…the ideal situation would be the ability to just bolt on the hardware, wire-up the electronics, and then hit the streets

The next step up is the HP-Series system, with the HP ECU at the heart. Naturally, this engine management system employs Holley’s latest self-learning strategies, but where it differs from the Avenger is in its capabilities. With eight injector drivers, the controller will operate a V-8 engine in full sequential mode, which means this system is ideal for most port injection setups. On the ignition side, the HP has an eight-channel distributor output to operate coil-on-plug ignition systems, and is plug-and-play ready for GM LS engines with 24x or 58x crank trigger wheels. This only scratches the surface of the HP’s capacity, with other features such as four programmable input and output channels to support devices like boost control, progressive nitrous, water/meth injection, speed inputs, fuel pump control, AC inputs, timing retard inputs, and various other uses.

At the top of the spectrum is the Dominator Series system. Again, the step up is in system capabilities, and the Dominator ECU has it all and more. Inside there are 12 injector drivers, 12 channels of distributor-less ignition output, and the input and output auxiliary channels to run just about any engine system imaginable. The system even has integrated transmission controls for GM 4L60/80E transmissions, and astounding data-logging capabilities. The full list of features is far more than we can outline here, but we can say if you are looking for the maximum level of control capabilities in a system with self-tuning logic, the Dominator delivers the goods.


Taking a different strategy to the goal of self-compensating EFI systems are the offerings from Mass-Flo. While the other systems rely on variations of the speed-density strategy, as the name implies, Mass-Flo uses a mass-flow strategy, centering upon the readings of a mass airflow sensor. This is the strategy used by most OEM EFI systems, using the actual measured quantity of air as signaled by the mass airflow sensor to form the basis for the required amount of fuel. In fact, Mass-Flo uses OEM ECUs, which are built to a very high degree of reliability, and have the sophistication of OEM-level engineering built in.

The beauty of using a mass flow is that the amount of air entering the engine is constantly monitored, and the air/fuel ratio is proportionally adjusted to compensate for the load and operational conditions as recorded by the engine sensors. This makes the system very neutral to changes in the engine combination, allowing substantial changes to the basic engine configuration without the arduous re-tuning process required of a typical speed/density system. With changes in specifications, such as a cam swap, new heads, or intake and exhaust changes, the Mass-Flo system will measure the resultant change in airflow directly, and always compensates with a proportional change in fuel quantity. If very large changes are made requiring a change in injector size, the ECU can be sent in to Mass-Flo and recalibrated.

Mass-Flo provides a complete engine management system, with full ignition and sequential fuel control in every system. As far as the tuning, the mass air system takes care of the details in a way that a carburetor or speed density system just isn’t capable of. This makes the Mass-Flo system remarkably user-friendly. The goals are improved power, torque, fuel economy, performance, and reliability. In contrast to a conventional programmable speed density system, the end user will never have to tune this system. The cost savings are obvious here, with no need to employ the services of a professional tuner, and no need for the dyno service usually associated with tuning an EFI system. This also saves time and the logistics of getting a vehicle to the dyno. With the Mass-Flo system, once it is installed, you are done.

Mass Flo EFI
77 Snow Road
West Brookfield
MA  01585
1801 Russellville Road
Bowling Green
KY  42101
3400 Democrat Road
TN  38118