Citroen ZX Tuning

"Tuning guide to the most effective Citroen ZX modifications."

The ZX is a good car tuning project to play with and was designed by Citroen to compete with the Astra, Golf and similar sized family cars.

The car is a good effort and certainly popular among tuners so let's take a look at the best modifications for the ZX.

Because so many forum members have asked about the ZX and recommendations on how to modify one, so we've created this page to cover the primary areas which make for improvement and tuning success on this great car.

The ZX is a brilliant project car to try. Take your time and research ZX tuning to avoid making the usual expensive mistakes we typically hear about.

 

Tuning tips and articles
ZX suspension is pretty soft and as it gets older the handling really starts to suffer.

For NA (naturally aspirated) engines please watch our video which covers the 5 principles of tuning your ZX. Be sure to keep up with our latest YouTube content and subscribe.

 

Best mods for your ZX

  1. Fast road Camshafts are are often the best upgrade for an engine, but they must be fitted by someone who knows what they are doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  2. Air Induction and Sports Exhausts - Please note that on their own these mods won't ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  3. ZX Handling Mods (suspension) - Fitting a more sporty Suspension kit radically improves your ZX handling Coilovers and Bushings are the usual go to mods
  4. Brake Mods - Enhancing your stopping power ought to be listed in your priority list.
  5. Flowing and porting the engine head - for larger gains, you will get better flow and make a more efficient engine if you do this to support your other mods.

ZX Tuning Stages

Typical stage 1 mods often include: Lighter flywheel, Panel air filter, Alloy wheels, Sports exhaust, Engine Tunes/Remapping, Suspension upgrade (drop ).

Typical stage 2 mods often include: fuel pump upgrades, Fast road cam, Power/Sport clutch, high flow fuel injector, Ported and polished head.

Typical stage 3 mods often include: Internal engine upgrades (pistons/head/valves), Adding or upgrading forced induction (turbo/supercharger), Competition cam, Sports gearbox, Engine balancing.

Turning our attention to the ZXs engine we need to get a bit more power out of the top end.

With just a few mods you can transform your ZX into a fun car, beating larger cars on the track and being a fun car to drive on a daily basis.

The best power gains come from larger engine sizes. The more you start with the bigger the return on investment so engine swaps are good value mods for small engined cars.

This means that although you can do modifications to engines lower than the 1.6 you will not really get much of a return from it.

ZX Handling/Suspension upgrades

Improving the handling for people often first priority in your ZX tuning project.

We would go to a maximum drop of 27 - 42 on most models. You risk handling compromises if you go lower than this.

Upgrades to the ZX's suspension and handling

Handling upgrades are often the initial step for the ZX.

Is there anything I should keep in mind while deciding on suspension for my ZX?

Uprated Bushes

What factors should you consider when setting up and selecting your suspension if your ZX is also used as a daily driver?

It is possible to connect the ZX's suspension components around the chassis of the ZX using poly bushes, which are replacements for the rubber mounts. The rubber ones will degrade with time and need replacing anyway so why not upgrade.

New OEM rubber bushings may have a major impact on the performance of your vehicle.

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

The increased vibration and play may also lead to an increase in the depreciation of other suspension parts.

A new set of poly bushes may be able to eliminate the excessive play that comes with rubber bushes.

Rare and older models may only have polyurethane main bushes available in aftermarket bushing kits, however most recent models feature a complete set of suspension bushes.

You may be able to have custom bushes created to suit your needs.

A frequent misconception is that the best setup would be a non-adjustable suspension system that lowers the vehicle by 50mm purchased from a franchised component shop.

Vendors may claim that their ZX suspension kits are compatible with any or all model year ZXs.

For a vast variety of vehicles, a 'generic one set for all models' approach is obviously incorrect.

How low should you go on the ZX?

According to TorqueCars research and testing, the maximum amount of suspension drop for most road vehicles is 27 - 42 millimetres, whereas cars that are factory fitted with lowered springs have a maximum suspension drop of 17 millimetres.

These tolerances may be drastically lowered if the wheel size is changed. Even with 17"wheels and stock suspension, lowering the vehicle might result in a slew of complications.

Stability may be improved by lowering the ZX, but the ultimate goal should always be to enhance handling. It is critical to use the right shocks when employing lower springs.

Putting some negative camber on the wheels and around 1 to 1.7 degrees of toe (in for better stability or out to improve cornering), will usually improve your ZX in handling and cornering.

ZX Brake Upgrades

For sharper improved braking add better high friction brake pads and mate this with bigger discs.

Please note that some performance friction pads can grind and will have to be hot before they are effective.

On your regular commute to work the brakes are only used rarely, therefore won't be as effective at slowing you up so choose pads which have a low working temperature.

Citroen ZX Tuning Modifications.

One of the best mechanical mods you can do is to fit a fast road cam. When pushing up the power you will need to pay attention to the fuelling.

The standard ZX fuelling can cope with most mods but if you go with a supercharger kit you certainly need to look at fuelling. More power needs more fuel.

To get sufficient fuel you may need to uprate the injectors on your engine. When increasing your fuelling with bigger injectors you will also need to get a bigger fuel pump to supply it.

Engine work like a fast road cam, a 3 angle valve job and porting and polish the head are the top ZX tuning mods you can do. So lets look at the engine tuning options you have on the ZX.

Many owners go with inductions kits and sports exhausts but the gains on these, especially the induction kits are questionable. A sports cat will free things up and make the top end of the engine seem much more responsive.

Citroen ZX Intake and Exhaust Tuning.

Breathing mods are your first consideration. For small ZX engine sizes go with a washable panel air filter. On larger engines we would also recommend a sports panel air filter and you need to ensure that the intake gets plenty of cold air.

Do not go with the biggest exhaust you can find this will actually slow up the exhaust flow rate - the best for power gains are usually between 1.5 to 2.5 inches.

Gas flowing the head will allow you to maximise your air/fuel charge. Leave this to a professional though with a proper flow bench and machine tools and you are guaranteed a power increase and will also notice that economy improves (providing you don't exploit the extra power).

When you start tuning your ZX beyond 30% of standard power you may well find that the standard clutch starts to complain so get an uprated clutch.

Power Mods and Upgrades

Top end torque should be your overall aim with a nice fat wide peak torque band.

Following our guidance for tuning your ZX you will create a practical but sporty car that will potentially beat bigger cars.

The best power gains come from larger engine sizes. The more you start with the bigger the return on investment so engine swaps are good value mods for small engined cars.

The typical target when modding the engine should be a wide torque output. You don't want all the torque to be at the top end unless you are creating a motor sport car.

In this article we shall give your a good starting base to the best upgrades for your car, but we'd encourage you to spend some time on the site looking into the details of each type of performance part.

Fast road cams offer one of the biggest torque gains for your money as far as a solitary tuning upgrades goes on a NA (naturally aspirated) engine.

The exhaust and intake durations play a huge factor in your cars power band, but be careful here, getting this wrong can upset the idle and make the car hard to drive in traffic. You'd need to follow a cam upgrade with other mods and finish with a performance chip for the best performance gains.

You will need to ensure that the engine is not starved of fuel so will need to ramp up the fuelling.

Frequently power losses, flat spots and erratic idling after performance upgrades are done can usually be traced to fuelling or timing issues. Upgraded injectors will enable you to supply sufficient fuel to the engine.

A fuel pump will only deliver a finite amount of fuel, so you may need to uprate this if your injectors are demanding more fuel.

Citroen ZX Wheel Modifications.

The benefits of alloy wheels include a lower unsprung weight and more efficient brake cooling. It is worth noting that although they can look cool on the ZX Big alloy wheels will actually decrease your performance.

The larger you go the lower your acceleration will be - this is due to the change in your effective final drive ratio.

For this reason we would advise sticking to a maximum wheel size of 17 inches, although we know some of our members have gone larger than this with no problems.

If you would like to know more, or just get some friendly advice on Tuning your car please join us in our car forums where you can discuss ZX options in more detail with our ZX owners. It would also be worth reading our unbiased Citroen tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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