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.

11. In the case of the 1.9, you can opt to run an elbow for a smaller stock throttle body, or move up to an elbow that can accept GT500 and larger aftermarket bodies. Naturally, we opted for the latter and ran a GT500 throttle body (bottom), which you can see is significantly larger than the GT unit (top). Stepping up to the larger throttle body can be worth anywhere from 10 to 30 horsepower, depending on whether you run a stock GT500 throttle body or move up to a larger Cobra Jet or VMP body. We stuck with the GT500 for our 10-psi setup, but with more boost a higher-flowing unit would be prudent.

12. With the blower bolted into place, it’s time to start reconnecting things and reinstall the driver-side fuel rail. Ricardo T’d into the vacuum line for the fuel-pressure rail sensor to provide a signal for the bypass valve. On ’10 Mustangs, the fuel-rail crossover is in the rear, so you don’t even have to disturb the fuel system. For the earlier cars, it is also important to install the protective sleeving provided in the kit to protect the crossover where it touches the larger supercharger.

13. When parts are built for maximum performance, it can make installation a bit trickier. It’s not a big deal, but the larger inlet makes accessing the lower fasteners a bit more challenging. Fortunately the inlet mounts are slotted, so you simply start the two lower fasteners, then slide the inlet into place and use an Allen-head extension to tighten them down.

14. After installing the inlet, Ricardo bolted on the GT500 throttle body and made the wiring and PCV, EVAP, and brake booster vacuum connections. The VMP kit includes all the needed wiring-harness extensions and new hoses to simplify this process.

15. VMP offers pulleys from 63 to 85 mm, and they all are easily swapped. We chose the 75mm pulley to generate about 10 pounds of boost, and Ricardo bolts it on here. Be sure to use thread-locking adhesive on the fasteners to ensure the pulley stays put. You can go up to 15 pounds of boost with the 63mm pulley on the six-rib belt standard on the Roush kits. For engines with stroker kits or aftermarket camshafts, Justin recommends an overdrive crank damper and an eight-rib conversion, which VMP offers.

16. The aforementioned inlet is essentially the same hardware used on the Roush P51. Its installation is straightforward clamp-and-hose work. Ricardo installed the heatshield first, then assembled the inlet tubing and filter so he could slide them on it as one piece. Then it was just a matter of connecting the breather tube and plugging in the mass air sensor.

17. Here is a look at the completed install. VMP says it will take 1 to 2 hours to perform the swap. It might take a little longer if you’ve never done this work before, but it is a straightforward install. Moreover, the finished product looks factory. If it weren’t for the VMP logo on the blower, the average passerby might think this combo came straight from Roush.

18. Before installing the belt, Ricardo reinstalls the alternator. The alternator installs right back in the same spot it did with the M90 supercharger. With the alternator back in place, Ricardo loosens the tensioner and reinstalls the serpentine belt.

19. If you push the boost beyond 10 psi, as we did, you will need to either install a fuel-pump-voltage booster or a GT500 dual-pump setup. Naturally VMP offers its own pump booster (VMPAMP; $249.99). To address the need for more fuel, Ricardo turned to a Kenne Bell Boost-A-Pump (KB-89067; $239.99), as Kenne Bell HQ is right around the corner from GTR. The single BAP is easily installed with a plug-and-play harness. “We used the KB BAP ‘jumpered’ for full-time operation and opted to control all the fuel pump duty cycle, pressure, and such through the tune,” Ricardo explains. “This avoids and spikes in fuel pressure when the BAP is triggered with a boost switch and avoids the possibility of the adjustment knob getting moved around.”

On The Dyno
Baseline VMP TVS Difference
RPM Power Torque Power Torque Power Torque
2,600 162.7 328.66 179.89 363.34 17.19 34.68
2,700 169.33 329.39 191.45 372.4 22.12 43.01
2,800 178.3 334.45 203.13 381.01 24.83 46.56
2,900 184.78 334.63 212.83 385.42 28.05 50.79
3,000 193.34 338.47 222.65 389.77 29.31 51.3
3,100 200.19 339.18 232.58 394.06 32.39 54.88
3,200 205.64 337.52 243.92 400.27 38.28 62.75
3,300 212.41 338.03 256.03 407.5 43.62 69.47
3,400 221.14 341.62 265.07 409.44 43.93 67.82
3,500 229.84 344.9 275.44 413.32 45.6 68.42
3,600 235.28 343.26 283.39 413.43 48.11 70.17
3,700 245.21 348.03 295.23 419.05 50.02 71.02
3,800 251.52 347.67 307.47 424.96 55.95 77.29
3,900 255.77 344.44 313.06 421.61 57.29 77.17
4,000 263.7 346.24 317.58 417 53.88 70.76
4,100 273.34 350.11 328.73 421.07 55.39 70.96
4,200 286.51 358.3 336.96 421.39 50.45 63.09
4,300 292.63 357.43 347.43 424.35 54.8 66.92
4,400 298.61 356.42 357.43 426.65 58.82 70.23
4,500 306.55 357.79 365.84 426.98 59.29 69.19
4,600 313.66 358.12 373.61 426.58 59.95 68.46
4,700 324.83 362.98 382.64 427.56 57.81 64.58
4,800 336.31 367.99 392.63 429.63 56.32 61.64
4,900 342.79 367.42 401.53 430.36 58.74 62.94
5,000 350.79 368.49 412.02 432.79 61.23 64.3
5,100 357.53 368.19 418.21 430.69 60.68 62.5
5,200 363.47 367.13 427.62 431.9 64.15 64.77
5,300 365.4 362.1 430.21 426.34 64.81 64.24
5,400 372.05 361.87 437.4 425.43 65.35 63.56
5,500 374.7 357.82 443.21 423.24 68.51 65.42
5,600 378.02 354.56 443.83 416.27 65.81 61.71
5,700 383.15 353.03 449.12 413.84 65.97 60.81
5,800 386.93 350.37 454.28 411.36 67.35 60.99
5,900 391.96 348.91 455.53 405.51 63.57 56.6
6,000 394.05 344.96 458.67 401.52 64.62 56.56
6,100 395.35 340.41 460.13 396.2 64.78 55.79
6,200 398.25 337.36 464.22 393.22 65.97 55.86
6,300 399.71 333.21 467.20 389.5 67.49 56.29

Thanks to the wonders of the Internet, a skilled tuner can now put a Mustang under his sway and make it work with new hardware. In the case of this installation, the GTR High Performance crew turned to noted tuner Bob Kurgan at Kurgan Motorsports.

"With today's technology, we are able to remotely log onto multiple computers from across the country. I had GTR set up a laptop for datalogging procedures and the desktop to view the dyno runs," Bob explained. "It's better than being there in person, as I don't smell like exhaust when I'm done tuning. It's important to have a competent person on the other end, as he listens for detonation and things that don't seem right."

Experienced tuners know where to adjust the programming for a given combination, but in the end, it comes down to tweaking the timing curve and air/fuel ratio. In the case of this combination, the improved supercharger efficiency allowed for more aggressive tuning. "The TVS charge temps are much lower than its traditional Roots counterpart," Bob explains. "This means we can run the car a little leaner and with more timing. That equates to more power and torque!"

The results certainly speak for themselves. Matt's car had a strong baseline thanks to a smaller pulley on the M90, as stock setups usually clock in around 360 at the wheels. However, the power and torque improvements from the VMP TVS come on early and stay until the needle hits the top of the tach. These are the kind of gains that will not only make you smile every time you step on the loud pedal, but will really make the vehicle faster. Of course, you could see higher gains with good East Coast pump gas and higher boost, but these gains are stout.

Bob refined the combination over several pulls, and the result is a significant improvement in power and torque across the entire rpm range. Of course, the gains really start rocking around 3,100 rpm and swells all the way to redline, which shows off the efficiency of the VMP TVS technology.

"If the vehicle had an aftermarket motor with forged internals and a real fuel system, we could have easily made another 30-40 horsepower!" Bob said. "The VMP 1.9 TVS is a great inexpensive swap for the Three-Valve S197 platform!"

"On a conservative 91-octane tune and boost levels that are safe for the stock bottom end, that gain is pretty normal. I don't recommend pushing the stock engine beyond 500 rwhp, even when you consider the efficiency of the TVS." Justin explains.

"At the same boost level as the M90, you gain 50 rwhp right off the bat. Push the boost 2- to 3-psi harder and you can be at 500 rwhp pretty quick. Our local test car has made 698 rwhp with the blower on a 5.0L stroker with Hot Rod cams and Ford Racing heads."

Horse Sense:
If you don't own an early S197 Roush, don't fret. VMP offers a host of supercharger upgrades for Coyotes, GT500s, and Terminators.