The Lowdown on "QR25DE Modifications"

How to modify and upgrade the Nissan QR25DE

"Comprehensive guide to tuning the Nissan QR25DE engine!"

Forums like the one at TorqueCars are always getting posts asking how to improve the QR25DE from people inquiring about getting more power from the QR25DE and wanting to know what are the things tuners recommend when it comes to QR25DE power upgrades. So let us look into Nissan QR25DE parts and outline the best mods that work on this great engine and point out some frequent tuning mistakes along the way.

Car Tuning Tips will look into QR25DE tuning and highlight the greatest modifications. Nissan QR25DE make a good tuning project and with carefully chosen uprated tuning mods like remaps, turbo upgrades and camshafts you will positively maximize your driving pleasure.

The best QR25DE upgrades on an engine are in our opinion the ones that give the biggest return for your money.

We won't be swayed by popular QR25DE upgrades, they need to be cost effective.

Improving air intake on the QR25DE

You need air matched to fuel for an engine to work. If there is insufficient fuel then it will run lean, if there is insufficient air it runs rich resulting in lost power and potentially damaging the engine. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Pulling air and fuel into your QR25DE is the primary aim to any engine upgrade project.

It is not unusual that there's a restriction in the air flow sensor MAF/MAP on the QR25DE when loads more air is being fed 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 take the air during the suck phase from the filter and allow it to be drawn into the engine cylinders.

Shape and rate of flow of the Air Intake manifolds can make a big change to fuel atomisation and engine efficiency on the QR25DE.

Many mass produced engine headers are begging for a performance upgrade, although some OEM provide fairly well optimized headers.

Increasing the QR25DE valve size, getting 3 or 5 angle valve jobs and porting and head flowing will also increase performance, and more importantly will permit a greater performance increase on other mods.

QR25DE performance cam tips.

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

The ecu map and fuel pump and injectors also will say much 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.

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

NB: Fast road cams tend to increase the torque over the rev range, you might lose a little low end power but your high end rpm power will be lifted.

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

For a daily driver you must carefully try to match your engines power to your usage of the car.

I'd be surprised if you find a QR25DE Motorsport cam is a pleasure to live with when driving in heavy traffic.

Stage 1, 2 and 3 mods for the QR25DE

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 QR25DE parts:

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

Stage 2 QR25DE parts:

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

Stage 3 QR25DE parts:

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

Remaps will help to establish the full potential of all the modifications you've done to your QR25DE.

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 usually vary depending on the modifications you've fitted and the condition of your engine.

Turbo modifications on the QR25DE

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 QR25DE.

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 motor is turbocharged, tuning parts are giving better power gains and turbocharged engines are made with more solid components.

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

See where you'll find these limits and fit higher quality crank and pistons to utilize the power.

There are many people spending a lot of money on turbocharger upgrades on the QR25DE only to watch the engine block go up in smoke when it's used in anger.

Big upgraded turbo chargers commonly suffer no power at low rpm, and small turbo chargers spool up more quickly but don't have the peak rpm engines power gains.

In recent times the world of turbos is always increasing and we are seeing 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 2 channels and feed these at differently angled vanes in the turbocharger. They also help 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 gains, although more difficult to install. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the QR25DE

You will need to ensure that the engine is not starved of fuel so should look at the fuelling when you start extending past 20% of a performance hike. Most tuners we speak with say to over specify your injector capacity.

The accepted safe increase is to add 20% capacity when buying an injector, this accounts for injector deterioration and affords a little 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 QR25DE performance exhaust upgrades

You only need to to uprate your exhaust system with an upgraded one is if your exhaust is creating a flow problem.

On most factory exhausts you'll find your flow rate is 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.

Note that with the largest exhaust you can buy this will reduce the exhaust flow rate - the best exhausts 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.

Usual exhaust restrictions can be located the catalyst and filters installed, so adding a higher flowing sports alternative will help avoid this restriction.

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

Faults issues and things to look out for on the QR25DE

Like most engines an QR25DE, 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 QR25DE, failure to do this will exacerbate engine wear, on a tuned QR25DE 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 QR25DE why not pop over to the forums at TorqueCars where you can chat about QR25DE tuning options and read about others projects who may be planning to do similar modifications on their QR25DE.

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

We want to know your experiences with tuning mods on your QR25DE, it helps us improve our tips and keeps us current so please use the comments box to drop a tip.

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