A Look At The Installation And Dyno-Testing Of Vortech's Street Blower For the 2005-06 Mustang GTSupercharging the new Mustang GT has turned out to be a relatively easy endeavor – but one that had more than a few tuners worried when the cars were introduced more than a year ago.
The 2005/06 Mustang’s electronic elements, such as electronic throttle control and charge motion control (a.k.a. inlet manifold runner control, or IMRC for short), and the new engine controller raised concerns that they wouldn’t allow a supercharger to work effectively. At least, drivability would suffer and/or the blower’s full potential couldn’t be realized.
Turns out, they all work well the latest supercharger systems. In fact, we recently followed the installation and testing of a non-intercooled Vortech system on a 2005 GT at Mt. Clemens, Mich.-based Alternative Auto and found that, indeed, a bolt-on supercharger works. Bottom line: It put down a solid 399 horsepower and 367 lb.-ft. of torque to the wheels – a 55-percent increase in horsepower and a 30-percent increase in torque compared to the stock 259 horsepower/283 torque numbers. The non-intercooled system also squeezed a surprising 10.5 pounds of boost into the 281-cube V-8.
The root of the early tuning worries is that, unlike the days of “chip-able” controller systems, the ’05 Mustang (and 2006 versions, for that matter) used the Motorola-supplied “Spanish Oak” controller. It’s a flash-only system, so new programming must be uploaded to the vehicle directly. Beyond that, however, the stock system is set up to reject or repel just about any variance to its strict operation parameters.
Getting around the Spanish Oak’s seemingly endless parameters that will slam the door shut on mods like a blower requires reprogramming. Vortech includes a Diablo plug-in module to upload new operation tables, but frankly, we – and the tuning community – encountered drivability concerns with the first few kits. Alternative and a few other tuners we’ve talked to have had better luck with SCT’s programming, which is delivered to the computer via the Excalibrator controller. Such was the case with Iacobelli’s Mustang, which delivered excellent drivability after the supercharger installation.
But while the tuning and drivability fears appear to have been allayed, Iacobelli – and other tuners – have discovered another issue to deal with: fuel. On the dyno, the supercharged engine can get uncomfortably lean at the upper end of the rev range, starting just beyond 5000 rpm (see sidebar “The Methanol Option”). The Vortech kit includes 39-pound injectors and a 255-LPH in-tank fuel pump, but the combination doesn’t appear enough to satisfy the engine as the tach nears 6000 rpm. The stock engine comes with 24-lb. injectors and the now-famous Focus fuel pump.
When it came to keeping the hungry injectors fed, Iacobelli experimented with the stock pump and Vortech-supplied pump. He reported no significant performance difference between the two. Iacobelli ultimately re-installed the stock pump and bolstered it with a Kenne Bell Boost-A-Pump, which helps increase fuel pressure with an increase in voltage to the fuel pump – a sort-of supercharger for the fuel pump.
With the stock pump/Boost-A-Pump combination, the engine fuel pressure hovers between 38 and 42 psi under boost while maintaining a comfortable 11.8:1 air/fuel ratio. Without the Boost-A-Pump, fuel pressure was dropping off to 33 pounds.
“The engine runs great on 93 octane and there’s no detectable detonation,” said Iacobelli. “Maintaining adequate fuel is the key to the success of this system; we seem to have found it, but we’ll probably experiment with 60-pound injectors, too.”
Installation of the Vortech system is not unlike the installation of previous kits on Mod motors or the venerable 5.0. A bracket hangs the compressor off the front of the engine and, of course, the oil pan must be tapped for an oil return feed. It’s all standard Vortech stuff.
There appears to be adequate room to maneuver beneath the new Mustang’s hood and the basic installation requires only about a day of solid work (if you’ve got access to a lift and air tools). We’ve already followed the installation of an intercooled Vortech kit on another vehicle and it requires the removal of the front bumper cover to mount the heat exchanger. It’s not a difficult process, but it adds several hours to the installation time.
The potential of the supercharger system is exciting. Iacobelli expects to see more than 400 rear-wheel horses after some more tuning and complete exhaust system – starting with long-tube headers. He also admits the new 5R55S automatic transmission is an unknown factor. Will it survive behind the extra power delivered by the blower? Time will tell, but with already numerous runs down the drag strip, it seems to be holding up.
Iacoebelli’s car has a slightly looser torque converter, Steeda’s charge motion delete kit and 20-inch wheels. The 315/35-series rear tires are a whopping 28.7 inches tall, which puts quite a footprint on the starting line. They undoubtedly helped Iacobelli grab a 1.78-second 60-foot time, as the car has gone on to produce a best ET of 12.04 seconds at 112 mph.
Now, what were all those worries about?
Alternative Auto Performance
145 Malow, Unit D
Mt. Clemens, Mich. 48043
1650 Pacific Avenue
Channel Islands, Calif. 93033
The Methanol Injection Option
At our shop, we advise our customers to go with the non-intercooled Vortech supercharger for 2005-06 Mustangs. For more boost, we recommend a pulley change – increasing boost to about 12 psi – and use of a methanol injection kit, instead of an intercooler upgrade.
After careful consideration and experimentation, we’ve found the ethanol upgrade is a far more viable option for non-intercooled centrifugal blower applications.
Why? It provides the benefits of a cooler intake charge, with a measure of safety for those who are reluctant to run racing fuel. Convincing customers to run race fuel is touch, because it is, frankly, expensive and inconvenient.
But, it’s important to understand that when trying to safely make big power out of only 281 cubes – especially in a heavy car like the new Mustang – you have to sneak up added boost. This generally requires more octane, no matter how you look at it – even with an intercooled system. (By the way, reducing the compression on a street 4.6 engine is not the way to go fast.)
The upside of methanol is threefold: First is a big drop in inlet temperature that’s not affected by intercooler hardware heat saturation. Second is a big jump in octane. The third advantage is the methanol system’s capability to pick up where the engine’s fuel system leaves off, eliminating the need (in most cases) for larger injectors or other fuel system upgrades.
Alternative Auto has a package that involves a 12-psi Vortech package for ’05/06 Mustangs that will net 470+ rwhp. It uses the stock fuel pump, the Vortech kit’s 39-pound injectors and no Boost-A-Pump. With the methanol kit, which uses the stock windshield washer reservoir, the car runs 91-93 octane in the tank. This is all done with custom tuning with SCT software.
We’ve fond the inlet temp stays below 125 degrees F with methanol. To ensure safety, we typically move the ACT (Air Charge Temperature) sensor up-stream from the blower in the inlet track. This allows us to tune so that if the inlet temp skyrockets because of a methanol system failure, we can tune the ECU to significantly reduce ignition timing to save the motor.
We offer this entire Vortech package with them kit on 2005 and ’06 4.6L three-valve Mustang for $5,495.00; installed, dyno’d and tuned. It’s only the beginning, too, as there is still room for a bigger rear gear, exhaust work and more boost. We figure that, with a few tweaks and exhaust work, we will soon offer this as a reliable 500-rwhp package.
– Lidio Iacobelli