The Guide to Upgrading the Intercooler on a Ford Focus ST. When running stock boost levels, the factory intercooler on the Focus ST is excellent, but it is easily overwhelmed when boost is increased and more air enters the engine.
This tutorial will go over the performance advantages of upgrading your intercooler, as well as crucial aspects like intercooler design and sizing, as well as suggestions on our preferred Focus ST FMICs.
The Fundamentals of the Focus ST Intercooler
Turbocharged engines, such as the 2.3L EcoBoost found in the Focus ST, generate a lot of heat. The turbo runs at extremely high temperatures, which considerably warms the air it compresses. Because hot air is harmful for combustion, the air is cooled before entering the combustion chamber. This cools the air after it has been heated by the turbo’s compression.
The air-to-air intercooler is standard on the Focus ST. It is located within the front bumper and uses outside air to cool the compressed air contained within it. “Air galleries” are found in intercoolers. As you drive, outside ambient air travels through these air galleries, cooling the air inside the intercooler before it is supplied to the combustion chamber.
For factory STs and those running stock boost levels, the stock intercooler is completely adequate. However, after a tuner is installed and the turbo compresses more air, the stock intercooler becomes inefficient. This can result in higher IATs and a variety of performance concerns like as heat soak, knock, and misfires. Intercooler upgrades improve efficiency and cooling capacity, resulting in lower IATs, consistent performance, power improvements, and a healthier engine.
Sizing and Design of the Focus ST FMIC
FMICs are not all the same. When selecting a performance intercooler, we consider two distinct factors. The first consideration is the design, which can take the shape of a bar and plate or a tube and fin. The design influences how the air galleries are built, which affects efficiency and cooling capacity. The second factor is the size of the intercooler. Larger intercoolers are more efficient and have the ability to cool larger amounts of air. There is, however, such a thing as going too big.
Tube and Fin vs. Bar and Plate
This is a more subtle topic, but it is vital to address. Any modified intercooler will outperform the factory unit, but not all are created equal. Air galleries are used to cool charge air in air-to-air intercoolers, as previously explained. These air galleries can be built in either a bar and plate or a tube and fin configuration.
Because bar and plate intercoolers have more rectangular air passages, more ambient air goes through the intercooler. They are also more durable, albeit this means they weigh slightly more. One of the best aspects of bar and plate designs is that they have less pressure loss, allowing them to store more boost (psi).
Curved air galleries are more common in tube and fin intercoolers. They have a somewhat smaller capacity but are more efficient. They are lighter, which is beneficial for weight savings, but they are also less durable and readily damaged by pebbles and other objects that may collide with the intercooler while driving. Furthermore, tube and fin intercoolers have higher pressure loss and cannot tolerate as much boost.
Overall, we recommend intercoolers for bars and plates. Despite their weight, they have more cooling capacity and less pressure drop, resulting in improved performance.
The second distinguishing feature of intercoolers is their size. There are two components to intercooler sizing: core size and surface area size. The internal section of the intercooler and the volume of air it can retain are referred to as the core. The surface area of the intercooler is the part of the intercooler that is visible from the front bumper. Larger surface areas capture more ambient air, resulting in lower IATs.
A larger core means the intercooler can store more air, which is beneficial for individuals who use an intake in addition to a tune. When additional air is introduced into the engine, the stock intercooler’s limited size cannot always hold enough air, resulting in hotter IATs. Furthermore, the larger it is, the longer the air flow inside the intercooler is, which means it is cooled more effectively. Focus ST core sizes range from 60% to 200% larger than the stock intercooler.
The larger the surface area, the better. More surface area allows more outside air to pass through, increasing efficacy. Most aftermarket Focus ST intercoolers have surface areas that are 20%-50% larger.
Is it possible for an intercooler to be too large?
Absolutely. Intercoolers, like melodies, are best thought of in stages. You can choose between “Stage 1” and “Stage 2” intercoolers. The core volume of a typical stage 1 intercooler will be 100%-130% greater than standard. Stage 2 intercoolers will be roughly 200% larger in comparison. Furthermore, surface area sizing will be 20%-30% larger as opposed to 40%+ larger.
If you don’t have an upgraded turbo, the smaller stage 1 intercooler should suffice. Using a larger intercooler when not pumping as much air results in greater pressure drops inside the intercooler and increases turbo lag.
The majority of stage 1 intercoolers can handle more than 500whp. Given that these power levels cannot be achieved without a constructed engine and improved turbo, there is no need for a larger intercooler if you are merely tuned and complete bolt-on.
Piping Kits for the Focus ST Intercooler
You can upgrade your intercooler piping, or chargepipe, in addition to your intercooler. There are two types of piping: hot-side piping and cold-side piping. The pipe that transports air from the turbo to the intercooler is referred to as the hot side. Because the air hasn’t yet been cooled by the intercooler, it’s called hot side. The other is the cold-side, which is responsible for transporting air from the intercooler to the engine. This side is also known as the chargepipe since it transports charged (compressed) air.
Air flow to the intercooler and the engine will be increased by upgrading the piping. You may also add a blow-off valve for the amazing “pssshh” noises. If you can afford them, these are nice additions, but they aren’t necessary unless you’re pushing a lot of power, want the blow-off valve sounds, or want meth injection.
Advantages of an Upgraded Intercooler for the Focus ST
- Gains of 5-10whp and torque
- IATs have been reduced by 40 degrees or more.
- Performance that is consistent
- Heat soak at a lower temperature
- Misfire and knock prevention
Intercooler performance enhancements are typically proportional to existing power and adjustment. The more power you have and the more aggressive the tune, the more performance benefits an intercooler will provide. With an aftermarket intercooler, you can gain up to 10whp and even more.
An intercooler will not only aid enhance power, but it will also reduce power loss. When driven hard, such as on a track, the persistent high rpm, high boost nature of the engine can induce heat soak. This can result in a 10-20whp loss on the Focus ST. A better intercooler will not only increase power, but will also decrease power loss due to heat soak, resulting in more consistent performance.
Another significant advantage of an intercooler is its dependability. Heat is the number one killer of all engines. Hot air can cause the engine to misfire, misfire again, knock, or pre-detonate. Cooler IATs result in lower engine temperatures, lower exhaust gas temperatures, better timing, and less knock. As a result, one of the finest reliability upgrades for modified Focus STs is an intercooler.
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Best Intercooler Upgrades for the Focus ST
For the Focus ST, there are numerous improved intercooler options. The design and sizing are critical concerns. Remember that the largest intercooler is not always the best intercooler. I’m betting that the most of people here don’t have an updated turbo, thus our first option is definitely your best bet.
You may also update the intercooler pipe, though this isn’t really necessary unless you’re pushing 500whp. While any modified intercooler is preferable to the stock one, we avoid the Cobb intercooler because to its tiny size and the Mishimoto intercooler due to its tube and fin design and high price for its worth.
1) Intercooler for the Focus ST CVF Street
CVF supplies our preferred Focus ST intercooler because it gives the best value for money, quality, and performance. Their street intercooler has a core capacity that is 115% larger than the stock core and a surface area that is approximately 30% greater. IATs have dropped by 41 degrees according to testing. Because it is a bar and plate intercooler, it has the least amount of pressure loss, the most boost capacity, and is incredibly durable. It also has high-flow end tanks, which boost airflow to and from the intercooler.
CVF claims the intercooler can handle up to 670hp, which is more than plenty for any heavily modded ST. They also sell piping and chargepipe kits for those searching for more flow, meth injection, or the great blow-off valve noises. Overall, CVF is our favorite brand on the market and one of the most reasonably priced Focus ST intercoolers.
2) Delta Core Intercooler cp-e
For the Focus ST, cp-e has one of the largest intercoolers available. Its core dimensions are 288.5255.5 vs CVF’s intercooler’s 26x8x4.5. This results in a greater core size and surface area for maximum cooling capacity. It is a bar and plate design with high-flow end tanks for improved airflow. cp-e also provides a smaller “lightweight” intercooler, however it is somewhat small and hence cannot handle as much power as their Core intercooler or CVF’s Street intercooler.
This intercooler is ideal for anyone who has updated turbos or who tracks their Focus ST on a regular basis. It’s a touch more expensive, roughly $750, but it’s one of the better options for people looking for a large intercooler with maximum cooling capacity.
Summary of the 2.3L Ford Focus ST Intercooler Upgrade
One of the best performance and reliability mods for tuned STs is upgrading the intercooler on your Focus ST. An intercooler will not only provide solid 10whp power improvements, but it will also provide more consistent performance by preventing pre-detonation, knock, misfires, and heat soak. When optimized, this results in not only a more powerful, but also a more reliable engine.
When selecting an intercooler, we recommend focusing on two factors: design and sizing. We favor bar and plate intercoolers since they retain more boost and have a higher cooling capacity. They are also far more durable and are less prone to be damaged by rocks when driving. Unless you have an improved turbo, we recommend keeping with an intercooler that is 100%-130% greater in size. By using a smaller intercooler, you can avoid boost pressure reductions and significant turbo lag. If you want to make 500whp or more out of your ST, we recommend going as big as you can.
CVF makes the best intercooler on the market. It is 115% larger, thus it provides enough cooling capacity while not being too large to cause lag or pressure loss. It offers the finest value for money and can handle more than 600whp. For anyone searching for the largest choice on the market, we recommend the cp-e intercooler.