Part 1: Testing MSD’s Atomic EFI In a Big-Block Chevy

We were offered the rare opportunity of testing a new electronic fuel injection system – an award winning fuel injection system, as soon as MSD Ignition began shipping the Atomic EFI conversion kit. Of course we couldn’t turn that down, as a matter of fact, we had been dying to get our hands on the kit after the first viewing at this year’s SEMA tradeshow.

Fuel injection systems are not new, in fact, direct injection fuel systems have been common in diesel engines since the 1920’s. Mechanical fuel injection became the standard for racers, bonneville cars and midget race cars in the 1940’s when hot rodder Stuart Hilborn began offering the systems. Electronic fuel injection hit the commercial market in 1957 when AMC offered the Electrojector system on their Rambler Rebel.

Even with the race proven efficiencies and power gains in fuel injection systems, the public was slow to accept the idea of electronic fuel injected cars until the 1980’s. One major reason for the public’s lack of acceptance of electronic fuel systems was the sophisticated and confusing controls and sensors. Home mechanics often felt that they could no longer work on their own cars if electronic fuel systems were involved.

While the rest of the world was focused on splitting atoms and creating massive energy releases with Atomic bombs, automotive enthusiasts tightly held onto the status quo when it came to internal combustion engines. When electronic fuel injection became the only option on commercial vehicles coming out of Detroit, car enthusiasts besieged aftermarket manufacturers to make conversion kits that replaced EFI systems with mechanical carbureted intake systems.

We invited Corey Dotzler to bring his daily driver, a carbureted '69 Nova, to the garage for a carb to EFI conversion.

Coming Full Circle

1960’s muscle car enthusiasts loved the simple look of carburetors and uncluttered engine bays while most of the commercial EFI systems offered at that time held the opposite look. Long fuel rails running down the cylinder heads, wire bundles criss-crossing the engine bay and lots of black boxes that prevented the do-it-yourself mechanic from tuning the engine easily.

At this year’s SEMA Tradeshow in Las Vegas, Nevada, we ran across a fuel injection system that would have changed car enthusiasts early opinions on electronic fuel injection had it been produced in the “atomic age” era of the late ‘50s/early ’60’s. MSD’s Atomic EFI fuel injection system is user friendly and simple and maintains a clean look under the hood with all the added benefits of EFI. It’s a great choice for anyone planning on a carburetor swap to fuel injection.

MSD, a name that is synonymous with performance ignition systems, has now branched out into electronic fuel injection in a big way with the SEMA award winning Atomic EFI Kit. MSD's Atomic EFI master kit contains everything you need to perform the conversion, including a new fuel pump, fuel filter, throttle body, hoses and controllers. There were no additional parts needed and no headaches in installation.

We felt that the time was right to branch out into other areas of internal combustion and fuel injection was a natural fit.     – Todd Ryden

Branching Out

Seeing MSD’s name on a throttle body seemed strange after having spending decades of seeing the logo on ignition systems. “We’ve dabbled in fuel injection components over the years,” said MSD’s Street Performance Division Director, Todd Ryden. “We felt that the time was right to branch out into other areas of internal combustion and fuel injection was a natural fit.”

We couldn’t wait to get our hands on one of these conversion kits because we had the perfect project car in mind to convert to modern fuel/air induction technology and pristine stock-like appearance. We invited Cory Dotzler and his ’69 Nova daily driver down from Santa Barbara, California, to our garage in the Inland Empire Region of Southern California.

Getting a Baseline

Cory explained that the six hour drive would be tough because the Nova was equipped with a GM 454 big-block crate engine with a monster carb on top. It’s street manners would not be polite enough in the bumper to bumper traffic of the SoCal highways. He also explained that the engine had some stumble and hesitation at different points in the power curve, so putting the throttle down during the accordion game of catching up to traffic and slowing down suddenly, then speeding up again would make for an unpleasant trip. We assured Corey that it would be worth the trip and we could fix his temperamental engine problems. The ’69 Nova soon found itself strapped into a 20 foot enclosed trailer heading to the powerTV garage.

The baseline dyno runs showed a max rear wheel horsepower of 285.32 and a max torque of 296.32 ft/lbs.

The trailer, with the Nova arrived, and after a brief introduction session, we had Corey fire the street machine up and move it to our DynoJet Chassis dyno so we could see what we were dealing with. Although the vintage Nova looked good, it showed its age by starting a little slowly and cantankerously running until things were good and warm.

A misadjusted, and oversized carburetor for the low compression crate engine was part of the issue. Like many car enthusiasts, Cory took advice from other car enthusiasts that suggested “bigger is better” when it comes to carbs. Carburetor companies have tried to dispel this myth by educating enthusiasts, but the myth that bigger CFM and bigger jets make more power still exists in many regions.

Once the engine was briefly warmed up to the point where it would idle steadily, we made our baseline pull on the DynoJet. The Nova had never been on a chassis dyno before so Cory had no idea what power numbers to expect from the low compression crate motor. The first pull registered 285.32 rear wheel horsepower and 296.32 max rear wheel torque. A subsequent run registered lower numbers due to higher operating temperatures. With the baseline run established, our shop guys started removing the carburetor system and installing the Atomic EFI system.

Baseline Dyno Numbers

HP 285.32

TQ 296.32

Corey Dotzler’s 1969 Nova

  • GM 454 HO crate engine (Part #12568774)
  • Cylinder Head: Cast iron, rectangular port
  • Valve Diameter:2.19/1.88-inch intake/exhaust
  • Chamber Volume: 118cc
  • Camshaft: Hydraulic roller tappet
  • Lift: 0.510/0.540-inch intake/exhaust
  • Duration: 211 intake, 230 exhaust @ .050-inch tappet lift
  • Centerline: 112 ATDC intake, 112 BTDC exhaust
  • Rocker Arm Ratio: 1.7:1, stamped steel
  • GM Performance Parts aluminum dual plane manifold (Part #19131359)
  • 8.75:1 compression ratio
  • Stock TH350 Transmission
  • 3-inch-diameter exhaust system through Hedman ceramic-coated shorty headers and Flowmaster mufflers.
  • 10-inch converter with a 3,200-rpm stall speed

The Problem

While Cory is a car enthusiast through and through, there were some issues with carburetor adjustment and tuning that he was not comfortable with. It was clear that his daily driver would have benefited from some good old fashioned carb tuning and know how. A decent carb tuner can really make some serious horsepower in practically any engine, and that what Cory was lacking.

If you want to take advantage of fuel efficiency and are not worried about maximizing engine power to the ultimate ragged edge of the power window, or if you don’t have the skills in tuning a carburetor to the engine, this is where EFI units really shine.

The Goal

MSD’s Ryden explained “The key goal of the Atomic EFI kit is to take a complicated system and make it simple to install, use and simple for a user to adjust if they make engine upgrades. Simplicity and looks were the overall goal, but it had to operate well for us to put the MSD name on it.”

MSD's Atomic EFI throttle body was exactly as advertised...a true bolt on replacement part. The throttle body easily bolts on to any square bore intake.

We set out to judge for ourselves the level of simplicity MSD’s new EFI kit was. If we know anything about the laws of automotive maintenance, many components that advertise bolt on replacement, aren’t.

Opening the Atomic EFI conversion kit we took inventory, and for a system that monitors air temp, coolant temp, throttle temp, exhaust O2, manifold pressure, fuel pressure and throttle position…it looked like the kit was a little on the small side. As we inspected the throttle body and controllers, we noticed that MSD has ingeniously designed many of the sensors and fuel controls into the body of the unit.

Atomic EFI Master Kit (Part # 2900) Includes:

  • 1,000 CFM Atomic throttle body
  • Atomic EFI Power Module (With wide band O2 sensor)
  • Hand held controller
  • Standard Fuel kit for up to 525 hp (at the crank)
  • Suggested retail: $2,290.00

EFI systems require several sensors that relay data to the ECU in order for the system to work. MSD engineers have incorporated most of the input sensors into the throttle body which makes the system compact and clean looking. A bottom view of the throttle body shows all the technology that is actually involved in the EFI system. Once installed, this is invisible to anyone looking under the hood.

The throttle body itself looked very similar to the main body of a carburetor but Ryden assured us that airflow was not a problem, “The Atomic EFI throttle body can flow approximately 1,000 CFM. The horsepower is not limited by airflow, rather it is limited by injector size,” said Ryden adding, “With the large fuel pump, the maximum output of the Atomic is 625 hp.”

The wet flow throttle body houses the ECU and incorporates the throttle position sensor (TPS), manifold absolute pressure sensor (MAP), Intake air sensor (IAT), and fuel pressure sensors in one location on the right hand side of the unit. Also designed into the throttle body are internal fuel rails that provide fuel to four 80 pounds per hour (@60 PSI) fuel injectors, one for each corner of the throttle body. The body’s design creatively reduces the size of the kit as well as reducing the fuel lines and fittings where leaks could potentially develop.

Sensors like the Inlet Air Temperature (IAT) are discretely incorporated into the throttle body's design.

Ryden had told us about the quality components that made up the system, “the fuel injectors that we use feature a stainless steel ball and seat metering method. The stainless steel ball and seat are significantly stronger than other materials used in off the shelf fuel injectors.”

Key Features of the Atomic EFI System:

  • Fewer electrical connections
  • Returnless fuel system design
  • Controls the ignition timing through the ECU
  • Improved air/fuel distribution through annular ring injection design
  • Self learning technology eliminates the need for PC programming

Simple Installation

Ryden was correct about the simple installation. We removed the bulky carburetor that sat on top of the 454 crate engine and bolted up the Atomic’s throttle body. This is one case in the automotive maintenance world where the “bolt on” part actually is a bolt on part. The Atomic EFI throttle body bolts directly on to any square bore carbureted intake manifold, and it accepts the throttle linkage and air filter unit that were originally on the engine. We even noticed a smoother throttle operation with the unit.

Throttle linkage hooks up exactly like the carburetor that we removed. We were surprised at how smooth the throttle operation was with the new throttle body.

“Our Atomic EFI throttle body uses precision 1.75-inch diameter throttle valves (butterfly valves) attached to a throttle shaft that rides on precision roller bearings,” said Ryden of the throttle controls. In using high quality throttle valves, throttle shafts and ball bearings, the transition throughout the full range of the throttle was noticeably smoother at the pedal.

He also explained that the “throttle positioning sensor is a proprietary non-contact sensor,” which reduces any setup configuration. The TPS is self calibrating, so once the throttle linkage is hooked up, you don’t have to worry about it again.

The throttle body bolted on easily and the linkage required no adjustment, it bolted on without any issues. The next step was hooking up the fuel line, which turned out to be the most labor intensive part of the whole installation. When hooking up the fuel line is the step that is the most difficult…you know that the installation is easy.

Return or Returnless?

When it comes to hooking up the fuel line, there are a couple of things that need to be clarified. If the engine that you are installing the EFI system on is currently operating with an engine driven fuel pump, we have good news. You can pull the mechanical fuel pump and push rod and use a blocking plate to seal the block. Engine driven fuel pumps do not operate with enough psi for a fuel injection system. MSD includes an electronic fuel pump in their master kit, and offer it as an accessory to their other Atomic EFI kits. The good news in switching to an electronic fuel pump is a reduction in parasitic drag on the engine typical of mechanical fuel pumps. Electronic fuel pumps also have an advantage in placement and higher psi performance.

We decided to use the PWM fuel pump in a returnless fuel system. Finding a good place to mount the pump is one of the first steps.

The other issue that you need to resolve when plumbing the fuel system is whether to run the system as a returnless fuel system or run a return line back to the fuel tank. MSD includes instructions for both, and either way is simple to plumb in, but we suggest using MSD’s flow chart to determine if you need to install a return line or not.

MSD even includes fuel line to make the connection from the fuel tank to the throttle body.

According to Ryden, “The operating fuel pressure for the system is between 30-75 psi if you are using a PWM system (Pulse Width Modulated) returnless system. If you have your own, or installed a regulated system, the required pressure will depend on horsepower. Most engines will use close to 45 psi while engines pushing 600 HP will need closer to 70 psi.”

Everything needed is supplied in the kit to make a complete fuel supply from tank to engine.

We decided to run the system as a returnless fuel system on Corey’s car, which meant that all we had to do was locate a suitable spot for the fuel pump and filter and install the fuel line from the gas tank to the pump and filter, then from the filter to the throttle body. Cory’s car had an off-the-shelf electronic fuel pump already installed, so we located the MSD fuel pump in the same spot and used the existing positive and ground wires to power the pump. It simply doesn’t get any easier than that.

Determining to run the system with a return line or returnless is a matter of using the chart in MSD's instructions.

O2 Sensor and Water Temp Sensor

The only two external sensors to the throttle body assembly can be installed at this point. Chances are most likely that if you are performing a carb to EFI swap, your exhaust system does not have provisions for an O2 Sensor.

The sensor supplied in the MSD Atomic EFI conversion kit is a wide band Oxygen sensor which helps real time determination if the air fuel ratio (AFR) in the engine is rich or lean. O2 sensors are very sensitive to air leaks in the exhaust system so now would be a great time to check over the entire exhaust system.

Installing the O2 sensor is simply a matter of drilling a 7/8-inch hole and welding the sensor's bung to the exhaust tubing.

Once the exhaust tubing is back in place, the O2 sensor can be installed in the tubing with ease.

Installing the O2 sensor is a matter of drilling a 7/8-inch hole in the exhaust where the O2 sensor will go. The weld the supplied bung in the newly drilled hole or have an experienced weldor perform the welding. After the exhaust system is back in place, put a light coat of anti-seize on the O2 sensors threads and install the sensor.

The engine coolant temperature sensor can be installed in an open port on the intake manifold or in the cylinder head.

Most engines have provisions for a coolant temperature sensor on the cylinder head or intake manifold. Find a location for the sensor and remove the old sensor or plug, then wrap the threads with teflon tape or sealer and install the new coolant temp sensor.

Power Module

The power module component of the EFI system handles the higher current circuits of the system, like cooling fans, fuel pumps and the wide band O2 sensor. Locating the power module is much like mounting MSD’s ignition boxes. They can be mounted practically anywhere.

Installing the power module to the firewall gives it a place away from direct heat and close enough to route the cable to the handheld controller to the driver's compartment.

With the Atomic EFI’s power module, the unit is best if kept away from direct heat, like radiant heat from headers, and in a location where fresh air flow can aid in cooling. We mounted the power module in Corey’s Nova to the back engine firewall and connected the five wires that must be connected for the system to operate.

The hand held controller plugs into the power module, so mounting the power module on the firewall allowed us to route the hand held controller’s electrical harness through the firewall and into the driver’s compartment. Having the hand held controller inside where the driver can see the display comes in handy when you want to verify your instrument gauges or trouble shoot fault codes.

Setting Up The System For Operation

The initial setup takes about five minutes and a little information. When you power up the system for the first time, you will be asked to answer six questions about your engine. This information provides the Atomic EFI controls data that will ensure your engine works properly.

Setting up the system for operation is also a snap. Simply answer 6 questions about your engine and get ready to fire up.

The system will ask you the basics of your engine like engine displacement, number of cylinders, fuel pump type (return or PWM), idle RPM, Rev-limit, timing control and camshaft type (street, mild, performance).

Frequently Asked Questions

Will the unit compensate for altitude and does the key need to be cycled to do so?
On altitude changes, the unit will compensate for altitude changes if you go above 50% throttle and are between 1200 and 3000 RPM. You can also cycle the key to the off position for 3 seconds which will have the same effect.

Does the unit increase idle speed and fuel for cold starting?
Cold start conditions will be automatically compensated for and will decay out as the engine warms up. By the time it reaches 145F, idle speed and fuel compensation are completely removed.

What are the temperature limitations (hot and cold) for the system?
The Atomic EFI can withstand under hood temperatures in excess of 200*F and as low as 0*F.

If you want to get a little deeper and do some advanced setup, the hand held controller allows you to setup your electrical cooling fans (separate on temp for both fans), AFR targets (idle, part throttle, wide open), Ignition timing (curve settings), and Pump squirt (0-100%).

We dialed the system in for Corey’s Nova and prepared to fire the beast up. Immediately the PWM fuel pump started clicking away moving fuel up to the throttle body. When we were certain that the fuel had reached the throttle body, we hit the starter and the engine came to life.

Corey couldn’t wait to drive the car around the block a couple of times, so we let him warm the engine up and let the ECU start self adjusting the fuel curves. After a few laps around the parking complex, we brought the Nova in for another run on our DynoJet chassis dyno to see what the performance difference was.

Once the engine was cooled down, we fired up the newly EFI equipped Nova for a final run on the dyno. With eager anticipation, the wheels of the dyno slowed down to a stop and the final numbers appeared on the screen.

When the run came up showing 315.19 rear wheel horsepower and 322.93 max rear wheel torque, Corey’s faith in the crate engine was restored. A twenty nine real horsepower gain right out of the box with an additional 26 ft-lb., with no other modifications. What’s more, when the A/F ratio was compared to our initial baseline run at wide open throttle, we found it was the A/F was a full point under. We saw 13.54 A/F versus a cleaner, 12.55 A/F at maximum horsepower on the dyno.

Keep in mind that a properly selected carburetor that was tuned for the engine would have also made substantial gains. For Cory and this project car, a simple installation with a “fire and forget” self tuning system was a better choice. It’s likely that many of the “self-learning” EFI systems would have seen similar type power gains, but Cory liked the simplicity and look of the MSD Atomic EFI system.


Which Engines Can Benefit From The Atomic EFI?

Ryden explained that the Atomic EFI system was a perfect system for most engine sizes. “The Atomic EFI will support engines with at least 100ci to a very large 800ci maximum with only a few things that must be changed on the handheld controller for initial setup between combinations.”

With all the LS engine swaps taking place in different project car builds, we asked if the Atomic EFI could be used with an LS engine. “Yes, with the addition of a MSD PN 6010 box, it can handle the fuel delivery, but not individual coil spark. 
If you are running a front mount distributor and single coil, you will be able to use timing control with an ignition box,” said Ryden. In case you were wondering, there are plenty of aftermarket LS intakes with square bore carb mounting on the market. Swapping an LS engine into an early muscle car while keeping the benefits of fuel injection and making the swap easy and simple is a reality.

Corey was so pleased with the system that he put the Atomic EFI sticker on his windshield.

Getting Ready for Part II

We sent Corey and his newly EFI powered car out on the town for a week so we could get some feedback on how the system works after a week’s worth of self learning and tuning. In the meanwhile, we gathered together with our shop technicians to discuss this easier than easy carburetor to EFI conversion. In part two of this series we will bring you the aftermath of Corey’s week of driving and our own driving observations. Next month we’ll bring you these highlights of Corey’s Atomic-ly correct ’69 Nova.

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
Read My Articles

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