Ford Focus ST Mk4 Tuning Guide

Ford Focus ST Mk4 Tuning Guide

Tuning Guide for the Ford Focus ST Mk4 (2019+)

The Mk4 Ford Focus ST, with its 2.3L EcoBoost engine, offers a great platform for performance tuning. This guide explores common tuning stages, outlining what's involved at each level. Remember, modifying your car can affect your warranty, so proceed with caution and consult with reputable tuners.

Take a look through our wide range of aftermarket and tuning parts for your Focus ST Mk4 here

Understanding Tuning "Stages":

Tuning stages represent different levels of modification, each targeting specific power gains. They typically progress incrementally, building upon the previous stage. Please note, not everybody references "stages" when it comes to tuning, it is simply an easy to understand method of noting what hardware and software is required to hit a certain "stage".

Stage 1 Tuning (Up to 350bhp and 550nm):

Stage 1 focuses on optimising the car's existing hardware through software tuning. This is generally considered the safest and most cost-effective way to increase power.

  • ECU Remap: This is the core of Stage 1. The engine control unit (ECU) is reprogrammed with revised parameters for fuel, ignition, and boost, unlocking hidden potential. A custom remap, tailored to your specific car and fuel, is preferable to a generic "off-the-shelf" map.
  • Supporting Mods (Recommended): While not strictly required for a Stage 1 remap, a performance panel filter or upgraded induction kit can improve airflow and potentially add a few extra horsepower. It also sets the stage for future upgrades. Check out our range of Intake/Induction products for your car here
  • Clutch Upgrade: Whilst it's not entirely required, some owners have experienced clutch-slip once tuned to Stage 1. This could be down to the age, or use of the vehicle previously, however the standard OEM Ford clutch does not hold up well to the extra torque which the 2.3 EcoBoost produces.

Stage 2 Tuning (Up to 400bhp and 590nm):

Stage 2 builds upon Stage 1, requiring hardware upgrades to support the increased power.

  • Downpipe: Replacing the restrictive factory downpipe with a less restrictive aftermarket one is essential. This improves exhaust flow and turbocharger efficiency. A sports cat or decat pipe is used at this stage, a decat will offer greater performance however it is not road legal. JXL Performance recommends Milltek High-Flow Sports-Cat for Ford Focus ST Mk4
  • Intercooler: An uprated intercooler is crucial to manage the increased heat generated by the turbocharger. A larger intercooler keeps intake temperatures down, preventing power loss and improving consistency. JXL Performance recommends Wagner Tuning Ford Focus ST Mk4 Competition Intercooler
  • ECU Remap (Revised): The ECU map needs to be revised to take advantage of the hardware changes. A professional remap is vital at this stage.
  • Upgraded Clutch: As noted in Stage 1, many owners have experienced additional clutch slip once reaching Stage 2 tuning, replace this with a hardier, higher rated clutch to prevent any future problems.
  • Supporting Mods (Recommended): At this stage, it is highly recommended to consider uprated brake pads and potentially braided brake lines to handle the extra performance. Check out our range of brake products here

Stage 3 Tuning (400bhp+ and 600nm+):

Stage 3 represents a significant step, requiring extensive engine and drivetrain modifications. This is where things get serious, and costs increase substantially. Due to the relative newness of the Mk4 Focus ST, Stage 3 packages are less common currently, but as the cars age, we expect to see more options emerge.

  • Upgraded Turbocharger: A larger turbocharger is usually necessary to achieve these power levels, the end goal power level ultimately depends on the size of your turbocharger. Please note, the larger the turbocharger, the more "laggy" the car will feel. 
  • Forged Engine Internals: To handle the increased power and torque reliably, forged pistons and connecting rods are essential. Consider upgrading bearings too.
  • Fuel System Upgrades: Upgraded fuel injectors and a higher-flow fuel pump are required to supply the engine with enough fuel - consult with your chosen tuner for more information.
  • Exhaust System: A full exhaust system, from the turbo back, is often used at this stage.
  • Clutch Upgrade: A performance clutch is essential to handle the increased torque.
  • ECU Remap (Highly Customised): A highly specialised remap is required to tie all of the above required hardware together.
  • Supporting Mods (Essential): At this level, upgraded brakes (including potentially larger discs and calipers), suspension, and tyres are absolutely essential to handle all of the extra power gained through tuning.

Important Considerations:

  • Professional Tuning: It's highly recommended to have your car tuned by a reputable tuner with experience in Ford EcoBoost engines.
  • Hardware Compatibility: Ensure all hardware upgrades are compatible with each other and your car.
  • Fuel Quality: Use high-quality fuel, especially at higher stages of tuning.
  • Maintenance: Modified cars require more frequent maintenance.
  • Insurance: Inform your insurance company about any modifications.
  • Legality: Be aware of the legal implications of modifying your car, particularly regarding emissions and noise levels.

Tuning your Focus ST can significantly enhance its performance. However, it's crucial to do your research, choose reputable tuners, and understand the implications before making any modifications. Start with small, incremental changes and work your way up if desired.

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