Tuning Feature: Nissan QG18DE Modified

"Comprehensive guide to tuning the Nissan QG18DE engine!"

We are always getting posts requesting information on the best tips on QG18DE mods that work. So let us look into Nissan QG18DE parts and outline the best modifications on this great engine and point out some problems along the way.

Here we examine the options for your QG18DE tuning and show the greatest modifications for your car. Nissan QG18DE have loads of potential and with the right uprated mods like remaps, turbo improvements and camshafts you will greatly increase the drivers experience of your car.

Just because particular upgrades are appear in lots of QG18DE projects it doesn't mean you should fit it, instead we'll concentrate on the top upgrades to provide your QG18DE with the best power gain for you spend.

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 engines power gains are on offer for camshaft upgrades.

NB: Fast road camshafts usually increase the bhp across the rpm band, you may lose a little low end torque but your top end will improve.

Race camshafts, increase the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

In a road car one, ideally, should ideally to match your bhp range to your usage of the car.

I'd be shocked if you find a QG18DE Motorsport and race cam is a pleasure to live with when on the daily commute.

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

The ECU mapping and fuel pump and injectors also will say much on the bhp gains you'll achieve.

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.

QG18DE Tuning Stages

Stage 1 QG18DE modifications: Panel air filters, Remaps/piggy back ECU, Fast road camshaft, Sports exhaust manifold, Intake headers, Drilled & smoothed airbox.

Stage 2 QG18DE modifications: fuel pump upgrades, Ported and polished head, induction kit, Sports catalyst & performance exhaust, Fast road cam, high flow fuel injectors.

Stage 3 QG18DE modifications: Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Twin charging conversions, Crank and Piston upgrades to alter compression, Competition cam.

The QG18DE engines respond well to mods and we note that there are plenty of upgrades and tuning parts about.

Remaps allows a tuner to to establish the full potential of all the tuning parts you've done to your QG18DE.

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

Feeding more air into the QG18DE engine is the whole point to any engine performance tuning task.

The intake plenum carry the air from the filter and allow it to be drawn into the engine and mixed with fuel.

The bore size, shape and flow rate of the Intake can make a substantial effect on to fuel delivery on the QG18DE.

It's not uncommon that intake headers are improved through motorsport parts, although some car makers provide fairly well optimized intake headers.

Big valve conversions on the QG18DE, carrying out port matching and head flowing will also raise bhp, and significantly will allow you to get increasing the bhp increase on other upgrades.

Turbo upgrades for the QG18DE

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 QG18DE

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

If the engine has forced induction modifications are relatively easy and you'll see that turbocharged engines will have many forged and stronger components.

There are practical limits for every engine, with some being incredibly solid and some only able to handle stock power

Research these limitations and fit forged components to handle the power.

There are many people spending a loads on turbo upgrades on the QG18DE only to have the engine literally blow up just after it's completed.

Larger capacity turbo units commonly suffer low end lag, and low capacity turbo units spool up really quickly but won't have the peak rpm engines power gains.

In the last 10 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 performance.

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

You'll commonly see there's a limitation in the air flow sensor MAP/MAF/AFM on the QG18DE 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 sapped performance at a much lower level.

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

Uprating QG18DE fuel injectors

Don't miss you'll need to improve the fuelling when you are increasing the torque - it makes the car more thirsty. We would recommend you to be generous with your flow rate on the injectors.

As a rule of thumb add 20% to the flow rate when fitting an injector, this accounts for injector deterioration and affords a little 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 QG18DE performance exhausts

Only look to increase your exhaust if the existing exhaust is creating a restriction.

On most factory exhausts you should find that your 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.

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 much 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 freer flowing high performance alternative will help avoid this restriction.

Problems and issues to look out for on the QG18DE

The QG18DE 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 QG18DE, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your QG18DE engine please join us in our friendly forum where you can discuss tuning options in more detail with our QG18DE 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 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 QG18DE guides and tips are kept up to date.

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