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Self-tuning electronic fuel injection… sounds pretty complicated, doesn’t it? That sophisticated level of technology may be keeping enthusiasts from making the switch from carbureted to EFI fuel systems because of fear, yet nothing could be less fearful with the latest generation of self tuning EFI systems.

What’s even more important, these modern systems work with the newer ethanol fuels to the point where these fuels burn more efficiently with these EFI systems than they ever did with carbureted systems. Most of these self tuning EFI kits enhance the drivability of your vehicle just by bolting on a unit that looks and acts like a carburetor – and there is nothing scary about that.

We wanted to take a look at four of the most popular self-tuning EFI systems in the market today: Edelbrock E-Street EFI, FAST EZ EFI 2.0Holley Terminator EFI and MSD Atomic EFI.

What Is An Entry-Level, Self-Tuning EFI System?

Basically, I like the concept of self-tuning EFI systems.                   – Rich Gala, EFI expert at Billy Briggs Racing Engines

Ideally an entry-level EFI system is an electronic fuel injection system that can replace a carburetor yet doesn’t require users to understand complicated fuel maps or tuning strategies in order to setup and use the system. As an entry level system we expect any upgrade to be simple, functional, and made for the average guy. Having said that, most average guys don’t spend incredible amounts of money building ridiculous amounts of horsepower that makes a project car undriveable on the local streets.

Considering that NASCAR Sprint Cup cars recently started using a Holley EFI fuel system in 2012, and those engines are rated just north of 800 horsepower and Formula One naturally aspirated V8 engines create 740 horsepower, an entry level EFI system should easily support between 200 to 500 horsepower. 

Holley's Terminator EFI has a throttle body that looks like a four barrel carburetor but has the same airflow design characteristics as the Holley EFI used on NASCAR's Sprint Cup cars.

Holley’s Terminator EFI has a throttle body that looks like a four barrel carburetor but has the same airflow design characteristics as the Holley EFI used on NASCAR’s Sprint Cup cars.

Entry level self-tuning EFI systems were basically designed to replace four-barrel carburetors on naturally aspirated engines. This allowed the older non-EFI engines to take advantage of the reliability and efficiency that EFI systems bring to internal combustion engines. These modern systems from Edelbrock, FAST, Holley and MSD offer greater reliability, better fuel mileage, easy installation, are very affordable and work as a cohesive unit with the sensors and the ECU to adjust the fuel map by itself. No jets, no adjustments and no laptops!

If choosing one of the many bolt-on self tuning EFI kits worries you, then follow along as we do a closer look at four of the most popular self tuning EFI kits on the market. This detailed look at what each unit brings to the table will help you decide which is best for your application. 

Why Use A Self Tuning EFI System?

Part of the allure of an EFI system is fuel mileage. Efficiency and correctness stem from highlighting the features of the EFI system. Rich Gala, EFI expert at Billy Briggs Racing Engines, explained where the self-tuning EFI systems really shine. “Enthusiasts that are realizing that electronic fuel injection systems run better in the cruisers are really going to see the biggest advantage in converting to a self-tuning EFI system. Unless you like having to pump the gas pedal eight-times, then stall the engine and have to repeat the start up procedure.” Gala adds, “These new EFI kits are budget friendly and are perfect for the guy that doesn’t want to pay to have someone install a system and come up with a custom tune for the engine. These systems can easily be installed by the enthusiast.”

Self-tuning EFI systems are perfect for crate engines or mild build engines. “Anything that is not ridiculously wild and is streetable can benefit from these kits,” said Gala. “Any engine that has vacuum issues, brake booster issues or have radical cams may have some difficulty. If you have a wildly radical camshaft, you may need a custom built tune that accounts for the skewed vacuum signals,” adding, “Basically, I like the concept of self-tuning EFI systems. For cruisers, they work really well.”

We’ve taken all of these highlights from each system and compiled them into one easy to read comparison chart. This chart will help determine which system is best for the intended application.

The Systems

About Ethanol Fuels

Alcohol fuels, like ethanol, require certain adjustments in car engines to be fully operational. Engine tunes are not required for low concentrations of ethanol fuels but for E85 and E95, modifications are needed. Ethanol contains greater amounts of oxygen which can destroy car engines if the tune is not correct.

E10 – Composed of a mixture of 10% ethanol and 90% gasoline, commonly referred to as “Gasohol.” Can be used in automobiles without any modification to the engine or fuel system. E10 blends are typically rated as 2 to 3 octane higher than regular gasoline.

E15 – Composed of 15% ethanol and 85% gasoline. As of November 2012, sales of E15 are not authorized in California. The blend is awaiting approval by the California Air Resources Board (CARB).

E85 – Composed of 85% ethanol plus 15% gasoline, E85 is the concentration recognized by the US Department of Energy as an alternative fuel. This mixture has an octane rating of about 105, which is significantly lower than pure ethanol but higher than normal gasoline.

We’ve selected four popular self-tuning EFI systems from companies that make different product lines of electronic fuel injection systems. The EFI kits we are featuring in this article represent the entry level, self-tuning, four barrel carburetor replacement systems. Each system will find a group of enthusiasts that support the brand but we want to find out the reason why.

All four of the systems feature a handheld controller of some sort. None require a laptop but three of the four were laptop compatible. MSD was the sole exception to this feature because of the simplicity parameter that they set in the design.

All four had a setup wizard designed in the software to make getting started an easy process, even for users that were not as technologically savvy as today’s learn-by-the-web generation. Every one of the throttle body units from these four systems fit a square flange intake manifold with a Holley 4150 style bolt pattern. 

All four systems were E15 compatible but only the FAST EZ-EFI 2.0 and Holley Terminator EFI kits claimed to be E85 compatible. Often times the most time-consuming part of the conversion is upgrading the fuel system. EFI systems generally must have a high pressure fuel system to work, so an EFI high pressure fuel pump is used. Each manufacturer deals with the fuel system differently, and we found that Edelbrock has a unique solution that doesn’t even require you to get under the car or replace your low pressure fuel pump for their EFI system. 

We also called in Brian Macy, Owner of Horsepower Connection, Instructor at the EFI University and renowned EFI expert, for commentary on these popular systems. Let’s take a closer look at each system in alphabetical order.

Edelbrock E-Street EFI

Edelbrock’s E-Street EFI system supports a wide range of applications but was truly designed for the do-it-yourself’er that wants to make performance upgrades in stages. Edelbrock’s Smitty Smith told us,”The best feature of this system is that it is part of a complete power package. If a guy wants to add E-Street cylinder heads, valvetrain upgrades or intake manifold later, this EFI kit has been designed, tested and will work with those upgrades perfectly for a complete power package upgrade.”

“The home-run in this package is the ability to do the complete install under the hood,” said Smitty. “With our fuel sump kit, you never have to get under the car for any part of the installation. The sump kit uses the vehicle’s existing low pressure fuel system. This is perfect for any user desiring any easy installation that delivers reliable fuel pressure and performance with no potential for starvation at low fuel levels. The sump kit performs well in all weather conditions,” he added. 

Base Kit Price: $2,198.97

Horsepower supported in base kit: 650 hp.

Features of the E-Street EFI:

  • Ready to run right out of the box with a pre-loaded tune in the ECU to get you up and running
  • Dynamic Fuel Control
  • Fully assembled and pressure tested throttle body with injectors, fuel rails, linkage and sensors that readily accepts round air cleaners for a traditional look
  • Features progressive throttle linkage for great drivability and increased mileage potential
  • Includes a fully assembled OEM quality wiring harness with pre-terminated connectors for an easy installation
  • Easy to use software pre-installed on the supplied 7″ touch screen tablet
  • Wireless Bluetooth connectivity between the ECU and the tablet
  • Create, modify and save unlimited tunes
  • Capable of controlling electric radiator fan and A/C relays
  • Full feature software is simple to use for novice users, but also capable of complete control of all parameters for experienced EFI tuners
  • System will automatically adjust for future engine upgrades

E-Street EFI installed in the engine bay of a classic Corvette.

While the Edelbrock E-Street EFI system is a later entry into the market, Smitty assures us that the company did not want to rush a product on the market. “We have a solid core of customers that believe in the Edelbrock name. Edelbrock represents quality to them and we can’t release anything to the public that hasn’t been thoroughly tested.”

We recently installed Edelbrock’s E-Street EFI on a classic Corvette. To view the full article on the EFI upgrade, click here.

Power Automedia shop manager Sean Goude summed up the Edelbrock E-Street EFI system by saying, “This simple to install kit can be used with a return style fuel system, a returnless fuel system or the stock low pressure fuel pump with Edelbrock’s sump fuel system. The sump-style fuel system is ingenious and makes dealing with an EFI conversion incredibly easy. You don’t even have to get under the car to adapt the fuel system for EFI use.”

The E-Street EFI kit features a supplied 7-inch touch screen tablet that acts as the input controller for the system. The tablet has blue-tooth connectivity which means you don't have to drill holes through the firewall for controller cables.

The E-Street EFI kit features a supplied seven-inch touch screen tablet that acts as the input controller for the system. The tablet has blue-tooth connectivity which means you don’t have to drill holes through the firewall for controller cables.

When it comes to installation and use, Goude added, “The bluetooth connectivity made wiring the system even easier because it requires fewer wires. Plus, it keeps the installer from having to drill a hole in the firewall for controller cables. This is a major advantage when you are dealing with something like a classic Corvette.”

“Because it is more recent to the market than some of the other systems, the E-Street EFI is polished. Features like the cold start tuning are refined to the point where the system starts quicker and doesn’t have to do much seeking to optimize the tune right out of the box,” said Goude.

FAST’s EZ-EFI 2.0

FAST EZ-EFI 2.0

According to FAST’s Brian Reese, “Our system can handle 1,200 horsepower. That’s more than double what anybody else is doing. We can do that because we have eight-injectors and have better fuel distribution. This system can also handle E85 without changing a single component. All you do is tell the system through the handheld controller that it’s E85 and you’re good to go. The system will also do returnless fuel if you desire it.”

FAST EZ-EFI


FAST’s original EZ-EFI is still available as their entry level carb to EFI conversion system. Regardless of the engine make or size, the EZ-EFI system easily bolts on to any carbureted engine making up to 650hp. No manifold replacement is needed. The EZ-EFI fuel injection system also works with the original carb-style throttle linkage and features OEM sensors, including standard GM versions available at any auto parts store. The EZ-EFI system works with all ignition setups, including HEI ignitions.

EZ-EFI Features:

  • No tuning experience or laptop needed. Setup Wizard guides you through the start-up process & tunes itself as you drive
  • Built-in diagnostics & “limp home” mode is designed to provide maximum engine protection in the event of trouble
  • Bosch wide-band o2 sensor provides precise air/fuel readings allowing EZ-EFI exceptional tuning accuracy
  • Holley-style throttle linkage & 4150 bolt pattern allow for direct replacement of Holley 4 barrell carbs
  • 1100+ CFM 4 bbl EFI design allows for responsive low end w/ good drivability & support of up to 650 HP
  • Works w/ carb-type single or dual plane intake manifold
  • Uses all commonly available OEM GM sensors
  • Work w/ original carb-type ignition; Including HEI
  • Clearly labeled loomed wiring harness w/wide-band O2 sensor
  • Priced at $1,784.95

Our expert Brian Macy added, “In addition to the eight-injectors, the throttle body has an integrated MAP sensor, air temp and throttle positioning sensor. It is a pretty clean setup with the ability to make some horsepower for those that want more than the 500hp mark. We were very impressed with the throttle response of this unit and well as the look and overall drivability.”

Base Kit Price: $2,298.00 and comes with a Limited Lifetime Warranty

Horsepower supported in the base kit: 1,200 hp with the FAST in tank pump.

Features of the EZ-EFI 2.0:

  • Eight-injector throttle body supports stock to 1200 hp engines
  • Advanced color touchscreen hand-held doubles as sensor dash w/suction-cup mount – Same mounting points as Garmin GPS
  • ECU includes on-board LED diagnostics & EZ-Test indicator lights
  • Setup wizard guides you through start-up & tunes itself as you drive
  • High-quality harness w/ mesh loom & wide-band O2
  • Throttle body features Holley carb-style throttle linkage & 4150 bolt pattern
  • Works with standard carb-type distributor or FAST distributors for plug-and-play electronic timing control with nitrous timing retard
  • Markets only fuel pulse damper; return or returnless fuel systems supported
  • Available in Multi-Port Systems for GM LS engines & other multi-port EFI V8 engines
  • E85 fuel-capable

We installed a complete FAST EZ-EFI 2.0 fuel system upgrade on a vintage Nova recently. The article detailing the upgrade can be viewed by clicking here.

“It’s the most advanced self-tuning system we have installed in our shop,” said Goude, Power Automedia shop manager. “As far as installation goes, it is an entry-level system but the options that it offers makes it more of a mid-level EFI system.”

Defining the difference between entry-level and mid-level, Goude had this to say, “If you plan on doing any racing, there are plenty of options in this system that you would be interested in. That is what makes this an advanced system. A user with advanced tuning knowledge can customize the tune to their needs and application.”  

The advanced features screen on the EZ-EFI 2.0 handheld controller.

 Holley Terminator EFI

“The Terminator EFI unit has the same throttle body air entry area design that powers every NASCAR Sprint Cup Series car,” explains Doug Flynn, Holley Fuel Injection Engineer. “There are a lot of car owners out there that just want to drive their car and enjoy it for what it is. The Terminator EFI system helps make that possible. While it is important to keep a car original to some people, sometimes those views shift when you live in an area where cold starts are rough on a car, or there is a great deal of elevation change. The fuel that you purchase at the pump these days is also less kind to carbureted applications. All of those problems can be alleviated with the installation of a Terminator system, making it possible to add a degree of new-age technology to your vehicle while keeping the old school carbureted look.”

Holley’s Terminator Self-Tuning EFI kit.

Base Kit Price: $1,999.95

Horsepower supported in the base kit: 250-600 hp engines

Features of the Holley Terminator EFI:

  • No laptop required, self-tunes instantly to deliver the perfect air/fuel mixture in real time for optimized fuel economy and power
  • Virtually maintenance free–keeps your vehicle reliable and ready to drive
  • 950 cfm throttle body designed with CFD (computational Fluid Dynamics) computer software
  • Patent-pending annular discharge fuel ring for maximum flow and optimum fuel atomization
  • Serviceable sensors integrated into throttle body and pre-wired for a simple one-click connection
  • Connections for Ford, GM TH350, and 700R4 transmissions
  • Fits any square Holley 4150-style flanged intake manifold
  • 80 lb./hr fuel injectors support 250-600 hp engines
  • Provides ignition timing control on engines with small cap HEI and Ford TFI distributors
  • ECU can be used for LSX, boosted, nitrous, and many other applications

Holley’s Flynn explains that the Termintor EFI system can be used with the common ethanol blends on the market today, even the E85 blend. “The Terminator system does not utilize a ‘flex fuel sensor’, so it does not change its tune based on input from such sensor. However, the wideband oxygen sensor it utilizes will quickly correct for any ethanol content in the system, as well as the fact the self-tuning will adapt to the fuel.” The system is sold in two versions; the Tumble polished version and the Hard Core Gray version. 

Holley Terminator EFI installed.

We did a product review video and article on the Holley Terminator EFI when it was first released to the market. To view the article and video, click here.

Holley Terminator EFI’s handheld controller.

Brian Macy added this commentary, “The Holley Terminator EFI uses the same ECU as Holley’s HP system and can be tuned with a laptop. The laptop tuning available feature makes this a good choice for the cars that need a little tweaking.”

Power Automedia’s Project Manager Sean Goude had this to say about the Terminator EFI system, “It’s a nice and compact throttle body that can easily be hidden under the air cleaner. The system has well designed fuel tables and the sensors work well in this system. We installed it on a vehicle that unknowingly had very bad vaccum leak issues. While we spent several days tracking the vacuum leak down, the Terminator EFI made a crappy motor run pretty decently. Once we fixed the vacuum leak at the manifold, this unit really shined and the engine runs great.”

MSD Atomic EFI

MSD’s Erik Brock explained their thought process in developing the MSD Atomic EFI system. “We set out to design an EFI system that could replace a four barrel carb without any complications. To make it so easy that a guy like my Dad, who is intimidated by his smart phone, could install and use the system without any difficulty.”

The MSD Atomic EFI is also California Air Resources Board(CARB) approved. This means that on 1987 and older GM vehicles, this system is legal and will allow you to pass SMOG without any sort of hassle. 

“If you design an EFI system that terrifies people, then you’ve failed. With its ease of setup and use, we think that we hit it right on the head with the Atomic EFI,” Brock stated.

MSD Atomic EFI Self-Tuning throttle body.

Base Kit Price: $2,429.00

Horsepower supported in the base kit: 625 hp engines

Features of the MSD Atomic EFI:

  • Throttle body features an integral ECU built on the side
  • ECU incorporates the TPS, MAP, IAT, and fuel pressure sensors, all in one location
  • Fuel delivery is provided by four precision 80 psi injectors featuring a stainless steel ball and seat metering method for maximum internal sealing.
  • Bolts directly to any standard square bore carbureted intake manifold and accepts the same linkage as most carburetors
  • 1.75- inch diameter throttle inlets that ride in precision roller bearings for a smooth pedal transition
  • A unique TPS that is a self-calibrating, non-contact sensor
  • CAN-Bus technology that allows for a single, clean connection between the power units and the throttle body mounted ECU.
  • Hand-held device that controls the EFI system’s functions
  • Quick initial setup.
  • CARB approved on 1987 and older GM vehicles

It wasn’t enough to build a simple system, MSD wanted to allow for some expandability to those users that wanted to grow with the system. “There are a few options like ignition controller, and a fan controllers that steps outside the basic EFI system. It’s not a ‘me too’ EFI system in the marketplace, the Atomic EFI is simple to install with only 8 connections, yet it is boost or Nitrous ready in the base kit off-the-shelf,” said Brock.

The MSD Atomic EFI installed.

We street tested MSD’s Atomic EFI conversion kit on a 1969 Nova. To view the article on this upgrade, click here

Brian Macy, owner of Horsepower Connection, said this about MSD’s Atomic EFI, “The MSD Atomic EFI has an on-board ECU built into the side of the MSD throttle body. This system also had very good throttle response and overall packaging is clean and very easy to install. One cool feature of this system is that it will interface with all other MSD products like Racepak dash, MSD ignition products very well and very easy.”

Power Automedia shop manager Sean Goude explained why the Atomic EFI was a great entry level self-tuning EFI kit, “This system can be operated with a returnless fuel system which simplifies things for a home garage mechanic. He doesn’t have to drop the fuel tank, which makes for an easier installation.  It’s a super basic, great running, super easy to install and use system right out of the package. We installed it on a pretty decently built big block Chevy in a Nova and the project car ran much better than it did prior to the installation.”

MSD Atomic EFI handheld controller.

Summary  

Clearly there is a spot for each of these EFI systems in the aftermarket automotive industry. The audience for each system is, and should be, just a little different. The MSD Atomic EFI kit is perfect for the enthusiast that wants to upgrade from a carburetor to fuel injection but doesn’t want to be burdened with all kinds of technical inputs from the user. Just plug and play then go. 

Holley’s Terminator EFI is great for the enthusiast that wants something a little more in an EFI system. It is plug and play system that is as easy to use as the others, but the user has the ability to grow with the system and upgrade the software for even more flexibility. That is the draw with this self-tuning EFI kit. 

Edelbrock’s E-Street EFI is the perfect system for an enthusiast that wants to upgrade his complete power package in stages. From EFI to Cylinder heads and beyond, the E-Street kit is designed to work with all of the Edelbrock E-Street components for extra simplicity without sacrificing performance.

FAST’s EZ-EFI provides all the performance that a “techie” could want. Supporting 1,200 horsepower, it’s unlikely that an enthusiast will outgrow this system for a street machine. With options galore, this system will suit everyone including the local track weekend warrior.

In our view, this is a winning hand with four-of-a-kind and you can’t go wrong selecting one of these fine kits.