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You are here: Home | Fiesta | Focus ST Mk4 2.3T
Focus ST Mk4 2.3T
440bhp from the Mk4 Focus ST. Two demo cars, thousands of track miles, and an engine on the dyno with no limits at all.
2019 saw the launch of the Mk4 Focus ST in both 2.3T EcoBoost petrol and 2.0T EcoBlue diesel. Following our success with previous generations, we bought two ST Mk4s as demonstrators, one petrol and one diesel. Both have seen intense software and hardware development, alongside thousands of miles of road and track testing at Donington, Cadwell and Blyton Park.
No fuss, bolt-on, proven
Pumaspeed's aim is to simplify the whole tuning process for the Mk4 ST owner by supplying no-fuss, bolt-on quality parts and ECU remapping for the 2.3 EcoBoost. Whether you need a simple cat-back exhaust to enhance the note or want to push hard on track with a fully equipped 400bhp+ track-ready weapon, our no-nonsense approach to tuning kits has worked for many years. It works so well, in fact, that since 2015 we have sold over 1,400 340bhp hybrid turbo power kits for the Fiesta ST180.
Fully track tested at Blyton, Donington, Oulton and Cadwell.
405bhp and 650nm, with every limit removed
The Mk4 2.3 EcoBoost has a few limiting factors that stop the car showing its power and torque on the rolling road, so we bought a brand new fully dressed engine and strapped it to an engine dyno. With unlimited cold water, unlimited cold air, unlimited exhaust size and a fully unlimited SYVECS ECU we set about finding out what the 2.3 EcoBoost could really do. We bet you haven't seen that from anyone else.
With all limits removed and the engine freely programmable, the result was 405bhp at 7,200rpm and 650nm at 2,600-3,000rpm.
Under the bonnet it's a different story
In the car there are massive thermal issues with water cooling and induction temperatures, plus big induction restrictions from the air filter and induction tubes, not to mention boost pipes that are a little too small — so 405bhp and 650nm was never going to be an easy ask. After many months and years of testing we have released some very impressive numbers for our bespoke MAXD engine remapping. The limiting factors, one by one:
- Intercooler — the stock cooler is tiny; even at 330bhp base power it's totally useless in anything over 20-degree external temperatures.
- Air filter kit — the stock air box has limitations; most customers replace it even at basic power levels.
- Clutch — even on sub-10,000-mile cars the stock unit is too weak to live happily with more than 550nm, so we have limited the MAXD 1R maps to that torque even though we have pushed well over 600nm in testing.
- Stock GPF — dyno testing at Stage 1 surprisingly showed no massive pressure drop across the GPF, so it is not as restrictive as first believed; higher up the revs this changes slightly.
- Stock catalytic converter — to push high in the rev range it must be swapped out, as it will not flow enough for big power beyond Stage 2.
- Stock cat-back exhaust — a mild effect higher up the rev range; for the best outputs we suggest a free-flowing performance cat-back from Milltek, Scorpion or Dreamscience.
Clutch and intercooler: fix these first
The clutch and intercooler are the two key areas limiting even basic tuning. Even with our torque-limited Stage 1R map we can't say the stock clutch will not slip, so take a look at the Pumaspeed range of clutches below — they handle the extra torque without causing internal damage to your gearbox. The 2.3 EcoBoost produces immense torque low down, over 640nm in some cases, quite easily.
The stock intercooler has a big job and is only just suitable for a 330bhp (520nm) Stage 1 map. Air leaving it gets incredibly hot after just a few short pulls; in our track testing, after three laps of Blyton Park the datalogs showed the ECU restricting performance to bring temperatures back under control. We swap the intercooler when installing the higher-torque Stage 1R map, which develops up to 360bhp and as much as 550nm.
Stock versus Stage 1R on 99 RON.
So what can we actually achieve under the bonnet?
These are the results: one car, one dyno and over two years of road, dyno and track testing.
- Stage 1 — up to 330bhp / 520nm. Completely stock vehicle with a high-flow panel filter and MAXD 95 RON calibration. Limiting factor: intercooler.
- Stage 1R — up to 360bhp / 550nm. Intercooler, high-flow panel filter, MAXD 99 RON calibration. Limiting factor: clutch.
- Stage 2R — up to 400bhp / 590nm. Cold air intake, intercooler, downpipe and clutch, MAXD 99 RON Stage 2R calibration. Limiting factor: turbo.
- Stage 3R — up to 440bhp / 600nm (capped). Hybrid turbo, cold air intake, intercooler, downpipe and clutch, MAXD 99 RON Stage 3R calibration.
ST440 dyno testing.
Pumaspeed recommends MAXD bespoke engine calibrations — 25 years' experience, better by design. Call 01924 360260 and talk to the people who built the cars.
