If you ever want to get a heated debate started on an internet forum, just ask whether carburetion or electronic fuel injection (EFI) is the best route to fueling your classic. You will surely get more opinions than you really need. That’s to be expected, as the internet is full of old folks like me that know carburetors and young enthusiasts like some of you that are not afraid of EFI.
Heated debate aside, take the time to peruse the internet, and you will surely garner some great information, and likely, just as much misinformation about the subject. Since my goal here is to help you guys gather good information, I decided to forgo the forum discussions and actually get some solid information from people that really have solid knowledge about the subject — the good people at Edelbrock and Holley.
This EFI Stuff Had To Start Somewhere
If we take a look at the development of EFI over the years, pressurized fuel squirting as we know it has roots dating as far back as the 1880s. Back then, the complexity of making it work is what prevented it from being utilized on a large scale. That is, until the 1920s. Even then, it was limited to use on diesel engines. Eventually though, in the mid-1950s, EFI systems began to appear on both diesel and gasoline engines — in both mechanical and electronic versions.
Those early EFI systems were designed around a throttle body that replaced the carburetor. Many self-learning EFI systems on the market today still utilize this design. The next iteration of EFI design was port fuel injection, which placed individual fuel injectors closer to each intake valve. This design is also utilized by some current aftermarket systems. Most recently, modern gasoline engines are now being fitted with direct injection. This system supplies fuel directly into each cylinder, not via the intake port like previous designs. Some direct fuel injection systems even co-exist with port fuel injection systems. But for the sake of this article, I want to focus on the most user-friendly systems on the market — the self-learning aftermarket types that enthusiasts have at their disposal.
While some people are still hesitant to take the leap into EFI for their classic ride, there are several reasons why it could be a viable option. There are also as many that explain why it might not be the right choice. I am not here to decide that for you. This article is written solely to give you information you can use to make the choice on your own.
EFI Goes Aftermarket
One style of self-learning EFI that enthusiasts can choose is Edelbrock’s Pro-Flo 4. According to Edelbrock, this sequential Port fuel injection system is not just a replacement for your carburetor. It’s a complete, engineered system that provides the ultimate in performance, drivability, and quality.
This system functions much like most late-model cars, utilizing eight injectors — one at each cylinder that injects fuel on time with the intake valve opening. This provides the most consistent and balanced performance under all conditions. Installing either system does require some mechanical aptitude, as you will need to add the ancillary EFI fuel-system components.
If you’re on the fence about updating to EFI, Mark Honsowetz of Edelbrock has this to say, “The prospect of EFI and computer programming can be intimidating to many people considering the swap from a carburetor. The Edelbrock Pro Flo 4 and Pro Flo 4+ systems have been designed to reduce the complexity and engineering skills required to calibrate an EFI system for a specific engine configuration. There is no need for a laptop, computer skills, or even a dyno session for tuning. The entire system has been designed with an emphasis on EFI simplified.”
“In fact, the E Tuner 4 App includes a simplified setup wizard that guides the user through loading a pre-calibrated map specific for their engine configuration. The engine will start and run very acceptably from the first turn of the key. In most applications no further adjustments are necessary. The EFI system has a sophisticated Closed Loop Fuel Logarithm that continually adjusts the fuel mixture for optimum performance. It is also self-learning, so performance improves as the vehicle is driven.” You can check out an install and dyno session by clicking here.
Another type of self-learning EFI is a throttle body injection (TBI) like Holley’s Sniper. This throttle body can be bolted onto your existing four-barrel intake in place of a carburetor. However, unlike a carburetor, there are no jets or adjustments that need to be made with a screwdriver. You literally bolt it on and turn the key. By delivering the look and feel of a four-barrel carburetor, these units not only offer a “traditional” appearance, but are also unbelievably easy to install. In fact, you can read all about an install here.
Fuel system requirements for carbureted and EFI applications have varying needs. To keep it simple, carburetors have low-pressure fuel needs (6 1/2 to 7 psi) while EFI requires 58-plus psi. That means a stock-style carburetor-feeding system will not work. If you’re swapping to an EFI system, you’ll need to address your fuel-delivery system before you get your vehicle wired and fired. Learn more about EFI fuel systems here. A carbureted fuel system’s mechanical or low-pressure fuel pump will not deliver enough fuel pressure to run EFI — or will it? If you do not wish to upgrade your entire fuel system Edelbrock has an option that might be perfect for you.
Edelbrock’s Universal EFI Sump Kit is designed to provide the necessary high-pressure fuel required for EFI applications in vehicles still using a mechanical fuel pump. This is a completely self-contained system that can be easily installed under the hood. It is also available in either a 67- or 105-gph delivery capacity. Its unique design allows it to deliver a constant fuel pressure with no return line, external fuel pressure regulator, or fuel tank modifications. It is compatible with the existing factory fuel tank and fuel pump. The Universal Fuel Sump is perfect for use in cars with engine swaps and/or those with aftermarket carb-to-EFI upgrades.
I am sure that many of you reading this have questions about installing a self-learning EFI kit on your ride. These self-learning kits have a predesigned fuel table that uses feedback from the kit-supplied and user-installed wideband O2 to read the air-fuel ratio (AFR). Based on this reading, along with other sensor readings, the system will increase or reduce the amount of fuel delivered, to get closer to your target AFR.
Another question I get asked is, how long does it take these kits to fully learn? In a nutshell, that varies. These systems will seemingly never finish learning. Something as simple as weather, temperature, and elevation changes can dictate how much fuel an engine needs. Therefore, every time you drive, the system will keep learning in order to get closer to your target AFR. Generally, it only takes a few hundred miles of driving for either system to get fine-tuned, but that is heavily dependent on your particular driving style.
EFI Or Carburetor: The Good, The Bad, And The Ugly
Both Edelbrock and Holley have been in the carburetor and EFI business for a long time, so they definitely have some good advice. For instance, when I asked which offers the best performance — carburetor or fuel injection, Evan Perkins of Holley had this to say, “there is a slight drop in temperature that occurs in a carburetor’s venturi as the fuel transitions from a liquid to a gas state that can, in some applications, give a carburetor a slight advantage in peak power production. However, the overall better control that EFI offers across the entire RPM band from low-rpm to high-rpm, and idle to WOT typically provides a much more significant improvement in overall power and drivability.”
According to Mark, “a very refined and calibrated carburetor can yield very close power numbers to an EFI system. However, carburetor performance will be inconsistent with atmospheric changes and under-hood air temperature variations requiring continual tuning adjustments.”
“An EFI system like Pro Flo 4 has a fuel injector strategically positioned in each cylinder runner, providing optimal fuel atomization and cylinder-to-cylinder fuel distribution. The intake runners from the throttle blades to the intake valves are dry, providing an increase in airflow velocity and volume. Acceleration events are more instantaneous and clean because of the lack of fuel puddling in the manifold plenum. The EFI system’s closed-loop self-learn strategy provides constant fuel calibration adjustment to compensate for atmospheric changes. Generally, in most applications, an EFI system will provide a five to ten-horsepower increase in top-end power with overall performance increases.”
Contrary to what some enthusiasts think, it’s not all about peak power. The control offered by EFI is unmatched when discussing emissions control and fuel economy. Since that control results in more efficient use of fuel, equaling reduced fuel consumption, and fewer emissions, it’s no wonder it began to replace the carburetor in the 1970s.
When discussing power and performance, there is no arguing that EFI and modern electronic controls are more accurate than carburetion. With EFI, fuel delivery can be tuned to match driver demand. While carburetors can be properly tuned to offer precise fuel delivery, that tune is not able to alter for outside effects. In other words, they cannot account for and adjust for changes in air or fuel temperature or atmospheric pressure like EFI can.
The initial cost and perceived complexity of adding EFI does cause concern for many. Since a carburetor is a purely mechanical device, it definitely has some benefit over EFI in that regard. Case in point, if you have a can of carburetor cleaner, a few simple hand tools, and some spare parts, you can rebuild a carburetor on your porch or at a rest stop. With fuel injection, repairs might not be so simple and could require a tow home. EFI owners do not typically experience fuel delivery issues as often as those using carburetors, but it’s still a consideration.
“Holley EFI products, just like our mechanical fuel products (pumps and carbs), are engineered to be durable on-road and off,” says Evan. “That’s the reason our EFI systems are standard issue on the COPO Camaro, Drag Pak Challenger, as well as many off-road racing series. Both options, when set up properly can be extremely reliable, and EFI brings some additional driving convenience most carbs can’t match. For example, cold-start and cruising performance are much improved with EFI.”
Making The Right Choice
Since Holley and Edelbrock both offer carburetors and EFI kits, I wanted each company’s stance on talking to those enthusiasts who are undecided about upgrading. “I would ask them how they plan on using their car or truck,” says Evan. “EFI has some great advantages over a conventional carburetor in just about every application, but for those of us on a fixed restoration budget, there might be more enjoyable ways to upgrade a vehicle — such as wheels or suspension. Improved fuel economy, increased drivability, precision engine control and monitoring at the racetrack, etc. might mean everything to one enthusiast and far less to another. It’s about priorities and enjoying your vehicle.”
What about the cost? “Well, here again, it depends on what you want to do with your vehicle,” Even relays. “If you don’t mind drivability problems when the engine is cold, or the humidity is high, then carburetors are for you. Simply put, no carburetor can do what a feedback EFI system can do when compared by cost. I have never seen a carb that you didn’t have to tune to offset changing conditions. These changes require carb disassembly in most cases. EFI can compensate for almost any change in weather conditions. Those that cannot be automatically compensated for by the ECM can be easily reprogrammed by PC or laptop computer in just minutes without getting your hands dirty.”
When I asked Mark about the initial outlay of cash of an EFI system being more than a carburetor, he had this to say, “the overall performance increase and performance consistency with EFI is worth the swap. Also, the Edelbrock E Tuner 4 App interface makes the experience very enjoyable and fun. The App is so simple to use, and tuning changes are instantaneous and made on the fly. If a change doesn’t feel right, you can simply just change it back in seconds. There are also gauge packages to monitor performance, and a diagnostics page so there is very little to fear. In fact, the experience can be pretty enjoyable and educational.”
But is a carburetor a better choice than EFI? “For someone racing in a spec or sportsman class, restoring a vintage vehicle, or building a fun weekend cruiser, carburetors remain an affordable, reliable solution,” says Evan. “On many engines that didn’t come from the factory with EFI, carburetors and carburetor rebuilding are a great way of keeping engine costs down.”
Mark states that Edelbrock has an entirely different position on the subject. “If a user is looking for optimum performance, we would never recommend a carburetor. However, some people are budget conscious and are willing to give up the extra performance for cost. We understand this, and the Edelbrock AVS2 is a great solution for these projects.”
The next argument I often hear for not upgrading to EFI has to do with breakdowns along the side of the road. Many “seasoned” enthusiasts feel they can fix an ailing carburetor with a screwdriver, 5/8-inch wrench, and sometimes, a small hammer. EFI parts do not like meeting the hammer — no matter how “small” it might be. Both Evan and Mark have the utmost confidence in the available aftermarket EFI systems.
“I don’t think this is necessarily a concern with a quality EFI system,” states Mark. “Engine control modules and circuit board technology have advanced so far in recent times that failures are almost nonexistent. Most of the components used in our ECU are the same as current production vehicles that are much more reliable than old-school carbureted vehicles. If a failure does occur, it is most likely self-inflicted and should be easy to troubleshoot. The E Tuner 4 App even includes a diagnostics page to assist with troubleshooting.”
Whether you are old-school and still like to use a carburetor, it’s tough to argue about the benefits EFI can offer. If you instill better drivability in your classic, increase reliability, and eliminate the need for any manual tuning, what’s not to like?