Tuning Feature: Nissan QR25DD Modified

"Comprehensive guide to performance parts and tuning the Nissan QR25DD engine!"

We are always getting messages asking about the things we are recommending when it comes to QR25DD mods that work. So let us look into Nissan QR25DD modifications and outline the best upgrades on this great engine and point out some problems along the way.

The Nissan QR25DD are fantastic to work on and with a few sensible uprated upgrades like a remap, turbo improvements and camshafts you will really enhance your driving fun.

We shall review and look at QR25DD tuning and point out the premier mods that work.

When talking about the optimum parts for your QR25DD engine, we are going to concentrate on the tuning parts that give the best power gain for you money.

The cam profile plays a big part in the engines power output so cam upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen cam profile, so large power band gains are on offer for cam upgrades.

NB: Fast road camshafts usually boost the bhp and torque across the rev band, you could drop a little low end torque but the higher rpm power will improve.

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

A Motorsport camshaft is not great driving in heavy traffic.

You should ideally optimize your torque band to your cars usage so for a car driven daily stick with a shorter duration QR25DD camshaft

Some QR25DD engines respond better to more aggressive cam durations so view each engine as unique.

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

A longer valve duration 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.

QR25DD Tuning Stages

Stage 1 QR25DD modifications: Panel air filters, Fast road camshaft, Drilled & smoothed airbox, Intake headers, Remaps/piggy back ECU, Sports exhaust manifold.

Stage 2 QR25DD modifications: Fast road cam, Sports catalyst & performance exhaust, fuel pump upgrades, induction kit, Ported and polished head, high flow fuel injectors.

Stage 3 QR25DD modifications: Competition cam, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves).

A remap should help to fully realize the full potential of all the upgrades you've done to your QR25DD.

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

It is the aim to any performance tuning task to feed more air and fuel into your QR25DD

Intake manifold transmit the air during the suck phase from the filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

Structure and rate of flow of the Intake manifold can make a big effect on to fuel mixing and power on the QR25DD.

Many mass produced engine intake headers are improved through motorsport parts, although a few car makers provide reasonably good intake headers.

Fitting big valve kits, doing some port matching and head flowing will also raise power, and importantly will raise potential for raising the power increase on other parts.

Turbo upgrades for the QR25DD

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 QR25DD

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

If your car is turbo charged mods are relatively easy and we find turbo charged engines are made using better components.

However most engines will have power limits

Discover these restrictions and install better quality components to survive the power.

We've seen drivers spending a fortune on turbo charger upgrades on the QR25DD only to suffer the humiliation of seeing the motor literally blow up just after it's been finished.

Large upgraded turbos commonly experience low end lag, and small turbos spool up quickly but won't have the peak rpm power band gains.

Over the last 20 years the world of turbo chargers is always evolving and we are seeing variable vane turbo chargers, permitting the vane angle is altered according to speed to lower lag and increase top end power.

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

It is not unusual that there's a limit in the air flow sensor MAP/MAF/AFM on the QR25DD when considerably 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 performance at a much lower level.

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

Uprating QR25DD fuel injectors

You will need to ensure that the engine is not starved of fuel so will have to look at the fuelling when you start exceeding 20% of a bhp increase.We would recommend you to over specify your flow rate on the injectors.

The accepted safe increase is to add 20% capacity when specifying an injector, this allows for injector deterioration and gives 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 QR25DD performance exhausts

You only need to to replace your exhaust if the existing exhaust is actually creating a flow problem.

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 can help increase the flow of air through the engine.

But if the exhaust is too big, ie: it's over 2.5 inches bore, you will lose a great deal of the exhaust flow rate and end up lacking power and torque.

Common exhaust restrictions can be traced to the emissions filters installed, so adding a faster flowing high performance alternative will help avoid this restriction.

Problems and issues to look out for on the QR25DD

The QR25DD 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 QR25DD, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your QR25DD engine please join us in our friendly forum where you can discuss tuning options in more detail with our QR25DD owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We really like hearing from our readers, and hearing about which upgrades were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our QR25DD 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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