Upgrading Your Focus ST Intercooler

An intercooler upgrade is almost always an essential part of any performance turbo build. We recommend taking care of this early in the build process as it will maximize your stock components as well as the more powerful bolt-ons you might add down the road. The best time to put one on is the soonest you can after getting an AccessPort.

What's wrong with the OEM intercooler?

Factory engineers are limited by budget and space. The OEM intercooler on your Focus ST is thin, short, and it heats up quickly robbing you of power. A quality, aftermarket intercooler will do its job much more efficiently than the stock unit, which means providing your engine with the oxygen dense air it loves. 

When forcing air into your engine with a turbo, you need to make sure that air stays cool and dense by passing it through a quality intercooler. The act of compressing the air will naturally raise its temperature. As you can see in the diagram, hot air is much less dense, lacking the oxygen needed to make more power. There are different structural designs used to accomplish this heat transfer but regardless of which kind you go with, getting that air as cold as possible will lower your risk of knock, cool down your pistons, and most importantly, allow you to add more fuel to the mix. This all results in higher and more consistent power.

You will often hear engine builders describing engines as air pumps, because the challenge lies in its ability to move air. Adding fuel is easy, getting more oxygen into the mix is the hard part. The more oxygen you can get into the engine, the more fuel you can burn. And the more fuel you burn, the more power you have.

So which intercooler is right for your Focus ST build?

There are so many choices out there and without much experience, it's hard to tell them apart. Having seen how well certain intercoolers perform first hand with dyno tuning and eTuning over the years, we have a good handle on which ones are worth your money. Here's the three units we really like. There's more, but you cant go wrong with these. All of them mate with factory or any factory style piping and require minimal effort to install.

cp-e

In my opinion, this is probably the best overall intercooler you can get for a Focus ST. With smooth flowing cast end tanks, a bar and plate core, and easy fitment inside the bumper, it's a no brainer. The dense fin structure allows the heat to be fully transferred as the hot compressed air passes through one side to the other. cp-e is an American made brand and this is TIG welded by hand right here in the USA. It's perfect for any stock turbo and can handle any setup pushing 400whp, no problem. They offer a bigger core but you really don't need that until you get into a much higher power and boost range. The Lightweight version has a broad range of use.

Mishimoto

Their Focus ST intercooler comes in your choice of three colors (black, silver, gold). There's nothing wrong with a little vanity in your parts when you're going after a certain appearance. The good thing is Mishimoto backs up its style with performance too. Cast end tanks, perfect stock fitment, and a bar and plate core make this a massive upgrade over stock.

It's 128% larger overall than OEM. Plenty of cooling and flow happening inside this unit. Available separately or as a full kit, Mishimoto also makes a full piping setup to compliment the intercooler.

Garrett

Realistically, you could probably put this side by side with the cp-e for performance and quality. Garrett is one of the most reputable performance brands and they make the best turbos in the world. They eat, sleep, and breath turbocharging. So this intercooler is a result of a very high level engineering department. Same story as the others - cast end tanks, bar and plate, dense fin structure, and perfect OEM quality fitment.

This post was originally published in January, 2023 but has been updated to reflect current parts and accurate information!