MENUTuning the Nissan QR
"All you need to know about performance tuning the Nissan QR engine!"
Carref prides itself on providing the latest tips and guides to your modification project.
The Nissan QR really good project engines and with the optimum uprated parts like remapping, turbo upgrades and camshafts you will greatly increase your driving enjoyment.
This pages aim is look into QR tuning and point out the best modifications for your car.
We rely on our visitors to pass on tips and tell us about their projects and what worked on their car, and this article is the culmination of the feedback we have received. First let us look at the history and specs of this engine and then consider which tuning modifications work best on it.
History of the Engine
Configuration Inline-four with a capacity ranging between 2.0–2.5 L (1,998–2,488 cc)
Cylinder bore: 89 mm (3.5 in)
Piston stroke: 80.3 mm (3.16 in) OR 100 mm (3.94 in)
QR20 Engines
- QR20DE 148 hp at 6000 rpm 148 lb⋅ft at 4000 rpm
- QR20DD 148 hp at 6000 rpm 148 lb⋅ft at 4400 rpm
QR25 Engines
- QR25DE 175 hp at 6000 rpm 180 lb⋅ft of torque at 4000 rpm
- QR25DE 170 hp at 6000 rpm and 175 lb⋅ft at 4000
- QR25DD 168 hp at 5600 rpm 181 lb⋅ft at 4000 rpm
- QR25DER supercharged & 20hp electric motor 250 hp at 5600 rpm and 243 lb⋅ft at 3600 rpm
The QR25DE was revised in 2007 quite extensively with reduction in friction, higher red line and revised cam profile and relocation of the balancer.
Tuning the Nissan QR and best QR performance parts.
What are the most effective QR mods
When talking about the best ultimate for your QR engine, we are going to focus on the tuning mods that give the best power gain for you money.
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.
Fast road camshafts usually boost the bhp and torque across the rev range, you may sacrifice a little bottom end power but high end rpm power will be better.
Competition camshafts, boost the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.
A Race cam won't do well if on the daily commute.
QR25 cam specs
Stock 244 intake 232 exhaust
Stage 1 cams
262-264 intake 242-256 exhaust
Race cams
264-272 intake 257-264 exhaust
Replace springs and retainers at the same time.
You should ideally match your power band to your typical driving style so for a daily driver stick with a mild fast road QR cam
Different QR engines respond better to mild camshaft durations check your engine on a rolling road.
The map and injectors and fuel pump also will say much on the torque gains you'll achieve.
Extending exhaust or intake durations 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.
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How to tune your car
- Improve the handling
Focus on Suspension improvements, such as coilovers and make sure the bushings are in good order and that the alignment is correct. Then focus on improving the brakes, with a big disk brake conversion kit and fast road brake pads.
- Remove restrictions
Focus on the intake and exhaust with filters being the common point of restriction in a tuned car. Intercoolers may also become restrictive on turbo engines so this may also need to be uprated.
- Burn more fuel & air
Increase the fuelling so it matches the air coming into the engine. The ratio is important so you need to improve the fuel pump and injectors, so the head mods, big valve conversions, fast road camshafts and forced induction upgrades extra supply of air is adequately met.
- Test and replace any weak parts
Weak areas are commonly the clutch, the turbocharger and pistons and crankshaft in a highly tuned engine. Makes sure these components will cope with your power aspirations.
- The Tune or Remap
A cars ECU controls the fuel, timing, spark and even the turbo in some cases, so to fully extract your gains you should remap the car last and this will fully release the power. Some cars are easy to map, and others require piggyback ECU's or aftermarket ECU's but this is the most vital step of your tuning project.
Modifying to Stage 1:
Sports exhaust manifold, Remaps/piggy back ECU, Fast road camshaft, Drilled & smoothed airbox, Panel air filters, Intake headers.
Modifying to Stage 2:
Fast road cam, fuel pump upgrades, induction kit, high flow fuel injectors, Ported and polished head, Sports catalyst & performance exhaust.
Modifying to Stage 3:
Twin charging conversions, Adding or Upgrading forced induction (turbo/supercharger), Internal engine upgrades (head flowing porting/bigger valves), Competition cam, Crank and Piston upgrades to alter compression, Engine balancing & blueprinting.
Mapping will help unlock the full potential of all the upgrades you've done to your QR.
It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the outcome will vary depending on the upgrades you've fitted and the condition of your engine.
Forcing fuel and air into the QR engine is the aim to any engine tuning project.
Air Intake manifolds take the air from the air filter and allow it to be pulled into the engine cylinders with fuel for the squish phase.
Structure and flow rate of the Intake headers can make a substantial difference to to fuel mixing and power on the QR.
Removing the balance shaft will gain you another 7hp or so and will help the engine rev more freely although you will get more noise and vibration.
Rather than a removal kit, we've heard of many people cutting the chain that drives the balance assembly to achieve the same thing, and this mod is well documented online to allow you to research it thoroughly and assess its suitability for your QR20 QR25 engine.
It's not uncommon that intake manifold are in desperate need of a performance upgrade, although some makers provide reasonably good intake manifold.
Larger QR valves, getting port work and head flowing will also boost bhp and torque, and more importantly will afford you a greater bhp and torque increase on other tuning mods.
Which turbo upgrades are best?
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 QR
On the supercharged QR25DER you could add an underdrive pulley for a quick and easy power gain although this may affect the aircon compressor range as well.
The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes significant power gains.
If a car is fitted with a turbocharger modifications are going to net you a larger power gain and we find turbocharged engines are made using better components.
There are reliable limits for every engine, with some being incredibly solid and some only just able to handle stock power
See where you'll find these restrictions and upgrade to better quality crank and pistons to survive the power.
We see many people spending a loads on turbo upgrades on the QR only to have the QR explode on it's first outing after it's been finished.
Bigger capacity turbo units commonly experience no power at low rpm, and low capacity turbo units spool up more quickly but won't have the peak end engines power gains.
In the last 10 years the selection of turbo chargers is always moving on and we now see variable vane turbo chargers, permitting the vane profile is altered according to speed to lower lag and increase top end power.
Twin scroll turbo chargers divert the exhaust flow into 2 channels and feed these at differently angled vanes in the turbo charger. They also increase the scavenging effect of the engine.
It is not unusual that there is a limit in the air flow sensor MAF/MAP on these engines when loads 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 torque at a much lower level.
Adding a supercharger or additional turbo will make large bhp and torque gains, although more challenging to get working. We have this in depth look at twinchargers if you want to read more.
Fuelling
When you increase the torque you will need to pay attention to to the fuelling.
More torque needs more fuel. 
We strongly recommend you to be generous with your flow rate on the injectors.
The accepted safe increase is to add another 20% when specifying an injector, which takes into account injector deterioration and affords you some spare capacity should the engine require 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.
All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.
4 Cylinder turbocharged engines
- 58 PSI 340cc/min 200hp
- 58 PSI 511cc/min 300hp
4 Cylinder NASP engines
- 58 PSI 285cc/min 200hp
- 58 PSI 426cc/min 300hp
4 Cylinder supercharged engines
- 58 PSI 312cc/min 200hp
- 58 PSI 468cc/min 300hp
Choosing the right performance exhaust
One of the most common mistakes and problems we see in tuning projects is usually down to the exhaust, or rather a poorly chosen exhaust for your engine.
Only look to increase your exhaust if the current 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 will certainly help air flow through the engine but avoid an exhaust that is too large or you could will reduce the flow rate. Stick to 1.5 to 2.5 inches for best results.
Usual exhaust restrictions can be located the catalysts installed, so adding a faster flowing high performance alternative will help avoid this restriction.
Weak spots Issues & problem areas on the QR
The QR engines are generally reliable and solid as long as they are regularly serviced and maintained.
Valve clearances need to be checked and reset on all engines without hydraulic lifters.
Overheating can cause major issues so check the cooling system is in good condition especially the water pump.
Regular oil changes are vital on the QR, especially when tuned and will help extend the life and reliability of the engine.
For more information on Tuning your QR engine please join us in our friendly forum where you can discuss tuning options in more detail with our tuning articles to get a full grasp of the benefits and drawbacks of each modification.
Please help us improve these tips by sending us your feedback in the comments box below.
We love to hear what our visitors have got up to and which parts work best for them on each model of car. Comments are used to improve the accuracy of these QR articles which are continually updated.
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