VQ35HR
Nissan updated the VQ line for 2007. The 3.5 L VQ35HR (for "high revolution" or "high response") is likely to see front-drive use int the future as well.
The VQ35HR produces 306 hp
It seems like Nissan is up to something here as this engine is much more beefy inside than previously. In our opinion Nissan is getting ready to subject this engine to turbo boost for the long awaited R35 Skyline GT-R.
The block is much stronger. It uses a bed plate type lower end, much like that what is seen in engines designed specifically for racing like the Cosworth powerplant used in Champ Car racing and others used in F1. A bed plate block is one where the block is split at the crankshaft into an upper and lower portion. The crank is solidly supported by a huge girdle of aluminum solidly bolted to the block at many points instead of individual main caps that most motors have. There is little opportunity for block flex and bearing eating, crank breaking distortion here. This beefy lower end was first seen on the heavy duty VQ40DE motors used in the Pathfinder and Frontier trucks. The crank is beefed up as well featuring the larger rod and main bearing journal diameters of the heavy duty VQ40DE truck engine.
The stout bed plate block holds' the crank in this stout cage. This should take over 1000 hp no sweat.
Look at the beef behind the crank. Its way more stout than the VG30 or the VQ35DE. Plenty of journal overlap and bearing area should allow this pup to handle 1000 hp of boost.
The block itself has a taller deck height than the older VQ35DE. This was done to accommodate longer connecting rods. Longer connecting rods improve volumetric efficiency at high rpm by giving more dwell time at TDC. This gives the cylinders more time to fill on the intake stroke, improving high RPM power.
This looks like an old school VG or SR rod. Nissan beef is back. The rod has lots of material and is strong. It should probably be able to take 600 hp stock. See the thick parting line down the middle of the beam? This indicates that its forged or PM, not cast like NICO says.
Longer rods also improve mechanical and combustion efficiency. This is because the combustion event has a longer dwell time to initially push harder on the piston as it travels downward down the piston bore and the connecting rod has less angularity so it will not cause the piston to cock in the bore and dig as hard into the cylinder walls. This puts less stress on the piston and connecting rod as well as reduces friction.
The pistons have some interesting features, mainly an asymmetric shape with a larger skirt area on the thrust side for good support and a cut down skirt on the non thrust side for less friction and less weight. The rods themselves have been beefed up with more meat around the big end and a wider beam. VQ rods have been known to be problematic on higher revving and boosted motors and this appears to be a good thing, returning to Nissans prior heritage of having near bulletproof rods. The NICO website has reported the rods to be a high pressure casting be we think that is not correct, in photos of the rods the thick parting line of a forging die or a PM (powdered metal forging) die are clearly seen. A cast rod would be inferior to a forged or PM part so we think that NICO is mistaken. The piston ring lands have been hard anodized for better wear and the skirts feature a low friction polymer coating. The dome configuration appears to be little changed form previous VQ variants.
The pistons most innovative feature is the wide skirt on the thrust side to support the thrust loads better and the narrow skirt on the opposite side for less weight and friction. What a good idea! Soon the aftermarket will copy this.
The cylinder heads seem to be an evolution of the current VQ head rather than a revolution like the rest of the engine. The heads have a variable cam timing VTC device on both the intake and exhaust cams with the intake being infinitely variable hydraulic and the exhaust being a two step electromagnetic clutch. This configuration appears to be nearly identical to that found in the current Rev Up spec engine. VTC can control the cams advance, retard and lobe centers but not the actual lift and duration like Honda's VTEC system can. The intake port has a straighter more line of sight direction presumably for better tumble and mixture consistency in the cylinders as well as better flow.
A JDM Nissan diagram showing how the longer rod and the asymmetrical piston skirts work.
Unlike the VQ35DE, which had an open quenchless combustion chamber, the VQ35HR has a pentroof chamber with quench pads on either side of the intake and exhaust valves, much like the older VQ30DE had. This is presumably where the increase in compression ratio came from and should also result in better combustion and less detonation due to higher mixture turbulence and more homogeneousness of the fuel air mixture as the piston hits TDC on the compression stroke. There are rumors that the HR has larger valves but we cannot confirm this.
A big improvement over the VQ35DE, the VQ35HR has a combustion chamber that has two quench pads per cylinder for improved combustion and detonation resistance.
The tops of the cam followers are coated with a Diamond Like Coating for maximum reduction in friction.
The HR has different camshafts and valvesprings to support the higher revs and the cam followers use a DLC coating which Nissan is quite proud of. Nissan claims that this is the first use of DLC in a production engine. DLC is short for Diamond like coating. DLC coatings have been used for some time in NASCAR and drag racing for cam followers and piston pins to my knowledge and probably other high end motorsports applications for sure. DLC is a thin layer of diamond like carbon which is the hardest and slipperiest stuff known. Nissan credits much of the HR's friction reduction to this coating. The NICO web site has reported that DLC is used in the pistons, this is simply not true. The piston coating is an organic dry lube much like Teflon.
Looking at the front of the engine is interesting. The front cover no longer has an access port for the water pump. This means that changing a water pump is going to take some work. I hope Nissan improved the water pump while they were in there! The rear of the block has the same bellhousing bolt pattern as the VK45 and 56 as well as the VQ40DE, some interesting info for all of you swapaholics out there.
The peripherals of the engine have changes for the better as well. The exhaust manifolds are now close to equal length tubular headers! There is probably not much room for improvement by the aftermarket here. The intake manifold is now plastic with a larger plenum and shorter, bigger diameter runners. The plastic is very smooth in the ports which should result in excellent flow. The plastic does not conduct heat well which should mean a cooler intake charge. The most interesting thing is that the plenum now sports dual throttle bodies, dual intake tubes, dual MAF's and dual ram cold air airboxes. Again the aftermarket is going to be hard pressed to find improvement here.
The exhaust manifold is a close to equal length header. It looks very close to the DC header for the 350Z.
The exhaust is a true dual system and sports an X-pipe in the middle. The most powerful aftermarket 350Z exhausts by Stillen and B&B have found that an X pipe really helps improve low end torque with no sacrifices anywhere else. Nissan claims that the new engine sounds good due to the intake and exhaust systems having the same length but we feel that this is due to the X-pipe. The exhaust also features close coupled cats with low thermal mass for quick lite off and a big reduction in emissions. This usually means that the cat monolith is ceramic which has been the cause for a lot of grief with the QR25DE 4 cylinder. The ceramic is brittle and prone to fracture. The engine's VTC sometimes causes a vacuum in the exhaust manifold because it uses cam timing induced exhaust reversion in lieu of an EGR valve. If the cat fails, this can result in the abrasive ceramic getting sucked into the engine. Better hope Nissan has solved some of these problems.
The all plastic intake manifolds most noticeable feature is dual throttle bodies and intake tubes.
The engine also features improved faster warming wide band O2 sensors for better sensing of the A/F ratio. We figure that these are a refinement of the current Bosch technology with a hotter heater, like a Horiba reference sensor. The injectors are multi hole 50 micron spray type for super good atomization. A fine wire iridium center electrode on the plugs helps them get free of fouling from a cold start faster. The cats, O2 sensors, injectors, iridium plugs and dual VTC help the HR get the nearly impossible for a high performance engine, SULEV rating.
The HR engine will be the workhorse engine for the Z in the near future but even better stuff may be coming later. It is a strong, nearly confirmed rumor that the engine used in the upcoming super secret Skyline GT-R will use a twin turbo 3.7 liter version of the HR motor topped with some secret cylinder heads developed by none other than Cosworth. The new Cosworth heads will also feature Nissans VVL technology where lift, duration, lobe centers and advance can be controlled by the engines ECU, much like Honda's I-VTEC system. The turbos will be smog friendly using Cosworth technology that bypasses the turbos during cold start.
The rumor mill also states that a 3.7 liter version of HR will be coming for an enthusiast package Z and a very limited production high hp version of the 3.7 with high compression and Cosworth heads, naturally aspirated is on line for the track model. Interchangeability with the VQ40 means that other interesting combos can be made by the tuners. We predict that it will be fairly easy to get up to 4.5 liters from this platform.
The VQ35DE is dead, long live the VQ35HR.
