late 1997 as

162-491: A joint venture to manufacture vehicles to be sold under both brands. GM saw the joint venture as a way to get access to quality small cars and an opportunity to learn about the Toyota Production System and The Toyota Way , a series of lean manufacturing and management philosophies that had made the company a leader in the automotive manufacturing and production industry. For Toyota, the factory gave

243-480: A power valve system to get similar results to VVT. The valves within an internal combustion engine are used to control the flow of the intake and exhaust gases into and out of the combustion chamber . The timing, duration and lift of these valve events has a significant impact on engine performance. Without variable valve timing or variable valve lift , the valve timing is the same for all engine speeds and conditions, therefore compromises are necessary to achieve

324-478: A 4.4 L engine for a proposed replacement for the existing 30-98 model to be called the H-Type. In this engine the single overhead camshaft was to move longitudinally to allow different camshaft lobes to be engaged. It was in the 1920s that the first patents for variable duration valve opening started appearing – for example United States patent U.S. patent 1,527,456 . In 1958 Porsche made application for

405-707: A Delphi air conditioning system instead of the Corolla's Denso air conditioning system. The Prizms also used the contemporary Sprinter front end to differentiate them from their Corolla counterparts. The third-generation Prizm headlight, front turn signal, and taillight assemblies were also different, making them notable exceptions in a car that shared almost all of its parts with the Toyota Corolla through each of its model years. All Prizms are powered by engines from their contemporary Toyota Corolla models: NUMMI New United Motor Manufacturing, Inc. ( NUMMI )

486-478: A German Patent, also applied for and published as British Patent GB861369 in 1959. The Porsche patent used an oscillating cam to increase the valve lift and duration. The desmodromic cam driven via a push/pull rod from an eccentric shaft or swashplate . It is unknown if any working prototype was ever made. Fiat was the first auto manufacturer to patent a functional automotive variable valve timing system which included variable lift. Developed by Giovanni Torazza in

567-415: A VVT system requires a complex system, such as multiple cam profiles or oscillating cams. Late intake valve closing (LIVC) The first variation of continuous variable valve timing involves holding the intake valve open slightly longer than a traditional engine. This results in the piston actually pushing air out of the cylinder and back into the intake manifold during the compression stroke. The air which

648-539: A cam phaser, controlled by the ECM, which continuously varies advancement or retardation of the camshaft timing. In 2007, Caterpillar developed the C13 and C15 Acert engines which used VVT technology to reduce NOx emissions, to avoid the use of EGR after 2002 EPA requirements. In 2010, Mitsubishi developed and started mass production of its 4N13 1.8 L DOHC I4, the world's first passenger car diesel engine that features

729-521: A conventional cam lobe, while others use an eccentric cam lobe and a connecting rod. The principle is similar to steam engines, where the amount of steam entering the cylinder was regulated by the steam "cut-off" point. The advantage of this design is that adjustment of lift and duration is continuous. However, in these systems, lift is proportional to duration, so lift and duration cannot be separately adjusted. The BMW ( valvetronic ), Nissan ( VVEL ), and Toyota ( valvematic ) oscillating cam systems act on

810-588: A driver's-side airbag, and a new 1.8-liter four-cylinder engine optional on LSi trim. With the larger engine came a rear stabilizer bar, wider tires, and an optional automatic transmission with four speeds instead of three. A second airbag became standard in 1993 for the 1994 model year; leather seats were an option on the LSi of this generation. In contrast with the Sprinters sold in Japan, this generation Prizm lacked

891-422: A front stabilizer bar in its suspension. U.S. Electricar used the Prizm as the basis for an electric vehicle conversion that replaced the gasoline drivetrain with an electric traction motor and high-voltage lead-acid storage battery. It was marketed in 1994. The Prizm's 1998 redesign coincided with the conversion of all remaining Geo models into Chevrolets, as General Motors made the decision to discontinue

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972-488: A leader of the workers' own union, the United Auto Workers (UAW). GM as a company was departmentalized (design, manufacturing) as per Henry Ford 's division of labor , but without the necessary communication and collaboration between the departments. There was an adversarial relationship between workers and plant supervisors, with management not considering the employees' view on production, and quantity

1053-451: A mechanical VVT system. The system was engineered by Ing Giampaolo Garcea in the 1970s. All Alfa Romeo Spider models from 1983 onward used electronic VVT. In 1989, Honda released the VTEC system. While the earlier Nissan NVCS alters the phasing of the camshaft, VTEC switches to a separate cam profile at high engine speeds to improve peak power. The first VTEC engine Honda produced was

1134-548: A similar number of defects per 100 vehicles. In 1990, for the 1991 model year, Toyota started building the Toyota Hilux (also known as the Toyota Pickup) at NUMMI, allowing the company to completely avoid the chicken tax , a 25 percent tariff on light trucks imposed in 1964. Previously, the company had avoided a large portion of the tariff by importing the truck as an incomplete chassis cab (which included

1215-471: A slight increase in power from 120 to 125 hp (89 to 93 kW). The then-recently introduced VVT-i optimizes cam and valve timing to reduce emissions, and the addition of individual coils for each cylinder helped control spark timing to each individual cylinder. Due to decreased sales, low popularity, and being in competition with the Chevrolet Cavalier and GM's more direct competitor to

1296-403: A variable valve timing system. Manufacturers use many different names to describe their implementation of the various types of variable valve timing systems. These names include: This method uses two cam profiles, with an actuator to swap between the profiles (usually at a specific engine speed). Cam switching can also provide variable valve lift and variable duration, however the adjustment

1377-471: Is acted on by two lobes simultaneously. Each camshaft has a phasing mechanism which allows its angular position relative to the engine's crankshaft to be adjusted. One lobe controls the opening of a valve and the other controls the closing of the same valve, therefore variable duration is achieved through the spacing of these two events. The drawbacks to this design include: This system is not known to be used in any production engines. The operating principle

1458-431: Is close to the proposed site of Cisco Field , which was never formally approved. On March 10, 2010, Aurica Motors announced that it intended to raise investment capital and garner federal economic stimulus funds to help retrain the workers and retool the facility for production of electric vehicles. Both proposals went nowhere. On May 20, 2010, Tesla Motors announced that it would purchase most (210 of 370 acres) of

1539-419: Is discrete rather than continuous. The first production use of this system was Honda's VTEC system. VTEC changes hydraulic pressure to actuate a pin that locks the high lift, high duration rocker arm to an adjacent low lift, low duration rocker arm(s). Many production VVT systems are the cam phasing type, using a device known as a variator which changes the phase (Phase refers to the relative timing between

1620-429: Is driven by the crankshaft through timing belts , gears or chains . An engine requires large amounts of air when operating at high speeds. However, the intake valves may close before enough air has entered each combustion chamber, reducing performance. On the other hand, if the camshaft keeps the valves open for longer periods of time, as with a racing cam, problems start to occur at the lower engine speeds. Opening

1701-449: Is expelled fills the manifold with higher pressure, and on subsequent intake strokes the air which is taken in is at a higher pressure. Late intake valve closing has been shown to reduce pumping losses by 40% during partial load conditions, and to decrease nitric oxide ( NOx ) emissions by 24%. Peak engine torque showed only a 1% decline, and hydrocarbon emissions were unchanged. Early intake valve closing (EIVC) Another way to decrease

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1782-413: Is freed from this constraint, allowing performance to be improved over the engine operating range. Piston engines normally use valves which are driven by camshafts . The cams open ( lift ) the valves kind for a certain amount of time ( duration ) during each intake and exhaust cycle. The timing of the valve opening and closing, relative to the position of the crankshaft, is important. The camshaft

1863-446: Is of this type. Also known as "combined two shaft coaxial combined profile with helical movement", this system is not known to be used in any production engines. It has a similar principle to the previous type, and can use the same base duration lobe profile. However instead of rotation in a single plane, the adjustment is both axial and rotational giving a helical or three-dimensional aspect to its movement. This movement overcomes

1944-405: Is that it significantly lowers the temperature of the combustion chamber, which can increase hydrocarbon emissions. Early intake valve opening Early intake valve opening is another variation that has significant potential to reduce emissions. In a traditional engine, a process called valve overlap is used to aid in controlling the cylinder temperature. By opening the intake valve early, some of

2025-435: Is that the cam and follower profiles must be carefully designed to minimise contact stress (due to the varying profile). Ferrari is commonly associated with this system, however it is unknown whether any production models to date have used this system. This system is not known to be used in any production engines. It consists of two (closely spaced) parallel camshafts, with a pivoting follower that spans both camshafts and

2106-408: Is that the one follower spans the pair of closely spaced lobes. Up to the angular limit of the nose radius the follower 'sees' the combined surface of the two lobes as a continuous, smooth surface. When the lobes are exactly aligned the duration is at a minimum (and equal to that of each lobe alone) and when at the extreme extent of their misalignment the duration is at a maximum. The basic limitation of

2187-506: Is the process of altering the timing of a valve lift event in an internal combustion engine , and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combination with variable valve lift systems. There are many ways in which this can be achieved, ranging from mechanical devices to electro-hydraulic and camless systems. Increasingly strict emissions regulations are causing many automotive manufacturers to use VVT systems. Two-stroke engines use

2268-414: Is two eccentric drives and controllers are needed for each cylinder (one for the intake valves and one for the exhaust valves), which increases complexity and cost. MG Rover is the only manufacturer that has released engines using this system. This system consists of a cam lobe that varies along its length (similar to a cone shape). One end of the cam lobe has a short duration/reduced lift profile, and

2349-576: The B16A which was installed in the Integra , CRX , and Civic hatchback available in Japan and Europe. In 1992, Porsche first introduced VarioCam , which was the first system to provide continuous adjustment (all previous systems used discrete adjustment). The system was released in the Porsche 968 and operated on the intake valves only. Variable valve timing has been applied to motorcycle engines but

2430-758: The Tesla Fremont Factory , produces the Model S , Model X , Model 3 , and Model Y vehicles. As of 2023 , the plant employs 22,000 people, far greater than the 5,500 employees of NUMMI, and produced nearly 560,000 vehicles, 30 percent more than the maximum output of NUMMI. During its time in operation, the NUMMI joint venture factory produced the following models (model years): 37°29′41″N 121°56′41″W  /  37.49472°N 121.94472°W  / 37.49472; -121.94472 Variable valve timing Variable valve timing ( VVT )

2511-531: The Toyota Tacoma , a pickup truck designed exclusively for the North American market. Up to May 2010, NUMMI built an average of 6,000 vehicles a week, or nearly eight million cars and trucks since opening in 1984. In 1997, NUMMI produced 357,809 cars and trucks. Production reached its annual peak of 428,633 units in 2006. Toyota took the lessons it learned from NUMMI and went on to establish

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2592-417: The camshaft 25 times per second, so the valve timing events have to occur at precise times to offer performance benefits. Electromagnetic and pneumatic camless valve actuators offer the greatest control of precise valve timing, but, in 2016, are not cost-effective for production vehicles. The history of the search for a method of variable valve opening duration goes back to the age of steam engines when

2673-548: The 1920s when maximum allowable RPM limits were generally starting to rise. Until about this time an engine's idle RPM and its operating RPM were very similar, meaning that there was little need for variable valve duration. The first use of variable valve timing was on the 1903 Cadillac Runabout and Tonneau created by Alanson Partridge Brush Patent 767,794 “INLET VALVE GEAR FOR INTERNAL COMBUSTION ENGINES” filed August 3, 1903, and granted August 16, 1904. Some time prior to 1919 Lawrence Pomeroy, Vauxhall's Chief Designer, had designed

2754-600: The Corolla the Saturn S-series , the Prizm was replaced by the Pontiac Vibe starting in 2003. The Vibe was also made in tandem with a Toyota model, the Toyota Matrix , at the NUMMI plant. The Prizm along with its Geo siblings suffered severe sales loss when the brand denomination changed from Geo to Chevrolet in 1998. The Geo models outsold the rebadged Chevrolets three to one. In all three generations,

2835-402: The Corolla, became the first car in the compact class to offer optional side airbags. All 1998 Prizms without the LSi's optional handling package (containing a front stabilizer bar) were singled out by Consumer Reports for having sloppy emergency handling; Toyota addressed the problem for 1999 by making the handling package standard. For 2000, the engine gained variable valve timing ( VVT-i ) for

2916-554: The Geo brand entirely after 1997. The most notable change was an all-new 1.8-liter engine known as the 1ZZ-FE , which powered all Corollas and Prizms, making this generation lighter than its predecessor. It is all-aluminum, driven by a timing chain (instead of a timing belt), and making more power (with the same fuel economy) than with the A-series engines from the Geo era. This new engine incorporated laser etched valve guides directly in

2997-538: The Geo brand was phased out, alongside the newest North American generation of the Toyota Corolla. The last Prizm was built on December 13, 2001, resulting in a brief 2002 model year. The Prizm was introduced in February 1989 for GM's then-new Geo brand of import cars, for the 1990 model year. The hatchback version sold through 1991 was a rebadged version of the Toyota Sprinter Cielo , although unlike

3078-546: The Prizm was virtually the same car as the Toyota Corolla. It has more similarities with other Toyotas during the time period it was produced than it does to other cars from Geo and Chevrolet. The first and second generation Prizms shared body shells with the Japanese market Toyota Sprinter, the former featuring additional quarter windows in the C-pillars and the latter different doors and door apertures that wrapped upward into

3159-461: The Sprinter (and Corolla liftback) it received the same front clip as the sedan . The sporty GSi model of 1990–1992 was notable for its 130 hp (97 kW) twin-cam engine, sport suspension, disc brakes, and 14-inch wheels, which made it as a spiritual successor to the 1988 Chevrolet Nova twin-cam but less of a limited edition, available in both body styles and a full array of colors compared to

3240-611: The Toyota Production System to other assembly plants, but it proved largely unsuccessful. Despite having a front row seat to learn about the production system, by 1998 (15 years later) GM had still not been able to implement lean manufacturing in the rest of the United States, though GM managers trained at NUMMI were successful in introducing the approach to its unionized factories in Brazil. By 2009, GM

3321-690: The UAW, averaging $ 54,000 to the plant's 4,700 employees. Production of the Corolla in North America was shifted to Toyota Motor Manufacturing Canada until the new Toyota Motor Manufacturing Mississippi assembly plant could open in October 2011. Production of the Tacoma had already partially shifted to Toyota Motor Manufacturing de Baja California in 2004, and the remaining work shifted to Toyota Motor Manufacturing Texas . At 9:40am on April 1, 2010,

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3402-469: The block, rather than the old shrink-to-fit valve guides in the preceding Corolla motors (4A-FE & 7A-FE). This prevents oil burning and valve guide failure in the future. Although these efforts theoretically would have decreased oil burn, a flawed piston ring design affected all engines without VVT-i. This new engine design, although decreasing oil consumption from some components ultimately caused oil burning in higher mileage examples. The Prizm, alongside

3483-500: The camshaft by the governor. The Serpollet steamcars produced very hot high pressure steam, requiring poppet valves, and these used a patented sliding camshaft mechanism, which not only varied the inlet valve cut-off but allowed the engine to be reversed. An early experimental 200 hp Clerget V-8 from the 1910s used a sliding camshaft to change the valve timing . Some versions of the Bristol Jupiter radial engine of

3564-531: The closure of the plant, and the facility was appraised while operating. The talks ultimately failed and in June 2009 the GM announced that it would pull out of NUMMI. On August 27, 2009, Toyota announced that it would also discontinue production at NUMMI by March 2010, marking the first time the company had ever closed a factory. In November 2009 call with autoworkers Toyota's head of U.S. sales said that though it

3645-482: The company its first manufacturing base in North America allowing it to avoid tariffs on imported vehicles and saw GM as a partner that could show them how to navigate the American labor environment, particularly relations with the United Auto Workers union. The companies made the unusual choice to remake the troubled Fremont Assembly into the new NUMMI plant. The leadership of the UAW union insisted on re-hiring

3726-430: The desired result in intake and exhaust efficiency . This has been described in simulations. Practical results will vary based on available ambient combustion cycle gases in a naturally aspirated system, or forced air geometry as well as fuel pulse width timing and other factors which may or may not be available on vehicles equipped with variable valve timing. An engine equipped with a variable valve timing actuation system

3807-484: The development of the Corliss valve . These were widely used in constant speed variable load stationary engines, with admission cutoff, and therefore torque, mechanically controlled by a centrifugal governor and trip valves . As poppet valves came into use, a simplified valve gear using a camshaft came into use. With such engines, variable cutoff could be achieved with variable profile cams that were shifted along

3888-541: The earlier model's black-only color and sedan-only body style. They were the only four-door models offered with the 4A-GE engine in America; no other Toyota models ever offered that combination there. The regular engine offered 102 hp (76 kW). In addition to the base and the GSi, there was also a better equipped standard-engine LSi model. In addition to more equipment, the LSi also received body colored bumpers. In 1991,

3969-470: The early 1920s incorporated variable valve timing gear, mainly to vary the inlet valve timing in connection with higher compression ratios. The Lycoming R-7755 engine had a Variable Valve Timing system consisting of two cams that can be selected by the pilot. One for take off, pursuit and escape, the other for economical cruising. The desirability of being able to vary the valve opening duration to match an engine's rotational speed first became apparent in

4050-450: The emphasis on quality and teamwork by Toyota management as what motivated a change in work ethic. Among the cultural changes were the same uniform, parking and cafeterias for all levels of employment in order to promote a team concept, and a no- layoff policy. Built-in process quality and employee suggestion programs for continual improvement were other changes. Consensus decision-making reached management level, in contrast with

4131-540: The entire truck, less the truck bed) which only faced a 4% tariff. Once in the United States, Toyota Auto Body California (TABC) would produce the truck beds and attach them to the trucks. TABC was the first manufacturing investment in the U.S. for Toyota. This tariff loophole was closed in 1980. NUMMI did face some financial challenges, with cars costing more to build than at other GM plants and only operating at 58.6% capacity by 1988. The plant had not reached break-even by 1991. In January 1995, NUMMI began producing

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4212-421: The exhaust valve opens, and exhaust gas is pushed out of the cylinder and into the exhaust manifold by the piston as it travels upward. By manipulating the timing of the exhaust valve, engineers can control how much exhaust gas is left in the cylinder. By holding the exhaust valve open slightly longer, the cylinder is emptied more and ready to be filled with a bigger air/fuel charge on the intake stroke. By closing

4293-440: The factory for both companies, with Toyota even offering to build a version of its Prius hybrid for GM at the factory. Fremont Mayor Bob Wasserman , city officials and California Governor Arnold Schwarzenegger lobbied the automakers to find a product and keep NUMMI open. State officials crafted sales tax exemption on new factory equipment to preserve NUMMI. A regional committee was formed in February 2010 to investigate

4374-437: The former NUMMI site from Toyota for $ 42 million, significantly under market value. As part of the agreement, Toyota would also purchase $ 50 million of common stock when Tesla held its IPO the next month. In exchange, Tesla agreed to partner with Toyota on the "development of electric vehicles, parts, and production system and engineering support." The two companies would later end their partnership in 2017. The plant, renamed

4455-550: The inert/combusted exhaust gas will back flow out of the cylinder via the intake valve, where it cools momentarily in the intake manifold. This inert gas then fills the cylinder in the subsequent intake stroke, which aids in controlling the temperature of the cylinder and nitric oxide emissions. It also improves volumetric efficiency, because there is less exhaust gas to be expelled on the exhaust stroke. Early/late exhaust valve closing Early and late exhaust valve closing timing can be manipulated to reduce emissions. Traditionally,

4536-437: The inlet and exhaust camshafts, expressed as an angular measure.) of the camshaft and valves. This allows continuous adjustment of the cam timing (although many early systems only used discrete adjustment), however the duration and lift cannot be adjusted. These designs use an oscillating or rocking motion in a part cam lobe, which acts on a follower. This follower then opens and closes the valve. Some oscillating cam systems use

4617-687: The intake valve while the exhaust valve is still open may cause unburnt fuel to exit the engine, leading to lower engine performance and increased emissions. According to engineer David Vizard's book "Building Horsepower", when both intake & exhaust are open simultaneously, the much-higher-pressure exhaust pushes the intake-charge back, out from the cylinder, polluting the intake-manifold with exhaust, in worst cases. Early variable valve timing systems used discrete (stepped) adjustment. For example, one timing would be used below 3500 rpm and another used above 3500 rpm. More advanced "continuous variable valve timing" systems offer continuous (infinite) adjustment of

4698-412: The intake valves only. Eccentric cam drive systems operates through an eccentric disc mechanism which slows and speeds up the angular speed of the cam lobe during its rotation. Arranging the lobe to slow during its open period is equivalent to lengthening its duration. The advantage of this system is that duration can be varied independent of lift (however this system does not vary lift). The drawback

4779-421: The late 1960s, the system used hydraulic pressure to vary the fulcrum of the cam followers (US Patent 3,641,988). The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%. Alfa Romeo was the first manufacturer to use a variable valve timing system in production cars (US Patent 4,231,330). The fuel injected models of the 1980 Alfa Romeo Spider 2000 had

4860-513: The lettering of the car's name was changed, and the B-pillar and door frames on base models were body-colored instead of black. The hatchback body style was dropped. The Prizm was not sold In Canada, with GM offering a sedan version of the Geo Metro instead. The Geo Metro sedan was not available from Chevrolet dealers in the United States until 1995, although a Suzuki Swift -branded version

4941-501: The old departmentalization . By December 1984 (two years after the closure of Fremont Assembly), NUMMI's first car, a yellow Chevrolet Nova , rolled off the assembly line. The plant started producing the Toyota Corolla in September 1986. Almost right away, the NUMMI factory was producing cars at the same speed as the Japanese factories and Corollas produced at NUMMI were judged to be equal in quality to those produced in Japan with

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5022-483: The other end has a longer duration/greater lift profile. In between, the lobe provides a smooth transition between these two profiles. By shifting area of the cam lobe which is in contact with the follower, the lift and duration can be continuously altered. This is achieved by moving the camshaft axially (sliding it across the engine) so a stationary follower is exposed to a varying lobe profile to produce different amounts of lift and duration. The downside to this arrangement

5103-453: The plant and Toyota sent 30 managers and production coordinators from Japan, including the CEO, Tatsuro Toyoda , part of the company's founding family. Ahead of the reopening of the plant, Toyota sent many of the workers to Toyota's Takaoka plant in Japan to learn the Toyota Production System and actually work for a few days on the assembly line. Workers who made the transition identified

5184-566: The plant produced its last car, a red Toyota Corolla. NUMMI sold off equipment at an auction, with robots and tooling going to Toyota's plants in Kentucky, Texas and Mississippi. NUMMI sold some equipment to Tesla for $ 15 million. Ahead of the closure of NUMMI, several possible uses for the facility were proposed. In January 2010, the land was considered for a new stadium for the Oakland Athletics of Major League Baseball . It

5265-415: The production line could not be started), and even committed petty acts of sabotage such as putting "Coke bottles inside the door panels, so they'd rattle and annoy the customer." Attempts to discipline workers were often met with grievances or even strikes, putting the plant into near-continuous chaos. By 1982, GM had had enough and closed Fremont Assembly and laid off its thousands of workers. At about

5346-616: The pumping losses associated with low engine speed, high vacuum conditions is by closing the intake valve earlier than normal. This involves closing the intake valve midway through the intake stroke. Air/fuel demands are so low at low-load conditions and the work required to fill the cylinder is relatively high, so Early intake valve closing greatly reduces pumping losses. Studies have shown early intake valve closing reduces pumping losses by 40%, and increases fuel economy by 7%. It also reduced nitric oxide emissions by 24% at partial load conditions. A possible downside to early intake valve closing

5427-492: The roof; the third generation used the same body as the E110 Corolla sedan. Its distinctions from the Corolla came down to minor cosmetic differences, a GM Delco radio after 1992, the non-availability of a wagon in all three generations, and the availability of a hatchback for the 1989-1991 model years (the Corolla was not offered as a hatchback in North America during those years). The third generation Prizm also featured

5508-419: The same time, GM was struggling to profitably build high-quality and fuel-efficient small cars that consumers demanded after the energy crisis of the 1970s . Consumers started turning to foreign automakers for these vehicles, prompting the U.S. Congress to consider import restrictions to protect the domestic auto industry. That led GM and Toyota to team up and create New United Motor Manufacturing, Inc. (NUMMI),

5589-484: The same union leadership that had overseen GM's worst workforce. GM was against it, but Toyota agreed, believing that their system could turn things around. However, Toyota insisted that the plant would need to operate differently and old seniority rules would not apply. The workers hated the proposed changes, but desperately needed jobs. Ultimately, over 85% of NUMMI's initial workforce were the workers laid off at Fremont Assembly in 1982. GM would also assign 16 managers to

5670-497: The scheme is that only a duration variation equal to that of the lobe nose true radius (in camshaft degrees or double this value in crankshaft degrees) is possible. In practice this type of variable cam has a maximum range of duration variation of about forty crankshaft degrees. This is the principle behind what seems to be the very first variable cam suggestion appearing in the USPTO patent files in 1925 (1527456). The "Clemson camshaft"

5751-435: The valve opening duration was referred to as "steam cut-off ”. The Stephenson valve gear , as used on early steam locomotives, supported variable cutoff , that is, changes to the time at which the admission of steam to the cylinders is cut off during the power stroke. Early approaches to variable cutoff coupled variations in admission cutoff with variations in exhaust cutoff. Admission and exhaust cutoff were decoupled with

5832-437: The valve slightly early, more exhaust gas remains in the cylinder which increases fuel efficiency. This allows for more efficient operation under all conditions. The main factor preventing this technology from wide use in production automobiles is the ability to produce a cost-effective means of controlling the valve timing under the conditions internal to an engine. An engine operating at 3000 revolutions per minute will rotate

5913-422: The valve timing. Therefore, the timing can be optimized to suit all engine speeds and conditions. The simplest form of VVT is cam-phasing , whereby the phase angle of the camshaft is rotated forwards or backwards relative to the crankshaft. Thus the valves open and close earlier or later; however, the camshaft lift and duration cannot be altered solely with a cam-phasing system. Achieving variable duration on

5994-399: The wholly-owned Toyota Motor Manufacturing USA (later renamed Toyota Motor Manufacturing Kentucky ) and Toyota Motor Manufacturing Canada plants in 1986, and by 2009 the company was operating a dozen manufacturing facilities in North America. However, NUMMI remained Toyota's only unionized plant in the United States. GM executives, particularly CEO John F. Smith Jr. , attempted to spread

6075-541: Was a difficult decision to shut down the plant, "the economics of having a plant in California so far away from the supplier lines " in the Midwest "just doesn't make business sense" for Toyota. Autoworkers prepared for the shut down by refreshing skills and planning for career transitions. In March 2010, 90% of the workers at the plant approved a $ 281 million severance package from Toyota that had been negotiated by

6156-578: Was an American automobile manufacturing company in Fremont, California , jointly owned by General Motors and Toyota that opened in 1984 and closed in April 2010. The plant is located in the East Industrial area of Fremont next to the Mud Slough between Interstate 880 and Interstate 680 , the plant's peak production year was 2006, when it manufactured 428,633 vehicles. After the plant

6237-460: Was closed by its owners, the facility was sold to Tesla and reopened in October 2010, becoming known as the Tesla Fremont Factory . Before NUMMI, the site was the former Fremont Assembly that General Motors operated between 1962 and 1982. Employees at the Fremont plant were "considered the worst workforce in the automobile industry in the United States," according to a later recounting by

6318-1045: Was considered a non-useful "technological showpiece" as late as 2004 due to the system's weight penalty. Since then, motorcycles including VVT have included the Kawasaki 1400GTR/Concours 14 (2007), the Ducati Multistrada 1200 (2015), the BMW R1250GS (2019) and the Yamaha YZF-R15 V3.0 (2017), the Suzuki GSX-R1000R 2017 L7, the Moto Guzzi V85TT, the Harley Davidson Milwaukee-Eight, the KTM 1390 Super Duke. Variable valve timing has begun to trickle down to marine engines. Volvo Penta 's VVT marine engine uses

6399-554: Was in serious financial trouble and filed for Chapter 11 bankruptcy reorganization . In April the company confirmed its commitment to NUMMI and in June announced that it was scrapping the Pontiac brand which would end production of the Corolla-derived Pontiac Vibe at NUMMI by August 2009. That triggered several months of discussions between the automakers, trying to find products that could be produced at

6480-572: Was on sale from 1990. Design patents were filed by the Toyota Motor Corporation on December 6, 1985, using a final design 1:1 representation, under application number 1985-051078 and registered on July 13, 1988, under registration number 0718088-005. The Prizm's second generation, and the last under the Geo brand name, debuted in 1992 for the 1993 model year. The Prizm gained more room (resulting in an upgrade to United States Environmental Protection Agency "compact" car status),

6561-422: Was preferred over quality. Like all American car plants, the production lines at Fremont seldom stopped, and when mistakes were made, cars continued down the line with the expectation that they would be fixed later. By the early 1980s, the adversarial relationship had deteriorated to the point where employees drank alcohol, smoked marijuana (at the time, an illegal activity), were frequently absent (enough so that

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