Nissan VQ25DD Tuning

"All you need to know about tuning and performance parts on the Nissan VQ25DD engine!"

In this article we examine VQ25DD tuning and outline the greatest upgrades. The VQ engine platform was made from 1994 and has appeared in top engine lists and won awards every year since then. It is a smooth, rev happy V6 and the cc ranged from 2.0 to 4.0 liters.

Nissan VQ25DD make a good tuning project and with carefully chosen motorsport enhancements like remapping, turbo kits and camshafts you will certainly increase your driving experience.

History, Power & Specs of the VQ25DD Engine

Power ranged depending on it's application but there were primarily two power levels offered. This engine used the eVTC (electronically controlled continuously variable valve timing) later replaced with CVVTCS system keeps the valve durations shorter at lower engine speeds and can alter both lift and duration. When the RPM increases the valves open for longer durations.

  • 2010 PS (154 kW; 207.0 hp) at 6400 rpm 195 lbft (264 to 270 Nm) at 4400 rpm
  • 215 PS (158 kW; 212 hp) at 6400 rpm 199 lbft (264 to 270 Nm) at 4400 rpm

It was fitted to a few models over it's production run.

  • 1999–2002 Nissan Cefiro A33, 210 PS (154.4 kW; 207.0 hp) (JDM)
  • 1999–2004 Nissan Cedric/Nissan Gloria
  • 2001–2006 Nissan Skyline V35, 215 PS (158 kW; 212 hp)
  • 2001–2007 Nissan Stagea M35, 215 PS (158 kW; 212 hp)

Tuning the Nissan VQ25DD and best VQ25DD performance parts.

Best VQ25DD mods

When talking about the top modifications for your VQ25DD engine, we are going to focus on the tuning mods that give the best value for money.

Altering your VQ25DD camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

Fast road camshafts commonly push up the power through the rpm band, you may sacrifice a little low down torque but the higher rpm power will be higher.

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

For a car driven daily you should ideally to optimize your engines power to your preferences.

I would be surprised if you think that a VQ25DD Competition camshaft is a pleasure to live with when in heavy traffic because low end power will be very lumpy. Competition cams are designed for maximum power at the top end of the RPM range, a place that most daily commutes will not permit!

Each engine responds better to different cam durations so set your engine up on a rolling road.

The map and fuel pump and injectors also have a large bearing on the torque gains you'll get.

A longer valve duration can alter the torque 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:
    Fast road camshaft, drilled & smoothed airbox, Remaps/piggy back ECU, Intake manifolds, Panel air filters, Sports exhaust header/manifold.

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

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

    Plan your options and then source your parts and set yourself a power target to save yourself from expensive mistakes.

    Remaps helps to establish the full potential of all the upgrades you've done to your VQ25DD.

    (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 the outcome usually vary depending on the upgrades you've fitted and the condition of your engine.

    It is the main goal to any engine performance tuning task to get air and fuel into your VQ25DD

    Intake flow the air during the suck phase from the air filter and allow it to be drawn into the engine cylinders.

    Structure and flow characteristics of the Intake manifolds can make a large change to fuel mixing and power on the VQ25DD.

    I usually find air intake manifolds are ripe for an upgrade, although some car makers provide decently flowing air intake manifolds.

    Increasing the VQ25DD valve size, carrying out 3 or 5 angle valve jobs and porting and head flowing will also lift torque, and importantly will afford you an improved torque increase on other tuning mods.

    VQ25DD 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 VQ25DD

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

    If your car has a turbo already fitted parts are more reliable and most turbocharged engines are built using many forged and stronger components.

    There are tuning limits for every engine, with some being extremely strong and some just sufficiently able to handle stock powerResearch these restrictions and fit more solid crank and pistons to cope with the power.

    It's not unheard of mechanics spending a loads on turbo upgrades on the VQ25DD only to suffer the indignity of watching the motor go up in smoke soon after it's used in anger.

    Large capacity turbo chargers often suffer no power at low rpm, and low capacity turbo chargers spool up more quickly but won't have the top end torque gains.

    In the last 10 years the range of turbos is always improving and we now see variable vane turbos, where the vane angle is altered according to speed to lower lag and increase top end power.

    Twin scroll turbos divert the exhaust gases into a couple of channels and flow these at differently profiled vanes in the turbo. They also increase the scavenging effect of the engine.

    You'll commonly see there's a limit in the air flow sensor MAF/MAP on the VQ25DD when a lot more air is being sucked into the engine.

    We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited torque at a much lower level.

    Adding a supercharger or additional turbo will make large bhp and torque gains, although more complex to install. We have this article on twincharging if you want to read more.

    Fuelling

    Don't overlook the need to improve the fuelling when you are increasing the bhp - it makes the car more thirsty. It is important to over specify your injectors flow rate.

    The rule of thumb is to add 20% when buying an injector, helps cope with injector deterioration and allows a bit of 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

    VQ25DD Performance Exhausts

    You may need to replace your exhaust if your exhaust is actually creating a flow problem.

    On most factory exhausts you should find that the exhaust flow rate is still good 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 can usually air flow out of the engine but do not go 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.

    Typically exhaust restrictions come around the catalyst and filters installed, so adding a higher flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

    Weak spots, Issues & problem areas on the VQ25DD

    The VQ25DD 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.

    Regular oil changes are vital on the VQ25DD, 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 VQ25DD engine please join us in our car forums where you can discuss with our VQ25DD 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 hearing about our website visitors projects, especially the mods done and which 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 VQ25DD tuning guides which get regular updates and revisions.

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