Tuning Feature: Nissan QG15DE Modified

"Comprehensive guide to tuning the Nissan QG15DE engine!"

We are regularly getting messages asking about the optimum QG15DE modifications. So let us look into Nissan QG15DE tuning mods and outline the best modifications on this great engine and point out some common pitfalls along the way.

Now we shall review and look at QG15DE tuning and summarise the greatest modifications. Nissan QG15DE great bases for a tuning project and with carefully picked performance enhancements like ECU maps, turbo upgrades and camshafts you will dramatically maximize the drivers fun of your car.

The greatest QG15DE mods on an engine are usually the ones that give the best power gain for you spend.

We won't be swayed by popular QG15DE mods, they need to be cost effective.

Significant power increases can be made on engines, and the QG15DE is no exception, with camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

NB: Fast road cams commonly push up the bhp across the rev range, you could sacrifice a little low end bhp but higher rpm power will improve.

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

A Competition camshaft makes it harder when driving in heavy traffic.

You should ideally match your torque band to your cars usage so for a road car stick with a fast road QG15DE camshaft

Some QG15DE engines respond better to extreme cam durations so view each engine as unique.

The engine timing and fuelling also will make differences on the torque gains you'll hit.

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.

QG15DE Tuning Stages

Stage 1 QG15DE modifications: Remaps/piggy back ECU, Drilled & smoothed airbox, Sports exhaust manifold, Intake headers, Panel air filters, Fast road camshaft.

Stage 2 QG15DE modifications: Ported and polished head, high flow fuel injectors, induction kit, fuel pump upgrades, Sports catalyst & performance exhaust, Fast road cam.

Stage 3 QG15DE modifications: Internal engine upgrades (head flowing porting/bigger valves), Engine balancing & blueprinting, Competition cam, Crank and Piston upgrades to alter compression, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions.

Remaps allows a tuner to fully realize the full potential of all the modifications you've done to your QG15DE.

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

It is the aim to any engine upgrade task to pull air and fuel into your QG15DE

Intake manifold take the air from the intake filter and allow it to be drawn into the engine cylinders.

Shape and rate of flow of the Intake can make a large improvement to fuel delivery on the QG15DE.

We often see intake manifold are in desperate need of aftermarket parts, although some makers provide fairly well optimized intake manifold.

Larger QG15DE valves, doing a bit of port work and head flowing will also improve bhp and torque, the fantastic side effect is it will allow you to get a greater bhp and torque increase on other mods.

Turbo upgrades for the QG15DE

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 QG15DE

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.

When your car has a turbocharger parts are simpler to install and we find turbocharged engines will have many forged and stronger components.

However every engines will have power limits

Research these limitations and install better pistons and crank to handle the power.

We see many tuners spending a loads of money on turbo charger upgrades on the QG15DE only to suffer the indignity of watching the car throw a rod soon after it's used on the roads.

Bigger capacity turbo units will usually experience low end lag, and low capacity turbo units spool up more quickly but won't have the top end bhp gains.

Thanks to progress the selection of turbo units is always developing and we are seeing variable vane turbo units, permitting the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbo units divert the exhaust gases into 2 channels and flow these at differently profiled vanes in the turbo. They also help the scavenging effect of the engine.

It is common that there is a limit in the air flow sensor AFM/MAF on the QG15DE when considerably more air is being pulled into the engine.

Going up you'll find 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 gains, although more complex to setup. We have this feature on twinchargers if you want to read more.

Uprating QG15DE fuel injectors

Don't omit to increase the fuelling when you are increasing the power - it makes the car more thirsty. We would recommend you to over specify your injectors flow rate.

The rule of thumb is to add 20% capacity when buying an injector, this accounts for injector deterioration and provides 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 QG15DE performance exhausts

You should look to boost your exhaust if your exhaust is actually creating a restriction in flow.

On most factory exhausts you'll see the flow rate is still ok 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 generally help improve air flow out of the engine but avoid an exhaust that is too big or you may end up reduce the flow rate. Stick to 1.5 to 2.5 inches as a rule of thumb.

Typically exhaust restrictions can be traced to the filters installed, so adding a better flowing sports alternative will help avoid this restriction.

Problems and issues to look out for on the QG15DE

The QG15DE 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 QG15DE, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your QG15DE engine please join us in our friendly forum where you can discuss tuning options in more detail with our QG15DE 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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