Subaru Impreza WRX Gen1 Tuning

"All you need to know about tuning the Subaru Impreza WRX Gen1 engine!"

The first generation Impreza-based WRX models were offered by the company between the years 1992 to 2000.

Here we discuss the various performance modifications for these WRX Impreza versions. So, if you are lucky enough to own one and are looking forward to getting the most power out of it, this is the best guide for you (please add your tips and comments below so we can improve it further).

We were asked questions for more information on tuning and building a modified Impreza WRX Gen1 and particularly which turbo upgrades work best, so we've created this web page which covers our go to modifications for this engine and what we feel are the optimum value modifications you can do.

TorqueCars will review and look at Impreza WRX Gen1 tuning and highlight the best modifications for your car. Subaru Impreza WRX Gen1 are fantastic to work on and with carefully chosen mods like ECU maps, turbo kits and camshafts you will noticeably enhance your driving opportunities.

History of the Impreza WRX Gen1 Engine

First Generation

The first-generation Subaru Impreza hit the roads in 1992 as both the front-wheel (FWD) and all-wheel drive (AWD) configurations. The FWD was later removed making the Impreza AWD specific. We are going to focus on the World Rally Experimental (WRX) version of the Impreza in this article.

The Impreza first-gen had many variations during eight years, sold as a 4-door sedan (Code: GC8) in the beginning, a 5-door wagon (GF8) in 1993, and a 2-door coupe (GM) in 1995. The naturally aspirated engine choices for the base Impreza the WRX was based on was 1.5L EJ15 H4, 1.6 L EJ16 H4, 1.8 L EJ18 H4, 2.0 L EJ20 H4, 2.2 L EJ22 H4, and 2.5L EJ25 H4. Two turbocharged engines were also available: 2.0 L EJ20 H4-T and 2.2 L EJ22G H4-T.

The first generation has seven versions presented from 1992 to 2000 which are:

  • GC8A (1992-1993): The first Impreza WRX sedan featuring a boxer engine and an all-wheel-drive configuration is capable of generating 237 hp. WRX was introduced in Europe as the Impreza GT (208 hp).
  • GC8B & GC8C (1993-1996): Some mechanical modifications lead to the increase of WRX power to 256.4 hp in the 1994 model version. The WRX STI model was built to launch in 1994 and stood at 271 bhp. A WRX Sports Wagon was introduced in 1995, with 217 hp power.
  • GC8D (1996-1997): The updated version was rated at 276 hp. The coupe version WRX Type R, the sedan version Type RA, and another Version WRX Type R V-limited was available at that time.
  • GC8E (1997-1998): The interior of the European Subaru Impreza GT was updated but power remained at 208 hp. In 1998, 333 Turbo (Terzo) was released. After the third WRC win, Subaru launched a coupe WRX 22B STI in 1998 with 276 bhp/208 hp.
  • GC8F (1998-1999): In 1999, a limited edition of 444 Turbo (RB5) was introduced with an optional WR Sports Performance Pack for 237 hp power. An optional Prodrive suspension pack was also provided. In 1999, Prodrive restyled the European Impreza Turbo 2000.
  • GC8G (1999-2000): Apart from various cosmetic changes, Phase 2 engine was fitted to produce 215 bhp, a rise of 7 bhp over the previous model. In 2000, WRX STI ‘S201’ was produced with an engine output of 300 hp.

Tuning the Subaru Impreza WRX Gen1 and best Impreza WRX Gen1 performance parts.

Best Impreza WRX Gen1 parts

Even Though particular mods are popular with Impreza WRX Gen1 owners it doesn't mean its worth having, we will concentrate on the greatest mods that will give your Impreza WRX Gen1 the biggest power gain return for your cash.

Tuning tips and articles

Engine tuning Transmission tuning Care care Intake & Exhaust mods Improve handling Forums

Please watch our video which covers the 5 principles of tuning your Impreza WRX Gen1. Be sure to keep up with our latest YouTube content and subscribe.

Best mods for your Impreza WRX Gen1

  • Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
  • Air Induction Mods and Exhaust Upgrades - Be aware on their own these mods will NOT ADD TORQUE in most cases, but they can help release power after other modifications by removing the restriction.
  • Brake Upgrades - Enhancing your stopping power needs to be high on your agenda.
  • Remaps - A Remapped Impreza WRX Gen1 ECU gives the biggest gains in terms of your investment, aftermarket ECU upgrades, and Tuning boxes are all alternatives.
  • Lighter flywheels - a reduced weight flywheel will noticeably improve the engines rev changes. But not always suitable for all Impreza WRX Gen1 engines.
  • Impreza WRX Gen1 Handling modifications - Replacing worn bushings and shocks radically improves your Impreza WRX Gen1 handling Coilovers and Bushings are the usual go to mods
  • Performance Camshafts are are often the best upgrade for an engine, but ideally be installed in your engine by someone understands performance engines and it can sometimes be hard to find one but there might be a local firm to regrind a stock cam for you.
  • Forced induction upgrades - Adding a turbocharger is the most dramatic method to increase your intakes air supply, this means you are able to combust more fuel and make higher power. It is one of the most complex upgrades but provides the best gains.

Impreza WRX Gen1 Tuning Stages

Typical stage 1 mods often include: Fast road camshaft, Performance Brake Pads, Remaps/piggy back ECU, Sports exhaust manifold, New Bushes, Suspension (mild drop).

Typical stage 2 mods often include: induction kit, high flow fuel injectors, Ported and polished head, fuel pump upgrades, Suspension (Sports), Fast road cam.

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

Impreza WRX Gen1 Handling/Suspension Upgrades

A vehicle’s suspension determines the ride quality. So, if you have upgraded the engine-related parts of your first-generation Impreza-based WRX, it's time to give your vehicle a few new suspension parts as well.

You can choose the following parts from the below-mentioned manufacturers for getting the best results:

Handling mods are often the initial step for the Impreza WRX Gen1.

Coilovers permit you to adjust your ride height and this allows you to setup your cars handling to suit your driving style.

One of the most popular reasons for tweaking your Impreza WRX Gen1 suspension is to improve its cornering. However, we see the same issues regularly repeated again and over with people going too hard or too low.

These kits lower the centre of gravity of your car and are impressive when the aim is to improve the cornering ability of your vehicle at high speeds.

Major manufacturers of these kits for your car include:

  • H&R;
  • Yellow Speed Racing;
  • ST Suspension;
  • AirREX.

Coilovers

Coilovers are the best option when it comes to suspension upgrades. These parts are relatively expensive but then the results they deliver are second to none.

Choose the coilovers of your vehicle from one of the following brands for getting the best results:

  • D2 Racing;
  • GodSpeed Project;
  • KSport;
  • ISC Suspension.

Upgrading your Bushes

Enhancements to the bushings: Things you need to know

The suspension components of the Impreza WRX Gen1 may be mounted to the car's chassis through bushes, which are rotatable rubber mounts. These rubber ones will lose their shape over time.

Installing new OEM rubber bushings may dramatically improve the performance of your car.

It's probable that the ride may be a touch rougher because of the stronger polyurethane bushings but they'll last longer and maintain tighter handling.

They may also lead to an increase in the stress of other suspension parts due to the increased vibration and play.

A new set of poly bushes might assist in reduce the excessive play associated with rubber bushes.

You may struggle to find a full set of poly bushes, but most regions have the primary mounts available. Custom poly bushes are often made to your requirements.

A frequent misconception is that the best setup would be a non-adjustable suspension system that lowers the vehicle by 90mm purchased from a franchised component shop.

Claims are often made that all Impreza WRX Gen1 models and years may be able to utilise the same suspension kits sold by vendors.

To adequately support a diverse variety of vehicles, the "generic one set for all models" approach is obviously a mistake as engine weights and equipment trim levels all affect the cars handling characteristics.

How low should you go on the Impreza WRX Gen1?

According to TorqueCars research and testing, the maximum amount of suspension drop for most road vehicles is 30 - 42 millimetres, whereas hot hatchbacks with lower OEM sport suspension have a maximum suspension drop of 22 millimetres.

These tolerances may be drastically lowered if the wheel size is changed. Even with 16 or 17-inch wheels and conventional suspension, lowering the vehicle may create a lots of complications.

WRX Gen1 Brake Upgrades

Another important aspect that requires your attention while performing performance modifications is braking.

While you may have a large number of options in this regard, it is vital to choose the most appropriate option for your needs.

In case you choose a system that can’t stop your vehicle effectively, you will risk your life and those on the roads.

Contrary to this, if you choose an extra advanced system that exceeds your requirements, the cost will be much higher than what you had in mind.

Thus, first, sit back and determine your needs. Only then you will be able to decide what meets your needs in the best manner.

Here are a few options regarding brakes for your first-generation Impreza-based WRX.

You can either go for the brake pads and brake rotors or get the complete braking kits which include all of the required parts but cost significantly more.

So let’s see the options we have, one by one.

Brake Pads

As brake pads play a vital part in stopping your vehicle, it is necessary to get high-quality options for your modified first-generation Impreza-based WRX vehicle.

You can choose brake pads offered by Hawk HPS and the best aspect of these parts is that they don’t cost an exorbitant amount of money.

Brake Rotors

Brake rotors are also pivotal for a high-performance car because such high-end parts ensure that the vehicle stops within safe distances.

Brake rotors are relatively more expensive as compared to brake pads and are usually three or four times more costly.

StopTech offers two types of brake rotors for first-generation Impreza-based WRX models which are:

Slotted;

Drilled.

Brake Kits

If you feel that the brake pads and rotors alone do not serve your purpose well, you can ditch the idea of getting them and choose brake kits instead.

StopTech offers a premium replacement brake kit and we recommend you get it to considerably increase the stopping power of your car.

Impreza WRX Gen1 Camshaft Upgrades

Fast road cams come into their own at upper RPM range power so are more suited to petrol engines, than diesel ones. This will usually provide good peak power increases through performance camshafts on most engines.

Significant gains on the Impreza WRX Gen1 can be made from cam upgrades. Altering the cam profile alters the intake and exhaust durations on the engine and can dramatically change the torque and power output.

Fast road camshafts normally increase the bhp through the rpm range, you may sacrifice a little low down torque but the top end will be higher.

Competition camshafts, increase the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a car driven daily you should ideally to match your bhp range to your cars usage.

I would be surprised if you have ever asserted that a Impreza WRX Gen1 Motorsport camshaft is a delight when driving in heavy traffic. This is because the lumpy idle will make the car more likely to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

Different Impreza WRX Gen1 engines respond differently depending on how well made they are, when cams are fitted depending on the cam being more or less aggressive cam durations than others as unique due to manufacturing tolerances and quality variations so set your engine up on a rolling road.

The map and fuelling and fuel pump and injectors also have a large bearing on the power gains you'll make.

Longer valve durations can adjust the power band, and on most engines there are some advantages to extending the intake or exhaust durations and valve lift.

The Impreza WRX Gen1 engines respond well to mods and we're finding that there is a lot of modifications and tuning parts around.

ECU Mapping Improvements for the Impreza WRX Gen1

Mapping helps fully realize the full potential of all the tuning mods you've fitted to your Impreza WRX Gen1.

The performance of the WRX, even the STI versions of the car, can be considerably increased by reflashing the car’s ECU.

When it comes to performance chips, you have several options that suit the Subaru Impreza-based first-generation WRX vehicles.

Some of the manufacturers offering these parts include but are not limited to:

  • SmartTune;
  • JDM;
  • GTE;
  • PLP+;
  • D1 SPEC.

Air Flow improvements on the Impreza WRX Gen1

All internal combustion engine vehicles require a mixture of air and fuel to generate power and torque.

The higher the mixture, the more power generated by the vehicle. However, most factory-fitted parts are restrictive due to several reasons.

One way of enhancing the flow of air to your vehicle’s engine is by using a modified aftermarket performance air intake system.

You have several options available in this regard however some of the major brands offering these parts for your first-generation Impreza-based WRX include:

  • Takeda;
  • K&N;
  • Injen;
  • aFE.

It is to be noted that air intake systems are relatively expensive parts and thus you must be careful while choosing the part and its compatibility with your vehicle.

Air Intake manifolds take the air during the suck phase from the filter and allow it to be pulled into the engine and mixed with fuel.

The bore size, shape and flow rate of the Air Intake manifolds can make a large improvement to fuel atomisation on the Impreza WRX Gen1.

We often see intake manifolds are ripe for aftermarket parts, although a few car makers provide well optimised plenum chambers.

Increasing valve sizes on Impreza WRX Gen1, doing a bit of port matching and head flowing will also increase bhp, & more importantly will give you an improved bhp increase on other upgrades.

Impreza WRX Gen1 Turbo upgrades

While these WRX vehicles came with turbochargers installed in them, still if you are looking to upgrade the one on your vehicle or replace a faulty part, you have several options available.

One such example is ATP’s GTX3076 Turbo kit which is a bolt-on part that promises impressive performance.

Another option is to go for the BorgWarner AirWerks Series S200SX which is a universal turbocharger and costs considerably lesser than the vehicle-specific part.

However, turbochargers are expensive parts and thus you should only upgrade yours if the existing one is not performing as it should.

Radiator

When a mixture of fuel and air is mixed in the process of combustion a lot of heat is generated.

For a vehicle to continue delivering high performance for long periods, this heat has to be proper dissipated.

If the heat is not dissipated, the vehicle can overheat which can cause several problems and even lead to the leaking of valves.

Radiators of internal combustion vehicles are vital parts that play a key role in the cooling mechanism of such cars.

However, as the normal operation of cars does not generate as much heat as during their high performance, these stock radiators are unable to meet the requirements of modified cars.

You can install an aftermarket radiator for your Subaru Impreza-based first-generation WRX. One such example is the Aluminum Racing radiator manufactured by Mishimoto.

This is a moderately priced part but it does an impressive job of dissipating the heat in a modified vehicle.

Fan Shroud

You can also use a fan shroud to further improve the flow of air to the vehicle’s radiators. Mishimoto offers these parts for the Subaru Impreza WRX and they are reasonably priced.

The result is impressive and we recommend going for this option if you are looking for a way to get rid of the extra heat produced by your vehicle’s engine.

Intercooler

An intercooler is another imperative part whose function is to provide a constant stream of cold and dense air to the vehicle’s engine.

As such dense air is more oxygen-rich, the amount of power produced by the vehicle is considerably increased due to this part.

You can use a Mishimoto universal intercooler for your first-generation Subaru Impreza-based WRX vehicle and get impressive results.

Twin scroll turbo units divert the exhaust flow into a couple of channels and flow these at differently angled vanes in the turbo charger. They also boost the scavenging effect of the engine.

You'll commonly see there is a restriction in the air flow sensor AFM/MAF on the Impreza WRX Gen1 when considerably more air is being sucked into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped power at a much lower level.

Adding a supercharger or additional turbo will make large bhp gains, although more challenging to configure. We have this article on twincharging if you want to read more.

Impreza WRX Gen1 Fuelling Upgrades

When you raise the bhp you will need to uprate to the fuel system.

Any modified vehicle is no good if it is unable to produce enough power. After all, the primary purpose of performance modifications is to increase the power and torque output.

One limiting factor in this regard is the stock fuel system of the vehicle. Such systems are designed to provide only a limited amount of fuel to the engine.

This is done to increase the fuel efficiency of your cars. These days, many people are concerned about this aspect due to the ever-increasing fuel prices. So why do the manufacturers take this path makes sense.

Performance vehicle enthusiasts, on the other hand, are more concerned with the output of their vehicles and thus we recommend that they replace these stock fuel parts with aftermarket performance parts.

Some of the parts that can be upgraded for improving the fuel delivery to the engine of your first generation Impreza-based WRX include:

  • High-Pressure Fuel Pump;
  • Fuel Pressure Regulator;
  • Injector Driver;
  • Fuel Injectors.

Let’s also discuss some of the companies that offer these parts for the first-generation Subaru Impreza-based WRX.

High-Pressure Fuel Pump

A fuel pump is an important part of a vehicle’s fuel delivery system. So for getting better performance, you can get an upgraded pump from one of the following brands:

  • Walbro;
  • Radium;
  • DeatschWerks.

Fuel Pressure Regulator

The following companies offer these parts for your vehicle:

  • AEM;
  • Hybrid Racing;
  • BLOX.

You can also use the universal fuel pressure regulator made by TOMEI for upgrading the performance of your Subaru Impreza WRX.

Injector Driver

For the injector driver, we recommend choosing the one from Hondata. It is an expensive part but it's high-quality will aid in delivering optimal results.

Fuel Injectors

You can fit fuel injectors in your vehicle that deliver more fuel. By doing so, you will be able to considerably increase the power output of your car.

More bhp needs more fuel. Boosting the fuel pressure provides a more snappy the acceleration responsiveness.It is important to over specify your injectors flow rate.

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

Impreza WRX Gen1 Performance Exhausts

You should look to boost your exhaust if the existing exhaust is creating a restriction.

Another important performance upgrade that most people don’t give due importance to is the exhaust system of the vehicle.

The STI versions of the car, if fitted with the 4” turbo back exhaust systems generate much higher power than the vehicles which don’t have any such system installed in them. Besides this, such systems also make the vehicle sound more aggressive.

One great option for your first-generation GC8 WRX is the XFORCE Exhaust Cat-back exhaust system.

The aggressive exhaust system sound of this setup will definitely make your vehicle a head turner. However, it is an expensive part.

But if the exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose a lot of the exhaust flow rate and end up lacking power and torque.

Typically exhaust restrictions are in the filters installed, so adding a higher flowing sports aftermarket catalyst will improve air flow, and rather than doing an illegal catalyst removal, will keep the car road legal. We note that performance catalyst perform similarly to catalyst removal and have the added benefit of keeping your car street legal, as decat or catalyst removal is not a street legal modification.

WRX Wheel Upgrades

Wheels give your vehicle a distinctive feel and promptly pull up the entire look of your car.

Here are some of the manufacturer options that you can choose for giving your first-generation Impreza-based WRX one of a kind look:

  • Enkei;
  • SSR;
  • Gram Lights.

Weak spots, Issues & problem areas on the Impreza WRX Gen1

The Impreza WRX Gen1 engines are generally reliable and solid as long as they are well 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 By avoiding short journeys where the engine doesn't warm up and using good quality fuel you can reduce this risk.

Regular oil changes are essential on the Impreza WRX Gen1, especially when tuned and will help prolong the life of the engine.

If you want to learn more, or just get some friendly advice on Tuning your Impreza WRX Gen1 engine please join us in our friendly forum where you can discuss Impreza WRX Gen1 tuning options in more detail with our Impreza WRX Gen1 owners. It would also be worth reading our unbiased Subaru tuning articles to get insights into each modification and how effective they will be.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to know what our visitors have got up to and which tuning mods work best for them on each model of car. We use your comments and feedback to improve the accuracy of these Impreza WRX Gen1 tuning guides which get regular updates and revisions.

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