Tuning Feature: Nissan VQ25DE Modified

"Comprehensive guide to performance parts and tuning the Nissan VQ25DE engine!"

We often are getting messages asking how to improve the VQ25DE from people wanting to know what are the best tips for VQ25DE modifications. So let us look into Nissan VQ25DE parts and outline the best modifications on this great engine and point out some frequent tuning mistakes along the way.

This six cylinder V block boasted many versions over it's production run and engine size ranged from two to four litres. Nissan came up with a Race ready version badged as 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.

Therefore we look into VQ25DE tuning and report on the premier modifications. Nissan VQ25DE really good project engines and with the optimum sports parts like a remap, turbo improvements and camshafts you will substantially enhance the drivers fun of your car.

The greatest VQ25DE modifications on an engine are in our opinion the ones that give the biggest return for your cash.

We won't be swayed by popular VQ25DE modifications, they need to be cost effective.

Altering your VQ25DE camshaft will usually make a dramatic difference to your engines torque. Choosing a higher performance camshaft profile raises the torque especially at the top end.

NB: Fast road cams commonly raise the torque over the rpm band, you might lose a little low end power but the top end will be lifted.

Competition cams, raise the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a daily driver one, ideally, should ideally to match your bhp range to your cars usage.

I would be surprised if you have found a VQ25DE Motorsport camshaft is a pleasure to live with when in heavy traffic.

Each engine responds better to different camshaft durations so view each engine as unique.

The ecu map and injectors and fuel pump also will make differences on the bhp gains you'll get.

Longer valve 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.

VQ25DE Tuning Stages

Stage 1 VQ25DE modifications: Remaps/piggy back ECU, Intake headers, Fast road camshaft, Drilled & smoothed airbox, Panel air filters, Sports exhaust manifold.

Stage 2 VQ25DE modifications: Sports catalyst & performance exhaust, high flow fuel injectors, fuel pump upgrades, induction kit, Fast road cam, Ported and polished head.

Stage 3 VQ25DE modifications: Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Competition cam, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves).

Mapping allows a tuner to fully realize the full potential of all the tuning parts you've done to your VQ25DE.

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 may vary depending on the tuning parts you've fitted and the condition of your engine.

It is the whole point to any car tuning job to force more air and fuel into your VQ25DE

Headers flow the air during the suck phase from the filter and allow it to be drawn into the engine and mixed with fuel.

The bore size, shape and flow characteristics of the Intake can make a large effect on to fuel atomisation on the VQ25DE.

I usually find intake manifold are ripe for aftermarket tuning parts, although a few car makers provide well optimised intake manifold.

Adding a VQ25DE larger valve kit, doing a bit of VQ25DE port enlargement and head flowing will also boost power, and as an added benefit will give you increasing the power increase on other modifications.

Turbo upgrades for the VQ25DE

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 VQ25DE

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

When your motor has a turbo already fitted tuning mods are simpler to install and you'll see that turbo charged engines are built with many forged and stronger components.

However you will find an engines will have power limits

Research these restrictions and upgrade to better quality components to handle the power.

It's not unheard of drivers spending a loads on turbocharger upgrades on the VQ25DE only to watch the whole thing literally blow up on it's first outing after it's been finished.

Big turbos will usually experience low end lag, and little turbos spool up quickly but won't have the peak end power band gains.

Over the last 20 years the choice of turbo chargers is always developing and we now see variable vane turbo chargers, permitting the vane profile is altered according to speed to lower lag and increase top end bhp.

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

It is common that there is a restriction in the air flow sensor MAF/MAP on the VQ25DE when considerably more air is being fed into the engine.

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

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

Uprating VQ25DE fuel injectors

You will need to ensure that the engine is not starved of fuel so should uprate the fuelling when you start exceeding 20% of a bhp increase.It is important to over specify your injector capacity.

The accepted safe increase is to add another 20% when specifying an injector, helps cope with injector deterioration and allows 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.

Best VQ25DE performance exhausts

You only need to to increase your exhaust if the current exhaust is actually causing a restriction.

On most factory exhausts you'll see 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.

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

Usual exhaust restrictions are traced to the catalyst installed, so adding a freer flowing performance alternative will help avoid this restriction.

Problems and issues to look out for on the VQ25DE

The VQ25DE 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 VQ25DE, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your VQ25DE engine please join us in our friendly forum where you can discuss tuning options in more detail with our VQ25DE 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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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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