Muscle Mustangs & Fast FordsHow To Engine
Vortech V-3 SCi Supercharger Mustang 5.0L Engine Kit Upgrade
Adding A Supercharger To Your 5.0L Bullet Has Never Been Easier-Or Cheaper.
If you were to ask longtime enthusiasts about the quintessential Fox-body combination, odds are the answer would be a supercharged 5.0L engine. Since the late '80s/early '90s, adding a supercharger to our beloved 302 High Output engine has become a tradition. While there are nearly a dozen different supercharger systems available for the Three-Valve modular motor, the centrifugal supercharger system has been the mainstay in 5.0L supercharging. This compact and effective boost-maker for pushrod engines is simple to install, extremely effective, and reasonably priced for the gains. You can credit the blower wars of the 5.0L shootout days for advances in technology and encouraging the centrifugal blower's popularity.
As some of the 5.0L-specific blower kits are nearing 20 years on the marketplace, there is always room for improvement. Thanks to racing exploits in the NMRA and other heads-up racing sanctioning bodies, supercharger companies are continually improving the systems for street applications. One of the longtime supercharger manufacturers, Vortech Superchargers, has upgraded its entry-level centrifugal supercharger system to offer better output while maintaining its low cost.
Its 5.0L base kit is one of the most popular systems the company sells. We can point to a host of facts as to why the company cranks out so many kits but the underlying theme is that the base Vortech 5.0L system can be bought for under $2,000. As far as we can tell, it is the cheapest supercharger kit on the market-save for the leaf-blower/electric supercharger kits on eBay (insert sarcasm). The Vortech kit is a bare-bones system that comes with everything needed to run 5-6 psi of boost on top of a stock or mildly modified 5.0L engine.
The Low-Boost blower kit is essentially the original 5.0L blower kit that has served thousands of Mustang enthusiasts for almost 20 years, but Vortech now includes the latest head unit with its tried and true kit. The V-3 head unit is an internally lubricating supercharger that utilizes helical-cut gears to drive the impeller to a maximum speed of 53,000 rpm. "The V3 SCi is good up until 725 hp," explained Ricky Best, race and media relations manager at Vortech. "The SCi is included in our base kit. Then we upgrade the unit to a Si-trim blower for customers who want to run our High Output kit, which is 8-10 psi. The Si-trim supercharger is good up to 775 hp. It's what the NMRA Real Street racers are using in competition and going deep into the 9s."
According to Vortech's website, the Low-Boost kit is suppose to take a stock 5.0L from 225 hp up to 275 hp. We have been in this way too long to know that 5 psi of boost is worth more than just 50 hp-even if this is the company's extremely basic kit.
We tried to dig up a stock Fox-body of the '86-'93 vintage for this test, but that has become rather difficult, so we settled on a Stang with a heads/cam/intake upgrade. Justin Burcham of JPC Racing steered us towards one of his customers who was interested in tickling his 5.0 powerplant with a blower. Aaron McIntosh owns a clean '93 Mustang GT that features Trick Flow aluminum Twisted Wedge heads, Stage 1 cam, and Edelbrock Performer intake manifold, and a few other mods. In naturally aspirated trim, the car cranked out 309 rwhp on the chassis dyno at JPC Racing. We, unfortunately, don't have any information on the car's output in 100-percent-stock trim.
We ordered the Low-Boost kit from Vortech and while 5 or so psi is very mild for a stock engine, this one needed a few more mods to make the system operate effectively. The car was equipped with a UPR 255-lph in-tank fuel pump, and Burcham elected to add a Vortech T-Rex external pump for even more fuel flow. The T-Rex is the standard fuel pump upgrade included in the High Output system. This ensures the test subject will have plenty of fuel to feed the boost-hungry engine.
Another fuel system upgrade required was a swap to larger fuel injectors. Since Burcham is going to be tuning the system using a DiabloSport Delta chip, he elected to go right to a set of Ford Racing 60-pound fuel injectors. They might be overkill, but Burcham feels that while we are swapping injectors, we might as well go to a size that will be useful for many years-no matter what the combo is on the street.
The car was also equipped with a Pro-M 80mm MAF sensor, which was sent back to Pro-M for a new calibration to match the fuel injector size. Thanks to the massive 80mm size of the meter, we couldn't use Vortech's inlet tubing. That forced us to add a UPR inlet pipe, which places the meter in the fender and is a more efficient way to feed air to the supercharger. We were sure this molded plastic pipe was going to increase boost due to less restriction in front of the supercharger.
The car was equipped with an adjustable fuel pressure regulator, which we kept in place, along with the stock fuel rails. The fuel system upgrades were done because we elected not to use the Vortech-supplied FMU (fuel management unit). The UPR intake pump and Vortech T-Rex pump are more than enough to supply whatever we can throw at the engine-this is a stock short-block so we were limited to around 440-450 rwhp.
Essentially, the FMU is a secondary fuel-pressure regulator that increases fuel pressure based on boost. A vacuum line is run to the top of the FMU (which is installed on the return line), and a disk inside adjusts the fuel pressure based on boost. Adjustable fuel-pressure regulators increase pressure in a 1:1 ratio-1 psi of fuel pressure added for every 1 psi of boost. An FMU is set to a much higher rate than 1:1 for proper air/fuel ratio under boost (between 10.8:1 and 11.5:1).
The standard ratio in most Vortech applications is 12:1; meaning at 5 psi of boost the fuel pressure is spiked to 60 psi. If that pressure is increased to 6 psi, then the resulting fuel pressure is 72 psi at the boost level. The FMU operates at levels above the base fuel pressure setting. Vortech has different ratios for injector sizes up to 42 pounds. An adjustable knob for the FMU is also offered, to help dial-in the fuel pressure using minor psi adjustments.
The standard FMU from Vortech is calibrated to operate with factory injectors, which are 19-pound injectors. We, however, stepped up to the massive 60-pound units-putting us out of range of the optional Vortech FMU disks. Burcham programmed a custom DiabloSport chip to dial-in the fuel and ignition timing. He programmed the chip for a target air/fuel ratio and removed timing to prevent pre-ignition under boost.
Burcham also wanted to ensure that our test subject was more than capable of handling the extra air and fuel. He upgraded the ignition system by adding a set of spark plugs that are one heat range colder than stock; an MSD coil, cap, and rotor; and finally, a set of MSD spark plugs. "It's always a good idea to upgrade the ignition system when adding a supercharger," commented Burcham.
Vortech includes an ignition retard box in its High Output kit, which adjusts the timing based on boost. It is a fixed curve, which reduces timing 1-5 degrees for every pound of boost. The base kit doesn't require the timing retard, and Vortech recommends dialing back the timing to 10 degrees (with the spout out) for this kit. Since our engine was modified, Burcham backed the timing down using the computer and subtracted it from total timing, not the reading at idle, with the spout out. The stock total timing is set at 26 degrees in the computer (10 degrees base reading), and our baseline in naturally aspirated had 30 degrees total (14 degrees). Burcham removed 4 degrees of timing to bring it down to 22 degrees total due to the expected 5-6 psi of boost.
Bolting on this supercharger system was an easy task, not because JPC has done this combo many times over the years, but mostly because Vortech designed the kit to be simple. A couple of engine accessories are relocated using Vortech's cast brackets, the supercharger mounts easily on a plate, and a secondary pulley is bolted to the factory crank pulley. The company does a great job in providing every nut and bolt to install the system.
Our lives were also made easier thanks to the V-3 being a self-lubricating blower. That meant we didn't need to drill and tap into the engine's oiling system, like its V-1 and V-2 predecessor. The blower contains its own oil, which is checked with a dipstick, and there are holes for draining and filling the head unit with Vortech's special oil.
On the chassis dyno, we were simply blown away-no pun intended. The engine responded very well to a nominal amount of boost (6 psi at 5,500 rpm) and output climbed to an impressive 405 rwhp. The standard kit is advertised as producing 5 psi on a stock engine, so why did it make 6 psi on our modified one? Remember, boost is a byproduct of engine restriction (backpressure), and our bullet had a much more efficient top end thanks to the heads/cam/intake upgrade. Conventional wisdom dictates that our overall boost should have been lower than 6 psi since our engine was less restrictive than stock. Our best assumption is that the UPR inlet pipe increased boost by a few psi thanks to its more efficient and larger inlet to the impeller.
The amount of airflow through a supercharger is based on engine rpm since it is attached to (and driven by) the crank. The higher the rpm, the higher the boost will be (within reason and designed operating range of the blower). Burcham ran the car to 6,000 rpm and it did make upwards of 8 psi, but the power fell off as the engine didn't operate efficiently in that range.
"I have the tune very safe right now and the air/fuel is really rich. It was steady at 10.5:1 through most of the pulls. The tune is really conservative and it could probably make 30-40 more rwhp with more timing and less fuel."
Horsepower junkies may be wondering why we didn't make the jump to the higher power. The answer is because the car still features a stock bottom end, which is pretty tough, but has its limits. This is a '93 Mustang, which features hypereutectic pistons rather than the forged pistons normally found in '87-'92 5.0L H.O. engines. There are future plans for this car, so we didn't want to beat it up too badly with this first set of blower modifications. "This power is good for mid-11s with sticky tires and powershifting," proclaimed Burcham.
It took less than a day to install the base kit and get the car on the chassis dyno. That isn't bad for the 96-rwhp increase, which works out to be 16 rwhp per 1 psi of boost. We also love the classic supercharger whine at idle, although it's toned down compared to the original V-1 blowers. And if that isn't enough for you, Vortech offers upgrade kits to help raise the power level and keep you in front of the new Camaros and Challengers roaming the streets.