Converting an engine originally equipped with a carburetor to electronic fuel injection (EFI) is nothing new; though every year it seems as if interest in taking the EFI plunge gains momentum. OEM vehicles of the past two decades have firmly engrained the advantages of fuel injection to all but the most diehard enthusiasts. Far be it from us to suggest taking a show-bred Corvette and altering it in such a way. however, if serious road time is more important than originality in your Vette escapades, retrofitting to EFI is a modification worth considering. Late-model performance cars, such as the C5 and C6, provide all the evidence necessary to show the attributes of injection, including flawless drivability and remarkable reliability. Wouldn't it be nice to take some of that technology and apply it to an earlier carbureted Corvette?
For the vast majority of enthusiasts, the thought of running a custom aftermarket EFI system is filled with trepidation. Sure, it seems to work great on modern cars, but just what is involved in setting up an older engine to work with this modern technology? At first glance it might seem pretty complex, with items such as the wiring, sensors, the control box, and so on. In comparison to that old Quadrajet, it certainly involves more hardware and at a more sophisticated level, but breaking it down is nothing a seasoned wrench-turner couldn't handle. We sought just such a conversion to a small-block Chevrolet engine and found the changeover less daunting than anticipated, using components from FAST.
Back in the early days of EFI conversions, most efforts centered upon adapting the primitive OEM components of the time to vintage iron. Installing the hardware was simple enough, but the difficulty stemmed from gaining control of the tuning parameters. Such installations nearly always involved modifications to the factory specifications, and the control units that provided the logic to run the systems were notoriously inflexible. Times have changed, and these days companies like FAST do the work to produce components that have been designed to work together, in a wide range of potential applications. the technology is built into the system, so the end user does not need to be a fuel-system engineer. The software facilitates tuning the system to an unbelievable degree, making such installations flexible in controlling a wide range of likely combinations.
Whether you are looking to inject an older Corvette cruiser, or are looking to plant a modern, fuel-injected monster in your radically modified C3, the systems to make it happen have already been ironed-out to the nth degree.
Is there EFI in the future of your seasoned Vette? It's pretty hard to ignore the drivability of modern systems that continually adjust the fuel and spark to their optimal settings as you drive. Equipped with modern controls, you're practically rolling down the road with an ace tune-up man wrenching away under the hood at all times. An expertly calibrated fuel-injection system can eliminate the temperamental nature that some carbureted installations can exhibit, and make driving the pleasure it was intended to be. Everything you need is readily available from EFI specialty companies such as FAST, so what are you waiting for?
Carb vs. EFISuperflow 901 Engine Dyno Tested at Westech Performance Group STP Correction Factor
Carburetion Vs. Injection
Converting to EFI is not a decision that should be based upon looking for outrageous power gains, but rather for the best drivability and efficiency gains possible. The naked truth is, given exactly the same components, the power of a perfectly tuned carburetor will be virtually identical to an EFI system. One of the key differences is an EFI system is "smart" and once programmed correctly, will always be in perfect tune, no matter how the operating conditions of temperature and air density changes. We installed a Demon four-barrel carburetor to the tuned EFI system on the dyno just to compare the wide-open-throttle output. Not surprisingly, with the combination otherwise identical, the power curve was virtually unchanged, with the EFI gaining a modest advantage in low-speed torque. However, by taking advantage of the intake manifold design flexibility available when running EFI, the power characteristics can be changed significantly. Modern plenum ram manifolds of the type used on the LS-family of engines are a good example. This design takes positive advantage of inertia ram tuning for a healthy boost in torque, but such a manifold layout would be impossible in a carbureted application.
While an EFI system can be tuned to a fine set of parameters at the keyboard of a computer, a carburetor is a mechanical device with fuel curve adjustments primarily handled by changing jets, altering the orifice restricting fuel flow. Tuned for a perfect air/fuel ratio, output is about equivalent when considering full-throttle horsepower and torque, if all else in the engine remains unchanged.