All you need to know about "QG15DE Modifications"

How to modify and upgrade the Nissan QG15DE

"Comprehensive guide to performance tuning the Nissan QG15DE engine!"

Forums like the one at TorqueCars are frequently getting messages about how to improve the QG15DE from people wanting to know what are the things tuners recommend when it comes to QG15DE mods that work. So let us look into Nissan QG15DE parts and outline the best upgrades on this great engine and point out some potential pitfalls along the way.

Now we will examine the options for your QG15DE tuning and show the best mods that work. Nissan QG15DE offer good returns when tuned and with carefully chosen performance mods like remapping, turbo kits and camshafts you will really increase your driving fun.

The greatest QG15DE mods on an engine are as we have found the ones that give the best gains for your money.

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

Improving air intake on the QG15DE

You need fuel and air for an engine to work. If there is not enough fuel then it will run lean, if there is a lack of air it runs rich sapping 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 Feeding more air into each cylinder is the aim to any engine modification project.

It is common that there is a limit in the air flow sensor MAP/MAF/AFM on the QG15DE 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 was restricting bhp and torque at a much lower level.

Intake manifolds transmit the air during the suck phase from the air cleaner and allow it to be sucked into the engine cylinders.

The size of bore and shape and flow characteristics of the Plenum can make a big effect on to fuel delivery on the QG15DE.

I usually find plenum chambers are improved through aftermarket parts, although some OEM provide reasonably well designed plenum chambers.

Adding a QG15DE larger valve kit, carrying out port matching and head flowing will also improve torque, and importantly will permit an improved torque increase on other tuning parts.

QG15DE performance cam tips.

Different QG15DE engines respond better to more or less aggressive cam durations than others.

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.

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 power band gains are on offer for camshaft upgrades.

NB: Fast road cams usually bump the bhp and torque across the rpm range, you may lose a little bottom end bhp but your higher rpm power will be higher.

Race cams, bump the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a daily driver you must carefully try to optimize your bhp range to your usage of the car.

I'd be shocked if you find a QG15DE Race cam is a pleasure to live with when driving in heavy traffic.

Stage 1, 2 and 3 mods for the QG15DE

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 QG15DE parts:

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

Stage 2 QG15DE parts:

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

Stage 3 QG15DE parts:

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

Mapping helps fully realize the full potential of all the tuning mods you've done to your QG15DE.

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 will vary depending on the tuning mods you've done and the condition of your engine.

Turbo modifications on the QG15DE

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 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 superb power gains.

When an engine has a turbo already fitted upgrades are simpler to install and turbo engines will have many forged and stronger components.

There are common areas of failure for every engine, with some being incredibly solid and some just sufficiently able to handle stock power

Discover these limitations and upgrade to better pistons and crank to utilize the power.

There are many mechanics spending a loads of money on turbo upgrades on the QG15DE only to suffer the indignity of watching the motor catastrophically fail when it's been completed.

Larger capacity turbos often experience no power at low rpm, and small turbos spool up really quickly but do not have the top end power band gains.

Thanks to new tech the range of turbo units is always evolving and we now see variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo units divert the exhaust flow into two channels and feed these at differently profiled vanes in the turbocharger. They also increase the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large performance gains, although more challenging to install. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the QG15DE

When you raise the performance you will need to look at to the fuel system.

More performance needs more fuel. At this point we flag up the need to over specify your flow rate on the injectors.

The rule of thumb is to add 15% when fitting an injector, this takes into account injector deterioration and provides a bit of 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 QG15DE performance exhaust upgrades

You should look to replace your exhaust system with an upgraded one is if your current exhaust is creating a restriction in flow.

On most factory exhausts you'll see the flow rate is still ok 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.

Sports exhausts generally help improve air flow out of the engine but avoid an exhaust that is too wide or you could will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Usual exhaust restrictions can be located the catalyst installed, so adding a freer flowing race alternative will help avoid this restriction.

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

Faults issues and things to look out for on the QG15DE

Like most engines an QG15DE, 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 QG15DE, failure to do this will exacerbate engine wear, on a tuned QG15DE 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 QG15DE why not pop over to the forums at TorqueCars where you can chat about QG15DE tuning options and read about others projects who may be planning to do similar modifications on their QG15DE.

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