KJ Jones
October 15, 2013
Photos By: KJ Jones

Horse Sense: There are several new Mustang parts that meet CARB's strict criteria for receiving Executive Order certification—the board's official blessing (symbolized by a highly coveted number that is placed on a part). This is the story of one CARB-legal system that we think is pretty cool, and it confirms high-performance and the environment really can peacefully coexist!

The United States of America is a great country due to the freedoms its residents are granted by the Constitution. While these and many other rights are important and definitely appreciated by a majority of folks that live here, some of these freedoms are subject to restrictions.

There's no disputing the fact that we all enjoy our right to own, drive, and modify high-performance Mustangs. However, as such freedom goes, street performance mods are at the mercy of each state's government, and the exhaust output of internal combustion engines comes under intense scrutiny by state environmental agencies. In an effort to save our planet, states like California issue stringent regulations on aftermarket parts designed to improve engine airflow. The regs, especially those adopted by the California Air Resources Board, have been the proverbial thorn in the sides of the Golden State's 'Stangbangers and parts vendors.

Kurt’s clean, stock Pony goes by the handle Stealth 5.0, based on its black paint/cockpit/wheels appearance arrangement—a good look indeed, and a perfect platform for Roush Performance’s 2.3-liter smog-legal blower.

Unfortunately, economics drives this wicked catch-22. For manufacturers, CARB compliance carries a hefty cost thanks to the extensive development and testing necessary to gain compliance. Manufacturers quickly admit that it is a difficult balance. When an aftermarket company's costs for CARB compliance are weighed against the market share of California enthusiasts, it's often not a profitable scenario. As such, companies typically choose to not seek CARB approval. Instead they produce performance parts accepted by the 49 other states.

As we all know, a fuel-injected Mustang's engine performance hinges on how efficiently it uses air and fuel. Forcing air into an engine by way of power adders is the widely accepted shortcut to higher performance for late-model 'Stangs. These quick methods are complemented by higher-flowing cylinder heads and exhaust systems. Big fuel pumps and injectors also are incorporated in these systems. CARB typically frowns on such components as they increase the output of hydrocarbons, carbon monoxide, and NOX beyond accepted standards.

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History has shown that CARB-legal products typically fall just a bit short of the 49-state pieces. In a nutshell, while legal bolt-on parts do improve performance over OEM equipment, they still tend to be more restrictive than their non-compliant siblings. As such, its tempting to install 49-state pieces on street-driven Ponies in the Golden State, despite the legal ramifications and vehicle-inspection challenges.

One of the beautiful things about '11-'13 Mustang GTs' vaunted Coyote 5.0 engine is that it makes its impressive, clean power in bone-stock trim. Running clean is the name of the game today, and with a precise PCM calibration, a modified '11-'13 Pony should be just as capable of operating close to CARB's standards. Taking this efficiency into account, engineers at Roush Performance developed a PCM calibration for its '11-'13 Mustang Roushcharger system and submitted it for CARB authorization. Yes, it's the same 2.3-liter Twin Vortices Series kit (PN 421388/Phase 1; $6,099.99) introduced for Coyotes in 2011. However, it's now 100-percent smog legal—a definite boon for 'Stangbangers living in Cali, as well as '11-'13 Mustang owners interested in stepping up to eco-friendly forced induction.

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This is one of those times when we're glad the majority of our tech efforts are conducted in Southern California. It's the most appropriate place for us to install the new Roush blower for a before-and-after smog evaluation. GTR High Performance selected Kurt Schutte's “Stealth 5.0,” an '11 GT for the test. Aside from its clean triple-black interior/exterior layout, Kurt's Pony is stone-bone-stock, and ready for a performance bolt-on that will increase the rear-wheel horses in a hurry.

Ricardo Topete and Eddie Zapata of GTR turned wrenches for this effort, but PCM calibration comes by way of Roush Performance. Yes, that's technically the way it works with the 575hp (crankshaft) Phase 1—and all of Roush's supercharger systems for late-model Mustangs. An overnight shipping package is included with the kit, and a Pony's original ECU is sent to the calibrators at Roush for reflashing.

While highlights of the nuts-and-bolts action are normal for reports like this, it's the dyno and all-important emissions-test results that are critical for this effort. We suggest you follow the information closely, especially if you own a stock '11-up Mustang GT in California—or plan to own one in Cali at some point in the future.

The 2.3-liter Roush supercharger (Roush calls its blowers Roushchargers) is a positive-displacement Eaton TVS featuring two four-lobe rotors that both are twisted 160-degrees. This rotor configuration (as opposed to the three-rotor/60-degree design of other Eatons), along with newly redesigned air inlet and outlet ports, help enhance the supercharger’s volumetric capacity. Greater air volume allows the blower to spin quickly, which creates smooth, efficient airflow for the Coyote engine.

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On The Dyno

After taking the upgraded Pony for a California emissions test (detailed in the Smog Check sidebar), we immediately loaded it onto the rollers of the Dynojet chassis dyno at GTR High Performance to determine how much power a stock 5.0 makes with the new 2.3-liter TVS Roushcharger (PN 421388, Phase 1; $6,099.99).

It's not often that details on a power adder's performance and effectiveness are not the priority in a tech report about that particular power adder. However, for this report, it has nothing to do with the power adder being unable to perform. To the contrary, as you can see in the graph and numeric dyno information, the Roushcharger we installed on Kurt Schutte's stock ‘11 GT makes excellent pump-gas, California-emissions-compliant steam.

Of course, when it comes to Coyote Mustangs, we're quickly learning there's no such thing as enough rear-wheel horsepower. One of the 5.0 Roushcharger's beautiful qualities is that making bigger steam is done with ease. We went directly from Phase 1 to Phase 3 with Roush's bolt-on upgrade kit (PN 421596; additional $1,499.99) hoping to see Kurt's 'Stang rock the rollers with a lot more rear-wheel ponies.

We must note that the Phase 3 segment of this supercharger system is only available for Mustang GT's with six-speed manual transmissions. More importantly, the equipment that helps produce the additional power and torque are not legal for use in California.

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Baseline Phase 1 Glory Difference
RPM Power Torque A/F Power Torque A/F Power Torque A/F Power Torque A/F
3,000 177.35 310.49 12.13 234.58 410.60 11.37 238.62 417.67 12.01 61.27 107.18 -0.12
3,100 186.10 315.29 12.33 242.93 411.57 11.30 250.40 424.29 11.97 64.30 109.00 -0.36
3,200 195.61 321.04 12.48 252.17 413.88 11.27 257.46 422.50 11.89 61.85 101.46 -0.59
3,300 206.50 328.65 12.59 257.39 409.70 11.34 266.71 424.50 11.75 60.21 95.85 -0.84
3,400 217.80 336.43 12.63 265.33 409.81 11.44 274.09 423.42 11.68 56.29 86.99 -0.95
3,500 226.66 340.13 12.61 274.17 411.45 11.53 284.84 427.41 11.79 58.18 87.28 -0.82
3,600 238.25 347.59 12.58 284.00 414.30 11.59 295.23 430.68 11.92 56.98 83.09 -0.66
3,700 245.78 348.87 12.50 293.79 417.05 11.66 304.60 432.39 11.96 58.82 83.52 -0.54
3,800 252.49 348.98 12.41 307.28 424.64 11.69 317.63 438.97 11.99 65.14 89.99 -0.42
3,900 262.34 353.28 12.46 315.35 424.69 11.70 323.26 435.36 11.98 60.92 82.08 -0.48
4,000 275.40 361.60 12.53 329.21 432.27 11.73 342.28 449.36 11.90 66.88 87.76 -0.63
4,100 288.14 369.10 12.60 338.34 433.39 11.73 346.87 444.37 11.76 58.73 75.27 -0.84
4,200 301.03 376.43 12.64 344.65 430.99 11.60 355.07 444.01 11.76 54.04 67.58 -0.88
4,300 311.36 380.30 12.61 355.86 434.64 11.54 361.48 441.53 11.82 50.12 61.23 -0.79
4,400 316.23 377.48 12.49 362.79 433.08 11.65 367.63 438.85 11.80 51.40 61.37 -0.69
4,500 317.42 370.48 12.38 372.63 434.89 11.69 375.88 438.69 11.81 58.46 68.21 -0.57
4,600 320.60 366.06 12.33 375.74 429.00 11.62 380.20 434.08 11.89 59.60 68.02 -0.44
4,700 324.89 363.06 12.36 383.14 428.18 11.59 383.71 428.83 11.95 58.82 65.77 -0.41
4,800 331.78 363.03 12.44 393.62 430.67 11.59 395.36 432.59 11.96 63.58 69.56 -0.48
4,900 340.56 365.03 12.55 395.94 424.40 11.68 390.34 418.38 11.82 49.78 53.35 -0.73
5,000 349.39 367.01 12.61 405.60 426.07 11.71 403.96 424.34 11.64 54.57 57.33 -0.97
5,100 358.90 369.61 12.64 411.19 423.45 11.61 407.27 419.38 11.64 48.37 49.77 -1.00
5,200 365.67 369.34 12.67 413.06 417.20 11.55 410.65 414.79 11.69 44.98 45.45 -0.98
5,300 370.86 367.51 12.68 421.33 417.52 11.58 422.41 418.60 11.73 51.55 51.09 -0.95
5,400 373.10 362.89 12.69 423.17 411.60 11.59 430.72 418.92 11.72 57.62 56.03 -0.97
5,500 375.05 358.15 12.74 436.37 416.72 11.53 429.77 410.40 11.64 54.72 52.25 -1.10
5,600 375.66 352.33 12.82 437.65 410.43 11.15 438.23 410.99 11.63 62.57 58.66 -1.19
5,700 376.55 346.96 12.86 440.09 405.52 10.68 439.88 405.33 11.68 63.33 58.37 -1.18
5,800 377.34 341.70 12.86 449.12 406.71 10.25 448.67 406.29 11.75 71.33 64.59 -1.11
5,900 379.26 337.62 12.87 455.84 405.78 10.06 452.75 403.05 11.77 73.49 65.43 -1.10
6,000 382.79 335.08 12.90 460.83 403.40 10.01 461.03 403.57 11.76 78.24 68.49 -1.14
6,100 386.05 332.39 12.93 465.05 400.41 10.00 464.82 400.19 11.62 78.77 67.80 -1.31
6,200 390.11 330.47 12.96 468.40 396.76 10.00 466.25 394.97 11.51 76.14 64.50 -1.45
6,300 393.56 328.10 12.99 468.93 390.94 10.00 473.65 394.84 11.52 80.09 66.74 -1.47
6,400 394.67 323.89 12.98 482.06 395.61 10.00 480.69 394.48 11.55 86.02 70.59 -1.43
6,500 395.08 319.24 12.94 482.27 389.67 10.00 489.32 395.39 11.46 94.24 76.15 -1.48
6,600 393.25 312.94 12.88 481.81 383.44 10.00 483.71 384.95 11.09 90.46 72.01 -1.79
6,700 389.76 305.54 12.82 483.57 379.07 10.00 499.58 391.60 10.98 109.82 86.06 -1.84
6,800 383.91 296.52 12.70 487.13 376.25 10.00 487.85 376.76 10.96 103.94 80.24 -1.74

Smog Check

Seldom do other criteria take precedence over horsepower and torque figures when we install power adders on Mustangs. However, in the case of the Roush 2.3-liter Twin Vortices Series kit (PN 421388; Phase 1), the research we performed in another dyno cell makes performance a secondary subject.

Our objective was to independently test the actual smog legality of the new Roush unit by putting it through the paces of a California State Emissions Test. So to do this, before installing the Roushcharger we took Kurt Schutte's '11 Mustang GT to Haven Mobil in Rancho Cucamonga, California, where emissions technician Henry Mojica performed a non-official (test values are not reported to or saved in the state's database) emissions pre-test using the STAR-certified station's emissions dyno.

As expected, in stock trim Kurt's GT was well within legal smog parameters, registering low hydrocarbons (0 parts per million), carbon monoxide (0.01 percent), and nitrogen oxide (1 parts per million) in the 25-mph run test. However, results of the smog test which followed the blower installation were surprising. Contrary to our pessimistic thought, the Mustang GT's emissions actually were cleaner with the Roushcharger sending boosted air into the Coyote 5.0 engine.

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In this age of trying to maintain a clean “green” environment, there's a lot to be said about a bolt-on '11-'13 Mustang supercharger system that generates solid rear-wheel power, and still meets the tough emissions standards of California's Air Resources Board.