The bumper guard and the lower air shroud were removed by removing two Torx screws. This gave us access to remove the shutters.
Removing the shutters is simple, you just squeeze 4 tabs and a clip holding the wire harness in and out it comes.
To test the stock intercooler’s effectiveness, we put thermocouples in the charge pipes at the inlet and outlet of the intercooler. We placed the probes carefully to avoid contact with the walls of the pipe, making sure the probe was in clean airflow. We simply ran the wires under the couplers to the outside. This didn’t leak and worked really well.
Here is how it looked before we tightened the hose clamp down.
We ran the car on World Motorsports wind tunnel dyno to get a baseline power reading and to measure how well the stock intercooler worked. We use the World Motorsports dyno for critical testing due to its powerful fans that can give a close approximation to the actual road airspeed, this is critical for realistic intercooler testing.
We dynoed the car with the stock intercooler making 12 sequential pulls back to back. It took about 12 pulls for the intercooler discharge temperature to saturate and stabilize. Over the course of the dyno pulls the power output fluctuated a lot. We think this is because the engine control strategy is to hit the car early with a lot of boost and spike the torque at a really low RPM. This makes the engine highly likely to detonate direct injection or not. To keep the engine from destroying itself, Ford has very active detonation detection and the ECU has a lot of control authority. You can see this as the torque, especially at lower rpm is all over the place. The average torque over our runs was 259 lb/ft with a large standard deviation of 17.2 lb/ft of torque. Since peak power is obtained at higher rpm when the cylinder pressure is more stable and the propensity for detonation is less, our average power was 177 whp with a pretty large standard deviation of 8.9 whp. That is one active ECU. The Focus ST is the least consistent car we have tested on the dyno to date.