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If you knew Stephen Keen like we did, you would certainly find his attention to detail “just the norm” when it comes to him and his cars. Stephen wears many hats, you could say. He’s an entrepreneur and was the CEO of his own company, a Mustang enthusiast, a Ford fanatic, and a self-proclaimed EcoBoost nut.

All for good reason, of course, as Stephen has owned his fair share of Mustangs. He currently owns a 2017 F-150 Raptor, a 2017 Explorer EcoBoost, a 2014 Shelby GT500 (did we mention it has 800 horsepower?), a 2003 SVT Cobra convertible, and a brand-new Hellcat Challenger, just to name a few…

We were extremely excited, it was quite an accomplishment and a tremendous amount of work. I drove the car this way for a few months while working out the bugs. — Stephen Keen

However, Stephen says that his 3.5-liter, EcoBoost V6-swapped S197 Mustang is one of the most fun cars he’s ever owned – and driven – for that matter. Dubbed the EcoStang, Stephen’s Mustang racecar has been a project nearly three years in the making, and he’s on the quest for the title of the fastest EcoBoost-powered vehicle on the planet, but, as Stephen has divulged to us, it has not been an easy road.

When the project first came to fruition, Stephen disclosed that he’s just your average Blue Oval enthusiast.

“In a sea of Mustangs, I wanted something unique,” he said. “I’m not a professional racer, I just want to have fun in a car I built myself.”

The old saying goes, “If it’s meant to be, it is up to me,” and that’s exactly what Stephen set out to make happen. His love for the EcoBoost engine stemmed from the F-150 platform, but continued with his S197 Mustang build.

From Concept To Reality

The foundation for where it all began.

The foundation for where it all began…

As we mentioned above, nearly a year would pass before Stephen decided to put his EcoBoost plans into action. Back in late 2015, he owned an F-150 FX4 SuperCrew, which was powered by the same 3.5-liter twin-turbo EcoBoost V6 engine. He fell in love with it. Stephen enjoyed the low-end grunt of the turbocharged V6, and he knew he wanted to make this work in a Mustang platform.

“I bought this 8,000-mile V6 mustang — which was a total loss — in an auction in April of 2015,” Stephen said. “My plan was to rebuild it in to a racecar using a 3.5 EcoBoost engine from an F-150. This had never been done before, so I was certainly in uncharted territory. In a sea of Mustangs it’s hard to be unique – this was my chance to build a one-of-a-kind car. This was the first day of the project, delivered with a forklift.”

Thankfully, the exterior of Stephen's 2010 V6 Mustang received the brunt of the damage.

“The body damage was limited to bolt-on parts which was fine with me,” Stephen explained. “It needed new front and rear bumpers, a hood, and headlights. I replaced the 2010 V6 parts with a 2014 GT500 front bumper, grille, fog lamps, HID headlights, painted rocker panels, rear bumper, quad exhaust, trunk panel and LED rear tail lights. I did all the paint and body work myself in my basement. It wasn’t perfect, but I enjoyed the work. I chose a 2014 V6 hood because I didn’t want to be a complete poser,” he laughed.

Bring In The EcoBoost!

EcoStang6

When we first discussed the project with Stephen, he explained that the original plan was to replace the current 4.0-liter V6 powerplant with an EcoBoost V6 engine from a donor F-150. He also wanted to replace the five-speed automatic transmission with a Getrag MT-82 six-speed manual version from another V6 Mustang. Moreover, the V6’s 7.7-inch rearend would find its way to a junkyard in favor of the beefier 8.8-inch version found in the 2005+ GT.

Out with the old.

Out with the old.

“Had I understood exactly what I needed back when I purchased the car, I probably would have sourced a 2011+ car,” Stephen said. “If I had, I would have only needed to change out the engine – I missed it by one year. At the time, Ford Performance planned to come out with a Control Pack for the EcoBoost at any moment. This Control Pack required a manual transmission, and since I was planning to build a road race car, I was looking to use this unit.”

However, to Stephen’s dismay, Ford Performance had pushed the release date too far back for his timeline.

“I decided I would do this project without the Control Pack using the F-150 wiring harness and PCM. A very good friend of mine, Alex Sammer, is a Mustang wiring guru, and was instrumental in going this route. He’s responsible for getting the car running with the F-150 PCM and wiring harness, while HP Tuners helped by turning off the PATS device and automatic transmission features.”

The new EcoBoost engine, all buttoned up and ready for tuning.

The new EcoBoost engine, all buttoned up and ready for tuning.

After spending a few days removing the old 4.0-liter SOHC V6 engine, Stephen installed the new EcoBoost V6 and MT-82 manual transmission promptly after.

“If you replace the EcoBoost motor mounts with 3.7 Mustang motor mounts, the engine bolts right in to the 4.0 motor mounts on the factory K-member,” he added.

Once the new EcoBoost engine spread the shock towers of Stephen’s S197 Mustang, a fuel solution for this twin-turbo V6 ’Stang was in order. Stephen decided on a GT500 gas tank and utilized the factory dual fuel pumps. While the factory GT/V6 setup could have worked, Stephen planned to run the car on E85 fuel.

“The EcoBoost needs a pressure regulated return-style fuel system, which is how the F-150 EcoBoost and 2011-plus GT/V6 Mustang operate,” Stephen confessed. “Most people don’t realize the pump returns fuel back into the tank – there is a port on the side of the fuel pump basket that opens at 58 psi, and the additional pressure is bled back to the tank. The GT500 pumps, however, do not have this feature; their flow is adjusted by the GT500 PCM, which is similar to the 2010-and-older S197s.

“For this reason, I had to install a fuel regulator under the hood and run a return line back to the tank. I replaced the Mustang fuel pump module with twin F-150 fuel pump modules to control the pumps. It’s a return-style system, but the pumps are also ramped up and down by the F-150 PCM. This creates less heat in the fuel tank while idling. We connected the low-pressure fuel system to the EcoBoost high-pressure fuel pump for the direct injection.”

After spending months on end wiring everything to make it work, Alex and Stephen were finally able to get the car to start. With everything buttoned up, including the manual transmission and  8.8-inch rearend, Stephen was able to drive the car. “We were extremely excited, it was quite an accomplishment and a tremendous amount of work. I drove the car this way for a few months while working out the bugs.”

Automatically Converted

But all was not well in paradise. Stephen confessed that he wasn’t a fan of the manual transmission behind the EcoBoost, and that he hated the 3.73 gearing with the V6’s MT-82 six-speed.

“The car wouldn’t spool the turbos until the end of second gear, and I lost my boost momentum between shifts,” he confessed. “I love the manual in my Shelby, and I love the auto in my EcoBoost truck. The new build just didn’t have the right combo.”

Stephen also said that another game-changer came in the form of the announcement that the all-new 2017 F-150 Raptor and 2017 Ford GT would come with an EcoBoost engine.

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“The RXC 500 would go on to use a powerful EcoBoost engine, and that Roush Yates built a 1,000-horsepower 3.5-liter EcoBoost V6 for the record setting Daytona race car. I knew then the engine I had was more capable than I thought. I realized that it could become a competitive drag car, and after a few trips to the road course track in my Shelby, I realized my passion was drag racing,” he said. “At this point, the build took a new direction. Drag suspension from BMR Suspension, a roll cage, a set of Weld Racing RT-S wheels and Mickey Thompson drag radials, a nitrous system, a 6R80 automatic transmission, and a goal of 1,000 horsepower were in my future.”

Opening The Floodgates

Ready to go for the NMRA EcoBoost Battle in Ohio.

Ready to go for the NMRA EcoBoost Battle in Ohio.

It was then that Stephen decided to enter into the NMRA’s EcoBoost Battle class, after swapping to a EcoBoost F-150’s 6R80 automatic transmission and switching to 3.31 gears in the rearend. For him, this was the perfect combo. Stephen tells us that to achieve bigger numbers, he still needed more fuel, which is the Achille’s heel of the EcoBoost. He added fuel injectors to the top of the OEM EcoBoost intake manifold, and controlled them by a supplemental fuel controller.

“Once all this was running reliably, I trailed the car from Boulder, Colorado, to More Power Tuning in Florida, to have it tuned before the first race in Hebron, Ohio. MPT was the perfect partner to help with this build. Mike really knows the EcoBoost engine, and what attracted me to those guys was the F-150 shop truck they built that nearly broke in to the 11s at a previous EcoBoost battle.

Photo credit: NMRA

(Photo Credit: NMRA)

“Mike worked on the car for five days straight, even until 3:30 in the morning; dialing in the car with the nitrous, additional injection system, and E85 fuel. We had multiple issues, but we powered through them. The car made 324 horsepower at the rear wheels on a stock tune, 413 horsepower tuned, and 519 horsepower at the rear wheels with a wet shot of nitrous. At this point, we were limited by the factory turbos.

“I left MPT and drove to Hebron, Ohio, for the EcoBoost Battle. Mike flew there to meet me and tune the car in between runs. We had issues with the transbrake, and since I had removed the vacuum pump to save weight, I wasn’t able to footbrake and build boost off the line. Leaving off idle RPM, I was able to run an 11.38, which is a new record for any 3.5-liter EcoBoost engine.”

A New Beginning

And just like that, the Mustang was un-EcoBoost-swapped.

And just like that, this Mustang was unswapped.

Unfortunately, on the last run, the engine had become damaged. Stephen said that it turned out to be broken piston skirts. “We didn’t expect the engine to last long, but we hoped it would have lasted more than a few passes,” Stephen told us.

"We have decided to build a new engine with larger turbos, hopefully to be at 1,000 horsepower at the rear wheels," Stephen said. "The 3.5-liter EcoBoost V6 has an open deck, so I sent the block out to Cylinder Support System to have the deck closed. Modular Head Shop is doing all of the cylinder head work, and rebuilding the engine using the factory forged crank that's been balanced and shot-peened, along with Manley Turbo Tuff connecting rods and custom Diamond Racing pistons were brought on deck to complete the forged bottom-end."

He and one of his engineering buddies designed an aluminum intake manifold that Modular Head Shop assembled for the new engine. The new manifold included port fuel injectors to use alongside the direct injection setup, and it also has individual nitrous ports for each runner.

"The turbo setup is twin mirrored Garrett GTX3071Rs, one turbo is standard rotation and the other is reverse rotation. I'm also having a one-of-a-kind front mounted air-to-water intercooler made that has an air-to-air pre-cooler. This is the first of its kind, and it's also being built by Modular Head Shop in Florida. This intercooler uses air to remove the bulk of the heat, and then chilled water is pumped from the trunk to drop the temps well below ambient," he said.

The turbo system finished in full, along with the custom air-to-water intercooler setup.

Finally, the 6R80 transmission is getting some attention too. Stephen used an Exedy clutch pack and an intermediate shaft from Teem Beefcake Racing, and a torque converter by Circle D Specialties (as well as a deep pan).

Now that his Mustang is up-and-running with the new engine, Stephen is working with MPT to get his EcoBoost-powered Mustang tuned and ready to set some new EcoBoost records. “I’m also adding a new a K-member, radiator support, adjustable motor mounts, and upper control arm mount from BMR,” he concluded.

We like the sound of that, sir.