Nissan VQ38HR Tuning

"All you need to know about performance parts and tuning the Nissan VQ38HR engine!"

The Nissan VQ38HR are good project engines and with the right performance tuning mods like remaps, turbo upgrades and camshafts you will definitely increase your driving fun.

The VQ platform even formed the basis for Nissan's race engines - the VQ30DETT they are a well designed V6 and engines were used by Renault. We shall look at the 3.8 version, which shares much with the 3.5 block and see which mods will take this engine into the realm of supercar.

Our aim here is to review and look at VQ38HR tuning and point out the best modifications for your car.

History, Power & Specs of the VQ38HR Engine

By taking the VQ35HR and increasing the displacement we see higher power figures,

  • 257 kW (345 hp 349 PS) at 7200 rpm, and maximum torque of 397 Nm (293 lbft) at 4800 rpm
  • 294 kW (394 hp 400 PS), and maximum torque of 421 Nm (311 lbft) (Race engine)

This engine block was used in some very tasty Fairlady versions from NISMO.

  • 2007–2008 Nissan Fairlady Z Version Nismo Type 380RS-C
  • 2007–2008 Nissan Fairlady Z Version Nismo Type 380RS

Tuning the Nissan VQ38HR and best VQ38HR performance parts.

Best VQ38HR upgrades

Just because particular upgrades are popular with VQ38HR owners it doesn't mean its worth having, instead we will focus on the ultimate upgrades that will give your VQ38HR the best power gain for you spend.

Altering your VQ38HR camshaft will make a dramatic difference to the engine torque. Choosing a higher performance camshaft profile raises the torque accordingly.

Fast road camshafts tend to push up the performance across the rpm band, you could sacrifice a little bottom end bhp but your high end rpm power will be higher.

Motorsport and race camshafts, push up the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a road car you should ideally to match your bhp range to your cars usage.

I would be surprised if you find a VQ38HR Motorsport cam is a pleasure to live with when driving in heavy traffic. The low end idle will be very lumpy and irregular, so something you would notice on a track when you drive in the upper third of the rpm band, but on roads this is a serious issue and we've heard from lots of drivers lamenting their decision to add an extreme competition cam profile to their engine.

Different VQ38HR engines respond better to different camshaft durations than others.

The map and fuelling also have an effect on the power gains you'll hit.

Extending exhaust or intake durations can alter the power band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

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Best Engine Mods for your car

  1. Mapping - remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
  6. Typical stage 1 mods often include:
    drilled & smoothed airbox, Fast road camshaft, Remaps/piggy back ECU, Sports exhaust header/manifold, Intake manifolds, Panel air filters.

    Typical stage 2 mods often include:
    Ported and polished head, induction kit, fuel pump upgrades, high flow fuel injectors, Fast road cam, Sports catalyst & performance exhaust.

    Typical stage 3 mods often include:
    Twin charging conversions, Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves), Competition cam, Crank and Piston upgrades to alter compression.

    Review your options and then acquire your upgrades and set yourself a power target to avoid disappointment.

    A remap allows a tuner to unlock the full potential of all the parts you've done to your VQ38HR.

    (In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

    It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but your results will differs on the parts you've applied and the condition of your engine.

    Feeding more air into your VQ38HR is vital to any engine tuning project.

    Intake Manifolds carry or channel the air during the suck phase from the filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.

    Structure and rate of flow of the Air Intake manifolds can make a large difference to fuel atomisation on the VQ38HR.

    Commonly we find the air intake manifolds are ripe for motorsport parts, although some manufacturers provide fairly well optimized air intake manifolds.

    Increasing the VQ38HR valve size, doing some port matching and head flowing will also improve bhp, the fantastic side effect is it will make space for raising the bhp increase on other upgrades.

    VQ38HR Turbo upgrades

    NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your VQ38HR

    The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes excellent power gains.

    If a car is fitted with a turbocharger parts are more reliable and turbo engines are built with harder and stronger components.

    There are tuning limits for every engine, with some being very over engineered and some only able to handle stock powerSee where you'll find these limitations and fit better quality crank and pistons to handle the power.

    We've seen car owners spending a fortune on turbocharger upgrades on the VQ38HR only to experience the motor catastrophically fail when it's been finished.

    Large capacity turbos will usually experience a bottom end lag, and smaller turbos spool up really quickly but don't have the top end bhp gains.

    Thanks to new tech the market of turbos is always improving and we commonly find variable vane turbos, where the vane profile is altered according to speed to lower lag and increase top end torque.

    Twin scroll turbos divert the exhaust flow into 2 channels and feed these at differently designed vanes in the turbocharger. They also increase the scavenging effect of the engine.

    It is not unusual that there is a limitation in the air flow sensor (AFM/MAF/MAP) on the VQ38HR when a lot more air is being pulled into the engine.

    We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting bhp and torque at a much lower level.

    Adding a supercharger or additional turbo will make large performance gains, although more difficult to install. We have this guide to twinchargers if you want to read more.

    Fuelling

    Don't omit to look at the fuel system when you are increasing the performance - it makes the car more thirsty. It makes sense to be generous with your flow rate on the injectors.

    As a rule of thumb add 20% when buying an injector, this allows for injector deterioration and gives you some spare capacity should the engine need more fuel.

    We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

    All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

    6 Cylinder NA (naturally aspirated) engines

    • 58 PSI 189cc/min 200hp
    • 58 PSI 284cc/min 300hp
    • 58 PSI 378cc/min 400hp
    • 58 PSI 568cc/min 600hp

    6 Cylinder turbocharged engines

    • 58 PSI 227cc/min 200hp
    • 58 PSI 341cc/min 300hp
    • 58 PSI 454cc/min 400hp
    • 58 PSI 682cc/min 600hp

    VQ38HR Performance Exhausts

    Only look to uprate your exhaust if the existing exhaust is actually causing a restriction in flow.

    On most factory exhausts you'll find the exhaust flow rate is fine even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

    Sports exhausts will certainly help air flow through the engine but avoid an exhaust that is too wide or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to around 2.5 inches to maximise flow rates, and this should take into account the amount of air your engine is moving.

    Common exhaust restrictions can be located the catalysts installed, so adding a higher flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

    Weak spots, Issues & problem areas on the VQ38HR

    The VQ38HR engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

    Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

    Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

    Keep an eye on the oil consumption, piston ring and cylinder wear is exacerbated by poor quality fuel resulting in blow by.

    Exhaust cam cover wear and failure can result in rough idling.

    Regular oil changes are vital on the VQ38HR, especially when tuned and will help extend the life and reliability of the engine.

    If you would like to know more, or just get some friendly advice on Tuning your VQ38HR engine please join us in our car forums where you can discuss with our VQ38HR owners. It would also be worth reading our unbiased articles to get a full grasp of the benefits and drawbacks of each modification.

    Please help us improve these tips by sending us your feedback in the comments box below.

    We love to hear what our visitors have got up to and which upgrades work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these VQ38HR tuning guides which get regular updates and revisions.

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