The path to a 550HP daily driven 2L Ford Focus ST250

Everyone has an ultimate goal of what they would like to achieve from their vehicle once they begin with modifications. In the case of this customer’s vehicle, his goal kept rising and his dream is on the verge of being realised, so what does it take?

The path to a 550HP daily driven 2L Ford Focus ST250

This vehicle came to Karter Performance in 2015 with very little mileage on it, the owner was looking for a little more power just to set the car apart from other standard Focus ST250’s available from Ford. The team at  Karter Performance made some small changes to the clients vehicle and the bug bit. By 10’000km the vehicle was running a Garret GTX2867R and went from 150wkw/380Nm to 290wkw/530Nm. A few months went by where the power was enough, he loved what the car felt like and how it had so much more power on tap. The biggest drive was the fact that his two boys loved it and are pure petrol heads just like him.
As you can guess this power became normal and the search for more was asked for. What about a target of +400wkw? Was it achievable and practical for an everyday car? This is a lot for a front wheel drive vehicle to transfer to the wheels let alone to the tar, and so the journey began.

What was fitted to the vehicle before the 550HP goal was realised:

  • Karter Performance Complete Cold air intake
  • Karter Performance Turbo-back exhaust
  • Karter Performance Hot side boost pipe
  • Airtec intercooler
  • Cobb Accessport
  • Karter Pro-Tuned ECU map for the bigger turbo set up.
  • COBB Rear motor mount
  • Garret GTX2867R gen1


The most critical factor for the guys at Karter was reliability, with the power target falling in a close second place. Karter is known for performance without sacrificing reliability.

The standard fuel components on the 2L Eco-boost motors are known for not being able to supply fuel at the correct rate when you get close to the 300wkw mark. This problem was solved by fitting a further 4 injectors (bringing a total of eight) using a stand-alone ECU to manage the fuelling based on boost and RPM. This still enabled Karter to achieve the same fuel economy when driving under normal conditions. Using their custom designed spacer bracket, fuel rail, a set of Precision injectors and controlled by a stand-alone ECU they were able to achieve their fuelling target.

The path to a 550HP daily driven 2L Ford Focus ST250

The next question was, would the standard pistons and rods be able to handle the additional stress? They needed to deal with the extra cylinder pressure/air density and force which would be experienced when making such power. The team chose to increase the compression ratio from 9.3:1 to 10:1 and import a much stronger set of H beam rods with an equally good piston and pin set up. This setup gave Karter an ultra-light yet strong combination able to handle much more power than the customer was after.

With all this extra air and fuel being pumped through the system the head needed to to be gas flowed and port tuned. The end result looks like this:

The path to a 550HP daily driven 2L Ford Focus ST250

The OEM exhaust manifold is cast into the head as one unit so they did as much as they could to get enough flow through the head however it is still a limiting factor on this motor. Without machining a custom head, this is as good as it’ll get.

Keeping everything bolted together and the head down under high boost Karter replaced the head studs with a custom forged set. This allows the motor to withstand boost pressures into the 3bar range without the head lifting- even though such high pressures won’t be targeted. The guys at Karter Performance planned on increasing the rev range on the vehicle so they added a set of uprated main studs to handle the additional forces applied to the cradle, by the crank, when revving beyond the factory 6’500RPM limiter. Although they only made a small modification to the valve springs, they have lifted the limiter to 7’500rpm. This was done to compensated for future upgrades to the valve train and cams.

The friction components were also replaced with only the best allowing the engine to rotate with as little resistance as possible.

This vehicle now makes 255% more power than it did in its OEM form as well as 160% more torque and it hasn’t reached its’ full potential just yet.

The path to a 550HP daily driven 2L Ford Focus ST250

Being a Cobb Dealer, and distributor for Southern Africa, they took full advantage of their knowledge and experience of the Cobb custom features available using the V3 Accessport.
Numerous tables were changed to adjust both torque, power and boost. This allowed them to get maximum power to the ground and ensure the vehicle is manageable on the road. Hours were spent testing various calibrations until they were happy with the outcome. Utilising COBB’s additional tuning features, the best part was that the car wouldn’t reduce power unless it saw a specific “slip ratio” between the front and rear rotational speed of the wheels, allowing a better traction control strategy. Once the tires rotate at equal speeds again, the power gets fed back in.

Two different maps were written for this vehicle, one for daily driving on 95Ron fuel and one for a blend of Ethanol. This meant that the owner could still drive the vehicle to Cape Town if he choose to, without the need to be concerned about having access to Ethanol. The pump fuel map had the power turned down slightly (if 207% more power over a standard Ford focus ST is turned down) to allow for variations in fuel quality.
For now, they have run a 25% ethanol blend as the OEM low pressure fuel pump has not yet been upgraded and does not keep up with the required flow if they increase the content.
Both maps that were written included various map slots for different launch control and boost level set ups, allowing the customer to make quick changes depending on his requirement at the time.

The flexibility and ease of use of the COBB Accessport allowed the customer to easily switch maps for different fuel requirements, taking roughly 1 minute to change between the pre-loaded maps that were on the unit. He enjoyed that the Accessport didn’t need to be plugged in permanently as the maps are flashed onto the ECU with map slot switching active. He’d only use it for the monitoring of gauges, the peace of mind if he’d have to troubleshoot error codes if they came up and taking performance measurements (0-100km/h and 1/4Mile) if he so wished.

Karter couldn’t have done it without those involved, a big thank you to them!