Focus Mk3 ST Diesel Tuned to 240BHP!

Focus Mk3 ST Diesel tuned to 240bhp and 480Nm.

It is not often Ford produce a performance diesel to rival what VW have been doing for over 20 years, but the Focus ST in 2.0 TDCi form, with a strong 184PS as standard, is the first in what we hope is a line of performance diesels from the Ford stable. Here is how we took it to 240bhp.

A leap of faith

The ST Diesel on the MAXD OUT dyno

The Pumaspeed development team had the Focus Mk3 ST Diesel on the radar for some time, but with the new RS on the horizon we held back on buying one and concentrated on the RS. We know many passionate ST owners, but none as passionate as Alex Paull, who had just bought his new ST Diesel and really needed some extra power from it. He had already tried another device that promised 39bhp, but after a few days decided to hit the MAXD OUT dyno to see what the increase actually was. Needless to say the other device went back to the supplier, and heavy discussions began with the development teams at MAXD and Pumaspeed.

Developing any new tuning package takes time. Luckily Alex had his old company car for two extra weeks, so he was happy to loan us the ST-D, and Pumaspeed, never one to back out of a challenge, duly collected it and set off on a voyage of discovery.

Problem one: a locked ECU

Before we even started, we were up against the fact that the ST-D has a totally new ECU that only Ford and one locked-down company had OBD read and write access to. Step up MAXD-OUT: Andy at MAXD has over 20 years of tuning experience, and if anyone could crack the Delphi ECU, he could. It took a full week, many hours and calls to and from countries far and wide, but he was in.

Development started a week behind schedule, but it was full steam ahead, with boxes of air filters and intercooler cores and the car strapped to the MAXD OUT dyno. Maps were written and rewritten, the power and torque curves adjusted and smoothed, new filters tried and intercoolers fitted and tested. The car was taken on long power runs to heat-soak the stock intercooler and short ones to see the difference. At Stage 1 the only filter that worked without sending the ECU into limp mode was the stock-replacement K&N panel filter; we believe a higher-flowing unit could gain a little more with Stage 2 mapping.

The MAXD OUT tuning box was tested again and again with the new communication protocol and worked faultlessly every time, so you can use it at home through the Pumaspeed mail-order service.

The K&N stock-replacement filter

The MAXD OUT tuning box

Stage 1 results

K&N panel filter fitted throughout; no intercooler for this test

For Stage 1 MAXD OUT mapping we advise the K&N replacement air filter and the optional R-Sport Stage 3 intercooler. The graph shows the gain from the remap alone: stock power with the K&N filter is 190bhp; MAXD Stage 1 with the filter only is 219.3bhp. Torque is the most significant data point, with a massive 72Nm increase.

• Power: 185bhp stock (no K&N fitted) to 220bhp, up 35bhp
• Torque: 380Nm stock (no K&N fitted) to 466Nm, up 86Nm

MAXD Stage 1 dyno graph

The intercooler

The core we chose is the 13.5-litre R-Sport Stage 3 taken directly from the Focus ST250, relocated forward into full view of the front bumper for maximum airflow, exactly like the R-Sport Stage 3 intercooler for the non-facelift ST250 and identical to the arrangement on the new Focus RS Mk3. Its two main benefits: none of the unit is hidden behind the crossmember, so the huge 760mm x 90mm x 200mm core gets full frontal flow, and the logo is fully visible through the bumper. It is good to know Ford believe this is the correct way to mount a Focus Mk3 intercooler as well as R-Sport.

R-Sport intercooler on the ST Diesel

Full view through the front bumper

The 13.5-litre core

Stage 2: DPF delete and 240bhp

We did not initially have time to look at the exhaust, but we believed huge gains were available from cat and DPF deletes plus further mapping, and after the success of Stage 1 we took the ST Diesel to the next level: a DPF delete and a larger-bore exhaust. Removing a DPF has its hazards, so we had the MAXD team ready to work their magic on the Delphi ECU, not only to raise the power but to make sure the deletion did not throw errors or lose power. As usual they pulled it off, fixing any running issues first and then running the car on the dyno again and again with different file revisions.

With the help of the prototype R-Sport DPF-delete exhaust, MAXD extracted a colossal 240bhp and 480Nm. And that is not even the best bit: look at the power curve and you will see it transformed from the usual low-down burst you expect from a diesel into a delivery not unlike the petrol ST. Plenty to steal the limelight from the VAG TDI boys. An X-27 hybrid turbo and a turbo-back system have been talked about for a Stage 3; we will see how demand grows.

MAXD Stage 1 Plus and Stage 2 dyno graph

Looking the part

More visual enhancements have found their way onto our demo car too. The Pumaspeed Turismo wheels suit the car perfectly and, along with H&R springs, give it an aggressive sporting stance. The Maxton front splitter adds to the motorsport look and matches the lines of the front bumper perfectly.

The Pumaspeed ST Diesel demo car

Turismo wheels, H&R springs and Maxton splitter

The ST Diesel on the dyno

ST Diesel Stage 1R 235bhp package →Stage 2R 250bhp package →Stage 3R package →All Focus ST Diesel tuning →

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