300whp in a well balanced, 3,200 pound, front-wheel drive hatchback is underrated. Don't get me wrong, 400 is better if you're....me, or anyone else like me. But 300whp is nothing to shake a stick at. That's good enough to take down many other $40k-50k range performance cars while paying a fraction of the price and being able to comfortably take 3 or 4 kids to school (not while you're taking down the other car, of course). With the Focus ST, it's relatively easy to get there.
The Focus ST comes out of the factory with a potent 250+ horsepower at the crank. I say potent because anything else in that class and price range usually isn't nearly as inspiring to drive. Apples to apples, it's not bad. But even for the casual automotive enthusiast, it leaves you wanting more. With a turbocharger on board, it's a few parts and a few buttons on an AccessPort away from giving you more.
While there are a handful of ways to slice the pie, we'll tell you how we would do it if we were in your shoes.
There are 2 main ways to go about getting 300whp. If you don't know already, wheel horsepower (whp) is what we're discussing here. Once you get into the act of modifying, this is the only value that matters when it comes to measuring power, because it's the actual number that propels you forward and the number able to be accurately measured in a real world scenario while the engine is in the car. Stock Focus ST's usually yield about 220-230whp depending on the dyno, conditions, etc. So we're talking about 70-80whp bump here, an increase of over 35% more power. That's not insane, but it's not a little, and will absolutely change your experience with the car.
Method #1, our preferred way to achieve 300whp.
Believe it or not, it's less expensive. By no means does that mean less fun, lower quality, or a worse experience. In fact, this is what I would do (and we have with our own project to show it). It's as simple as this. Buy a Cobb AccessPort, Garrett PowerMax turbo, and a good intercooler. All said, that's about $2,500. That's right, for $2,500 and 3 parts, you can get 300whp. Without getting too much into supporting modifications, I will recommend a rear motor mount at this point. But a rear motor mount doesn't add power, it just allows you to use it better. One more thing, you'll need a custom tune, so add on another $295 for a single fuel, 91/92/93 octane tune, and you're on your way to taking a massive step in power and torque. The cool thing about this setup is once you're here, it's not maxed out. You can add other parts to expose the slightly higher potential of the Garrett PowerMax turbo and you can use an ethanol blended fuel to safely squeeze out another 20 horsepower.
One thing I really enjoy about the PowerMax is it feels just as punchy and responsive as the stock turbo while carrying power through those high rpms, instead of falling flat like the stock turbo. I'm not just saying that. I'm not sure you'd notice the difference in spool time. It's a legit stock replacement turbo while flowing more air than stock. It has a new boost controller built into it, as well.
Method #2, using the stock turbo.
I would never tell you not to do it, but I would just warn you of what you're getting yourself into. The stock turbo is small. It can only flow so much air before it starts breathing fire into your engine and experiencing a massive efficiency dip. On top of that, if you push it too far, you'll put too much of a physical demand on the turbo and subsequently, on the engine. This is definitely the culprit of many failed turbos and motors. Too much heat really does a number on an internal combustion engine and other surrounding components. You can get to 300whp on the stock turbo. However, it takes all the bolt-on parts external to the engine, mixed with a competent tuner, and polished off with a little bit of luck. For the record, I would recommend shooting for about 280whp if you plan to use stock turbo. It's still a kick in the pants at that power too!
The parts you'll need for this are, at minimum, an AccessPort, intake, exhaust, downpipe, intercooler, and the use of an ethanol blended fuel mixture. That's about $3,125 in parts, before the same $295 eTune, plus the inconvenience of having to mix your fuel. The inconvenience isn't as big of a deal to some. Ethanol is abundant in many areas across the country but not so much in others. Make sure you know how convenient it is to access ethanol either at the pump, or in something like 5 gallon jugs from more specialized fuel companies like Sunoco, VP, Ignite, etc. Those will be more expensive than ethanol at the pump and will only be available through specialty fuel retailers. Either way, you'll be mixing fuel frequently and always keeping the ratio in check. One last thing, an upgraded wastegate actuator might help in your 300whp quest as it will help hold the wastegate shut a little better than the stock canister.
The part about luck refers to a couple different things. The right day is required. If you show up to the dyno hoping for that magic 300 mark and it's 95 degrees out with a density altitude of 6,000 feet and 90 percent humidity, I'm sorry but it's just not going to happen. If it's a cool 60 degrees with lower humidity, there's definitely a fighting chance. The other factor is how tired the motor is. Some motors are tighter than others and spin really free, meaning there is less parasitic loss from all the rotating parts. This could be due to the smallest of tolerance differences from one motor to the next during the machining and assembly process before it ever gets put in the car. Also, you might have tires on the car that soak up some of that power. We've seen winter tires show over 20whp lower than it did with summer tires. So everything that moves, from the engine to the tires, matters.
Conclusion
Either way you slice it, you're going to have some fun. We're talking some serious bumps in power and torque from the stock levels. Do what is within reason for your time, budget, ability, etc. Make sure you do your research on what parts will help you get to where you need to be and make sure you partner with a great tuner (like us). 300whp is a solid goal and provides lots of smiles per gallon.