It wasn't really the best of times or the worst of times, but in the hot rodding world, the mid-'80s witnessed a peculiar convergence of euphoria and pandemonium. The decade prior had seen the heinous castration of muscle cars, as Chevy's flagship Corvette was emasculated to a pathetic 165 hp come 1975. Engineers made great strides, however, and the horsepower of performance cars was creeping back up near the 300 mark by the late-'80s. Interestingly, while some members of the power-hungry enthusiast crowd rejoiced, traditionalists balked at this frightening new technology called electronic fuel injection.

Fortunately, the aftermarket soon stepped in by developing stand-alone engine management systems that took over fuel and spark duties from stock PCMs. The aptly named Fuel Air Spark Technology (FAST) was one of those companies, and since the mid-'90s, FAST has been one of the most prolific manufacturers of stand-alone EFI systems on the market. Vehicles equipped with FAST electronics cover the gamut from 11-second street/strip machines to full-blown race cars kicking out thousands of horsepower. In 2001, FAST became part of the Comp Cams family of companies, and the additional resources resulting from this new relationship has enabled it to develop cutting-edge products at a staggering rate. Released in 2004, FAST's XFI engine management system continues to be a favorite with cruisers and racers alike, and the company's new EZ-EFI system can literally tune itself.

To get educated on the latest in EFI technology and to pick up some valuable tuning tips, we recently had a chat with FAST's David Page. The horsepower race is still full-steam, and with the goodies that FAST has in the works, it's obvious that they plan on being there every step of the way.

Impedance
As horsepower levels start approaching the 1,000 mark, a standard high-impedance injector will no longer cut the cheese. That's because it's tough to find a high-impedance injector that flows more than 72 lb/hr. After that point, high-flow, low-impedance injectors are a must, which requires upgrading to an aftermarket stand-alone ECU such as XFI. This begs the question, "What's the difference between these two types of injectors?" "Impedance is just another word for resistance. High-impedance injectors have 12-16 ohms of resistance while low-impedance injectors have 2-5 ohms of resistance," David explains. "The drivers in the engine management computer are what actually send the signal to open up the injectors. If you try to open low-impedance injectors with a stock PCM, the extra electrical current flowing through the drivers will burn up the drivers and the computer. A stand-alone system like XFI has much more robust drivers that act like relays, and can easily handle the extra load. Plus, the XFI box itself works like a heat sink to help dissipate the extra heat."

XFI vs. EZ-EFI
With the launch of FAST's new EZ-EFI system to complement its premiere XFI system, the company now has a two-pronged lineup that covers everything from mild street motors to full-blown racing applications. Each system has its benefits, and deciding between the two depends on a number of variables. "EZ-EFI is an entry-level system that's still extremely capable. If you have a naturally aspirated motor, but aren't too familiar with tuning EFI, then the system is extremely appealing," says David. "It includes four 83 lb/hr injectors, which are good for 600-650 hp. Beyond that power level, or with power adders, you probably want to step up to our XFI system. There's definitely a learning curve involved with figuring out how to tune a motor, but it allows for much greater tuning flexibility. If it's not something you want to tackle yourself, there's a large network of professional tuners out there who can help you out."