Ive done a number of long write ups on this subject and have installed a few different systems (Fitech 4bbl, Firtech tri power, F&B 6 pack with FAST controller, F&B with Holley HP controller). It isn't rocket science but can be pretty confusing if you don't have any experience with it. Here is a write I did for someone else.
What system you use is entirely up to you, each has its advantages and limitations. I am not sure what your experience is with EFI, so if I say something you know, my apologies.
There are a number of main issues here that require consideration and ultimately make a decision on, however in general is comes down to the EFI type, system, the fuel system, and the electrical system.
THE EFI TYPE - There are 2 types of EFI, direct port injection (DPI) and throttle body injection (TBI).
1. Direct port injection uses a modified intake or one purposely made to accept injectors and a fuel rail. These are very efficient and are used in all modern cars today. The intake remains dry meaning that no fuel enters the intake itself, rather fuel is sprayed directly into each cylinder.
2. Throttle body injection (AKA TBI) has injectors installed into the throttle body itself (usually with some other sensors as well) and sprays fuel into the intake much like a carb would. They are popular because you can use the same intake you used with a carb.
THE EFI SYSTEM - there are as you have discovered many different systems on the market, so much so that it makes it very difficult to make a coherent decision and given that none of them are exactly cheap, no one wants to make the wrong decision. In general, there are basically 2 types of EFI;
1. Basic (aka self-learning): This would be like Fitech or a FAST EZ system. In essence you bolt it on, connect the wires, answer some questions into the handheld and go. The system will learn as you drive. As far as I know, there are not any self-learning EFI direct port injection systems, all I have seen are throttle body designs. It’s worth noting that pretty much all EFI systems you look at will have a self-learning feature, however in a basic system that is all you have/get and you cannot make any changes directly. This is not an issue on a stock or mild engine, however an engine with a big cam, high compression, etc. may not do well with a basic system because the computer cannot tune correctly.
PROs - easy to install and connect, relatively inexpensive. Computer/controller is typically very small and easy to mount/hide and the wiring is very simple, Fitech needs 4 wires to run.
CONs - not as efficient as a direct port system, any problem affects the entire system (throttle body). In general, they are not as efficient or responsive because they normally only control fuel although there may be some systems that can integrate spark control.
2. Advanced - This would be like a Holly HP or some of the FAST systems wherein you have a fairly large computer and have to tune the computer with a laptop and perhaps a dyno. An advanced system can be used on a TBI or DPI type system, but is always found on DPI systems.
PROs - very comprehensive and able to be tuned to any engine setup and/or performance goal. Much more tunable and configurable. Typically, these systems are set up to control spark as well as fuel in addition to the fuel pump, fans, and AC. Some of these systems also can integrate into dash mounted control panels that will provide a wide range of data and even show various gauges. They are much more versatile overall and can control a wide range of functions, additionally they allow you to install specific tunes for specific conditions and can adapt to changes to the engine.
CONs - More expensive generally, computer is significantly larger and can be a challenge to mount in a classic car but certainly not impossible. They do require more understanding to make work well and in ideal situations you would want to tune the vehicle on a dyno, however this is not mandatory, it just takes longer to do it manually.
THE FUEL SYSTEM. This is the most discussed and misunderstood aspect of EFI. There is a lot of misinformation roaming around the internet and on forums, but more so there are a lot of DIY people out there who make something work initially and claim success, however in many cases these cobbled together systems are fraught with issues and problems that in many cases case people to hate EFI.
The biggest issue with EFI fuel systems revolves around the return line. There are systems on the market which are marketed with the “no return line required” statement. However, in almost everyone of them, once you get it and read the instructions you will find a statement saying “return line highly recommended”. While, it is possible to put a returnless system in, it is not optimal and comes with issues.
There are 3 types of EFI fuel systems out there;
1. Fuel command style systems – this is a system where a component is installed into usually the engine compartment where the fuel line from the normal fuel pump to the carb is rerouted to the fuel command system at low pressure. The command center turns the fuel into high pressure and a line is run from that to the EFI system. The return line from the EFI system is run back to the command center. The advantage of this system is that it is the least evasive system on the market, allows the standard fuel system to be used, and does not require return lines or a new fuel system. The down side to this type of system is that the command center is pretty large and does take up some room.
2. External fuel pump system – in this system, you have a fuel pump mounted under the car somewhere along with a pre and post filter. In most cases this requires new fuel lines (feed and return) and the stock fuel pump is removed and eliminated. The advantage of this system is that it is relatively easy to install, if the pump ever has issues it is easy to replace. The down side to this style is that the pumps tend to make some noise and they do not last as long because they get hot and of course they are subject to road damage.
3. Internal pump system – this is the most often used system and by far the most desirable. This places a high-pressure pump into the tank where it can remain cool as well as reduce a lot of the noise. The down side is that to replace them can some times be an issue depending on the application.
2 other issues involved here fuel lines and filters.
FUEL LINES – Fuel lines for an EFI system must be rated for a high pressure (EFI can run 60+ psi whereas a carb system runs around 7 psi). Steel lines will work as may aluminum lines (some manufacturers state aluminum cannot or should not be used), also steel braided or EFI rated nylon braided line). Of course, the appropriate ends must be used with whatever line is used.
FILTERS – EFI requires a very clean system and most systems demand that you use a 40-micron pre-filter and a 100-micron post filter. Failure to use the appropriate filter will result in the failure and potentially the destruction of the EFI system.
THE ELECTRICAL SYSTEM. Many thinking about installing an EFI system do not think about the electrical system, however EFI demands clean steady power to operate correctly. The old 60 Amp alternator with original wring will most likely not suffice, or suffice for very long. It is usually recommended that at least a 100 Amp alternator be used, but to really know what to install, you need to determine what the electrical needs are.
There are other aspects of installing and using EFI but none of it is super difficult, it just takes some careful thought and approach.
