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Big Bolt-On Power for Your Focus ST
What handles like a go-kart, runs 13s with minor mods, has the carrying capacity of a small SUV, gets 30 mpg, and is affordable? The Focus ST, that’s what.
Prior to diving into this Race Red Focus ST owned by Landon Cummings for this month’s performance bonanza, we spent a week cutting through the canyons with a box-stock example in order to help us decide where it could be improved upon. After several hundred miles of backroad bombing, freeway cruising, and navigating stop-and-go traffic, we walked away impressed, but that doesn’t mean the aftermarket can’t make it better.
Crank it up
In stock form the Focus ST handles like it’s on rails. It has brakes that easily scrub speed and enough power to keep things entertaining. But after living with the stock car, we ultimately decided that more power and whole lot more personality would do this hot hatch wonders.
We know what you’re thinking: Horsepower is only part of the equation. But stick with us here. Stock vehicles favor throttle response and minimal turbo lag over outright power, so it is no surprise that the stock BorgWarner K03 turbo on the Focus ST is sized for midrange punch and sharp throttle response rather than a big top-end hit. This means that with the stock turbo in place and boost levels raised, the Focus ST produces massive amounts of torque only to run out of air before redline. But don’t think this is a travesty; realize that big torque is exactly what you want in a lightweight street car where instant power is far more engaging than wicked boost lag that eventually leads to a quick burst near the fuel cutoff.
Instead of a massive hole in the midrange with nothing until 5,000 rpm like many big turbo, small-displacement engine combos possess, a tuned ST lights the turbo at just 2,000 rpm and makes V-8–like torque for the majority of the curve. For those wondering, that kind of torque yanks this feathery hatch around with authority.
But back to our goals. We’re not looking to add another 100 hp; instead, a useable increase in torque and midrange punch would bolster the driving experience tenfold.
As for adding personality, while the EcoBoost four-banger sounds good, it certainly isn’t an American V-8. In stock trim the whooshing and swooshing of the turbo is indeed addicting, but a more aggressive exhaust note and an unmuffled turbo would be nice.
Building a better hot hatch: The plan
In search of more power, we turned to a pair of legendary powerhouses in Focus performance, one from the U.S. and the other from across the pond: Ford Performance and Mountune.
With street-friendly goals in mind, we picked their brains about the right recipe of performance, civility, and reliability. “The Focus ST responds well to relieving restriction and tuning the ECU, but careful attention must be paid to thermal management,” said Jesse Kershaw of Ford Performance. In other words, the Focus ST comes with factory forced induction, which means large gains are easily had by raising boost, perfecting the tune, and maximizing efficiency. But simply cranking the boost can turn these motors into heat monsters, quickly killing any power gains.
After speaking with Mountune and Ford Performance, we decided on a simple combo that would net great performance gains and preserve them even in the hottest of temperatures. This recipe came in the form of a Ford Performance ProCal ECU Calibration Kit and high-flow cat-back exhaust system. From Mountune we sourced an MP275 Performance Kit, which includes a stealthy yet massive front-mount intercooler (FMIC) and high-flow cold-air intake (CAI) system. Together, the simple additions would net significant real-world gains.
But wait, you already know all about Ford Performance, so what about Mountune? If you’re familiar with the motorsports industry in Europe then you have likely heard of Mountune since the company has been at the forefront of engineering and technology in racing since the 1980s when it prepped legendary Cosworth engines for countless championship winning motorsport cars, teams, and drivers. We’re not talking just a few award-winning motors either, but rather countless high-end engines for Ford, Formula Palmer Audi, and many front-running British Touring Car teams. You get the point. A company doesn’t become that successful without being the best. After years of racing success, Mountune ventured into street car performance with equal success tuning cars like the Focus ST.
Ford Performance ProCal tune and exhaust
Factory forced induction might mean that power gains are easily had with an aftermarket tune, but finding the right tune can also be a challenge since all-out performance means nothing without buttery drivability and OEM-like reliability.
“Ford Performance spent a lot of R&D time designing the ECU programming for the Focus ST so the engine would produce solid performance figures without concessions to reliability or civility,” Kershaw told us.
We’ve all heard of tuning horror stories that ended up costing the owner their new engine. Well, this is no such story. Kershaw said, “The Ford Performance tune not only greatly improves torque, but it also does so without detriment to the engine or drivetrain.”
The Ford Performance tune (PN M-14204-FST) claims to greatly increase the torque at 2,800 rpm on 93-octane and preserve it up to 4,200 rpm. If that’s not solid enough, the tune is 50-state smog legal and is backed by a three-year/36,000-mile warranty, which puts this tune in a league of its own. Yeah, a tune with a warranty. How do you like that?
Other interesting additions include a revised Sound Symposer software calibration for a more natural engine sound as well as colder plugs (PN M-12305-20T) for carefree performance even under high boost. As we are sure you already know, Focus STs, like many new cars, produce an engine note through the speakers for a more engaging driving experience. In this case, the Ford Performance calibration not only tunes the ECU but also the acoustic experience inside the cabin.
We also ditched the factory cat-back exhaust system for a freer flowing unit. In our case, we chose the Ford Performance high-flow exhaust system (PN M-5200-FST) to let the EcoBoost motor expel spent gases in a hurry. More than just great power, the system is a work of art thanks to large 2 1/2-inch stainless steel piping with smooth mandrel bends and a pair of equally stunning 4 1/2-inch high polish, stainless steel vented tips that look wicked inside the rear valance. As for fitment, it is factory perfect.
Despite increasing the diameter of the piping from the factory 2-inch system to a larger 2 1/2-inch unit, on our scales the Ford Performance unit dropped roughly 6 pounds. Other attributes include a 50-state drive-by noise legal certification and the benefit of knowing it’s made in the USA. But no exhaust system is purely about fit, finish, or performance; it’s also about the sound. Thankfully this system has a deep, mellow tone that is drone-free on the highway, civil around town, and rowdy under WOT.
Mountune CAI and FMIC
Knowing full well that a free-flowing exhaust system and increased boost were only part of the equation, we also turned to Mountune to uncork the inlet side of the engine and to address the increased inlet temperatures associated with more boost.
To relieve the restriction forward of the turbo and keep inlet temperatures consistent even in 100-degree ambient temps, we chose a Mountune Focus ST MP275 Performance Upgrade Kit (PN 2363-280-BBUSA), which consists of an FMIC upgrade (PN 2363-IC-BA) and the Low Restriction Intake Kit (PN 2363-CAIS-BA) for the ultimate in airflow and inlet-temperature preservation.
After copious amounts of research, Mountune discovered that the biggest restrictions on the stock Focus ST intake system were the OEM plastic crossover pipe and the stock air filter. In place of the brittle plastic stock crossover pipe, Mountune adds a cast aluminum low-restriction crossover duct that is free of internal restrictions and immune to boost leaks.
Along with the trick crossover pipe, Mountune also employs a unique dual-inlet, high-flow filter that pulls air from two locations to increase airflow. The result is improved throttle response, more power, and a big grin every time you enter boost. The unit also installs in minutes, features quality support hardware (like a silicone coupling hose), and is available in a silver or black finish.
Last up on our mod mafia was a FMIC from Mountune, a must-have upgrade on a tuned Focus ST if you want to preserve power in the real world. “A quality front-mount intercooler is crucial once the boost is turned up since it can better handle the higher inlet temperatures associated with the additional boost,” explained Kershaw.
More boost equals more heat, and since modern motors already run on the ragged edge of heat and detonation, increasing the boost and therefore heat requires an improved method of managing the thermal levels.
“Modern cars have far greater cooling needs than cars of five and 10 years ago,” Ken Anderson of Mountune said. “Engines run at higher operating temperatures, and frontal air inlet areas have become smaller. This makes the requirement for airflow critical. The tube-and-fin-type of intercooler generally has better airflow through the core assembly compared to bar-and-plate designs. This is important because an increase in coolant temps can actually cause the power to be de-rated, negating the effect of a larger intercooler.”
Choosing the right tool for the job is always important, especially when it comes to maximizing the performance of a forced-induction system. In this case, choosing the right type of FMIC is crucial. “There are basically two types of air-to-air intercoolers: bar-and-plate and tube-and-fin. From our validation and testing, the only real choice for our specific application is the extruded tube and fluxed-fin arrangement,” said Anderson.
As with most performance parts on the market, you get what you pay for. Assuming that all FMICs are created equal can leave you with a lighter wallet and in a heap of disappointment.
“The low-cost option primarily used is the bar-and-plate arrangement, which is extremely cost effective but has the added penalty of weight, poor heat transfer from the external ambient air cooling source, and high pressure drop internally from its core design,” explained Anderson. “The bar-and-plate intercooler matrix tempts the user into thinking they have purchased a road-usable product because it performs extremely well for short periods of time, typically on dynos. The mass of the unit is the key to its ability to give good air charge temperatures. However, once warmed up, it is very difficult for the bar-and-plate core to dissipate this heat.”
Mountune is a wealth of knowledge when it comes to high-boost, small-displacement Ford motors, so it was no surprise that Anderson went into even greater depth about the FMIC unit. “The other issue with bar-and-plate intercoolers is the matrix core density, which hinders across core airflow on the ambient side. This causes cooling issues for any other radiators or cooling requirements packaged behind it. In other words you get great air-charge temperature reduction on a dyno, but the engine temperature skyrockets as the radiator can't get enough cooling because it’s behind the intercooler, which is why Mountune does not utilize that style of FMIC.”
The 14-row extruded lightweight design is said to reduce outlet temperatures over 39 percent while still retaining the OE mounting locations, including the ram-air guides. Even though the unit measures a massive 29.5 by 11.7 by 2.0 inches, it doesn’t require any drilling and it fits like factory. Speaking of a clean install, the FMIC is available in two powdercoated finishes, silver or black.
From the moment the key is turned, it is evident that this is a whole different animal. The motor barks to life, and the hiss of the open intake is evidence that the restrictions have been relieved.
Although the throttle response is much improved and the power curve is buttery smooth, too much throttle in the lower gears produces wicked wheelspin thanks to V-8–like torque. Highway onramps are suddenly a little shorter, and a third-gear punch from 60 mph swings the speedometer needle with quickness.
Forget revving it to the moon. Light the turbo down low and ride the massive swells of torque until it is time for the next gear and another rush of torque. Speaking of rush, there’s no shortness of acceleration even after back-to-back pulls. Forget heat-soak—this ST never gives up.
Looking at the final numbers, it is hard to believe our Focus ST is now making 350 lb-ft at the wheels with 263 wheel horsepower to match. In case you’re wondering what that’s like in such a lightweight hatch, it’s a rocket. On the street it can paint strips of rubber in the first three gears, and unassuming competitors have no idea what they’re in for. If more performance and attitude without concessions to civility isn’t having your cake and eating it too, we don’t know what is.
Ford Performance ProCal
1. The Ford Performance ProCal is a handheld tuner that increased torque by a large margin, is 50-stage smog legal, and is backed by a three-year/36,000-mile warranty.
2. The ProCal comes with this form that prompts users to visit a special website to submit their VIN and other pertinent information. Several days later a preloaded ProCal shows up ready to add big torque to your Focus ST. Newer versions of the ProCal forgo the handheld tuner for an even simpler OBD-II plug and cable that connects straight to your laptop. This cuts out the wait time since users register their unit, download their tune, and plug the laptop into their Focus ST—that’s it.
3. What hasn’t Ford Performance thought of with its ProCal kit? It even comes with colder Denso Iridium spark plugs to better handle the boost and added heat.
The Mountune Low Restriction Intake Kit
4. The Mountune Low Restriction Intake Kit comes with everything needed to uncork the intake side of a Focus ST.
5. We start the intake installation by removing the plastic stock crossover pipe and its associated components.
6. The Mountune crossover pipe is made from sturdy cast aluminum, is immune to boost leaks, and features a larger internal diameter that also doesn’t have the internal obstructions of the stocker.
7. Unlike the stock intake, the Mountune CAI utilizes a unique filter with twin inlets. On the stock intake, the filter top is closed and only ingests air from the grille-mounted snorkel. The Mountune CAI sucks air from the aforementioned snorkel and from the fenderwell side pictured here for twice the flow.
8. Just as you’d expect, the Mountune CAI fits like factory and relieves inlet restriction for more power and all the whooshing and swooshing turbo fans love.
Ford Performance High-Flow Cat-Back Exhaust
9. Behold, the Ford Performance cat-back exhaust system, that's as nice as it is nasty. It is made from stainless steel construction and features 2 1/2-inch piping and a dual-muffler design with a resonator and main muffler that is the ultimate in flow without the dreaded drone.
10. We had to cut the stock system off where it crossed over the rearend since it was too tight to be removed in once piece. Landon Cummings, the owner of the Race Red ST, can be seen carefully sawing the stock pipe in half.
11. Once the 2.0-inch stock system is off, it is clear that the Ford Performance unit is bigger, badder, and much nicer looking. Note how the stock unit necks down, hindering power.
12. The pair of 4 1/2-inch stainless steel ventilated tips look great inside the stock valance. The tone is deep and mild while cruising, yet aggressive under WOT.
Mountune Front-Mount Intercooler Kit
13. The Mountune front-mount intercooler kit is a thing of beauty. The 14-row extruded lightweight design is said to reduce outlet temperatures over 39 percent and is available in a black or silver finish.
14. After the hood-latch cable and the front bumper are removed, it is time to unplug the Active Grille Shutters because they are no longer used with the FMIC. The first step is to unplug the connectors.
15. Next come the securing clamps. Then the stock FMIC can be removed.
16. It pays to have helping hands. In this case, fellow NorCal ST member Brian Reich helped out during the install. Here he is seen removing the Active Grille Shutters.
17. Even though the Mountune FMIC measures a stout 29.5 by 11.7 by 2.0 inches, it still retains the OE mounting locations and doesn’t require any drilling or cutting. It also utilizes an extruded tube and fluxed-fin arrangement for the ultimate in thermal management without the weight.
18. Don’t forget to move the IAT sensor from the old intercooler to the Mountune unit. Note the evident quality of the unit up close.
19. Two people make the job of installing the Mountune unit much easier. As you can see, so as not to skew dyno figures with varying strap tensions, we left the car on the dyno for the install.
20. Double-check that everything is buttoned up, then it is time to reinstall the stock pieces in the reverse order they were removed so you can reap the fruits of your labor. See the accompanying sidebar for all the nitty-gritty dyno information.
On the dyno and fighting ambient temperatures
After baseline pulls early on a cool morning, we uploaded the Ford Performance tune first. Next we added the Mountune CAI kit followed by the Ford Performance exhaust and finally the Mountune FMIC. A quick note about the FMIC: We got the car nice and hot on the dyno, like in the real world, and then made three back-to-back pulls with the stock intercooler and then the Mountune FMIC in order to see how the car responded to heat-soak. The results were eye-opening.
One more thing before we divulge the numbers. On the day of the dyno we saw a temperature variance of over 40 degrees, which means our baseline pulls were made on a cool 50-degree morning and with each mod and subsequent dyno the temperature continued to rise. Why do you care? Because as the mercury rose it partially offset the power gains from the mods since forced-induction motors are sensitive to temperature changes. In the end we gained impressive power, but had we been able to redyno the car after the mods on the following 50-degree morning, the gains would have been even greater.
We started with a baseline pull of 248 hp and 302.8 lb-ft at the wheels on 91-octane pump gas. With the Ford Performance tune in place and no other changes, those figures jumped to 253.3 hp and 343 lb-ft at the wheels for gains of 5.3 hp and 40.2 lb-ft at peak with an additional 60 lb-ft under the curve.
Next came the Mountune CAI. It pushed the figures to 255.5 hp and 339 lb-ft for another 2.2 hp and a slight loss in torque. To be honest, at this point the rising ambient temperature paired with the additional boost and stock exhaust was a mismatched combo. Although we knew the intake wouldn’t show its full gains until the entire system was uncorked, we wanted to follow the most common method of ST modding.
As the day wore on the temperature continued to climb and we knew it would negatively impact our gains, but we soldiered on. Despite the afternoon sun heating the shop like an oven, we again hit the dyno after the Ford Performance exhaust and produced 247.8 hp and 337 lb-ft at the wheels.
Last up we added the Mountune FMIC, and it brought the day’s mods full circle by not only uncorking the last bottleneck but also keeping inlet temps in check. After the dyno drum stopped, our new peaks jumped to 262.5 hp and 350.4 lb-ft at the wheels for total gains of 14.5 hp and 47.6 lb-ft at the wheels on 91-octane California pump gas with gains in the midrange that approach 70 lb-ft.
Cure for heat-soak
Since we love crunching numbers, we got the Focus ST nice and heat-soaked with all of the mods and the stock intercooler and then made three back-to-back pulls to see how the heat would affect power. We then repeated the same process once the Mountune FMIC was installed. Needless to say, we were impressed.
Study the accompany dynos for all the info, but the difference between the first heat-soaked run with the stock intercooler and the third was a drop of 16.1 hp and a whopping 42.3 lb-ft less torque at the wheels. With the Mountune FMIC in place we repeated the scenario and recorded a horsepower variance from the first to the third pull of 2.2 hp and 3 lb-ft. For those counting, the FMIC preserved another 14 hp and 40 lb-ft over the stock intercooler. Had we done even more pulls, it would have continued to hold steady while the stock intercooler would have turned the motor into a heat-pump.