Tuning Feature: Nissan QG18DEN Modified

"Comprehensive guide to tuning and performance parts on the Nissan QG18DEN engine!"

We are always getting messages requesting information on the premier QG18DEN modifications. So let us look into Nissan QG18DEN upgrades and outline the best modifications on this great engine and point out some frequent tuning mistakes along the way.

We shall examine QG18DEN tuning and point out the ultimate modifications for your car. Nissan QG18DEN are fantastic to work on and with a few sensible performance parts like ECU maps, turbo improvements and camshafts you will increase the drivers experience of your car.

Just because particular modifications are are common on QG18DEN it doesn't mean its worth having, so we'll concentrate on the greatest modifications to provide your QG18DEN with the best power gain for you spend.

Significant power hikes can be made on engines, and the QG18DEN is no exception, with cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road camshafts tend to raise the power across the rev range, you may lose a little bottom end bhp but high end rpm power will be lifted.

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

In a car used daily one, ideally, should ideally to match your bhp range to your driving style.

I'd be gobsmaked if you find a QG18DEN Motorsport camshaft is a pleasure to live with when in heavy traffic.

Different QG18DEN engines respond better to extreme cam durations so view each engine as unique.

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

Extending exhaust or intake 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.

QG18DEN Tuning Stages

Stage 1 QG18DEN modifications: Fast road camshaft, Panel air filters, Intake headers, Drilled & smoothed airbox, Sports exhaust manifold, Remaps/piggy back ECU.

Stage 2 QG18DEN modifications: fuel pump upgrades, Fast road cam, induction kit, Ported and polished head, Sports catalyst & performance exhaust, high flow fuel injectors.

Stage 3 QG18DEN modifications: Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves), Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Competition cam.

Remaps helps release the full potential of all the upgrades you've done to your QG18DEN.

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 differs on the upgrades you've fitted and the condition of your engine.

Pulling air into the QG18DEN engine is the aim to any performance tuning task.

Intake take the air during the suck phase from the intake filter and allow it to be pulled into the engine cylinders.

The shape and rate of flow of the Headers can make a noticeable change to fuel atomisation on the QG18DEN.

Commonly we find the intake headers are improved through an upgrade, although some OEM provide well optimised intake headers.

Big valve conversions on the QG18DEN, carrying out 3 or 5 angle valve jobs and porting and head flowing will also increase torque, & more importantly will permit a greater torque increase on other tuning mods.

Turbo upgrades for the QG18DEN

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 QG18DEN

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

When a car is fitted with a turbo parts are giving better power gains and we find turbocharged engines use uprated components.

However most engines have limits

Discover these limits and upgrade to forged components to handle the power.

We see many people spending a fortune on turbo charger upgrades on the QG18DEN only to watch the motor throw a rod when it's been finished.

Larger capacity turbo units tend to experience low end lag, and little turbo units spool up much more quickly but won't have the high rpm torque gains.

Thanks to new tech the choice of turbo chargers is always developing and we now see variable vane turbo chargers, where the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

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

You'll commonly see there's a limit in the air flow sensor AFM/MAF on the QG18DEN when a lot more air is being drawn into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting bhp and torque at a much lower level.

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

Uprating QG18DEN fuel injectors

When you improve the performance you will need to ramp up to the fuel delivery.

More performance needs more fuel. We strongly recommend you to over specify your injector capacity.

The rule of thumb is to add 20% when fitting an injector, this accounts for injector deterioration and provides 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 QG18DEN performance exhausts

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

On most factory exhausts you'll find your flow rate is ok even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Don't go with the largest exhaust you can buy this will slow the exhaust rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Common exhaust restrictions are in the catalyst installed, so adding a higher flowing race alternative will help avoid this restriction.

Problems and issues to look out for on the QG18DEN

The QG18DEN 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 QG18DEN, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your QG18DEN engine please join us in our friendly forum where you can discuss tuning options in more detail with our QG18DEN 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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