cp-e’s Install Department recently had the chance to install one of our very own Focus ST Atmosphere™ Turbo Kits. We ran one of these turbos on our shop car a few years ago, and the result was an incredibly fast and fun to drive car that doesn’t lose the factory response and reliability. Any time that you’re adding a larger turbo, you can expect a later spool, but we’ve done everything possible to maximize the spool time on our kit.
Compared to other cast manifold turbo kits that we’ve seen in our shop, we’re seeing about 500 rpm quicker spool with the same turbo. Some of this is due to the manifold design, but also our choice of a Tial turbo as opposed to a stock Garrett unit greatly helps spool times.
The car in question chose a Tial Gen 1 GTX2867R along with matching Tial MVR Wastegate in Silver. This combination looks very sleek and since it’s tucked away between the engine and firewall on the Focus ST, it takes a very keen eye to spot the turbo kit.
Being a veteran owned company, we were pleased that this Focus ST was owned by a member of the military. Prior to the turbo kit, this 2016 ST3 had some key modifications such as a cp-e intake, COBB FMIC with TiAL BOV, COBB catback exhaust, Enkei RPF 1 Wheels, Boomba short shifter kit, stock fuel system, and a 3 Port MAC solenoid boost controller. With the exception of the wheels, we’ve installed all of these parts here.
After installing all of the parts, we gave this car a custom tune to get everything settled with perfect drivability and power delivery. Our tuner had some feedback on both the kit and also general notes on tuning the EcoBoost vehicles with a big turbo. With a 2 day session for the install and tune, our install and tuning department was able to shed some light on the common questions with this kit.
Installer & Tuner Notes
The Focus ST struggles on the fuel system side.
With the GTX2867R being able to hit 20psi by 3500rpm, the cam driven HPFP cannot keep up, because its flow ability is linked to RPM, limiting the amount of boost in the lower RPM’s. In the high RPM’s, the HPFP can keep up, but the injectors start to be the limiting factor. In a direct injection system, the fuel injectors are really only supposed to spray in the intake stroke. If you think about the fact that the engine cycle consists of 2 revolutions and 4 modes (intake, compression, power, exhaust), direct injection cars can really only spray during one of those modes, where as port injection, best sprayed at the back of the closed intake valve, have 3 of the modes to spray fuel in. The direct injection systems must do a lot of spraying in a short amount of time. On the stock fuel system on the focus ST, this limits how much boost we can run at high RPM’s, limiting power. With the fuel system limiting the focus in both mid and high RPM’s its hard to make full potential of the larger turbo. Furthermore, when doing ethanol mixes, lambda of 1 changes from 14.08 (e10) to 12.96 (e30), so approx 10% more fuel must be sprayed in the same amount of time, putting further stress on the fuel system. Good thing ethanol can run leaner and make more power with the same boost safely.
External wastegate control on the Atmosphere kit.
As a tuner, one of my favorite aspects of the CP-E atmosphere kit is the external wastegate system combined with the headifold adapter design. With the wastegate being smoothly merged into the path of the exhaust air, its ability to control boost is unrivaled. Paired with the well controlled PID system of the Ford PCM, and Cobb’s custom features in Accesstuner, the boost almost controls itself. For the first WOT pull, I was able to zero out the WGDC tables, aim for 20psi of boost and was able to stay within 1 psi for most of the run. In my history of tuning turbo kits, I have seen way too many kits boost creep, where the boost would go out of control at high RPM’s, or come on too hard and overboost after spool. This kit was able to hit boost targets and stay on target. Especially with the fuel system dictating max boost levels, this is very important for a reliable focus ST. I found that boost was very predictable and changes could be made with small changes to the wastegate table. If the car is overboosting, the ECU will be able to take out duty cycle and get boost where it should be faster, without overshooting, taking out too much boost, or allowing the car to be overboosting for a long period of time. In addition, with only a 1 bar spring, we were able to keep the actual duty cycle very low. This will allow us to easily turn up the boost once we upgrade the fuel system without having to change the wastegate spring.
Advantages over the stock turbo: POWER!
The stock K03 on the focus ST hasn’t really seen much past 300WHP. At 300whp on the stock k03, the turbo shaft speed is spinning way faster than the turbo was ever designed to do, creating a lot of heat. Most focus ST owners will tell you that the car is a torque monster, but when it comes to torque after 5000 rpms, the car is dead. Without seeing compressor maps on the ko3, I would estimate that its efficiency will fall off around 25-27lb/min of air. When it comes to horsepower, airflow is going to be your biggest factor. The GTX2867R is rated at about 47lb/min. We have made 470whp on this turbo in the past! What does this mean? The torque curve with this turbo is WAY different than the stock k03 and will not die out in the high RPMs. On the stock fuel system and stock bottom end, we do not see a big increase in torque over the stock turbo. In fact, with 25psi at less than 3000rpms, the k03 makes boatloads of torque! With the GTX2867R we are able to push over 20psi at 6000rpm, vs less than 15 with the ko3. The torque gains in the top end are huge. Totally stock, the focus made about 175ft/lbs @ 6000rpm. With full CP-E bolt ons and a custom tune, we were able to push that number up to about 200ft/lbs. With the turbo kit, we were at around 255ft/lbs. In percentages, thats 45% over stock, and the only limit with the turbo was the fuel system!
Power under the curve
We have a lot of customers that come to us looking for peak HP numbers, which I totally understand. However, what really makes a car fun? How much fun is 500hp if you only have a power band of 2000 rpm? It may do well in drag racing where you are staying in the power band, but what about a circuit course? A bad shift can take you out of the power band and loose a few seconds of lap time. One of my favorite aspects of the mustang dyno is the fact that it reads out average HP and torque. Suppose you have two cars. Each make a peak HP of 400hp and 400ft/lbs, however, from 2500-6000, car A averages 200hp and car B averages 300hp. Which car is going to be faster? Car B! So, while we made about the same peak torque with and without this turbo, the turbo brought the average power up 7% from full bolt ons and 18% over the stock configuration. Further more, the Atmosphere kit made more torque from 3500rpm to redline, which is most of the powerband. In other words, the <1000rpm lost from the spool time of the bigger turbo is made up from the 4500rpm of powerband with a significant torque increase.