Custom EFI Component Selection Step 1: Choose ECU

Overview

The first and most basic choice when building a Holley EFI system is the selection of the ECU. In this course, we will review the different types of Holley EFI ECU's, discuss the differences, and will give some guidelines to assist the student in the selection of the correct ECU for his or her intended application.

What About the Sniper EFI System?

This article was originally written quite some time before the Sniper EFI System was available, so you won't find mention of that here. The purpose of this series of articles is to explain how to build a custom EFI system from the ground-up. The Sniper (as well as the Terminator and Avenger systems before it) is designed to be a complete system in one kit. The Sniper is fairly universal, and will work on any engine that can accommodate a 4-barrel carburetor with a 4150 (square) or spread-bore flange. No external ECU, minimum wiring, and no laptop is required. And, about half the cost of the cheapest of these other EFI options. If that sounds like you, then check out the Sniper EFI System.

Different Holley EFI ECUs

The easiest way of thinking of the Holley family of ECU's is that there are only two different ECUs: The HP and the Dominator. The HP is the physically smaller of the two, with only two harness connectors in addition to the USB and power connectors that are common to both. The Dominator is a larger ECU, mostly to accommodate the three additional harness connectors beyond the two on the HP.

"But wait", some will protest, "what about the Terminator and the Avenger?" These are not different ECU's, but rather the same ECUs that are pre-kitted with components and have a pre-loaded tune that allows the user to perform a very simplified setup process that accommodates those kits. In fact, any Terminator or Avenger ECU can immediately have access to all of the features of the HP and Dominator ECUs (at the loss of the simplified configuration, of course.)

This is one of the benefits of the Holley family of ECU's. If you want to start with a completely pre-configured fuel injection system such as the one of the Terminator or Avenger systems, but feel that you may later want to access some more advanced features later, you lose none of your investment in waiting until you are more comfortable in making that switch.

Holley didn't limit the interoperability of their ECUs to those sharing the same box. If you want to start with an HP ECU and later decide that you need the additional capability of the Dominator, simply replace the HP with the dominator, upload the same global configuration file that was running on your vehicle with the HP, and it will run identically on the Dominator ECU. There will be absolutely no difference. You can then add whatever Dominator-specific features you wanted to your configuration file and access the entire capability of the Dominator.

Selecting the right ECU

It has been said that the best way to start anything is with the end in mind and this is true when configuring a Holley EFI system for your application. You likely already have the information you need to make the right choice if you simply ask yourself some questions.

Are you ever going to want to do Electronic Transmission Control? If the answer is, "Yes" then it may be wise to start out with the Dominator. Even if you aren't going to do this right away, you lose nothing by going with the Dominator rather than the HP. Currently, the only transmissions that the Dominator controls are the 4L60/65/70/80/55E transmissions, but it is certain they will be doing more. If your application has a popular electronic transmission this is worth considering.

Are you ever going to need to do Drive-By-Wire throttle control? Again, if the answer is, "Yes" then you should probably opt for the Dominator. Harnesses are already available for both GM LS and Chrysler Hemi applications, and more are bound to be available.

Might you want to have multiple configurations available at the turn of a keylocked switch? Only the Dominator can provide this at this time. You can build a full race configuration, a daily driver configuration for yourself, a "safe" calibration for your kids, and a "just drive it slowly to the nearest parking space" calibration for the valet. Or, leave one of configuration free that will completely disable the ECU to protect the car from theft. The options are really endless.

Are you the sort that will keep finding things you want to control? Then, without a doubt, opt for the Dominator. This is where this ECU outshines just about everything on the market. The huge range of additional inputs and outputs allow this ECU to control anything you could possible want to control--and more. Holley markets their Dominator as a "Vehicle Management System" and that is spot-on. If you electronically "see" something, and if it is possible of electronically "touching" it, then you can control it with breathtaking precision.

Do you have a very firm notion of what you want to do with your EFI system, and does that not require transmission control, drive-by-wire, more than four programmable input/outputs, or multiple driver-selected calibrations? Then stick with the HP ECU. The HP is no weak sister. Other than the noted exceptions, it does everything as well as the Dominator and costs a good bit less. And, keep in mind that in the event that you find yourself months down the road needing something that only the Dominator can provide, you simply unplug the HP, buy the Dominator, plug the exact same harnesses in, download the same configuration to the new ECU and start the engine. You've lost no of your investment of time and effort in setting up the HP.

Buying the right ECU

Ok, by now you may have decided which ECU you need. To simplify the discussion, we will presume that most would want to build a Terminator or Avenger system will do so by purchasing one of the pre-configured kits. The rest of the class should at this point be equipped to select the right ECU for their requirements. Be sure to recognize that whether you purchase a Dominator ECU or HP ECU, you will need to also purchase a power harness for it. The same power harness works with either the HP or Dominator.

At this point it is important to note that Holley offers HP ECU/Harness Kits for the very most common applications on the US market. These kits contain not only the HP ECU but also all of the harnesses, and sensors required for the installation. The purpose of this series of articles is to allow you to individually select not only the ECU but each harness, sensor, and various other accessories that you will require.

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