Boosting our 2008 Shelby GT500 project with VMP Tuning’s Gen2 TVS supercharger case upgrade
By Steve Turner
Being at the forefront of Ford performance is a blast. We love being on the front lines as new cars and products come into the world. Watching the progression of vehicles and aftermarket gear is always exciting. Of course, the downside is that we can often get jealous. It’s only human to fall for some of these cool cars and products, but there’s only so much room in the garage.
Our 2008 Shelby GT500, Project Vapor Trail, had a great run with a Ford Racing 2.3-liter TVS supercharger modified with VMP Tuning’s case, inlet, and pulley modifications. Running the VMP 2.5-inch upper pulley and a 10-percent-overdriven lower, PVT baselined with 655 horsepower and 648 lb-ft of torque on 93-octane pump gas.
That was definitely the situation when we first covered VMP Tuning’s new Gen2 2.3-liter TVS supercharger upgrade for 2007-2014 Shelby GT500s and 2011-and-up Mustang GTs. If you followed our coverage of testing this supercharger versus both a standard TVS and the upgraded Trinity TVS found on 2013-2014 GT500s, you know this new supercharger works well.
It was cool seeing the new blower in action, but then we looked under the hood of Project Vapor Trail, our 2008 Shelby GT500 project car, and the Gen1 TVS was starting to look a bit outdated. Fortunately for us, Justin Starkey, the main man at VMP, decided to offer a Gen2 case upgrade (PN GEN2SWAP; $1,499.00) for those of us already rocking a 2.3-liter TVS.
VMP Tuning’s Joe Goodnough gets down to business by removing PVT’s GT500KR strut-tower brace. Maintaining this brace is one reason we opted to follow the TVS upgrade path on this car.
“With our Gen2 case swap the same airflow benefits you would realize from a VMP Gen2 TVS are available to those running older style TVS blowers,†Justin explained. “Do you get to have your cake and eat it too? Mostly, but purchasing the whole blower from VMP gets you a one-year warranty and nose drive machining that allows for smaller pulleys. Either way, the rotor set is the same, the magic of the Gen2 case is in airflow potential of the housing.â€
So when we could both clear a moment in our busy schedules, yours truly made a date to head over to VMP Tuning to document the case swap and its benefits. If you read our prior stories on the Gen2 TVS, you know that this new case not only features a much larger inlet, but numerous internal improvements designed to feed the TVS rotors with as little restriction as possible. If you know anything about positive-displacement superchargers, you know they abhor inlet restrictions, so on look at the Gen2 and you know it is going to make power.
Next, Joe removed PVT’s JLT Big Air cold air inlet.
If you are thinking that swapping the rotors into a new case might be too daunting, we are here to tell you it is not that difficult a swap at all. It just requires some basic tools and some attention to detail. It really only adds a few more steps to a straight supercharger swap, and the extra work is well worth the effort.
Those who aren’t familiar with Project Vapor Trail, it runs a pretty basic combo. Underneath the Gen1 TVS, VMP throttle body, VMP 2.5-inch pulley, and JLT Performance Big Air CAI is a stock engine fitted with a 10-percent-overdriven lower damper and exhaling through a Bassani 3-inch exhaust. Coming into this test the car ran the stock fuel pumps and set of Ford Racing 80 lb/hr injectors. It is a pretty mild combo that typically put down rear-wheel horsepower in the upper 600 range on pump gas and low-700 range on 100-octane unleaded.
PVT’s Gen1 TVS features a case port-matched to the free-flowing VMP inlet elbow and one of VMP’s twin 72mm throttle bodies, which are no longer produced. VMP does, however, produce a Twin Jet 67mm throttle body that offers big flow and better driveability than the old twin 72.
“The gains were what we would expect at this boost level, Steve’s TVS was working hard with a 10-percent-overdriven lower and 2.5-inch upper pulley,†Justin said. “Now, with the Gen2 housing, it can finally breathe, realizing great gains in horsepower and torque. The larger displacement ’13-’14 5.8-liter GT500s will benefit from the Gen2 case as well.â€
As you will see, by swapping PVT’s existing 2.3-liter TVS rotors into the Gen2 case, adding a new custom tune from Justin Starkey, and adding a bit more fuel via VMP’s plug-and-play fuel pump voltage boosters put this GT500’s pump gas output into the range that used to require 100-octane fuel. Consider our TVS envy resolved!
With all the connections separated, Joe starts unbolting the supercharger.Thanks to PVT’s aftermarket fuel rails and rear fuel crossover, the blower can come right out without disturbing the fuel system.As you can see, the big difference between PVT’s outgoing TVS and the new VMP Gen2 case is the much larger inlet with integral elbow. There are numerous detail improvements, all focused on feeding the 2.3-liter rotors more efficiently.With PVT’s blower removed, we were able to scope out the intercooler core. It looked pretty clean, so those JLT oil separators are doing the job.VMP’s Justin Starkey starts the case swap, removing the front-drive fasteners.With all the front-drive fasteners removed, Justin breaks the seal with a bit of gentle encouragement from a mallet.Be sure you are prepared to drain the gear oil from the front drive before you separate it from the case.After draining the drive oil, you can safely remove the TVS rotor pack from the blower housing. It slides right out.You’ll want to clean any remaining lubricant or dirt from the rotor pack before you install it in the new case. Brake cleaner does the job nicely.The bearings at the rear of the Gen2 case are pre-greased, so you can just slide the rotor pack in and start the reassembly process.With the rotors in the Gen2 case, Justin applies a thin bead of sealant to seal the front drive to the rotor pack.After cleaning the front drive, Justin installed it on the Gen2 case using the same fasteners. He torqued them to the prescribed 25 to 30 lb-ft in alternating pattern.Included with the Gen2 case upgrade kit is a bottle of premeasured gear lube for the front drive. Simply remove the fill plug, stand the blower up, and pour in the oil.The bottle is filled with just the right amount of lube, but you’ll want to check the level just to be sure. The gear oil should come up to the edge of the opening.The Gen2 case provides the provision for retaining the factory EGR system, but for off-road applications, you might chose to delete this system using one of VMP’s handy delete kits (PN EGRDEL; $39.99). These kits include a block-off plate for the blower and a cap for the exhaust manifold.Justin and Joe carefully lower the fully assembled Gen2 TVS onto its rightful home atop PVT’s 5.4-liter V-8.The VMP Gen2 bolts right in place of its little brother.Joe went about reinstalling all the connections to the supercharger, and then he swapped over the throttle body gasket to the new larger inlet.A big inlet deserves a big throttle body, and the twin 72mm looked right at home on the Gen2.Justin reinstalled the belt while Joe buttoned up the rest of the gear, including the JLT Big Air and the strut-tower brace. The new Gen2 case looks like it was born on PVT.Hardware is only one part of this equation. With the greater airflow afforded by the Gen2 TVS it was necessary for Justin to retune PVT. He had it dialed in right away and it made great power, but the increased flow had the car at the limit of its stock fuel pumps and Ford Racing 80 lb/hr injectors.With an adequate fuel supply and a fresh tune the, the VMP Tuning Gen2 TVS case upgrade proved its worth on our 2008 Shelby GT500. It put down a massive 705 horsepower and 675 lb-ft of torque at the rear wheels burning 93-octane pump gas!To feed the Gen2-boosted 5.4, Joe augmented PVT’s fuel system by installing VMP’s dual plug and play fuel pump boosters (PN VMPAMPPNP2-0710; $549.00). Just as described, these units plug in between the fuel-pump driver modules and the fuel pump. They increase voltage, which increases flow. They instantly brought PVT’s fuel flow up to snuff. The boosters dropped the duty cycle of our 80-lb/hr injectors by 20 percent, which returned a nice margin of safety to the car’s fuel system.We told you that positive-displacement blowers like a free-flowing inlet. PVT picked up peak-to-peak gains of over 50 horsepower and over 45 lb-ft of torque with the new Gen2 case, adequate fueling, and a fresh VMP tune.We like to take a closer look at the numbers when we can, and this upgrade proved to be a story of efficiency. The car only really gained boost at the top of the tach, but the freer-flowing inlet added power and torque early in the pull and really started pumping out double-digit gains around 4,200 rpm.
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