The Purple Project – Mk3 Focus RS 5-Cylinder Conversion

Back in 2021, we set out to do something no one else had done.

The goal was simple on paper — but seriously ambitious in reality:

fit the legendary 2.5L 5-cylinder engine from the Mk2 Focus RS into a Mk3 Focus RS.

This wasn’t just another build. This was about pushing boundaries.

The Mk3 RS platform was never designed to house the iconic 5-cylinder, meaning everything had to be reworked — from engine mounting and fabrication to electronics and integration. After extensive development, we successfully got the engine installed and running, bringing that unmistakable 5-cylinder character into a modern RS chassis.

But the real challenge came behind the scenes.

At the time, standalone ECU integration for the Mk3 RS was still relatively unexplored. Running a Syvecs ECU, we faced a major hurdle — getting the ECU to communicate with the rest of the car’s systems. With no available wiring diagrams or proven solutions back then, it became a constant battle of trial, error, and problem-solving.

Despite multiple attempts and significant progress, the limitations of the platform and available data meant the project couldn’t be completed to the standard we demand.

So, we made the call.

The car was returned to its original 2.3L Mk3 Focus RS engine, allowing it to be enjoyed reliably while still standing as one of the most ambitious and technically challenging builds we’ve ever taken on.

⸻

Why This Build Matters

Even though the final setup changed, this project represents exactly what BD Performance is about:

• Pushing the limits of what’s possible

• Taking on builds others wouldn’t attempt

• Learning, developing, and evolving with every project

This wasn’t a failure — it was a foundation for future innovation.

And today, with more data, better integration solutions, and evolving ECU technology, builds like this are closer than ever to becoming fully realised.