Richard Holdener
March 29, 2010

The supercharger kit required installing the factory water pump (we ran a Meziere electric pump on the NA and Zex combinations), along with all the accessories. A single belt was employed to run the accessories, as well as the supercharger.

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Our previous fuel system upgrades would now come into play, as the supercharger was first configured to produce a peak boost pressure of 11 psi at 6,200 rpm. So equipped, the 4.6L produced 559 hp at 6,200 rpm and 513 lb-ft of torque at 5,300 rpm. A quick pulley change netted an increase in boost pressure to 13.7 psi, and with it an increase in peak power to 613 hp and 545 lb-ft of torque. Without the intercooler, that was about as far as we dared push the stock motor, despite the use of race fuel.

Run at the higher boost level, torque production exceeded 500 lb-ft from 4,200 to 6,200 rpm. All cranked up in intercooled form on an otherwise-stock Three-Valve motor, this same Vortech supercharger kit pushed the author to 192 mph in an '05 Mustang during a top speed test.

Turbocharge It
Putting the final super in supernatural was a twin-turbo kit from HP Performance. The kit features a pair of 57mm Garrett turbos, a pair of Tial wastegates, and a pair of blow-off valves. Naturally, the turbo system was equipped with a front-mounted, air-to-air intercooler. When run on a Four-Valve Terminator crate motor, this same system produced nearly 1,000 hp at 20 psi of boost.

The turbo kit certainly had the power potential if you have the motor properly built to withstand the intended output. For our needs, we limited boost on this stock motor first to just 6.2 psi, then to 11 psi. The reason for limiting the boost pressure was that the motor produced so much torque that we began to fear for the strength of the internals.

HP Performance now offers an equally powerful single turbo kit for the '05-up Mustangs, as well as a full array of kits for 5.0L and modular Mustangs. Hellion Power Systems and a few others also offer suitable turbo kits.

On this stock 4.6L application, the twin turbos improved power output from 361 hp and 381 lb-ft to 500 hp and 530 lb-ft at just 6.2 psi. Imagine that-adding 140 hp with just 6 psi of boost.

Things really got serious once we upped the boost pressure to 11 psi, as the Three-Valve produced 624 hp and 664 lb-ft of torque. Torque production exceeded 600 lb-ft from 3,500 to 5,400 rpm, making this one serious torque monster. Even down at 3,000 rpm, the twin-turbo motor belted out 575 lb-ft of torque-so much for turbo lag!

The question now is not which form of supernatural aspiration is better, but which one works best for you?

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HP Numbers
Stock, 150hp Zex, Vortech (13.7 psi), HP Turbos (11 psi)

TQ Numbers
Stock, 150hp Zex, Vortech (13.7 psi), HP Turbos (11 psi)