Nissan s13 service manual / Nissan s13 injection manual / Nissan R33 GTS service manual


1. Engine breathing

  • Air-box panel filter

  • Induction kit

  • Big bore (cat-back) exhaust

  • Front pipe

  • De-cat pipe

  • Turbo elbow

2. Increasing the boost

  • Boost gauge

  • Gated boost valve

  • Uprated/adjustable actuator

  • Electronic boost controller

  • Spark plugs

4. Intercooler modifications

  • Uprated wing-mounted IC

  • Front-mounted IC

5. Turbo modifications

  • Generel

6. Fuelling modifications

  • Fuel pump

  • Fuel Pressure Regulator

7. Fuel injector modifications

  • 370cc injectors - standard injectors.

  • 450cc injectors

  • 550cc injectors

  • 740cc injectors

  • 850cc injectors

8. ECU Upgrades

  • Advantages

  • Disadvantages

  • Piggyback ECUs

9. ALS - Anti Lag System

  • General

Engine breathing


The s13 200sx seems to have been designed and marketed not as an out-and-out sports car, but as a sporty car with suitability for the company-car market. With this in mind, the air intake and the exhaust are quite restrictive, making the car more refined. Removing these restrictions will unleash a good few horsepower just by allowing the engine to do its job unfettered, and as such, may even increase the fuel efficiency!


Air-box panel filter

  • The filter element from the standard air-box can be replaced with a less restrictive version, making it easier for the engine to suck through a bit more air. The power increase will be relatively small with this modification, as a large part of the restriction in the air intake comes not from the filter, but from the design of the air-box itself. One test of various filters (albeit not on a 200sx) found no performance gain whatsoever from a panel filter. This modification is useful as it isn’t obvious, and some people won’t worry about declaring its presence to their insurance company.

Induction kit

  • Complete removal of the air-box and replacement with an induction kit will allow even better breathing, as it eliminates both the restrictive filter and its air-box. There are various types of induction kit available, all with different types of filter & different filtration abilities. The ideal would be a kit with good filtration properties (which prevents dust particles from reaching your turbo blades) but that is not too restrictive.

  • One possible drawback of induction kits is that they are more prone to sucking in hot air from the engine bay than the standard air-box, slightly decreasing the amount of oxygen actually taken in (as the air is less dense). It has been debated how much of an effect this might have. This problem can be lessened by either ducting cold air to the intake, forming a barrier between the engine and the intake, or moving the intake further from the engine, to an area of direct cold air feed.

Big-bore (cat-back) exhaust

  • For the sake of quietness, the standard exhaust is quite narrow, which unfortunately also restricts the flow of exhaust gases. This can be improved with a larger bore exhaust, letting the gasses flow freely, making the engine more responsive. This will also have the effect of making the car sound more ‘sporting’. Stainless steel exhausts have a harsher boomier, and will last for many years. Mild steel exhausts have a throatier subtler sound, but will last for a shorter time.


  • If you’re going to de-restrict the exhaust from the catalytic converter(s) backwards, it also makes sense to enlarge the bore of the front pipe. This will not only improve the power, but also the "driveability" of the car, giving it better low-rev responsiveness.

De-cat pipe

  • The catalytic converter also significantly restrict the flow of exhaust fumes. Replacing it with a simple de-cat pipe results in a significant increase in power and torque, but has moral and environmental consequences. It will also make the exhaust a lot louder, too! The cat would need to be replaced prior to an MOT test.

Turbo elbow

  • The standard turbo exhaust elbow is fairly poorly designed, being too narrow for efficiency, and creating too much turbulence. Replacing it with an aftermarket model will increase the power from the turbo (especially at higher revs) and make the engine quicker to rev too. Due to the position of the turbo, this is a time consuming modification to fit.

Increasing the boost


This is a simple idea – increasing the level of boost will increase the amount of air the engine receives, the Engine Control Unit (ECU) will monitor this air-flow, and add more fuel to maintain the mixture, resulting in more power. After a point (around 300-350 bhp), all increases in power will come via more boost through a bigger turbo; other modifications after this point are merely to allow the engine to cope with the high boost levels.

The standard DK-spec 200sx CD18DET runs at about 7psi. The standard ECU can only cope with a certain level of increased boost (and correspondingly, air-flow), before it finds itself unable to provide enough fuel to maintain the combustion mixture. If the level of boost is too high, the risk is that the combustion mixture could become too ‘lean’ – this would make the combustion hotter than normal, which could damage the engine.

To guard against this, the ECU monitors the amount of air entering with the Air-Flow Meter (AFM), which feeds the ECU a voltage (up to 5 volts) which is proportional to the air-flow. Faced with too high an air flow, the ECU will act to protect the engine, by triggering the ‘fuel-cut’. This prevents combustion, presenting potentially dangerous combustion cycles, but it also cuts the power produced by the engine dramatically, making the car jerk violently.

There are ways of overcoming this ‘fuel-cut’, notably the HKS Fuel–Cut Defender (FCD). This works by ‘capping’ the voltage the ECU receives from the AFM, so that the ECU is tricked into thinking the air flow is lower than it really is. However, if you prevent the fuel cut from operating on an engine with a standard ECU, you obviously run the risk of the engine ‘running lean’, as the ECU will only provide fuel to match the air flow it knows about, when in reality, the air-flow could be much higher. If you have an engine with an uprated management system, removing the fuel-cut would be safe, assuming you are certain the fuelling is set up well for all possible boost values, and will not run lean. An alternative approach is to swap the 200sx AFM for the larger model from the 300zx, which can cope with a greater air-flow; various engine management systems have a setting to allow this change. Some engine management systems will remove the fuel-cut altogether.

Another factor to consider is the ambient air temperature – colder air is more dense, so will provide a greater amount of oxygen at a given boost level. You might find that a car well set up for the summer will trigger the fuel cut in the winter.

Some methods of increasing the boost can be susceptible to ‘boost spikes’ – short-term increases in boost above the expected level. Brief spikes rarely cause problems with ‘running lean’, but can lead to uneven power delivery and hitting the fuel cut. These spikes are unpredictable, and thus it is sensible to always install a boost gauge to monitor the boost pressure, before you embark on any of these modifications.


Boost gauge

  • A variety of these are available. At their simplest, they are just a mechanical pressure gauge that is plumbed into the boost circuit via a long pipe. More complicated versions may run electronically, orhave features such as ‘peak boost hold’, which lets you know the highest level of boost achieved without staring constantly at the gauge whilst driving. They are usually mounted either in the driver’s eye-line (such as on the A-pillar) or on the central console, near the stereo. They display the current boost pressure (either in bar or psi).

Gated boost valve

  • This modification involves inserting a valve into the pipe controlling the turbo’s actuator. The valve involves a variably-spring-loaded ball-bearing in a tube; when the level of boost pressure reaches the level set by the spring pressure, the ball-bearing moves, allowing excess pressure to leak out, maintaining a steady boost pressure. This allows the boost pressure to run higher than that set by the actuator.

  • This is a development of a similar valve, called the Bleed Valve, which was renowned for boostspikes.

Uprated/adjustable actuator

  • This replaces the standard turbo actuator, and allows a different peak boost pressure to be set. These are more difficult to integrate with an electronic boost controller, should you later wish to fit one.

Electronic boost controller

  • An in-car module, combined with a replacement boost solenoid under the bonnet, allows different boost levels to be set, and also changed from the cockpit whilst driving. Can also feature extra functions, such as an incorporated boost gauge, and look good too!

Spark plugs

  • As the power produced by the engine increases, you’ll need to exchange the spark plugs for ‘colder’ rated equivalents. This is because a more powerful engine will run hotter, and this can cause the tips of the standard plugs to become hot enough to ignite premature detonation of the fuel, before they actually provide a spark. Colder plugs are formulated to resist this. The ‘coldness’ of the plug needs to be suitable for your level of power; if you choose a plug that’s too cold for your engine, it won’t reach its optimum temperature, and will become ‘coked up’.

Intercooler modifications


The intercooler comes after the turbo, before the engine. It cools the air from the turbo prior to it reaching the engine, making it denser, therefore allowing a greater amount of oxygen to reach the combustion chamber for a given volume or air. This increases the power and efficiency of the turbo system, compared to non-intercooled turbocharged engines. Cooling the charge air also lessens the liklihood of detonation. The standard 200sx intercooler is mounted in the left front wing, and is reasonable for everyday driving. However, it is insufficient for more powerful engines, and can suffer from ‘heat-soak’ upon hard driving with standard engines – it becomes too hot to function usefully as a heat exchanger.


Uprated wing-mounted IC

  • This is suitable if your tuning intentions are only up to about 300bhp. It’s a straight replacement for the small standard IC, but provides better cooling abilities. As it’s well-hidden and fairly similar to the original item.

Front-mounted IC

  • These intercoolers are improved by virtue of providing a much larger surface area for cooling, and by being better positioned for access to cool air, in the middle of the front spoiler, below the bumper. They can require cutting of the front bumper to be fitted, and some will require the installation of a smaller battery, or relocation of the battery to the boot.

Turbo modifications


The standard turbo on the CA18DET is a Garrett T25. This can be exchanged for a large range of turbos, each of which will alter the engine’s characteristics in various ways.

  • Larger turbos can provide a greater volume of air for a given boost pressure, meaning that lower boost levels are required for the same level of performance.

  • Larger turbos are less restrictive to the engine at the exhaust manifold, so provide greater performance for a given pressure.

  • Larger turbos heat the air less for a given pressure, resulting in cooler and denser charge air.

  • Larger turbos can provide more boost in the higher reaches of the rev range, where smaller turbos start to run out of puff and drop the boost they produce.

  • Larger turbos generally require a longer time to ‘spin up’ and start making boost – they have a greater ‘lag’. This can make them less convenient for every-day driving, but is less of a problem for power/speed applications. This can be minimised by specifying a ball-bearing turbo.

  • Ball-bearing turbos suffer from less friction, so spin up faster (and therefore have less lag) than their non-ball-bearing equivalents. Thus you could have a significantly larger turbo than standard, without sacrificing driveability. Also, ball-bearing turbos such as the Garrett GT series are stronger and not prone to fail at high boost like conventional 270 degree bearing turbos. Unfortunately, they are also much more expensive.

  • Conventional turbos have 270 degree thrust bearings – the bearings go three quarters of the way around the shaft. This is fine until you start running much higher boost than standard, which puts much higher thrust loading on the bearing, causing the turbo bearing to wear rapidly and eventually fail. Turbos with 360 degree thrust bearings are designed to be much stronger, and are necessary if you want to run above (approximately) 17 psi.

  • Some turbos will be direct ‘bolt-on’ replacements for the standard T25, other turbos will require modifications to be made to the turbo manifold or the oil/water feed pipes.

Fuelling modifications


Fuel Pump

  • As the engine becomes more powerful, it will require more and more fuel, and at higher pressures, especially at times of peak power output. The standard fuel pump can only safely provide fuel to around 240bhp (or more accurately, about 14-15psi), at which time it is prudent to replace it with an uprated model, to guard against underfuelling and running a lean mixture.

Fuel Pressure Regulator

  • The fuel pressure regulator (FPR) regulates the pressure in the fuel rail. Typically a fuel pump will pump much more fuel than is actually used by the injectors. The excess is returned to the fuel tank. The regulator maintains a constant fuel pressure by controlling how much is returned to the tank (it operated by a simple diaphragm and spring). At atmospheric pressure (i.e. vacuum hose disconnected) standard fuel pressure is 43 psi. An uprated FPR will allow a degree of control over the eventual fuel pressure, which can help wring more performance out of hard-pushed injectors. This can be slightly risky long-term, however, and larger injectors should be considered. Another factor operating on the FPR is intake manifold pressure: fuel pressure is then varied according to manifold pressure in a 1:1 additive ratio. So if running 15 psi of boost, the regulator supplies fuel to the injectors at a pressure of 58 psi (that is 43 psi + 15 psi)

Fuel injector modifications


Put simply, larger injectors can provide more fuel per single injection, so can maintain the correct air:fuel mixture at a higher boost level, in a more powerful engine. One pitfall is that the standard ECU cannot cope with controlling larger injectors; they must be accompanied by some form of improved engine management system. 80% is generally the industry’s maximum desired duty cycle for continuous operation of fuel injectors.


370cc injectors - standard injectors.

  • It may surprise you to learn, that the standard are only suitable for up to approximately 235 bhp at 80% duty cycle at normal fuel pressure. For shorter periods of time they can be run at 90%, usually without any problems, but under no circumstances should they go above 95%. At 90% duty cycle, assuming fuel line pressure of 58 psi, they can support around 270 bhp. At 95% they can support around 280 bhp at the same fuel pressure. At 68 psi fuel pressure (this is an estimate of the pressure you might see at 15 psi boost, with a 1.7:1 fuel regulator) they can support just over 300 bhp at a 95% duty cycle. Remember, the fuel pump will be working hard to supply fuel at this fuel pressure, so a decent upgraded fuel pump is essential. So 370cc injectors CAN support 300 bhp, but it is not recommended, and only for short periods.

450cc injectors

  • Can support 295 bhp (at 80% duty cycle assuming fuel pressure of 61 psi, i.e assuming you are running 18 psi boost). At 95% duty cycle at this fuel pressure they can support a maximum of 350 bhp.

550cc injectors

  • Can support 370 bhp (at 80% duty cycle assuming fuel pressure of 63 psi, i.e assuming you are running 20 psi boost). At 95% duty cycle at this fuel pressure they can support a maximum of 440 hp.

740cc injectors

  • Can support around 515 bhp (at 80% duty, assuming fuel pressure of 68 psi, i.e assuming you are running 25 psi boost). At 95% duty at this pressure they can support a maximum of 610 bhp.

850cc injectors

  • Can support around 590 bhp at 80% or 700 bhp maximum at 95% (fuel pressure values as above)

ECU Upgrades


Standard ECU modified by daughterboard (e.g. “Jez Chip”, Norris, Blitz Access, Mines VX). A modification is made to the car’s standard ECU allowing a modified set of maps to be run (these are burned permanently into an EPROM).



  • Allows modification of all engine parameters, including those which cannot usually be altered by piggyback systems. Generally the cheapest route to ECU modification.


  • Might be tricky to re-map (usually has to be sent back to its maker). In seriously modified vehicles the need to retain an Air Flow Meter may cause a problem (as explained above). Unless mapped actually on the vehicle, you may still need a piggyback computer to get it “perfect” due to differences in particular modifications, and variances between individual vehicles.

Piggyback ECUs


These are wired into the car’s ECU loom and work by modifying the signals that the ECU sends and receives.

  • Apexi S-AFC/S-AFC II - This nice looking unit with a blue screen acts on the cars MAFS signal allowing you to trim fuelling +/- 50% at a number of RPM and throttle points. Can be used to install larger MAFS and/or injectors. It has no ability to alter ignition timing, nor any “fuel cut defencer” function. It is however quite cheap and is very popular worldwide.

  • Greddy E-manage – this is a relatively new system. Out of the box, it is a very basic Air Flow “trimming” device similar in capability to the old model S-AFC, with 5 screws on the front to adjust fuelling at 5 RPM points. With the optional software and harnesses it becomes a fully mappable piggyback capable of controlling ignition timing as well as fuelling. It also has built in drivers for 2 extra injectors, “fuel cut defencer” function, and an idle stabiliser. An optional pressure sensor allows it to operate when the cars AFM’s capacity has been exceeded. Unfortunately, few tuning companies in the UK are currently familiar with the product, although it is quite straightforward to use the software.

  • Dastek Unichip - Commonly offered by tuners in the UK. This operates in a similar manner and offers similar capabilities to the E-manage. Some reports suggest it may be less able than other systems when it comes to dealing with larger injectors due to a limited range of adjustment.

  • HKS Fcon Pro V - This takes the concept further in that it is actually a complete management system installed in the manner of a piggyback. It is actually capable of running the car without the original ECU according to HKS. This system is used in many “big power” cars in Japan. Custom fit looms for many applications. Specialist (expensive!) set up required.

Full management systems are available, such as those from Motec, Omex, DTA, GEMS, etc. These completely replace the cars standard management system. They generally require a large amount of custom re-wiring and may require other changes, such as to the ignition system. They are getting more competitively priced now, and it may be possible to get one installed for less than £1000.


ALS - Anti Lag System


The reason for Anti-lag is, as it's name suggests, to decrease or eliminate the lag induced by a turbocharger. It is mainly used in rally where all Group A or WRC cars are turbocharged. When you want big power out of a 1.8 / 2.0 litre engine you need a turbocharger, and the more power you want the bigger the turbocharger has to be. But a big turbocharger takes a long time to spin up and create boost pressure and that's where the ALS (Anti Lag System) comes in. Because every second a car is off boost a lot of time is lost on a rallystage. To get rid of the lag the needs to keep spinning at full speed at all times. This includes when the throttle is closed for a gearchange, when braking for a turn and when you're a the start line ready to take off. To keep the turbo spinning while the throttle is closed you need exhaust (lots of hot air basically) to keep turning the turbine wheel.


What you need for ALS:

  • A ECU capable of ALS.

  • Anti-lag valve - Replaces the original idle speed control valve.

  • Turbo with minimum 360thrust bearing.

  • EGT gauge - So you know when your turbo and manifold is going to melt.

  • Wiring to "arm" the anti-lag and switch it off - This simply involves wiring in a switchable earth to one of the ECU pins.

This goes for so-called "mild" anti-lag (see further down for info), for the real WRC stuff you need another (very expensive) turbo, exhaust manifold and a few other bits.

With the ALS installed - when you let go of the throttle, the valve that replaces the standard idle valve in a modified throttle body opens to let the air continue through. The amount of air this valve can flow is the only thing that affects anti-lag, the less the airflow, the less effect the anti-lag has. Then the ECU retards the ignition timing by 30 degrees so the fuel is ignited when the exhaust valves are open and most of the fuel is already in the exhaust manifold and turbo. That makes lots of nice and hot exhaust to spin the turbo and create boost pressure.

A small "mild" ALS valve can flow enough air to make 0psi boost pressure at idle/off throttle (rather than -25psi of vacuum), sometimes up to 7psi of boost, which makes the turbo hit full boost almost straight away when you press the throttle. The big WRC anti-lag valve can flow enough air to produce 22psi at idle (or off throttle), which makes the car have no lag at all. That will increase the driveability of the car a lot.

Unfortunately the WRC ALS puts a big strain on the turbo and exhaust, whereas with the 'mild' anti-lag setup is practically as reliable as not using an ALS at all. It will gradually burn out your silencer baffles, but all that does is make your exhaust louder.
Some people say that the fuel will cause "borewash" making the need for a rebuild all the time. But that is not the case. The amount of fuel used in anti-lag is not enough to cause any significant bore wash (unless you use £5 budget oil), most performance cars fuel on overrun, unless they have been mapped for good emissions, not mapped like that because of reliability reasons.

The only real thing you have to be wary of with anti-lag is that Exhaust Gas Temperatures (EGT) go sky high but there's no real worry as you could be on the overrun for well over 30 seconds on 'mild' anti-lag before the EGT will get dangerously high. If EGT gets too high it could melt the exhaust and/or turbo. The engine internals will not have any problems.

For full-on WRC anti-lag the specs is as with 'mild' anti-lag but with a bigger WRC ALS valve, and a anti-lag turbo with Maram 247 shaft and turbine wheel with 7° cut-back blades, Nimonic wastegate spindle and everything nicely put together by a reputable company. You will need that as the extra stop/start shocks and extra heat would eat a standard shaft in minutes. A stainless steel exhaust manifold may be handy too as it could stand more heat than standard one.

For road use you will not need more than 'mild' anti-lag, and for track use it might be best too as you're on track at sustained periods of time and the WRC anti-lag may be too severe for those long sessions.

The ALS system won't increase the outright power of your car but it will significantly increase the power delivery - much much more low down torque since the car gets on boost a lot earlier than without the ALS.