Tuners tips on "VQ25DET Modifications"

How to modify and upgrade the Nissan VQ25DET

"Comprehensive guide to tuning the Nissan VQ25DET engine!"

TorqueCars are always getting messages requesting information on how to improve the VQ25DET from people inquiring about getting more power from the VQ25DET and wanting to know what are the things tuners recommend when it comes to VQ25DET modifications. So let us look into Nissan VQ25DET parts and outline the best mods that work on this great engine and point out some potential pitfalls along the way.

The Nissan VQ25DET great bases for a tuning project and with carefully chosen mods like remapping, turbo kits and camshafts you will improve your driving experience.

Our aim here is to examine VQ25DET tuning and point out the premier modifications for your car.

The best VQ25DET tuning parts on an engine are typically the ones that give the best power gain for your hard earned cash.

We won't be swayed by popular VQ25DET tuning parts, they need to be cost effective.

Improving air intake on the VQ25DET

You need air and fuel for an engine to work. If there is not enough fuel then it will run lean, if there is a lack of air it runs rich resulting in lost power which risks damage to the VQ25DET. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Forcing more fuel and air into the VQ25DET engine is the aim to any engine performance tuning project.

It is not unusual that there is a restriction in the air flow sensor (AFM/MAF/MAP) on the VQ25DET when a lot more air is being pulled into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting torque at a much lower level.

Engine intake manifolds carry the air during the suck phase from the filter and allow it to be drawn into the engine cylinders.

The size of bore and shape and flow rate of the air Intake manifold can make a substantial improvement to fuel atomisation and engine efficiency on the VQ25DET.

On popular production engines intake headers are needing aftermarket parts, although a few makers provide reasonably good intake headers.

Larger VQ25DET valves, doing a bit of VQ25DET port enlargement and head flowing will also raise torque, and as an added benefit will afford you a better torque increase on other upgrades.

VQ25DET performance cam tips.

Some VQ25DET engines even from the same production line will vary with some working better on different setups or needing less aggressive camshaft durations, but porting and flowing the head should reduce the differences and give consistent results.

The map and fuelling also have an effect on the bhp gains you'll get.

Altering 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.

Altering your VQ25DET camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

NB: Fast road cams tend to raise the bhp throughout the rev band, you may lose a little low down bhp but your higher rpm power will be better.

Motorsport and race cams, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a car driven daily you should ideally to match your engines power to your driving style.

You will never find a VQ25DET Motorsport cam is a pleasure to live with when driving around busy urban areas.

Stage 1, 2 and 3 mods for the VQ25DET

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

1. Suspension Upgrades - always improve your cars handling
2. Brake Upgrades - Even before adding power improve those brakes
3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
6. Fuelling - when you've increased power you'll need to match this with more fuel
7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 VQ25DET parts:

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

Stage 2 VQ25DET parts:

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

Stage 3 VQ25DET parts:

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

ECU flashing helps release the full potential of all the modifications you've done to your VQ25DET.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved often depend much on the modifications you've done and the condition of your engine.

Turbo modifications on the VQ25DET

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the VQ25DET.

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.

When your motor has forced induction tuning mods are simpler to install and most turbo engines are built with more solid components.

However every engines will have power limits

We recommend you find these restrictions and install forged components to handle the power.

We've seen people spending a loads on turbo upgrades on the VQ25DET only to experience the car throw a rod soon after it's been completed.

Bigger capacity turbochargers commonly suffer no power at low rpm, and little turbochargers spool up really quickly but don't have the peak end bhp gains.

Thanks to new tech the range of turbos is always moving on and we now see variable vane turbos, permitting the vane profile is altered according to speed to lower lag and increase top end bhp.

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

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large bhp and torque gains, although more complex to install. We have this article covering twinchargers if you want to read more.

Tips about fuel supply on the VQ25DET

When you raise the torque you will need to increase to the fuel system.

More torque needs more fuel. It is important to be generous with your injectors flow rate.

As a rule of thumb add another 20% when buying an injector, helps cope with injector deterioration and allows a bit of spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended VQ25DET performance exhaust upgrades

The only time you should look to replace your exhaust system with an upgraded one is if your exhaust is creating a restriction.

On most factory exhausts you should find that the flow rate is still good even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Please dont run with the largest exhaust you can find you'll reduce the exhaust flow rate - the best for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

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

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the VQ25DET

Like most engines an VQ25DET, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the VQ25DET, failure to do this will exacerbate engine wear, on a tuned VQ25DET this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your VQ25DET why not pop over to the forums at TorqueCars where you can chat about VQ25DET tuning options and read about others projects who may be planning to do similar modifications on their VQ25DET.

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This entry was posted under Makes and Models. Tags: engine, nissan
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