Today, our product spotlight is on MSD Atomic EFI Fuel Injection Systems.

We’re going to talk about the various components that make up these systems, what they do, how they do it, and how they can provide an easy path to quick starts, smooth idling, and instant throttle response.

In addition to great performance, the Atomic EFI was designed for simple installation.

MSD Ignition officials say it can be done in one day. One of the major perks of this system is that you can run a returnless fuel system, eliminating the need for fuel tank modifications or installation of an additional fuel line.

The Throttle Body 

Full of unique design features and capabilities, the Atomic EFI throttle body is designed to bolt in place of standard square bore carburetors and accepts the same linkage.

Highlights of this throttle body include:

  • Engine Control Unit (ECU) and Sensors
  • An Internal Fuel Rail
  • The Annular Rings
  • The Throttle Position Sensor (TPS)
  • The Injectors

Engine Control Unit and Sensors

The ECU is vital to the throttle body. It features a design that reduces wiring for easy installation and a cleaner look. The throttle position sensor, manifold absolute pressure (MAP) sensor, intake air temperature (IAT), and fuel pressure sensor are all incorporated inside the Atomic EFI’s ECU. Because of this, the only sensors you have to connect are the coolant temperature, and oxygen, sensors.

Internal Fuel Rail

The fuel rail is important to the throttle body assembly’s design. It looks cool and it eliminates certain fitting connections susceptible to leaking. With a single fuel line, you can bring up the fuel line from the back, or use the front fitting.

The Annular Rings

The annular rings on the throttle body were designed to provide superior atomization of fuel—giving you the best air/fuel mixture possible to each cylinder.

The Throttle Position Sensor

The Atomic TPS is an automatic, non-contact sensor that MSD says is unlike anything you’ve used before, and auto calibrates at every start up. All of that means you don’t have to fuss with any configurations during set up. Because there is no contact, nothing can wear out or requires replacement.

The Injectors

Four precision 80-pound injectors deliver the fuel. The injectors contain a stainless steel ball and seat metering for optimum internal sealing. The injectors are sealed between the housing and the cast fuel rails, providing a secure mount.

The Power Controller

The compact power controller controls all of the high power systems, like electric fans and the fuel pump control. A single connection plugs into the throttle body. Two fan control wires allow you to program at what temperatures your fans should activate.

The Handheld Controller

MSD introduced this controller so that you racers can leave your laptops at home or at the office. Combined with the self-learning capabilities of the Atomic’s ECU, you can set up the system to play nicely with your particular engine in a matter of minutes. The handheld also acts as a dash display that will feed you information about how your Atomic system is running.


Consult the diagram below for the proper way to configure the fuel system, or visit for more product and installation information!


Author: Matt Griswold

After a 10-year newspaper journalism career, Matt Griswold spent another decade writing about the automotive aftermarket and motorsports. He was part of the original OnAllCylinders editorial team when it launched in 2012.