Steve Turner
Former Editor, 5.0 Mustang & Super Fords
July 14, 2014
Photos By: KJ Jones

If you don't own a Terminator or a GT500, you might be feeling a little left out on all the fun owners of those cars can have by simply swapping out factory superchargers for more efficient aftermarket units. The ease with which these cars are improved with bolt-on upgrades has made them exceptionally popular. The good news is that owners of '05-'10 Mustangs with Roush superchargers can get in on the easy-upgrade trend thanks to VMP Tuning.

Over the years, Justin Starkey at VMP Tuning has expanded his company's vision from mainly offering tuning solutions to becoming the source for upgraded versions of Eaton's Twin Vortices Series superchargers. VMP began by offering smaller pulleys and improved inlets, to eventually offering TVS superchargers that incorporate a host of improvements that Justin has perfected over the years. These VMP Superchargers offerings are engineered and built with Roush, so the quality is top notch. That also makes them a natural upgrade for Roush Mustangs.

"I've been knee-deep in the Roush market for years. We had a very successful VMP 500hp kit for the '05-'10 Roush Stage 3/427R cars. With it, customers could add our pulley, tune, and a Steeda CAI we packaged with the upgrade, and get a good bump in horsepower," Justin explained. "However, it pretty much stopped there. Engine modifications like camshafts and overdrive crank balancers were required to go further, and even then the combos still topped out around 530 horsepower due to the small M90 blower."

The 1.9L VMP TVS is good for up to 15 pounds of boost on the six-rib belt, and is far more efficient than the M90 Roots blower that is standard on the ’05-’10 Roushcharger kits. Among its many VMP-engineered benefits is a bolt-on pulley arrangement, which allows for easy pulley swaps should you want more boost at the track than you run on the street.
Designed to lift a Three-Valve 4.6L to 435 horsepower and 400 lb-ft of torque at the flywheel thanks to 5 pounds of boost, the Roush M90 supercharger kit provides a fun-to-drive gain, especially down low. However, the Roots-style blower tends to heak-soak rapidly, especially if you turn up the boost with a smaller pulley.

Until recently, many of the full supercharger systems were dedicated to newer Mustangs and the vaunted Terminator. VMP certainly offered upgrades for Eaton-supercharged Three-Valve 4.6s, but the newest addition to its line of supercharger upgrades is a 1.9L TVS supercharger that's a direct bolt-on for '05-'10 Mustangs equipped with Roush superchargers. That includes Roush Stage 3 and 427R Mustangs, or Three-Valves equipped with the aftermarket version of the Roushcharger kit.

"Our manufacturing partnership with Roush allowed us to design and build a turnkey TVS upgrade for the M90. It was tough, but we were able to fit the larger TVS in the M90's place and give it a correct driver-side inlet," Justin said.

"Space was the driving factor to use the 1.9L. It limits peak boost, but has a host of other benefits. The 1.9 takes less power to turn and is less prone to belt slip with smaller pulleys. It's more efficient in the midrange than the larger unit."

The VMP TVS Upgrade Kit for '05-'10 Three-Valve 4.6L with M90 superchargers (PN 19TVSM90; $3,599) can deliver a gain of up to 250 horsepower at the wheels on a vehicle with a built engine, an overdrive crank damper, and an eight-rib belt. Our test vehicle is a slightly modded '08 Roush 428R owned by Matt Silvares. It obviously wasn't ready to max out the boost, but it serves as a great testbed to see what the average Roushcharged 4.6 owner can expect to see from this upgrade.

"The TVS 1.9 is an ideal swap for a customer that currently owns a Roushcharger. It allows for a very easy swap that is DIY-friendly, looks factory, and significantly increases power output in a cost-effective package," says Ricardo Topete of GTR High Performance. "Since a great deal of the Roush-supplied supercharger components are re-used, it really keeps the cost down to a minimum and provides a blower that has room to grow."

To find out what it's worth, we met up with Ricardo at GTR's Rancho Cucamonga, California, facility to follow the installation and testing of this offering.

01. This Eaton blower has served Matt Silvares’ ’08 Roush 428 well, but it’s time to see what the VMP TVS can do. Ricardo starts by removing the strut-tower brace and driver-side fuel rail—you need to safely relieve the pressure before unbolting it. Then he loosens the supercharger belt, and disconnects the electrical and vacuum connections. With that done, only six bolts hold the Eaton M90 to the intercooled Roush lower intake manifold. After freeing the fasteners, Ricardo lifts the blower off the engine. You might want a friend to help with this part.

02. Now it’s time to see what this new combo can do. Ricardo straps the TVS-equipped Roush to GTR’s Dynojet chassis dyno. At press time, Matt was still breaking in a new clutch, so he had yet to experience a full-throttle hit. The only WOT pulls were made on the dyno for our story.

03. Of course, VMP can provide a tune with its kit, but GTR has a standing arrangement with Bob Kurgan at Kurgan Motorsports to dial in and remotely tune vehicles. As such, Ricardo ran the dyno and listened for detonation, while Bob looked over the datalogs and dyno data to tune the combination.

04. While the outgoing Roots blower is shiny, the 1.9L VMP TVS is obviously a bit larger. It also features a driver-side inlet as opposed to the passenger-side inlet on our test vehicle. The ’10 Roush Mustangs feature a driver-side inlet, so installation is further streamlined. Though it is physically larger, we weighed the two superchargers and the VMP TVS (38 pounds) only clocks in 5 pounds heavier than the M90 (33 pounds). The extra power will more than make up for that modest weight increase.

05. As you can see from the belly of the two superchargers, the VMP TVS (left) features a much larger discharge area for boost to exhale from its more efficient rotors. The real calling card of the TVS is its helical rotor pack, which is far more efficient than traditional Roots rotors. Interestingly, the 1.9 rotors are the same diameter as its 2.3 big brother, they are just shorter, which decreases their displacement, but improves efficiency a bit.

06. To reorient the inlet to the driver side on ’05-’09 Roushchargers, the VMP kit includes a P51-style cold-air inlet, as well as the necessary hoses and harnesses to facilitate a hassle-free install. If you own a ’10 Roush, you can save money and install time by retaining the factory air inlet (if you run a GT throttle body). In either case, you can also opt for an aftermarket CAI if you are so inclined.

07. While the blower and inlet hardware was out of the way, Matt took the opportunity to have Ricardo install a set of powdercoated cam covers from Ford Racing Performance Parts. Though this is not a required part of the supercharger install, the black finish really meshes well with the black finish on the VMP TVS.

08. Like its VMP 2.3L big brother, the 1.9 is equipped with VMP’s signature Q-port inlet, which Justin has perfected after years of porting TVS inlets. Now these inlets are cast into the VMP superchargers, so no porting is necessary. This opening maximizes flow and allows for the installation of VMP’s high-flow inlet elbows. “With the proper pulleys sizes, gains of 50-250 rwhp are possible over the M90. A larger throttle body such as the VMP Twin Jet 67mm will yield as much as a 30-rwhp gain, while the stock GT500 dual 60mm is an inexpensive upgrade that is worth about 15 rwhp,” Justin said. “We make two elbows for the VMP 1.9L to allow use of the GT bolt pattern if you already have an upgrade you like, or the use of the larger GT500 bolt pattern.”

09. With an increase in boost, it is wise to install a set of colder plugs and rein in the gap a bit. Here Ricardo uses this handy tool to set the new Autolite HT0s at a boost-friendly 0.032 inch.

10. Now we are getting somewhere. It’s time to drop the VMP TVS onto the Roush lower intake. It is a direct bolt-on, and reuses the metal blower-to-intake gasket. Just be sure that the alignment dowels are in place before you lower the TVS into place. Also, the left-rear mounting hole is slotted, so you need to start the fastener, and slide the blower over the dowels and onto the fastener before dropping it down. There is enough clearance, so don’t worry. With the blower in place, tighten the bolts to 20-30 ft-lb of torque. The intercooler core in the manifold is approximately the same size as the core in factory Terminators. VMP has successfully run big boost with the 2.3L TVS, so this setup works well for the 1.9.