Tuning Feature: Nissan VQ25DD Modified

"Comprehensive guide to tuning the Nissan VQ25DD engine!"

We are regularly getting emails asking about the ultimate VQ25DD power upgrades. So let us look into Nissan VQ25DD parts and outline the best modifications on this great engine and point out some potential pitfalls along the way.

This six cylinder V block boasted many versions over it's production run and cylinder capacity ranged from 2.0 to 4.0 litres. Nissan came up with a Race ready version the VQ30DETT showing what this platform is capable of. Some of the 3.5 liter engines have pretty strong internals and can withstand up to 1000hp in ideal conditions, and parts from these high spec engines are often sourced and fitted into others accross the range.

We shall review and look at VQ25DD tuning and show the greatest upgrades. Nissan VQ25DD are good project engines and with carefully picked performance mods like a remap, turbo kits and camshafts you will really increase the drivers experience of your car.

When talking about the greatest parts for your VQ25DD engine, we are going to focus on the parts that give the biggest return for your cash.

Altering your VQ25DD cam will make a dramatic difference to your engines torque. Choosing a higher performance cam profile raises the torque .

NB: Fast road camshafts commonly push up the performance through the rpm range, you may lose a little low down bhp but your 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.

A Competition cam will just annoy you whilst on the daily commute.

You should ideally optimize your bhp range to your typical driving style so for a car driven daily stick with a mild fast road VQ25DD cam

Some VQ25DD engines respond better to different cam durations so view each engine as unique.

The ECU mapping and fuel pump and injectors also have an effect on the bhp gains you'll get.

Extending exhaust or intake durations can alter the bhp 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.

VQ25DD Tuning Stages

Stage 1 VQ25DD modifications: Remaps/piggy back ECU, Sports exhaust manifold, Panel air filters, Drilled & smoothed airbox, Intake headers, Fast road camshaft.

Stage 2 VQ25DD modifications: induction kit, Sports catalyst & performance exhaust, high flow fuel injectors, Fast road cam, fuel pump upgrades, Ported and polished head.

Stage 3 VQ25DD modifications: Competition cam, 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, Twin charging conversions.

ECU flashing will help release the full potential of all the tuning mods you've done to your VQ25DD.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage will vary depending on the tuning mods you've applied and the condition of your engine.

Pushing fuel and air into your VQ25DD is vital to any car tuning job.

Intake flow the air from the air cleaner and allow it to be fed into the engine and mixed with fuel.

Structure and flow characteristics of the Intake manifold can make a substantial difference to to fuel atomisation on the VQ25DD.

Commonly we find the intake manifold are in desperate need of aftermarket parts, although a few manufacturers provide well optimised intake manifold.

Adding a VQ25DD larger valve kit, carrying out port work and head flowing will also boost bhp, the fantastic side effect is it will raise potential for raising the bhp increase on other parts.

Turbo upgrades for the VQ25DD

NASP 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 excellent power gains.

If your car has forced induction upgrades are going to net you a larger power gain and we find turbo charged engines are made using stronger components.

There are reliable limits for every engine, with some being over specified and some only able to handle stock power

Discover these restrictions and fit better quality crank and pistons to handle the power.

We've seen mechanics spending a loads of money on turbo charger upgrades on the VQ25DD only to suffer the indignity of watching the motor explode on it's first outing after it's been completed.

Big upgraded turbos tend to suffer low end lag, and smaller turbos spool up much more quickly but don't have the peak end engines power gains.

We are pleased that the market of turbo chargers is always developing and we are seeing variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end performance.

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

You'll commonly see there is a limitation in the air flow sensor MAP/MAF/AFM on the VQ25DD when loads more air is being drawn into the engine.

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

Adding a supercharger or additional turbo will make large bhp gains, although more challenging to install. We have this feature on twinchargers if you want to read more.

Uprating VQ25DD fuel injectors

When you increase the power you will need to ramp up to the fuel system.

More power needs more fuel. Don't forget to over specify your flow rate on the injectors.

The accepted safe increase is to add 20% to the flow rate when specifying an injector, which takes into account injector deterioration and affords a bit of spare capacity should the engine require 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.

Best VQ25DD performance exhausts

You only need to to improve your exhaust if your exhaust is actually causing a restriction in flow.

On most factory exhausts you'll find the 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.

Do not go with the biggest exhaust you can get you'll slow up the exhaust flow rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Typically exhaust restrictions can be located in the catalysts installed, so adding a faster flowing race alternative will help avoid this restriction.

Problems and issues to look out for on the VQ25DD

The VQ25DD engines, if regularly serviced and maintained, are generally very reliable and have few issues. {But if neglected they can cost a small fortune|When neglected they get very expensive to run|They can however be quite expensive if neglected| }

Regular oil changes are vital on the VQ25DD, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your VQ25DD engine please join us in our friendly forum where you can discuss tuning options in more detail with our VQ25DD owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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We really like hearing from our readers, and hearing about which mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our VQ25DD guides and tips are kept up to date.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Nissan. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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