In recent months, companies like Holley, Edelbrock, Fast, and MSD have each released self-tuning EFI systems. These slick systems bolt in place of a standard 4150-style carburetor, and literally tune themselves. All you have to do is install a high-pressure fuel pump, hook up a few wires, enters a few basic engine parameters into a hand-held tuner, then turn the key. In the past, the biggest drawbacks of an EFI system were cost and complexity, but the sub-$2,000 price and self-tuning ability of these new systems make upgrading to EFI more appealing than ever before.
Among the major benefits of a fuel injection system is its superior drivability, fuel mileage, idle quality, and cold-starting ability compared to a carburetor. EFI systems constantly monitor engine load and ambient air conditions, and consequently, adapt to variations in weather conditions and altitude. This means less tuning. Even though a carburetor can be adjusted to run sufficiently, air pressure and weather changes can affect the performance of you engine. Likewise, starting your fuel injected engine is made much easier, as a carburetor uses a manual, vacuum, or electrically controlled choke to mechanically restrict air flow. On the other hand, a fuel injection system automatically adjusts for the proper air/fuel mixture depending on environmental conditions.
Traditionally, one downfall of a fuel injection system has been complicated installation procedures, but manufacturers have taken great strides to take this hurdle out of the equation. Let’s take, for instance, GM Performance Part’s Ram Jet 350 EFI crate motor. This system is can be bought as a complete setup that includes the wiring harness and computer. To simplify the installation process, all wires are pre-terminated and labeled for their specific location. All that’s left to wire up is the ignition wire, 12v power supply, and the ground. While that’s simple enough, what can be challenging at times is converting the gauges in an older vehicle to work with an EFI system. Finding the proper ports for sending units can usually be done, but when running certain accessories the ports that are available may be limited.
The new crop of self-learning EFI systems eliminate these challenges by vastly simplifying how the computer interfaces with the engine. The fuel injectors, fuel rails, manifold pressure sensor, and idle air control valve are all integrated into the throttle-body assembly, so all you have to do is bolt it to the manifold and you’re good to go. All these sensors plug directly into the EFI computer, and don’t interface at all with the existing gauges, drastically simplifying the installation process. One caveat is that self-learning EFI systems to require installing a wide-band oxygen sensor into the exhaust system, but this is a simple task that only takes 20 minutes or so to pull off, and the result is ultra precise control over the air/fuel mixture.
Each of these systems includes a hand-held controller that connects to the computer. Once installed, all you have to do is enter some basic engine information such as the displacement, target idle rpm and rev limit, and camshaft size. Using that information, the computer generates a baseline engine tune, and once the car is on the road, it uses feedback from the oxygen sensor and MAP sensor to tune the engine automatically on-the-fly. The starting price of these systems is roughly $2,000, which is still more than twice the price of a carburetor, but for many hot rodders the benefits are well worth the price of admission.