Since the dawn of the Terminator in 2003, the positive-displacement supercharger has become a mainstay in the lexicon of Ford performance. As the first factory supercharged Mustang, the â€™03 Cobra entered the world with an Eaton M112 supercharger, a traditional Roots supercharger that, obviously, displaces 112 cubic inches of air. This configuration ushered in an era of easy supercharger swaps with more efficient blowers easily supplanting the stock unit.
Even the factory got into the upgrade act, with each generation of a factory-supercharged SVT Mustang receiving an improved supercharger unit. The stock 2007-2012 GT500s rocked the larger Eaton M122 Roots blower. Both of the aforementioned units were traditional Roots units with three-lobe rotors that feature a 60-degree end-to-end twist.
While these Roots superchargers provided a nice boost in power, they quickly reached the limits of their efficiency as modders spun them harder with smaller pulleys.
Eventually, Ford Racing Performance Parts offered a direct-bolt-on, 2.3-liter upgrade based on a more efficient Eaton designâ€”the Twin Vortices Series. A variation on the Roots design, the TVS is based on two four-lobe rotors. These rotors feature a 160-degree end-to-end twist, which is said to move air in a smoother, more-efficient flow. They are also quieter than traditional Roots units.
For those of us into performance, the reduced noise was of little concern. The increased efficiency, however, meant that modding maniacs could push these blowers harder and create even more power. One such TVS modder is Justin Starkey of VMP Tuning. A noted tuner, he began upgrading TVS superchargers with smaller pulleys. Soon thereafter he offered improved inlet elbows, larger throttle bodies, and more. It escalated to the point that VMP worked with Roush to create a ported version of the 2.3-liter TVS designed to maximize its high-flow elbow and VMP Superchargers was born. Eventually, however, Justin found the limits of that supercharger.
â€œThe VMP GT500 TVS with the VMP high-flow inlet elbow was my first supercharger back in 2010,â€ Justin explained. â€œWe were able to take an existing design and make a few small changes to improve its performance. Coupled with our line of VMP elbows and pulleys, this combination offered great performance for the time.â€
â€œSince then we have introduced supercharger upgradesâ€”that are unique, VMP-owned-and-designed castingsâ€”for the â€™03-â€™04 Cobra and Roushcharged â€™05-â€™10 Three-Valve 4.6. It seemed like the time to go back and re-tool the GT500 head unit with all that we learned over the years,â€ he added. â€œYou rarely get a chance to do something over, but it seemed like a no-brainer since the factory TVS on â€™13-â€™14 GT500s had raised the bar considerably, thanks to the efforts of people like Sylvain Brunette (at Billet Pro Shop), Jimmy LaRocca, and Jay Teixeira.â€
Working with the proven Eaton 2.3-liter rotor pack, Justin looked to wring every last drop of airflow and efficiency out of the TVS. The goal was to improve flow and reduce inlet restriction without making the installation more difficult or giving up much of anything.
To achieve these goals; Justin worked hand-in-hand with VMPâ€™s longtime engineering partner, Roush Enterprises. It was only natural that they worked together again to further maximize TVS supercharger performance.
â€œWith all the hats I wear at VMP, CAD modeler is not one of them. I worked with the engineers and designers at Roush to optimize the TVS from every airflow standpoint,â€ Justin said. â€œWe were actually able to hit it the target with only a few revisions. From there we had a plastic rapid prototype printed so we would have something to put our hands on while the molds and fixtures were being built.â€
As it turned out, the results were well worth all the engineering and testing effort put into this program. Inlet airflow mods have long shown to improve TVS performance, but the completely re-engineered VMP Gen2 inlet delivered beyond even Justinâ€™s expectations.
â€œThe inlet is the most important part. To put things into perspective, there is no larger TVS at this time to step up to. We have to make the most of the 2.3 liters of displacement available to us. Weâ€™ve taken a different approach than everyone else in the industry by making the first rear-inlet supercharger (for a front-engine car) that uses a one-piece rotor housing and inlet elbow,â€ Justin elaborated. â€œThis allowed us to optimize airflow geometry into the rotors in every way possible. The Gen2 no longer starves the inside rotor like older designs, and it maintain laminar flow as much as possible on the short-radius (inside) turn into the rotors. We’ve made this 2.3-liter suck as much air as possibleâ€”and produce astonishing numbersâ€” while still keeping the reliability, torque, and economical price point that the 2.3-liter TVS is known for.â€
Proven by the test data here, the changes yielded impressive improvements. The Gen2 handily eclipses the VMP Gen1 TVS in performance. However, we bet you are still wondering how it stacks up to the factory Trinity TVS. Well, just stay tuned to SVTP and weâ€™ll bring you the full results of that test in a matter of days.