Nissan SR18DE Tuning

"All you need to know about tuning and performance parts on the Nissan SR18DE engine!"

In this article we review SR18DE tuning and provide tips on the premier modifications. Nissan SR18DE are awesome to work on and with carefully chosen modified enhancements like a remap, turbo upgrades and camshafts you will substantially enhance your driving opportunities.

The SR engine also came as an SR18Di single point fuel injection and had solid cast iron blocks, and there was a SR20 version which we will cover in another article.

It is a good solid 1.8 L (1,838 cc) DOHC engine and boasts multi point fuel injection and were fitted with a lightweight crankshaft, allowing the engine to rev more freely than the SR20DE varient it is based on.

History, Power & Specs of the Engine

• 1991-1997 Nissan Primera
• Nissan Sunny
• Nissan Avenir W10
• Nissan Rasheen
• 1991-1997 Nissan Bluebird U13
• 1989-1998 Nissan Bluebird U14 119 PS 117 hp
• 1990-1993 Nissan Pulsar GTi B13 and N14, 140 PS (138 hp) at 6400 rpm  (123 lbft) at 4800 rpm
• 1991-1999 Nissan Pulsar GTi N15, 140 PS (138 hp) at 6400 rpm (123 lbft) at 4800 rpm
• 1988-2001 Nissan Presea 125 PS (123 hp)

Best SR18DE modifications

When talking about the best best for your SR18DE engine, we are going to concentrate on the parts that give the best power gain for you spend.

The cam profile plays a big part in the engines power output so cam upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen cam profile, so large bhp gains are on offer for cam upgrades.

Fast road cams normally bump the performance through the rev range, you may sacrifice a little bottom end torque but your higher rpm power will be higher.

Competition cams, bump 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 is not great driving around busy urban areas. This is because a competition cam causes a very lumpy idle, and makes the car more prone to stall or jerk along in stop start traffic, sadly though many ignore this and end up ruining a perfectly good car and having to revert back to a fast road, or OEM cam profile.

You should ideally optimize your bhp range to your typical driving style so for a daily driver stick with a shorter duration SR18DE camshaft

Each engine responds better to more aggressive cam durations than others.

The ecu map and fuelling also will say much on the bhp gains you'll get.

A longer valve duration 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.

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

Best Engine Mods for your car

1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

Typical stage 1 mods often include: drilled & smoothed airbox, Fast road camshaft, Remaps/piggy back ECU, Intake manifolds, Panel air filters, Sports exhaust header/manifold.

Typical stage 2 mods often include: Ported and polished head, fuel pump upgrades, Fast road cam, Sports catalyst & performance exhaust, induction kit, high flow fuel injectors.

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

ECU flashing should help to release the full potential of all the upgrades you've fitted to your SR18DE.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but figures achieved often depend much on the upgrades you've applied and the condition of your engine.

It is vital to any tuning task to pull more fuel and air into the SR18DE engine

Your intake manifold will direct the air from the filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

Design and rate of flow of the Air Intake manifolds can make a large improvement to fuel delivery on the SR18DE.

Commonly we find the intake manifold are in desperate need of aftermarket tuning parts, although a few OEM provide well optimised intake manifold.

Larger SR18DE valves, getting port matching and head flowing will also increase bhp and torque, and more importantly will permit increasing the bhp and torque increase on other parts.

Turbo upgrades

NA (naturally aspirated) 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 SR18DE

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

If your motor is fitted with a turbo upgrades are giving better power gains and turbo charged engines will have strengthened components.

However you will find an engines have limits

See where you'll find these limits and install higher quality components to handle the power.

We see many car owners spending a loads on turbo upgrades on the SR18DE only to suffer the humiliation of seeing the engine block catastrophically fail just after it's completed.

Larger capacity turbo units will usually suffer low end lag, and small turbo units spool up more quickly but do not have the peak rpm power band gains.

Thankfully the choice of turbochargers is always increasing and we commonly find variable vane turbochargers, allowing the vane profile is altered according to speed to lower lag and increase top end power.

Twin scroll turbochargers divert the exhaust gases into a couple of channels and push these at differently designed vanes in the turbo. They also boost the scavenging effect of the engine.

You'll commonly see there is a limit in the air flow sensor AFM/MAP on these engines when considerably more air is being sucked 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 harder to setup. We have a twincharger power adding guide if you want to read more.

Fuelling

Don't dismiss the need improve the fuelling when you are increasing the torque - it makes the car more thirsty. Most tuners we speak with say to be generous with your injector capacity.

The rule of thumb is to add 20% when fitting an injector, which takes into account injector deterioration and allows 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.

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
• 58 PSI 682cc/min 400hp

4 Cylinder NA (naturally aspirated) engines

• 58 PSI 285cc/min 200hp
• 58 PSI 426cc/min 300hp

Exhaust

You only need to increase your exhaust if the existing exhaust is actually causing a flow problem.

On most factory exhausts you'll see your 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.

Do not go with the widest exhaust you can find this will reduce the exhaust flow rate - the best 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 can be located the catalyst and filters installed, so adding a higher flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots Issues & problem areas on the

The engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Regular oil changes are vital on the , especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your engine please join us in our friendly forum where you can discuss tuning options in more detail with our 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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