Mopar Mass-Flo Fuel Injection System - Lethal Injection

Electronic fuel injection. These three words can strike fear in even the most seasoned automotive technician. The reality, however, is that no carbureted induction system can match the fuel-metering accuracy of electronic fuel injection. The reason is simple, fuel injection is interactive and a carburetor is not. Once a carburetor is adjusted, the tuning can't be changed while driving to accommodate varying weather conditions and driving habits. This is what gives electronic fuel injection a huge advantage. By monitoring engine parameters, such as coolant temperature, throttle position, manifold air pressure, air flow through the engine, and the mixture of the spent gasses, fuel injection can actually adapt to changing conditions as the car is driving, always ensuring the proper fuel/air mixture no matter what the circumstances. Therefore, even the most sophisticated performance carburetors can't match the fuel metering accuracy of fuel injection.

Benefits of electronic fuel injection are many. Throttle response can be vastly improved as can all-around drivability. No more pumping the gas or setting the choke for cold starts either. Since most fuel-injection systems monitor the temperature of both the ambient air and the engine's coolant, it takes care of enriching the fuel/air mixture automatically for cold starts. Also, since fuel-injection systems require a higher fuel pressure and continuously return a portion of fuel to the tank, fuel starvation, or "vapor lock," is also a thing of the past. An additional advantage of fuel injection is an improvement in fuel economy. Because most carburetors only have two or three tunable circuits, they generally tend to run a little rich during certain driving conditions and waste fuel in the process. Since fuel injection is an interactive system, it can provide the engine with an ideal mixture of fuel and air during all phases of driving, thereby using less fuel than the typical carbureted engine. So with all these advantages, why aren't more people converting their older cars to fuel injection? While the many advantages of fuel injection make it a much better system, the complexity alone is enough to scare most people away from installing it.

Aside from system complexity, a slight drop in peak horsepower is the only downside when comparing fuel injection to carburetion. While we don't like losing power, even a small amount, we felt that since part-throttle power and torque are improved when fuel injection is used, that the all-around performance of our vehicle would increase. drivability and economy would likely improve as well, so we decided our car would benefit from fuel injection.

Since our project car is a '68 GTX clone with a mostly unmolested engine bay, we wanted a system that wouldn't require a bunch of holes drilled in our inner fenders, firewall, and interior. the system would also have to be easy to install, wire into our car's existing electrical system, and not require a computer science degree to make it run properly. While there are several EFI systems on the market for the big-block Chrysler, a company from Massachusetts called Mass-Flo EFI has developed what could be the simplest EFI system we've ever installed.

The Mass-Flo EFI system is a complete kit and includes everything needed for the installation, but we're getting a little ahead of ourselves. Since most fuel injection, the Mass-Flo system included, requires some 40 psi of fuel pressure, our car's existing fuel system would be inadequate. The higher operating pressures of fuel injection require not only an injection-specific fuel pump, but also high-pressure lines and a regulator with a return port to direct unused fuel back to the tank. Rather than piecing a system together ourselves, we contacted Aeromotive for one of their complete fuel systems designed for our injected application. The system we purchased has the capacity to supply an engine with 1,000 hp, so it shouldn't have any problem getting enough fuel to our mildly worked 440. Installing the fuel system was easy as all of the filters, lines, and connections were supplied with the kit. Wrenching the ends onto the steel-braided fuel lines is time consuming, but high-pressure lines are necessary to handle the increased fuel pressure of the fuel-injected system. We also had to block off the mechanical fuel-pump provision on our engine, but all in all this was an easy installation. Since fuel supply is critical to the proper performance of fuel injection, it is recommended the tank be sumped so fuel is pulled from the bottom of the tank. While we won't cover the modification of the fuel tank in this story, look for it in an upcoming issue. Once our fuel system was installed, we got to work on the EFI.