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69-606: The VQ series engine was honored in a record 14-straight selections by Ward's 10 Best Engines from the list's inception until 2008. 1st gen (1994-) The VQ20DE is an aluminium block , aluminium head , DOHC 24-valve 2.0 L (1,995 cc) V6, with a 76 mm × 73.3 mm (2.99 in × 2.89 in) bore and stroke and compression ratio ranging from 9.5 to 10.0:1. In base form it produces 150 PS (110 kW; 148 hp) to 160 PS (118 kW; 158 hp) at 6400 rpm and 137 to 145 lb⋅ft (186 to 197 N⋅m) at 4400 rpm (lean burn). It

138-478: 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

207-478: 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

276-415: 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

345-512: A bore and stroke of 93 mm × 73.3 mm (3.66 in × 2.89 in) respectively with a compression ratio of 10.0:1. It produces 192 PS (141 kW; 189 hp) to 230 PS (169 kW; 227 hp) at 6400 rpm and 205 to 217 lb⋅ft (278 to 294 N⋅m) at 4400 rpm. The VQ30DE was on the Ward's 10 Best Engines list from 1995 through 2001. It is an aluminium open deck block design with microfinished internals and

414-539: 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

483-559: A compression ratio of 10.3:1. It produces 221–228 PS (163–168 kW; 218–225 hp) at 6,800 rpm and 194 lb⋅ft (263 N⋅m) at 4,800 rpm. It has dual CVTC for both intake and exhaust, microfinished camshafts and a redline of 7,500 rpm. It is fitted to the following vehicles: The VQ35HR engine was first seen in the US with the introduction of the updated 2007 G35 Sedan model, which debuted in August 2006. Nissan updated

552-542: A compression ratio of 11 to 11.3:1. It produces 210 to 215 PS (154 to 158 kW; 207 to 212 hp) at 6400 rpm and 195 to 199 lb⋅ft (264 to 270 N⋅m) at 4400 rpm. It is fitted to the following vehicles: The 3.0 L (2,987 cc) engine has Bore and stroke of 93 mm and 73.3 mm, with a compression ratio of 11.0:1. It produces 230 PS (169 kW; 227 hp) to 260 PS (191 kW; 256 hp) at 6400 rpm and 217 to 239 lb⋅ft (294 to 324 N⋅m) at 3600 rpm. It

621-521: 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

690-451: 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

759-452: 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 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 )

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828-731: A relatively light weight. An improved version of the VQ30DE is known by the designation VQ30DE-K . The K designation stands for the Japanese word kaizen which translates to "improvement". The engine was used in the 2000–2001 Nissan Maxima and adds a true dual-runner intake manifold for better high-end performance compared to some earlier Japanese and Middle-East market versions of this engine (2000-2001 Infiniti I30 models added an additional fenderwell intake, boosting power to 230 PS (227 hp; 169 kW)). The VQ30DEK produces 227 PS (167 kW; 224 hp). The 1995–1999 US spec VQ30DE

897-403: 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

966-455: Is a 4.0 L (3,954 cc) longer stroke variant of the VQ35DE. Bore and stroke are 95.5 mm × 92 mm (3.76 in × 3.62 in). Compression ratio is 9.7:1 Improvements include continuously variable valve timing, variable length/volume intake system, silent timing chain, hollow and lighter camshafts and friction reduction (microfinished surfaces, moly coated pistons). It

1035-476: Is a variation of the VQ-HR engine series with Nissan 's VVEL ( Variable Valve Event and Lift ). It was the first production engine from Nissan using VVEL . It has a compression ratio of 11.0:1, with a displacement of 3.7 L; 225.5 cu in (3,696 cc), thanks to a bore x stroke of 95.5 mm × 86 mm (3.76 in × 3.39 in) and a redline of 7,500 rpm. It

1104-471: 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

1173-419: 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

1242-449: 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

1311-548: Is fitted to the following vehicles: A larger 3.5L with direct-injection is released for 2017 model year. It is fitted to the following vehicles: A 3.8 L version with direct-injection is released for 2020 model year. It is fitted to the following vehicles: The 2.5 L VQ25HR (for "High Revolution" or "High Response") is only offered on longitudinally-mounted engine vehicles which tend to be rear wheel drive or all-wheel drive . Bore and stroke are 85 mm × 73.3 mm (3.35 in × 2.89 in), with

1380-428: Is fitted to the following vehicles: The VQ23DE displaces 2.3 L (2349 cc) and is eqontinuously Variable-valve Timing Control). Bore and stroke are 85 mm × 69 mm (3.35 in × 2.72 in), and compression ratio is 9.8:1. It produces 173 PS (127 kW; 171 hp) at 6000 rpm and 166 lb⋅ft (225 N⋅m) at 4400 rpm. It is fitted to the following vehicles: The VQ25DE

1449-805: Is fitted to the following vehicles: The twin-turbo VQ30DETT is an engine used only in Nissan's race cars, primarily in the Super GT (formerly the JGTC). First used on the Skyline GT-R race cars during the 2002 season, this engine subsequently powered the Fairlady Z race cars. Homologation rules allow them to use the VQ30DETT in lieu of the stock VQ35DE. Race output of this engine is estimated at around 480 PS (353 kW; 473 hp). The VQ30DETT

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1518-462: 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 a power valve system to get similar results to VVT. The valves within an internal combustion engine are used to control

1587-446: 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

1656-531: Is port fuel injected with platinum-tipped spark plugs. It produces 261 to 275 hp (195 to 205 kW; 265 to 279 PS) at 5600 rpm and 281 to 288 lb⋅ft (381 to 390 N⋅m) at 4000 rpm. The DD series is a variant of the DE series engines with direct fuel injection (NEO-Di) and eVTC (electronically controlled continuously variable valve timing). The 2.5 L (2,495 cc) engine has Bore and stroke of 85 mm and 73.3 mm respectively, with

1725-505: Is rated at 332 bhp (337 PS; 248 kW) at 7,000 rpm and 270 lb⋅ft (366 N⋅m) of torque at 5,200 rpm, and up to 350 bhp (355 PS; 261 kW) at 7,400 rpm and 276 lb⋅ft (374 N⋅m) of torque at 5,200 rpm. Although the engine VQ37VHR gains only 2 lb⋅ft (3 N⋅m) and 8 lb⋅ft (11 N⋅m) in the Nissan 370Z Nismo, torque over the VQ35HR and this higher torque arrives at 5,200 rpm vs 4,800 rpm in

1794-580: Is similar to the VQ20DE, but is .5 L larger, at 2.5 L (2,496 cc) displacement. Bore and stroke are 85 mm × 73.3 mm (3.35 in × 2.89 in), with a compression ratio of 9.8 to 10.3:1. It produces 190 to 210 PS (140 to 154 kW; 187 to 207 hp) at 6400 rpm and 174 to 195 lb⋅ft (236 to 264 N⋅m) of torque. Later versions produce 186 PS (137 kW; 183 hp) at 6000 rpm and 171 lb⋅ft (232 N⋅m) at 3200 rpm. In some Nissans, this engine

1863-405: 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

1932-435: 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

2001-408: 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

2070-414: 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

2139-400: Is up 8 pound-feet (11 N⋅m) from the older "DE" engine at 268 lb⋅ft (363 N⋅m) and the torque curve is higher and flatter across most of the rpm range, and especially in the lower rpm range. The VQ35HR was utilized in rear-wheel-drive platforms while the VQ35DE continued to power Nissan's front-wheel-drive vehicles. In 2010, Nissan introduced a hybrid version of the VQ35HR, pairing

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2208-628: 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

2277-417: 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

2346-548: 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

2415-463: The 2005-2006 and the manual equipped G35 2005 through 2007 model years. A modified version of the VQ35DE, called the S1, is produced by Nismo (Nissan's motorsports and performance division) for the Fairlady Z S-Tune GT . It produces 300 PS (221 kW; 296 hp) at 7,200 rpm, a higher rev-limit than that of the original VQ35DE . North American JDM and other markets The VQ40DE

2484-439: The 2020 competition, the name was changed to Wards 10 Best Engines and Propulsion Systems . Number of times the following makes have received the award (excluding the special 20th century awards): Variable valve timing Variable valve timing ( VVT ) 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

2553-516: The 2020 list; this limit was eliminated for future competitions following the announcement of the 2020 winners. During a 2-month testing period, Wards editors evaluate each engine according to a number of objective and subjective criteria in everyday driving situations – there is no instrumented testing. The selection takes into account power and torque output; noise, vibration, and harshness (NVH) levels; technical relevance; and basic comparative numbers. Each engine competes against all others. For

2622-492: The 380RS-C develops maximum power of more than 294 kW (394 hp; 400 PS), and maximum torque of 421 N⋅m (311 lb⋅ft). In order to use this new engine in Super GT GT500, limited numbers of the engine were reproduced in the street-legal Fairlady Z Nismo Type 380RS. The VQ38HR engine mounted in the 380RS is a detuned, street version of the racing engine used in the 380RS-C. The engine displacement remains

2691-550: The VQ line with the addition of the 3.5 L VQ35HR (for "High Revolution"). It produces 315 PS (232 kW; 311 hp) (US market: 306 hp (228 kW; 310 PS) using the revised SAE certified power benchmark) at 6,800 rpm and 37 kg⋅m (363 N⋅m; 268 lb⋅ft) at 4,800 rpm, using a compression ratio of 10.6:1. As of 2009, the Infiniti EX35 produces 297 hp (221 kW; 301 PS) and

2760-441: The VQ35HR, the torque curve itself is improved and flattened via VVEL variable valve timing for better throttle response and low rpm torque. "Home of the VQ series Engine" . VQpower . Retrieved 8 December 2012 . Ward%27s 10 Best Engines Wards 10 Best Engines is an annual list of the ten "best" automobile engines available in the U.S. market, that are selected by Wards AutoWorld magazine. The list

2829-500: 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

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2898-484: 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

2967-470: 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

3036-626: The engine to a lithium-ion battery pack. By 2007, Nissan's ambition to increase the competitiveness of the Z33 chassis in Super Taikyu racing resulted in the development of a larger displacement engine based on the original VQ35HR Block. It featured the same bore but longer-throw crankshaft (bore × stroke: 95.5 mm × 88.4 mm). The end result was the VQ38HR powered Nismo Type 380RS-C which went on to dominate ST class 1 racing. The 3.8-liter racing engine in

3105-652: The exhaust cams to broaden the torque curve is new over the "DE" engine. The new engine block retained the same bore and stroke, but the connecting rods were lengthened and the block deck was raised by 8.4 mm to reduce piston side-loads. This modification, along with the use of larger crank bearings with main bearing caps reinforced by a rigid ladder-type main cap girdle to allow the engine reliably rev to 7600 rpm. With an increase in compression ratio from 10.3:1 to 10.6:1, these changes add 6 more horsepower (306 hp (228 kW) total + 3 hp ram air effect not measured by SAE testing = 309 hp (230 kW)). Peak torque

3174-421: 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

3243-530: 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 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

3312-550: 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,

3381-437: 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

3450-469: The intake is a high-flow tuned induction system. Since its inception Nissan has improved upon the VQ35DE with changes keeping it an efficient class leading V6 engine . The engine was updated in 2005 as the VQ35DE Rev-Up. It included variable exhaust timing, a higher rev limit, and a revised oil pump, boosting the output to 297 crank horsepower. This motor was only found in the manual equipped 350z for

3519-412: 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

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3588-563: The intake. It produces from 231 to 304 PS (170 to 224 kW; 228 to 300 hp) of power and 246 to 274 lb⋅ft (334 to 371 N⋅m) of torque depending on the application. The VQ35DE is built in Iwaki and Decherd, TN . It was on the Ward's 10 Best Engines list from 2002 through to 2007 and again in 2016. It features forged steel connecting rods, a microfinished one-piece forged crankshaft, and Nissan's nylon intake manifold technology. It has low-friction molybdenum -coated pistons and

3657-421: 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

3726-407: 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

3795-483: 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

3864-444: 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 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,

3933-616: 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

4002-629: The same torque presumably due to tighter regulations. It has NDIS (Nissan Direct Ignition System) and CVTC with hydraulic actuation on the intake cam and electromagnetic on the exhaust cam. Reportedly over 80% of the internal components were redesigned or strengthened to handle an increased RPM range sporting a lofty 7,600 rpm redline. A new dual-path intake (two air cleaners, throttle bodies, etc.) lowers intake tract restriction by 18 percent and new equal-length exhaust manifolds lead into mufflers that are 25 percent more free-flowing for all around better airflow. The electrically actuated variable valve timing on

4071-519: The same, while the intake manifold and exhaust, air-fuel ratio, ignition timing, VTC and other specs have been optimized for street use. The engine produces maximum power of 257 kW (345 hp; 349 PS) at 7200 rpm, and maximum torque of 397 N⋅m (293 lb⋅ft) at 4800 rpm. The VQ38HR fitted to the following vehicles: The VQ35HR and VQ25HR engines were built at Nissan's Iwaki Plant in Fukushima Prefecture. The VHR series

4140-497: 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"

4209-435: 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

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4278-437: 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

4347-422: 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

4416-480: 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 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

4485-1045: 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

4554-525: Was equipped with only a single runner intake manifold. The 3.0 L (2,987 cc) VQ30DET is a turbocharged version of the VQ30DE. Bore and stroke remain the same at 93 mm × 73.3 mm (3.66 in × 2.89 in) respectively, and it has a compression ratio of 9.0:1. It produces 270 PS (199 kW; 266 hp) and 271 lb⋅ft (367 N⋅m). From 1998 onwards, it produces 280 PS (206 kW; 276 hp) at 6000 rpm and 285 lb⋅ft (386 N⋅m) at 3600 rpm. It

4623-492: Was replaced by the QR25DE . The VQ25DET is a turbocharged 2.5 L (2,495 cc) engine with CVTC. Bore and stroke are 85 mm × 73.3 mm (3.35 in × 2.89 in), with a compression ratio of 8.5:1. It produces 280 PS (206 kW; 276 hp) at 6400 rpm and 300 lb⋅ft (407 N⋅m) at 3200 rpm. It is fitted to the following vehicles: The 3.0 L (2,987 cc) VQ30DE has

4692-578: Was replaced in 2007 by the VK45DE for use in the Super GT Fairlady Z 's and later in the GT-R. It was utilized in the following vehicles: The 3.5 L (3,498 cc) VQ35DE is used in many modern Nissan vehicles. Bore and stroke are 95.5 mm × 81.4 mm (3.76 in × 3.20 in). It uses a similar block design to the VQ30DE, but adds variable valve timing ( CVTCS ) for

4761-431: Was started in 1994 for model year 1995, and has been drawn every year since then, published at the end of the preceding year. Engines must be available in regular-production vehicles on sale in the U.S. market no later than the first quarter of the year. Eligibility has also been based on availability in a vehicle below a base price limit, which increased progressively from US$ 50,000 for the 1995 list up to US$ 65,000 for

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