The Fiesta ST (FiST) has a 1.6 Ecoboost engine.
The Focus ST (FoST) has a 2.0 Ecoboost engine.
The Focus RS (FoRS) has a 2.3 Ecoboost engine, as does the Ecoboost Mustang.
Ford’s 2.3-liter Ecoboost engine is an open deck block. Meanwhile, Ford’s 2.0-liter Ecoboost is semi-closed deck. So the 2.0 is stronger for that reason. But in addition, the casting on the 2.0 seems to be stronger as well. There have been reported cracks on the 2.3, for example, where a head-bolt would go. So the current, best-scenario solution, is to put the 2.3 RS head (twin scroll & better flowing) on the 2.0 ST block… which is what this article describes.
But keep in mind. The internet is a harsh place, usually a bit skewed from reality. The Focus RS is a fun car with a ton of spotlight behind its introduction to the US. And as Babe Ruth said decades ago way before the internet, “The loudest boos come from the cheapest seats.” Never does that hold truer than in the land of the world wide web. Because often times, the commenters piping up about faults with the RS, are the very same people who do not own one, have never driven one, and cannot afford one. These ‘issues’ with the 2.3 probably will never become issues until you’re nearing 400whp numbers. Of course on the internet, everything makes 800. So here you go.
This engine build (called the Spec-H2) from Panda Motorworks starts around $5000. And the built motors are capable of 600-800hp, depending on goals & budget.
This build is called the Spec-H.2
JE 88MM pistons
Manley Turbo Tuff I-Beam rods
King main bearings
Clevite rod bearings
ARP main studs
SuperTech head gasket
Piper stage-3 cams
Panda Built proprietary valve job
Panda Built light port job
Panda Built blue printed & assembled
FreekTune H11 head studs
Massive balance shaft delete
Massive oil pan baffle
Massive 2.3 keyed crank
Crower valve springs with titanium retainers
Custom Panda Built ‘Plug’ to modify the 2.0 block to accept the 2.3 head
…Machine work done by Terry’s Machine Shop