Ford Focus ST Tuning

"Thank you for reading my Ford Focus ST tuning guide."

The Focus ST, currently in it's third generation, is a brilliant project car to try. A site visitor asked for more information on the Focus ST and how to tune it up and modify it, so we've created an article to go over what we feel are the primary areas we find are the greatest tuning modifications you can do to this car.

After the Ford Escorts success there was a need for a credible replacment so Ford debuted the Focus in Europe in July 1998. In 2005, Ford produced the Focus ST, an MK.II version of Focus' sports division. When it came to acceleration, this one wa scertainly a nimble little thing with the ability to go from zero to 60 miles per hour (0 to 97 kilometres per hour) in 6.4 seconds.

As part of the 2009 British Touring Car Championship (BTCC), Ford debuted the Focus ST alongside Arena Motorsport showing off the motorsport underpinnings of this ST.

See our video which provides a complete introduction to Ford Tuning, it contains some tips on performance and handling modifications.

The Focus ST is an awesome project car to play with. Plan ahead and research Focus ST tuning to save yourself making the usual disastrous mistakes we regularly come across.

The 2.0 litre EcoBoost was designed for the ST, and offers an impressive 252hp and 270lbft of torque. The previous 1st generation ST engine offered 225hp.

If you were in Europe you could specify a 2.0L TDCi Duratorq  engine, offering mountains of Torque and 182hp of power.

The early ST builds on the success of the Focus, with the addition of aggressive styling, better engines and improved suspension and brakes.

With the right mods your Focus ST can be transformed into a stunning project. Don't waste money, do your homework and follow our unbiased guides to each performance upgrade to avoid disappointment.

Tuning tips and articles
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 mods for your Focus ST

  1. Tunes - A Remapped Focus ST ECU offers the most advantage with respect to your investment, aftermarket ECUs, and Tuning boxes are all alternatives.
  2. Focus ST Suspension Tuning - Replacing worn bushings and shocks radically improves your Focus ST handling Coilovers and Bushings are the usual go to mods
  3. Forced induction upgrades - forced induction is the most significant way to raise the intake air supply, which permits you to utilize more fuel and make higher power. It is one of the most costly modifications it does provide the largest gains.
  4. Brake Mods - Improve your Focus ST's stopping power needs to be somewhere in your mods list.
  5. Internal engine mods - crank, pistons, conrods & compression ratio including balancing and blueprinting
  6. Lighter flywheels - a lighter flywheel will significantly improve the engines ability to rev freely. In some cases flywheel lightening is not a great mod for all Focus ST engines.
  7. Intake and high flowing exhausts - Please be warned on their own these mods won't ADD POWER for most setups, but they can help enhance power after other modifications by lessening the restriction.
  8. Fast road cams are generally the biggest mechanical mod upgrade, but TorqueCars recommend they be fitted by someone qualified to set them up properly and it is often hard to find a suitable cam near you but there might be a local firm to regrind a stock cam .

Focus ST Tuning Stages

Typical stage 1 mods often include: Sports exhaust, Alloy wheels, Suspension upgrade (drop 25mm - 30 mm.), Remap, Lighter flywheel, Panel air filter, intake manifold spacer.

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

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

The Focus production run and revisions

  • First generation (1998)
  • Second generation (2004) ST Appears!
  • Third generation (C346; 2011)
  • Fourth generation (C519; 2018)

Focus ST Handling/Suspension Upgrades

Many Focus ST owners uprate the handling of their cars with modified suspension parts as a priority, this will certainly increase your enjoyment of the car.

We found that most Focus ST factory suspension setups need tweaking, a few degrees of toe out for cornering or toe in for stability, 1 to 2, and some negative camber will often enhance your cornering and handling.

We would go to a maximum drop of 25mm - 30 mm. on most models. You risk handling compromises if you go lower than this.

Focus ST make good sleepers if you debadge them and fit the most powerful engine upgrades and handling upgrades you can !

A rear sway bar will tighten up the handling and help to keep all the wheels on the ground under heavy cornering.

Improvements to the bushings

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

The suspension components of the Focus ST may be mounted to the car's chassis through bushings, which are rotatable rubber mounts. These rubber ones will wear out as they age.

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

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

Worn bushes may also hasten the depreciation of other suspension components due to the increased vibration and play.

With a new set of polyeyurothane bushes, the excessive play associated with rubber bushings may be mitigated.

Some poly bushings are hard to locate, but most will find the primary mounts readily available in their local stores Custom polyeyurothane bushes are often made to your requirements.

How low should you go on the Focus ST?

When it comes to road vehicles, the maximum suspension drop is 30 - 37 mm, but when it comes to hot hatchbacks with lower OEM suspension, the maximum suspension drop is 21 mm, according to TorqueCars.

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

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

If you set the toe out to around 1.5 degrees on the front, and add a small amount of negative camber then cornering will dramatically improve.

Focus ST Brake Upgrades

The Mountune big brake upgrade kit works really well, so if you are looking to replace your brakes, it makes sense to improve them with an upgrade. But we've seen quite a few very capable big brake upgrade kits out there.

Putting larger brake discs and better high performance brake pads will make for dramatically enhanced braking.

Bear in mind that race friction pads can be noisier and will have to be hot before they bite.

On your regular commute to work the brakes are occasionally used so will not be effective so source pads which work well in daily use.

Focus ST Engine Tuning Mods.

Our aim in Focus ST engine tuning should be to increase peak power and Torque at the top end.

Plan your mods carefully and always end with a remap, to fully realise the potential of your upgrades.

This list of the stages and sports parts are usually installed by our members, decide how far you want to go before you get going.

Getting the best motorsport mods for your planned usage of the car is vital. Stage 3 competition upgrades just don't work well on the road difficult in stop start traffic.

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

In a car used daily should ideally to optimize your torque band to your cars usage.

I'd be surprised if you find a Motorsport and race cam is a pleasure to live with when in heavy traffic.

The point of our articles is to give a brief overview of tuning modifications and point you in the right direction, our forum is the place to go for detailed advice and tips on your tuning project, the best motorsport upgrades and all aspects of modding cars.

Getting more air and fuel to burn in your Focus ST engine is the priority here.

Turbo upgrades unlock even more power, and most go for a hybrid turbo.

Focus ST Intercooler Upgrades

A front mounted intercooler upgrade and remap are one of the first modifications most Focus ST owners do.  In reality it is not required unless the car is mapped or running lots of power, although on track days you will notice the heat soak building up (see our intercooler article for an explanation of this.)

The closeness of the cold intake charge to the high exhaust temperatures inside the turbo is one concern with a turbo plus the act of compressing the air will increase it's temperature in your Focus ST intake.

Even a supercharged engine may benefit from an intercooler because of the significant increase in intake air temperature that occurs as a result of air compression. If you've ever touched a tire pump's nozzle, you know that air is heated as it is compressed.

The colder the air, the more oxygen it contains, as we learned in our chemistry and physics classes. What's the big deal? A Focus ST's power output may be increased by burning additional gasoline, which necessitates the presence of oxygen.

Intercoolers are radiators that cool the intake air charge before it enters the engine, allowing it to make power for longer periods of time. It would be perfect if the intercooler was placed in front of the Focus ST radiator to make full use of the incoming cool air.

Ideally, it would be installed after the air filter and before the turbo or supercharger. Front-mounted intercoolers, which sit in front of the radiator, are more common in automobiles, and they provide better air conditioning than those located on top.

As a general rule we recommend on the Focus ST that for every 100 horsepower, an intercooler capacity of three liters should be used. For automobiles with between 150 and 400 horsepower, this works wonderfully for most applications!

When it comes to intercoolers, obtaining the right size for the application is critical since installing an intercooler that is too big will impede airflow (this is something that can be discussed in more detail in our forum.)

Whoosh V1 - V3 or Depo are popular brands over here with Focus ST owners.

Sometimes it's not advantageous to fit a larger intercooler! We at TorqueCars anticipate a pressure reduction of .5 to.9 psi for a boost level of 15PSi, with certain applications losing 1.3 psi in the worst case situation. So drag from a large intercooler on your Focus ST needs to be factored against the drop in intake temps and ability to resist heat soak.

Reduced air temperature causes a decrease in pressure; thus, do not place the full responsibility on the intercooler design for the loss of pressure.

Many aftermarket intercoolers are both lighter and more powerful than their original counterparts, making them ideal for high-performance vehicles.

One of the most cost effective mechanical sports upgrades you can do to after a remap and turbo upgrade is to fit a fast road camshaft .

The intake and exhaust valve timings play a huge role 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 camshaft upgrade with other mods and finish with a reflashed ECU for the best performance gains.

When pushing up the power you will need to uprate to the fuelling. More power needs more fuel.

Using higher octane petrol is another option if you find you are suffering from detonation or premature ignition on your Ford project after fitting other sports modifications. To get sufficient fuel you may need to upgrade the injectors on your engine.

Uprate the fuel pump to cope with the extra fuel requirements of your tuned Focus ST's uprated injectors.

The rear engine mount is not great, and if you want to get rid of the annoying thud on rapid gear changes, then an aftermarket rear engine mount will make a big difference.

Focus ST Turbo Upgrades

The more air an engine receives, the more gasoline it can burn, hence adding a turbocharger boosts the engine's induction substantially.

While it's not always easy to change out a turbocharger, it's usually simply a question of removing the old one and replacing it with a new one.

Finding these limitations and upgrading to more solid crank and pistons is critical for every engine since some are over-specified and others are just barely able to handle stock power.

In other cases, technicians fork out a lot on turbocharger enhancements for the Focus ST just to be humiliated when they witness the car blow up after it's done because the mapping or the fueling isn't correct.

A bottom end lag is frequently added with larger turbochargers, whereas the power improvements at high rpm are absent with smaller turbochargers so there is a tradeoff here.

A good thing is that turbocharger technology is always evolving. This has led to the development of new turbochargers with variable-angle vane blades, which can be adjusted at different speeds for better acceleration and higher peak outputs, respectively.

The exhaust flow from a dual scroll turbocharger is split into two channels, each of which is directed towards a distinct set of turbocharger vanes. They also enhance the engine's ability to scavenge.

When a lot of air is being sucked into the engine, the air flow sensor AFM/MAP has a limit.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited bhp and torque at a much lower level.

Fuel limitations are hit around the 300hp region where a new fuel pump and uprated injectors will be required on your Focus ST

Focus ST Intake and Exhaust Tuning.

The next area for modification is the intake and exhaust. Air induction kits only help to add power if your air intake is struggling! Adding an induction kit to most stock engines will see NONE OF A LOW END POWER GAIN AT ALL. If you have heavily modified your engine and it's need for air INCREASES DRAMATICALLY then an induction kit is the answer and will help remove this restriction.

The intake manifold spacer is a budget option (compared with a whole new intake) and it will bring up the low to middle range torque, thanks to the fast flowing intake air.

Derestricting the air feed into the engine is the primary part of tuning so get a better flowing air filter if you find that the car is running lean. Induction kits can sound sporty but due to the warm air in the engine bay they will not do much to increase power and actually rob you of power.

Sports exhausts generally help improve air flow out of the engine but do not go too big or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to around 2.5 inches to maximise flow rates, and this should take into account the amount of air your engine is moving.

Getting a professionally gas flowed head with larger valves can fully release the engines power. A good triple plate fast road sports clutch will help to keep that power going where it should. Never skimp or think that the standard clutch to cope. The best mods we would do for your Focus ST are remaps, sports camshafts and induction improvements.

Focus ST Remapping / Tunes

ECU flashing should help to to establish the full potential of all the upgrades you've done to your Focus ST.

It will usually give around 30% more power on turbocharged vehicles and 15% on NA (naturally aspirated) engines, but you mileage will vary depending on the upgrades you've done and the condition of your engine.

Remaps offer big power gains on all turbo charged cars. and will help unleash the potential if you have done a lot of mods. We see most of our members opting for the Cobb Tuning AccessPORT to flash maps via the OBDII port. But if you've done quite a few mods you can't beat a custom rolling road map setup with a specialist tuner.

We've also seen some tuners experimenting with twin charging conversions and making some impressively high power gains.

Adding forced induction will see impressive power gains but this is usually too expensive to be cost effective. It is often easier to add a supercharger than it is to fit a working turbo. Turbos increase power in exponential proportion to rising engine speed and this can make mapping difficult.

The nice directly proportional boost and rpm characteristics of the supercharger make them simpler to map. To cope with forced induction you will usually need to decrease the engines compression ratio .

Focus ST Alloy Wheel Mods.

Alloy wheels will help the brake cooling and are generally lighter than the steel ones. Pay attention to your choice of tyres (tires) for your car, a good track legal slick tire can really enhance your cars handling. The drawback to large rims on your Focus ST is that you alter your effective final drive ratio and this will have a negative effect on performance and acceleration.

Due to this try to keep the overall rolling diameter of the wheel the standard factory sizes. In all cases avoid going over 18 inches.

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

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