Muscle Mustangs & Fast FordsHow To Engine
Our One-Day DIY Roush Install
Part 2: We add a custom tune, a few other mods, and go 10s with almost 600 rwhp.
Last issue, my husband, JD, and I tested the latest 2.3-liter TVS Roush supercharger on our shiny new automatic-equipped 5.0-equipped Pony. Benefits include OEM-like fit and finish plus excellent power, all wrapped in a 50-state-legal package with a warranty.
Hopefully you caught the first segment where we took the GT from 368 rwhp and 12.80s in stock trim (12.70s with Bogart wheels and M/T tires) to 469 rwhp and 11.60s. With the Roush plug-n-play tune, the GT remained 50-state-legal, and ran solid 11s, but as you know, more power can be had with a custom tune.
In this issue, we pushed the power level up with a Jon Lund tune, a Roush cold-air inlet, and a few gallons of Shell URT Advanced unleaded race gas. So get ready for a heaping plate of boosted Coyote goodness as we bring you up to speed on our testing.
Craving forced induction and wanting to save a few bucks, we installed the kit ourselves, proving this can be a weekend warrior project. Sure, it's a solid 10-hour job, but anything resulting in an increase in horsepower is a labor of love. I'm proud to say we completed the project relatively unscathed with very few wounds, thanks to the well-thought-out kit and installation manual from Roush.
We started with Phase 1 (PN 421388), which retails for $6,099.99. It is rated at an impressive 525 hp, (while remaining 50-state-legal), as long as you're running the stock air-box and mild Roush calibrated tune. I say mild because a proper custom tune will unlock more power—a lot more, and it will make your engine really snappy at part-throttle and WOT.
Nevertheless, bolting on an additional 100 hp to the tires over the stock 368 rwhp is impressive, especially when the kit is warrantied by Roush for three years and is 100- percent emissions-legal in all 50 states. California Mustang owners, are you paying attention?
One hundred ponies equated to 469 rwhp and a full 1.1 second faster than our Mustang in stock trim—11.61 at 118.4 mph to be exact, which is more than enough power to take random victims on your morning commute. The power was subdued until about the eighth-mile mark, and that's when the boost and extra power was very apparent. We had our fun with the first phase of this kit, but this wasn't going to be the end of our boosted Coyote adventure.
The power goals were pretty clear—we wanted 10-second e.t.'s, as did Roush. When a woman wants to go really fast, what man can say no? After all, a happy wife equals a happy life, and I think my darling husband would agree.
With Roush leaving so much power hidden in the depths of its conservative (and 50-state-legal) in-house calibration, a custom tune was a must. Jon Lund of Lund Racing is known for his outstanding results on the new 5.0 platform (as well as other platforms) and is the man behind some record-breaking Mustangs, and we commissioned Lund for three custom email tunes: one for 93-octane, one for 93-octane with the Roush cold-air, and another for Shell URT Advanced race fuel. Our friends at SCT were awesome enough to donate a X3 Power Flash programmer, and we transferred the emailed tune files to the handheld device and flashed the PCM with the 93-octane Lund tune.
Roush Supercharger with 93-Octane Lund Custom Tune (Stock Airbox)
With a couple of trips to the track under our belts, first in factory form, then in Roush-calibrated Phase 1 form, it was time for yet another saunter down the 1,320. We loaded up and headed to the local track. With a density altitude (corrected altitude) of 1,400 feet above sea level, the conditions were good and the track prep was even better.
Within moments of the first launch, I knew this was a totally changed animal. With the prior Roush calibration, our Mustang that had a soft throttle was now a fierce, torqued-out machine. This time, a quality burnout was easy to achieve (before it was hard to do a burnout due to the lack of response down low), in fact, the throttle-feel was outstanding with the Lund tune.
Boasting an aggressive stance on Bogarts and Mickey Thompson drag radials, with completely stock suspension, and still with the stock airbox, our base-model automatic '13 GT produced an impressive 1.55 60-foot and a staggering 10.95 at 129.33 mph. Sure, it wasn't 50-state-emissions-legal anymore, but this thing was a complete beast! And technically, our mission was complete—10s with just a blower, tune, and traction.
We voided the Roush warranty, but Roush actually wanted us to push the GT as far as the blower would take us. Now, it's a 10-second daily driver, fully intent on devastating Corvette and ZL-1 drivers. I dare them to try their luck with the innocent-looking half-breed.
Our visit to Stang-Hi Performance in Baton Rouge with the stock air-box, pump gas, and Roush calibration put out an ample 469 rwhp and 415 lb-ft of torque. That's with an 85mm pulley (yielding about 9psi of boost). The results of the tune swap alone were enough to bring a tiny little tear of joy to JD's eye—542 rwhp and 458 lb-ft of torque for a total gain of 73 hp to the tires.
With these results, it's safe to say a custom tune is a must in order to get into the 500-rwhp range with the first phase of this Roush supercharger. It's also the tune that netted us 10s.
105mm Roush Cold-Air with 93-Octane Lund Tune
The Phase 2 Roush supercharger kit (PN 421390), retailing for $6,599.99 and rated at 625-flywheel horsepower, is basically the Phase 1 kit with the addition of the supplied 105mm cold-air intake and a more aggressive in-house Roush calibration, removing the 50-state emissions-legal status.
Since we jumped right into having a custom tune from Lund Racing, we bypassed sending our PCM back to Roush. However, we did install the cold-air kit trackside with zero directions. Lucky for us, there was a Roush representative on hand and that helped us with one frustration-saving tip that we are passing on to you—it's much easier to install if you pre-assemble the entire airbox kit prior to replacing the stocker.
Overall, the swap was simple and only took a few minutes. With the newly installed addition it was time for another trip down the quarter-mile. With the assumption that the cold-air modification would help things “breath” a little better, we were surprised at the results—or should I say lack thereof: 10.90 at 128 mph, but still impressively fast.
Overall, we aren't quite sure the additional cost of the cold-air intake supplied in the second phase is really worth it since we easily achieved 10-second e.t.'s with the stock piece. We may not have been wowed, but it is more aesthetically pleasing than the factory airbox, and may help when higher power levels are reached for. These results go to show us that Ford didn't hold back on the 420hp 5.0, including the factory induction system.
Shell URT Advanced Race Fuel/Lund Tune
There has been quite a bit of buzz around the newest fuel to hit the race scene as Shell URT Advanced has proven to be a viable option to many commonly used fuels. After loading in the third and final custom email tune, we filled up the Pony with Shell URT Advanced and strapped her down on the Stang-Hi Performance DynoJet. We had to do a double-take when the numbers came up on the computer screen—582 rwhp and 462 lb-ft of torque for a gain of 38 rwhp from race fuel alone over the 93-octane.
One final track test was in order and with identical conditions as the previous track visit, we headed to the local test and tune session. Still being fed by the race fuel and Lund Racing tune, our five-oh screamed down the track with a best e.t. of 10.74 at a blazing 130.89 mph! This factory suspension Coyote actually lifted the front left wheel off the ground a couple of inches.
Lets recap for a moment from the start of the Roush Phase 2 project. We bolted on an astonishing grand total of 214 rwhp and nearly 120 lb-ft of torque in our home garage. We chiseled away about 2 full seconds from the stock quarter-mile time, and backed it up with multiple consistent runs. All of this while maintaining completely factory exhaust, converter, rear gears, fuel system, and suspension setup. This proves we haven't even tapped into the full potential of this 2.3-liter supercharger.
For Mustang lovers who live in states with strict emissions mandates, bolting on the Phase 1 Roush supercharger will get you deep in the 11-second range with ease, while maintaining factory driveability and virtually unchanged fuel economy. And gears and exhaust will likely get you 10s. Meanwhile, boost-junkies willing to spend a full Saturday with a buddy installing this Roush kit can be at the track running in the 11- and 10-second range on Sunday, or quicker with more mods.
In the near future, we plan to go faster than 10.70s, but in order to achieve any additional horsepower, we need to address the fuel system by adding a Boost-a-Pump (or similar system) to support those extra ponies. Combining more fuel with a converter/gear upgrade should yield us low 10s.
These results are a true testament to the quality of Ford's Coyote and Roush's engineering. We are seriously blown away.