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Putting Down 400whp In Your Focus ST Blog Feature
JP Alonso

By: JP Alonso on September 25th, 2017

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Putting Down 400whp In Your Focus ST

Ford Focus ST

400whp (that's wheel horsepower just in case you've been living under a rock) seems to be the magic number in front wheel drive turbo cars. If you have one, you know what I mean. If you want one, it's probably because 385whp is way too close to 400 for you not to get there. It's almost like being in a club. "It has 400 at the wheel." It's one of the most proud statements you can make if you have a Focus ST and it's making that much power.

500, 600, 700 horsepower, they're all worth bragging about too. But 400 is sort of the gold standard for a good front wheel drive street car. With better tires than stock and some basic chassis and drivetrain modifications to help your car grip better during acceleration, it's just the right amount of power that features a turbo that can still spool relatively quickly and lay the smack down on almost any showroom crowd pleaser costing $70k+. But what's involved? How do you do it without turning your reliable turbocharged grocery getter into a living nightmare taking space up in your garage with a hole in the side of the engine?

Believe it or not, it's relatively easy to do on the Focus ST. I can't say it's cheap because that's dependent on your budget. But we're here to tell you it's attainable with any modest budget.

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The Basics

If you haven't been introduced to the basics of modding your Focus ST, check into these mods.  In our opinion, you should not try to attain 400whp without these upgrades.

  • ECU Tuner
  • Intake
  • Intercooler
  • Downpipe
  • Exhaust
  • Blowoff Valve
  • Rear Engine Mount
  • 1 Step Colder Spark Plugs
  • Sound Symposer Delete (I'll tell you why shortly)

There are a handful of other items we highly recommend but this is the bare minimum. Yes, you need a bigger turbo, but we're specifically referring to supporting modifications here.

A couple notes about the parts above - you NEED a blowoff valve with any non-BorgWarner EFR turbo. Whether it's a Garrett, Precision, or other brand that you're customizing around, you'll need to get a completely new blowoff valve setup. The Focus ST comes with a blowoff valve built into the turbo which means when you replace it, you need to source a new BOV. This also means you need to source at least one of the 2 intercooler pipes since that's where the new BOV will be located. These are all readily available in kits with a few different blowoff valve options.

The sound symposer delete is the easiest way to create a vacuum/boost source for your BOV. Most people that mod their ST want it gone anyway, but this gives you a really good reason to do such a simple modification.

Turbo Choice

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This isn't optional, you need a bigger turbo. Luckily, there are many options for you to choose from. ATP Turbo was the first to come out with a bolt-on solution based around Garrett's GT and GTX style turbos and it's truly "bolt-on". It fits with virtually all intake kits made for the Focus ST and it fits any stock style downpipe. It comes with all hardware you need for installation. Basically, you're swapping out the turbo only. One feature the ATP kit has that no other does is the ability to easily setup an external wastegate (EWG). It comes blocked from ATP but you can remove the vband blanking plate and setup a Tial 38mm, or other similar wastegate. There is actually a bolt-on dump tube available from 3P Performance to complete this setup without any custom fabrication needed on your part.

Those that want to get fancy can opt for the BorgWarner EFR turbo kits made by Full Race and Mountune. They're slightly different from each other but both include the cylinder head adapter that feeds exhaust to the new turbo and a new intake. The Full Race kit includes a downpipe and the Mountune kit has a downpipe available separate from the kit. The intake system included in the Mountune kit is slightly different as it connects to the stock piping right above the engine but it will fit fine with Mountune's upgraded intake pipe kit if you still want to upgrade that part. Full Race's intake is a full replacement.

The ultimate turbo kit which features a stainless steel Tial turbine housing, Garrett turbo, external Tial wastegate, a cast turbo adapter, and every single part that you need to install the turbo kit is made by cp-e (Custom Performance Engineering). In addition, you can actually pick your turbine housing A/R which adjusts where you want the power to be made. If you're shooting for quick spool and don't care about top end as much, pick a smaller A/R. If you're shooting for top end only and want the highest power level possible while losing a bit of spool, pick a bigger A/R. In addition, if you decide you want to get a different turbo down the road, you can. For example, let's pretend you get a GTX3076R and the next year, you want to change to a GTX3582R Gen2 setup. All you need to do is get a new turbo and swap them out. All components still line up. This kit is truly a home run and will outperform most anything out there along with being the most technically sound turbo kit. We can't begin to describe how awesome this turbo kit is. Yes, it's the most expensive. Yes, it's the best one available. To date, this kit is used on the some of the fastest and most powerful Focus ST's in existence.

Download our Turbo Kit Buyer's Guide for the Focus ST right here.

Here's a quick rundown of all the turbo options with an estimation of how much power they'll each be able to produce at the crank without considering the supporting modifications needed to get there. These are manufacturer estimations and are completely dependent on each platform. Typically, you want to pick a turbo that has slightly more power capability than what your goal is. For example, if you're shooting for 400whp exactly, a GTX2871R might be better than the GTX2867R. There are other factors to consider and it wouldn't be a bad choice, but get something that you're not stretching the limits of.

  • ATP Turbo
    • GT2860RS (360hp), GT2871R (475hp)
    • GT3071R (480hp)
    • GTX2860R (420hp), GTX2863R (440hp), GTX2867R (475hp), GTX2871R (550hp)
    • GTX2971R (560hp), GTX2976R (620hp)
    • GTX3067R (480hp), GTX3071R (560hp), GTX3076R (640hp)
    • GTX2867R Gen2 (550hp), GTX3071R Gen2 (650hp), GTX3076R Gen2 (750hp)
  • Full Race
    • EFR6258 (450hp), EFR6758 (500hp)
    • EFR7163 (550hp)
  • Mountune
    • EFR6258 (450hp), EFR6758 (500hp)
  • cp-e
    • GT2871R (475hp), GT3071R (480hp), GT3076R (525hp), GT3582R (675hp)
    • GTX2867R (475hp), GTX3071R (560hp), GTX3076R (640hp), GTX3582R (760hp)
    • GTX2867R Gen2 (550hp), GTX3071R Gen2 (650hp), GTX3076R Gen2 (750hp), GTX3576R Gen2 (750hp), GTX3582R Gen2 (850hp), GTX3584RS (1000hp)

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Aside from what type of fuel you use, you need more of it to reach 400whp. It seems the stock fuel system's potential is right below or at 400whp. With that said, an auxiliary fueling strategy is usually required unless you're injecting a significant amount of methanol or using some sort of impractical setup. Stratified Auto's throttle body port injection system is the simplest way to setup an aux fuel system on your ST. This adds 2 injectors at the throttle body location and sends fuel through the intake manifold to mix with the air going into the cylinders. This extends the range of your power significantly.

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400whp requires better fuel than what's at your local Safeway gas station. Getting there on pump gas isn't realistic and even if you could, you're riding the edge of a dangerous limit to what pump gas is capable of. It doesn't have the properties that help control what's happening inside the cylinder. Too much heat, a bad mixture at a random gas station, or too low of an octane can be a recipe for disaster. There are 2 easy ways to get around this.

The most popular way is blending ethanol (or E85) with your pump gas. Ethanol has awesome cooling and knock prevention properties. It's basically race gas available at the pump. Honestly, it's probably better than most race gasses out there. You can't run full E85 for a couple reasons but you can run up to about 50% of a mixture of ethanol and regular petroleum based gas. With ethanol in your tank, your tuner is able to raise your timing values, run more boost, etc. That's why you can make more power with ethanol, it allows your tuner the safety in running a more aggressive tune to get more power.

The next option is methanol injection. There are many quality methanol/water injection kits available with different size nozzles for different amounts of methanol to be injected into the intake system. This is a simpler type of auxiliary fueling that sprays methanol into the intake system before it hits the cylinders. It cools the intake air down and increases the octane of the fuel mixture in the cylinder. Just like ethanol, it allows you to run more boost and more timing, among other things, to achieve more power than pump gas alone allows. Meth injection is not necessary to get to 400whp. Rather, it's a cheaper alternative. If you do this, you can potentially avoid the aux fueling setup. However, we recommend the aux fuel over this if we had to pick one or the other.


400whp requires tuning. You probably already knew that. Just to reiterate though, you cannot put a bigger turbo on your car and use a better fuel like ethanol without having a professional tuner calibrate your ECU. A dyno tune is an ideal way of getting this done as it takes the shortest amount of time and can be done in a very controlled manner. It's safe and doesn't brake any laws. Score 1 for dyno tuning. However, coming from being street tuners ourselves, we understand that tuning your car on the street can be a necessary evil to some. It's time consuming, most of the time you're breaking some sort of speed limit law, and it's not the safest thing in the world. However, it can be very accurate because you're getting to see how the car is actually loading up the engine when it's in a real world scenario, unlike the dyno. Score 1 for street tuning. Either way, properly calibrating your ECU is not optional. We recommend searching for the best tuner you can find. Do your research on who a good tuner might be and if they have experience tuning setups like yours and Focus ST's in particular.

On the subject of tuning, if you're running an auxiliary fueling setup, you'll need to tune a second device, usually a Split Second Controller or something similar. This is what controls the extra injectors you added and it's a more simple ECU in and of itself. So you need to tune that alongside your car's ECU. If you didn't think you needed the best tuner for your car before, this will expose who knows what they're doing and who doesn't.

Do you have to build your engine?

Many of you are aware that adding about 200 horsepower to your stock 2.0 liter EcoBoost is stressing it out just a little more than how it came. We can't say you need to build your engine but we can't say that you don't either. It's really at your own risk. For the record, 400whp is about the most we feel comfortable with on a stock engine.  Anything more and we recommend reinforcing your engine with better internals.  But here's what you need to know. There are many stock engine ST's running around right now with 400whp that have been boosting strong for dozens of thousands of miles. There are ST's that have also blown up within the first few drives. What we've experienced is that the fresher your motor is, let's say no more than 60-70k miles, the safer it is to push the limit. But there have been plenty of guys that have put a big turbo on at 100k and it has lasted to 150k or further. It's weird. The most important variable is your ECU tune. Please, don't take shortcuts with this and don't pick a tuner that isn't trustworthy or doesn't have a good rep. There are a handful of experienced EcoBoost tuners in general that have done this over and over and over on the car you're reading about here. Pick one of them.

One other thing, if you don't take care of your car, it doesn't matter how much power it has in it. You're going to screw it up. So treat it like you paid thousands of dollars to have the car and the mods on it because you did. Change the oil, check the compression, swap the spark plugs out when they need to be, change the belts, do what it says in the manual and maybe a little more now that you're modded and your car will be nicer to you than if you didn't.


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You need to consider a few things if you're going for it. I'm not going into detail about them but I will let you know these things are important when pushing this much power and boost.

  • Catch can - I almost put this on the necessary list. It's important, we highly recommend a catch can (or two)
  • Upgraded PCV plate for extra crank case ventilation
  • Brake upgrades to slow you down better - pads and stainless brake lines are a great upgrade
  • Upgraded clutch - if you don't now, you'll need to soon
  • Limited Slip Differential
  • Better tires - we don't care what wheels you have but if you went for the "Buy 3 Get 1 Free" deal, get ready to buy new tires again soon and not get off the line very quickly
  • Stiffer, lower suspension will help your car make better use of the power but that's up to you and it's not critical. You're still going to have a ton of fun even on stock suspension.
  • Different ECU maps for different fuel - if you're traveling and don't have E85 available easily, you'll need to run a pump gas map
  • Valet mode map - if someone gets their hands on your car like a mechanic or a valet driver, it's going to be hard not to go WOT down a back road before they give it back to you

About JP Alonso

I'm the founder of Edge Autosport and I remember first getting into cars in high school. I read all the magazines, bought a bunch of technical books, and finally got to start wrenching around the age of 19. I really enjoy modding and being able to live out a passion is truly awesome. I wouldn't change a thing.

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