VQ35HR VQ25HR Engine Technology Overview

Transcription

1 VQ35HR VQ25HR Engine Technology Overview V6 GASOLINE ENGINE

2 Advanced technology takes the next generation of Nissan s world-renowned VQ engine to new pinnacles of high-rev performance and environmental friendliness. Nissan s latest six-cylinder V-type engine inherits the high-performance DNA that has made Nissan s VQ series famous. Taking the acclaimed VQ engine s smooth transition concept to higher revolutions than ever, this VQ is a powerful and agile new powerplant for Nissan s frontengine, rear-wheel-drive vehicles. Smooth transition up to high-rev redline Lengthened connecting rods, addition of a ladder frame and other improvements greatly reduce friction. The result is effortless throttle response all the way to the 7500-rpm redline. Top level power performance in class Improved intake and exhaust systems, raised combustion efficiency, and other enhancements achieve class-leading power. Fuel efficiency and emissions are also exceptional. Thrilling acceleration sound A symmetrical intake and exhaust system helps produce a linear and clear throttle sound in response to engine rpm. contents 2 Taking the award-winning VQ series another step toward the ultimate powertrain, Nissan s nextgeneration VQ35HR & VQ25HR are thoroughly reengineered to boost the rev limit and deliver greater power, while achieving exceptional fuel economy and clean emissions. Higher revolution limit By greatly reducing friction, Nissan engineers achieved a smooth transition to the high-rev limit, which has been boosted to a 7,500rpm redline. New VQ Engine Advantages Higher revolution limit Top-level power performance in class Thrilling acceleration sound Better fuel efficiency & cleaner emissions Major technologies Lengthened connecting rods Lengthening the connecting rods by 7.6mm reduces piston sideforce on the cylinder walls. This reduces friction for smoother piston action to support highrev performance. New ladder frame The lower cylinder block that supports the crankshaft uses a ladder-frame structure for increased stiffness. This suppresses vibration to minimize friction at high engine rpm. Higher power performance Power boosting technologies include a symmetrical twin intake system and continuously variable valve timing control systems. Better fuel efficiency & cleaner emissions The world s first use of hydrogen-free, diamond-like carbon (DLC) coated valve lifters and other frictionreducing measures help raise fuel efficiency by about 10% and attain a class-leading emissions rating. Thrilling throttle sound The symmetrical intake and exhaust system configuration helps generate a stable, linear and clear sound signature for the new VQ.

3 VQ35HR VQ25HR Engine Technology Overview New heights of VQ performance Since its 1994 debut, Nissan s VQ engine series has continued to evolve, based on its original engineering goals of simplicity, light weight, low friction and responsive power. The VQ s exceptional performance has put it on Ward s 10 Best Engines list every year since the list s inception in The Nissan VQ is the only engine to hold this record. The latest VQ in this distinguished lineage has been redesigned with new dimensions and higher rigidity, yet weight remains about the same in the 3.5-liter VQ and has actually been reduced by about 8kg in the 2.5-liter VQ, while lowering the center of gravity. The result is an even more impressive VQ powerplant. Output New VQ35HR VQ35DE New VQ35HR engine Engine speed (rpm) New VQ25HR engine 3

4 Higher revolution limit By reducing friction in all the engine s moving parts and increasing the stiffness of the crankshaft and its ancillary components, Nissan engineers achieved smooth and effortless transition throughout the powerband. Lengthened connecting rods To support higher engine speeds, Nissan applied a friction-reducing solution used in racing car engines: lengthening the connecting rods. Raising the cylinder block deck height permits a 7.6mm increase in connecting rod length. This reduces piston inclination and the resulting sideforce exerted against the cylinder wall, thereby reducing friction particularly at high speed. The result is effortless acceleration with a smooth powerband extending up to the 7,500rpm redline. (VQ35HR only) VQ35DE New VQ35HR Side force Side force Friction is reduced with the higher block deck and longer connecting rods Raised block deck height and longer connecting rods New ladder frame At high rpm, crankshaft deformation leads to increased vibrations. As a countermeasure, the VQ35HR engine employs a stiff ladder frame to support the crankshaft. This enhances the rigidity of the engine as a whole, thereby greatly reducing vibrations at the high rpm rates for which the engine is designed. (VQ35HR only) VQ35DE New VQ35HR Cylinder block vibration analysis Vibration Small Ladder frame effectively suppresses vibrations Ladder frame 4 Large

5 VQ35HR VQ25HR Engine Technology Overview Increased crankshaft stiffness During high-rev operation, the crankshaft may flex and twist, causing noise, vibration and, potentially, damage to the journals. To deal with this issue, the new VQ engine uses a larger journal diameter and a stiffer crankshaft. This minimizes vibrations at higher revs. In the VQ35HR, the connecting rod bolt diameter has also been increased from 8mm to 9mm to gain about 25% in strength. These measures help achieve the connecting rod and crankshaft durability required in a high-speed engine. Pin diameter 52mm increased to 54mm (VQ35HR) 45mm increased to 50mm (VQ25HR) Journal diameter 60mm increased to 65mm (VQ35HR) Crankshaft 8mm increased to 9mm Stronger connecting rod bolt (VQ35HR engine) Asymmetric piston skirt Pistons are normally designed with a skirt to prevent rocking within the cylinder. The new VQ engine uses asymmetrical piston skirts to reduce friction. A smaller skirt area is used for the part of the piston receiving less sideforce during reciprocal piston motion. This reduces friction by about 7.6%, thereby contributing to smoother revving performance. Large skirt on high-pressure (thrust) side Small skirt on low-pressure side Asymmetric piston skirt 5

6 Top level power performance in class A symmetrical twin intake system and Continuously Variable valve Timing Control (CVTC) help the new VQ achieve class-leading output. Symmetrical twin intake system To reduce air intake resistance, the new VQ engine adopts a symmetrical twin intake configuration. Compared to the usual single intake, this enhances the engine s breathing for more efficient air distribution. Because it does not require enlargement of the duct diameter, this approach helps save space, thereby offering more leeway in engine compartment layout. Symmetrical twin intake system Straight intake port (VQ35HR only) To support high-rev, high-power engine performance, the new VQ adopts a straight intake port design. This configuration significantly improves intake efficiency by providing air to the engine in the quantity required during high-speed, high-load engine operation. Straight intake port 6

7 VQ35HR VQ25HR Engine Technology Overview CVTC The VQ engine adopts a valve control system that optimizes both intake and exhaust side timing according to engine rpm. Employing hydraulically actuated Continuously Variable valve Timing Control (CVTC) for the intake cams and electromagnetic Valve Timing Control (e-vtc) on the exhaust side, the system enables high flexibility in valve timing operation. The result is improved combustion efficiency throughout the powerband. CVTC for intake valves e-vtc for exhaust valves Continuously Variable valve Timing Control (CVTC) system Optimized valve diameter (VQ35HR only) Although it would seem a larger valve diameter would improve airflow, it can actually increase airflow resistance, particularly when it is partially open and there is an interfering flow through an adjacent valve. In the VQ35HR, valve diameter is optimized to minimize intake resistance and improve breathing efficiency throughout the operational cycle from low to high valve lift conditions. Constricted VQ35DE engine Large diameter Free fl ow New VQ35HR engine Small diameter Intake valve diameter decreased from 37.0mm to 36.6mm. Exhaust valve diameter decreased from 31.2mm to 30.2mm Result: Improved fl ow at low lift Optimized valve diameter Raised compression ratio (VQ35HR only) The new VQ engine uses a higher compression ratio to raise thermal efficiency and achieve greater power output. This also contributes to improved fuel economy. At the same time, refinements in the exhaust system effectively minimize NOx to compensate for increased generation due to the higher compression ratio. VQ35DE engine New VQ35HR engine Redesigned combustion chamber permits higher compression ratio 7

8 Thrilling acceleration sound Drivers enjoy a clearer, more thrilling throttle sound, thanks to the symmetrical intake and exhaust system. Symmetrical intake and exhaust system Engine speed (rpm) Volume Large Overtones Frequency (Hz) VQ35HR frequency distribution * subharmonic: Unlike regular overtones, this harmonic component muddies the sound * 2 Input resonator: This uses resonance to emphasize desirable frequencies and tune the engine sound * 3 Overtones: Regular harmonic components of the engine sound that increase with rising engine rpm. Twin intake system Equal length exhaust manifold 左右完全対称腴吸排気システム Twin exhaust system 8 Optimized front pipe merging structure Twin exhaust system End plate Small The VQ engine uses a symmetrical intake and exhaust system to help produce clear and powerful sounds that rise along with engine speed as the throttle is opened. The area where the left and right sides of the exhaust system merge is designed so that the two flows do not mix, thereby suppressing generation of 0.5 subharmonics*1. Muddy sounding components are also cut by optimized tuning of the twin intake system s resonator*2, use of an equal length exhaust manifold, the twin exhaust system s curved end plate and other refinements. Together, these emphasize the desirable overtones*3, producing the VQ engine s exciting 6-cylinder sound.

9 VQ35HR VQ25HR Engine Technology Overview Isometric exhaust manifold Adoption of equal-length left and right exhaust manifolds helps produce a clearer and more dynamic exhaust note. This isometric design prevents unwanted interference between the exhaust pulsations produced by each cylinder following combustion, thereby minimizing undesirable sound components. Exhaust efficiency is also improved, which contributes to increased torque at low to mid speeds. Isometric exhaust manifold Muffler backpressure reduction Tuned front pipe length and an efficient merging structure help maximize low- to mid-range torque. Extending into a symmetrical dual-exhaust system, this configuration effectively uses the vehicle s underside space to increase total muffler volumetric capacity. While suppressing exhaust backpressure, this also helps with sound attenuation. Front pipe length is optimized for performance New high-efficiency front pipe merging structure 9

10 Better fuel efficiency & cleaner emissions Friction reducing measures, including the world s first use of hydrogen-free diamond-like carbon (DLC) in a production vehicle, and enhanced combustion efficiency give the new VQ engine better fuel efficiency and cleaner exhaust emissions. Hydrogen-free DLC coated valve lifters As one of the ways to minimize friction on critical moving surfaces, Nissan has adopted a hydrogenfree diamond-like carbon (DLC) coating for the valve lifters. This application of nanotechnology provides an extremely slippery finish, which results in a dramatic 40% reduction in friction. Use of an oil additive developed for DLC applications creates a more durable ultra-low friction lubricating film. The resulting reduction in cam lifter friction significantly boosts fuel efficiency. Ultra-low friction lubricating film Cam contact surface Hydrogen-free DLC coating Substrate Hydrogen-free DLC coating Mirror finish The crankshaft and camshaft journals are critical components for engine performance. Therefore, the VQ engine employs journal surfaces finished with polishing tape and lapped to create a mirrorsmooth surface. This is another example of how friction is minimized throughout the VQ engine. Crankshaft journal 10

11 VQ35HR VQ25HR Engine Technology Overview Atomizing fuel injector The smaller the fuel droplets sprayed by the injectors, the better the fuel mixes with the air to support more complete combustion and reduce unburned hydrocarbon (HC) emissions. The newgeneration VQ engine employs injector nozzles having 12 holes (of 130µm diameter each), up from the previous 4-hole (250µm diameter) format. This multi-hole high-atomization design provides broad dispersion to raise combustion efficiency. Conventional 4-hole type New 12-hole injector Atomizing fuel injector 250µm diameter 130µm diameter Nozzle plate (injector tip) Super-ignition iridium spark plugs The spark plug s center electrode has an iridium alloy tip for high ignitability. This helps achieve cleaner emissions by stabilizing combustion when starting the engine. Iridium center electrode Platinum ground electrode Super-ignition iridium spark plug 11

12 Nissan Motor Co., Ltd. Global Communications, CSR and IR Division Communications CSR Department February Nissan Motor Co., Ltd. All Rights Reserved