It was not that many years ago, when most classic cars were still carburated and Electronic Fuel Injection or EFI was something that was really only found on new cars. Back in the early days of EFI, as with any new automotive technology, there were those brave pioneers who chose to retrofit “the new technology” into their classic cars.
Those who did it first did not have the benefit of documented swaps on the Internet to guide them through or an aftermarket full of accessories and options. They simply took the drive train from a modern car and stuffed it in to their project. In most cases it was a complete swap that required the complete engine and engine related electrical systems from the donor car to be used. This had the limitations of having to use all the power robbing emissions and fuel economy parts.
Over time, techniques were developed to “trick” the computer allowing you to use OEM EFI systems but eliminate many of these power-reducing features. Once this happened the door was opened for EFI to be an option for more then just those looking for a challenge. The benefits of a properly tuned EFI system are clear, better fuel economy, lower emissions, longer engine life, and power equal or grater than that available from a carburetor.
As EFI took hold as a viable option for classic cars the aftermarket got in on the action and began developing all kinds of complete kits that would allow you to replace any carburetor with EFI. These kits started out as CFI/TBI units with analog adjustments on the computer and advanced all the way to complete multi- port injection systems where the computer controlled spark and a laptop or desktop computer was required to tune the EFI system. These aftermarket kits can be purchased for any where form $500.00 to $4000.00 depending on features, how complete they are, and weather you are purchasing the kit new or used. Most new kits start in the $1500.00 range.
My 62 Galaxie is soon to be receiving an upgrade to EFI and my attitude has always been Do it yourself, or DIY. In my personal attitude of DIY, I tend to stay away from ready-made kits and like to assemble my own collection of parts, one piece at a time. The advantage to doing this is that you can hand pick the best part for your application and get the optimum setup.
The down side is that you must have a fairly good understanding of what each part does, how it works, and how changing it effects the system to make the correct component choices. The following is a listing of the basic parts needed to install EFI, a comparison of some of the options, what I chose for my project and my reasoning for picking one type of part over another.
The early days of OEM EFI and a still very viable option when it comes to an aftermarket kit is Throttle Body Injection or TBI. Ford referred their version of TBI, as Central Fuel Injection or CFI. These types of systems are basally the melding of a carburetor and fuel injection. The CFI/TBI unit, comes in 2-barrel and 4-barrel verities, bolts to a standard carburetor intake and has fuel injectors mounted down the throat of the carburetor.
The advantage of a system that bolts to the intake just like any carburetor it is much easier to make the swap. There is no need to swap out the intake, mess with changing the air cleaner or changing the air inlets. Also this type of a setup is Less obviously EFI so if you want to retain that “carbureted” look than this is the way to go. The disadvantage to this system is just like a carburetor there can be some variance between the fuel to air ratio at each cylinder. And for this reason I chose to not use CFI/TBI for my project.
Just as the name indicates multi-port injection involves multiple injectors. In this type of set up each cylinder has its own injector, which allows for more consistent fuel delivery to each cylinder. On a most OEM Multi-port system the intake is a two-piece unit with an upper and lower intake.
A multi-port injection system will outperform a CFI/TBI unit but requires changing out the intake manifold, requires more hood clearance for the upper intake, and will require modification to the air inlet and air filter. These potential issues aside this is the way I plan on upgrading. It is not only the better working system but is also unmistakably EFI under the hood and I want people at shows to know the car has been modified.
All fuel injectors are basically the same. An electric current opens the injector allowing pressurized fuel to spray out. What separates one injector from another is the injector flow rating. It is important to have the correct injector flow rate for you application as injectors that are to small will starve the engine of fuel and injectors that are to large will make tuning difficult.
There is a formula that you can use to calculate the correct flow rating for your application based on horse power, but rather than bore you with the math the list below gives the basic Ford Injector sizes, the approximate horse power per cylinder these injectors can support and the color of the injector top so you can more easily identify them.
14 Lb/Hr 29 HP:Cyl Gray
19 Lb/Hr 39 HP:Cyl Orange
24 Lb/Hr 49 HP:Cyl Light Blue
30 Lb/Hr 61 HP:Cyl Red
36 Lb/Hr 73 HP:Cyl Dark Blue
42 Lb/Hr 86 HP:Cyl Light Green
For my application I am going to be starting with the stock 19 lb/hr orange top injectors found on most ford 5.0 engines. However given that my motor is a mostly stock (other than headers and a performance ignition) 1984 5.0, I am only estimating about 225 to 250 HP which means 14 lb/hr injectors would probably be a better choice and I may end up having to change them.
Regulator and fuel rail
The regulator and fuel rail is the most important non-computer controlled components in a DIY EFI system. The reason for this is that it is potentially the main mechanical adjustment to the system. The fuel rail provides even fuel pressure to all the injectors, and the regulator controls how much pressure is set at.
Even though I could have gotten an OEM type fuel rail and regulator for less than $100, I chose to upgrade to a Mallory Performance Fuel Rail and Regulator Kit 4306M
There are lots of good reasons for making such an upgrade, the biggest of which is that the Mallory unit can flow more fuel. Currently I do not need more fuel, but at some point in the future I will be upgrading the motor to a high performance 351 and when I do that, an OEM fuel rail will not meet my needs.
Another benefit of the Mallory rail is that comes with an adjustable
regulator, which is a significant improvement over a stock unit as adjusting fuel pressure can help compensate for injectors that are slightly to big or to small. Other features of this performance rail include:
*CNC Machined billet fuel rails
*Fits all popular injectors
*Fits all popular OEM intake manifolds without spacers or matching
Will handle up to 2000+ HP
*Designed for use with oversize fuel supply/return lines
When you see the OEM unit next to the Mallory unit there is no contest as to which one is the better unit and I am glad that I made the upgrade to a Mallory unit.
An EFI fuel pump is a little different than the mechanical or electric pumps used on non-EFI cars. EFI pumps are all electric and designed to pressurize the fuel lines anywhere from 55 to 100 PSI. In order to more efficiently facilitate these high pressures the pumps are designed to push fuel rather than pull it. For this reason most modern EFI pumps are located in the gas tank. Unfortunately for the DIY type project there is no easy way to mount a modern EFI fuel pump in a classic gas tank with out major modification. This means an external pump must be used.
I chose a high-pressure fuel pump from a 1987 Ford F150 as it is one of the few OEM high-pressure pumps that can be externally mounted. Being that it is not in the tank a second, low-pressure pump, will be needed to get fuel to the high-pressure pump. I am undecided as to weather or not I will run the stock ford mechanical pump or use an electric pump as the initial pump.
Emergency shut off switch
In a DIY situation an emergency shut off switch is one of the most important and most over looked components in an EFI system.
As I said above the high-pressure fuel pump on an EFI system is electric and because of this, is not dependent on the engine running for the pump to be working. This could be a problem in the case of an accident. If during an accident the fuel lines were to rupture and the electric fuel pump remained running, the pump would pump fuel out through the rupture out and around the vehicle resulting in a serious fire hazard.
An emergency shut off switch is a simple fix to this potential problem and is wired in line with the fuel pump relay. The switch is impact sensitive and if an impact occurs the switch breaks the connection cutting power to the fuel pump relay, which shuts off the pump. These types of switches have a reset button on them allowing you to manually reengage the switch should it be unintentionally triggered.
You can’t have EFI with out a computer. The computer is what controls the system and triggers the exact amount of fuel needed based on information provided by various sensors on the engine and exhaust. With out the correct computer you will not be able to get an EFI system working. Ford has developed a fairly good line of EFI computers that they referred to as an Electronic Engine Control or ECU.
These units work very well, and as I mentioned earlier can be modified to eliminate some of the les desirable aspects of modern EFI. They also can be plugged in to aftermarket tuners and code readers to improve performance and diagnose issues in the system. The one thing that a person really has to look out for if sourcing an OEM ECU is the number of cylinders on the donor car. If you want an ECU for your V8 than the donor car must have an 8-cylinder engine. The same is true of a 6 cylinder or 4 cylinder engine.
The down sides to the OEM computer is that the programming and adjustability is limited and the ECU unites them selves can be cost prohibitive as used unit start around $500.00.
Another option and the one I chose is the Mega squirt home built EFI computer. This kit comes with everything you need to build your own EFI computer.
And once you have it built you end up with a quality fully tunable unit. This EFI computer is tuned using a laptop or desk top computer and is so versatile that it has been used on things as small as a 2-cycle boat motor and as fuel demanding as forced induction V12.
The down side to this kit is that you must build it your self. The direction are very clear, all the components are clearly label and where the components go on the circuit board are also clearly labeled making the actual assemble relatively simple.
With that said if you have no experience soldering components on to a circuit board than you probably shouldn’t learn on a Mega Squirt unit. Do not let me dissuade you as even those lacking in experience could successfully put a kit together. My warning is this if you have never done this type of work; you need to realize it takes practice to solder components on to a board with out damaging the components. So if you want to build your own Mega Squirt computer and have never soldered anything like this before, find and complete a few practice projects before you attempt to assemble a Mega Squirt computer.
The relay box is an important link/isolator between the computer and the components.
The advantage of a Relay box is that it serves as a bridge that separates the computer from the EFI components and the computer. If there were no relay box the full power being drawn by the components would have to flow directly through the computer requiring higher amp connections, and resulting in the computer producing a lot of heat.
Also not having relays to isolate the computer form the components would result in damaging the computer if there were any shorts or issues in the system. Most any EFI equipped car will have a relay box that could be adapted to your specific application, however I chose to purchase a relay kit designed to work with my Mega Squirt unit.
If you are running an OEM computer and OEM injectors you will also need an OEM wiring harness. At that point everything is fairly straightforward and you simply plug in all the connections.
In the case of my DIY EFI system the wiring harness will be a custom built piece. I will need to connect all the injectors, sensors and pumps to the relay board and an OEM harness will not work for my application, however purchasing an OEM harness designed to work with the injector system you choose to use is a huge benefit, as all the injector plugs are a specific configuration and will require the OEM clips. Also the OEM harness is nicely wrapped and gives an idea of exactly where to route said wires when building the custom harness.
The oxygen sensor or O2 sensor is the main feedback for the computer. It sits in the exhaust and sends signals back to the computer letting the computer know how the fuel is burning in the engine by measuring the oxygen ratio in the exhaust. This information specifically relates to the fuel air ratio and is what helps the computer know exactly how much fuel is being injected and how much needs to be injected to correct meet the engines current needs.
These sensors come in two categories, a one wire and a three/four wire. The 1 wire unit is the basic sensor and needs to be placed in the exhaust near the engine because the sensor needs to be hot to be accurate. Placing a one wire O2 sensor further back in the exhaust will cause it to be less accurate. A three/four wire O2 sensor is self heating and because of this has the advantage of being accurate anywhere on the exhaust you choose to place it and provides consistent results regardless of engine temps. Even though a three/four wire O2 sensor is typically more expensive than a one wire unit I chose to use a three/four wire type sensor for its obvious advantages in consistency.
EFI is more complicated than a carburetor but that added complication can be more easily managed with gages and idiot lights. Putting a gage on your fuel rail will allow you to check fuel pressure with out having to install an external gage. This is also important when using an aftermarket regulator so that you can see what pressure you are setting the system to. These gages come in both a mechanical and electrical configuration. I chose a mechanical unit as it was inexpensive.
The biggest advantage to an electrical unit is that the gage can be mounted in the cab so that you can monitor fuel pressure when driving where as the mechanical gage will need to be mounted directly to the fuel rail. Idiot lights can also be an added benefit. I plan on using LEDs tapped in to the outputs coming off of my relay board. This should tell me if the fuel pumps and any other relay controlled components are getting power.
As you can see there is a lot involved in an EFI system and the allure of a ready made system becomes apparent as you begin to look at all the potential parts and pieces needed to sources to put together a home built system, but with a little patience and research, you can learn how all these parts work and how to piece together your own system. I found two sites extremely educational as I was in the research phase of this project: Ford Fuel Injection
I will be brining two future articles on this subject with the next one covering the install of my DIY system and the final article covering tuning and the results of the install.