Focus ST – Big Turbo Build

Introduction

This past week my big turbo build for my Ford Focus ST was completed! I’m happy with how it turned out and the car is even more fun to drive. This isn’t meant as a step by step guide but as a summary of the project.

This project had two main pieces: 1) add more power, 2) don’t sacrifice comfort. It’s certainly possible to make pretty much any car faster but faster for the sake of being fast isn’t good enough. This car is my daily driver which means any changes I need to live with on a day to day basis. I’ve seen / heard plenty of cars that are loud and obnoxious. That’s not at all what I want. My goal is to do a conservative (by most peoples standards) upgrade and only add around 100 horse power (hp) at most. I really wanted 300 wheel horse power (whp) (not quite 100 but a good measurable target).

A lot of people might say 300 whp isn’t really worth the effort of a big turbo. Honestly, 300 wph in a front wheel drive car is plenty. Too much power to the front wheels and the car becomes hard to handle. Torque steer is present in the ST when it’s stock; adding power would just exacerbate this. Also, if you go too far above 300 whp fuel starts to become a concern. The injectors and fuel pump would need to be upgraded and that’s not something I wanted to deal with. 300 whp is a safe amount.

Others will say you can get near this amount with bolt on mods. Honestly I don’t believe them. Show me dyno numbers and I’ll believe. Everything I’ve seen has been anecdotal and not backed up by measurable performance numbers. That’s not to say you can’t add quite a bit of power without doing a turbo swap but I’m not convinced you can get the numbers I’m looking for without a turbo swap. Also, trying to hit 300 whp without changing the turbo you’re going to end up with a an obnoxious car. It’s going to be loud and annoying.

My goal was less than a 5% increase in any of the following:

  • Noise
  • Vibration
  • Clutch feel (harshness, heavyness)
  • Drivability (maintaining control of the vehicle)

Comfort is a high priority for me while driving so this wasn’t a do what ever it takes for speed project. I do realize that this isn’t the most expensive or luxurious of cars to begin with. It is a Focus after all. That said, I don’t want the ride (which I find acceptable) to become unbearable. I want to enjoy being in my car and I don’t want dread having to drive the car.

The Turbo

With these requirements in mind I started the build about a year ago. The turbo I chose is the ATP GT2860RS (.64 housing). I chose this turbo for a few reasons.

At the time ATP had two turbos on the market designed for the ST and there were no other manufacturers with ST specific turbos. Technically I could use any turbo but one designed for the ST is a lot easier to manage. The exhaust manifold is integrated with the turbo exhaust housing. So ATP was the only option.

ATP had two turbos. The GT2860RS they put on an ST and were able to achieve about 300 whp. That’s exactly where I wanted to be. The other turbo is bigger and could go higher but 300 wph is where I want to be. I didn’t see any reason to spend more money to have more turbo potential that wouldn’t be used. Not to mention I was concerned about what would happen with lag by having a turbo much larger than I need.

Adding a new turbo isn’t as simple as it sounds. The stock setup is recirculating (which is ideal) but this is built into the turbo housing. The ATP turbo’s don’t include this. Most people doing big turbos for the ST (and ATP) relocate the stock blow off valve (BOV) (or add a third party one) and vent atmospherically. I didn’t want to do this because you get a distinctly annoying sound when ever it vents. Recirculating just like stock is a requirement.

Supporting Mods

Adding a bigger turbo isn’t the only thing that needs to be done. The car was designed for the power it makes. Some parts can easily handle more power but others can’t. To achieve my goals I needed to add/replace with the following parts.

  • CP-E intercooler
  • Spec Stage 2 non-SAC clutch
  • Spec lightweight flywheel
  • MBRP Catted downpipe
  • Quaife LSD

The intercooler is an easy part to replace. It’s also necessary. The stock intercooler is pretty much maxed out with the stock turbo. Anything larger and there isn’t adequate cooling. CP-E’s intercooler is designed for the ST, so it fits perfectly and mounts easily.

The clutch was another part that wouldn’t be able to handle the increased power. The flywheel was because it’s required to use that clutch. Talking to Spec they assured me that it feels nearly identical to the stock clutch. I’m pleased to say that it does. It’s not identical but close enough you really don’t notice a difference. I’m also very happy with the flywheel. It does increase vibration because it’s a lightweight flywheel and not a dual mass one like comes with the car but overall I think engine breaking feels smoother.

The downpipe was necessary because the stock one has a nasty restriction where it connects to the turbo. ATP also said it was required to replace to use the turbo.

The Quaife LSD was the only part that wasn’t strictly necessary. I wanted to add it because it improves power transfer. Having more power I should see a benefit.

Notice how intake and exhaust (aside from the downpipe) are not on my supporting mod list. Those are stock. There is no need to replace these. Muffler deletes, resonator deletes, open air boxes, larger intake piping… None of this is necessary. It increases noise and there is little to no benefit in this application.

The Build

I had a local shop do most of the heavy lifting for the installation of these parts.

Transmission

Here are some pictures of the transmission opened up for the LSD install.

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Turbo

The new turbo attached without heat shield.

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With heat shield.

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Recirculating BOV.

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The full engine.

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Tuning

The car was turned by Torrie from Unleashed Tuning. He did a fantastic job. I couldn’t be happier. There were some issues when I got the car back from the shop that did the installation and Torrie took care of everything. He went above and beyond. Not to mention the car drives perfectly.

Here’s a picture of it on the dyno.

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Torrie is the person to talk to if you’re looking for a tuner. He really is the best. In summary, Torrie:

  • Willing to work around my schedule and even allow me to drop/pickup night and weekends
  • Fixed issues that weren’t created by him or even in scope for what he was doing for me
  • Gave me daily updates on his progress
  • Got the job done in the time frame discussed
  • Did a great job with the tune

How It Turned Out

In a word, perfect.

It feels like stock just more powerful. It turned out exactly like I wanted. Noise, vibration, clutch and driving feel were either not impacted or were minimally impacted that it was within my less than 5% goal.

As for power, 324 whp. Torrie said he could have easily hit 350 whp and probably gone higher. He said that 324 whp was solid and he felt more than comfortable at that level. I trust his judgment so we left it there. Fuel wasn’t an issue at this amount.

Proof of power; the dyno chart.

JS1