Deep Dive: A Look at the Latest Upgrades in Holley EFI V6 Software

10 min read

Deep Dive: A Look at the Latest Upgrades in Holley EFI V6 Software

10 min read

Computer software is a lot like Midwest weather. If you’re not satisfied with it at this moment, just wait and it will change. The same could be said for Holley’s latest Version 6 (V6) software for the Dominator and HP computers. While Version 5 offers immense power and control and its popularity is growing – drag racers needed a leg up on the ultra-quick cars that are now becoming increasingly popular.

Holley’s aim with this latest upgrade targets the more sophisticated drag racers using the Dominator and HP ECU packages. While V6 will work as an upgrade, the changes from V5 are focused on strictly drag racing innovation and control. The V6 can be used as the latest version of Holley’s ECU software for street or autocross applications, for example, it’s just that the major upgrades won’t apply to anything outside of high-end drag racing.

Holley EFI V6 software update

This V6 upgrade can only be used on Holley Dominator or HP (shown) ECU’s and is also intended specifically for drag racing applications and not necessarily for street use but certainly it can be used as the latest version of Holley’s software.

But for those straight-line enthusiasts, there’s plenty to talk about. In the early days of drag racing, creating horsepower was the primary focus for running quicker than the next guy. Today, horsepower is easy to make with No Prep racers and other radical door-slammers managing in excess of 3,000 horsepower.

This has changed the current drag racing landscape so that now the focus has shifted from making power to how to control all that power. The successful racer is the one who best manages that power to put down what the track and traction will allow. Control by way of digital manipulation is what Holley’s new Version 6 is all about. We’ll run through a brief description of each bullet point to make it easier to understand.

Shift Outputs

With serious door slammers now well into the 3.50’s in the 1/8th-mile, manually shifting a car consistently requires superhuman concentration. Holley’s V6 system offers the ability to upgrade to digital shift control for both two- and three-speed autos as well as Liberty and Lenco manual transmissions.

The V6 system can now control up to an 8-speed drag racing manual or automatic. Management falls under one of two different configurations with either single or discreet operation. The single configuration is used when the shifter operates a single solenoid even if it shifts multiple times. The Discreet version is the control side for multiple solenoid operations.

Regardless of whether you prefer a CO2 air shifter or an electric solenoid, Holley’s new software can control both. On a TH400, for example, the Shift Output would be configured under a single output since a single solenoid is all that is required to execute both shifts.

In Shift Power Management, the software allows you to retard (or advance) timing during the shift to better manage the gear change. It is often advantageous to retard timing through the completion of the shift to not break the tires loose on the gear change. We’ve plugged in some random values to illustrate the power of the software. The red line represents the 1-2 shift while the blue is 2-3. Note that the values for each series are listed in the lower portion of the display. In this case, the timing is retarded 2.5 degrees during the 1-2 shift (red scale) at the 1.494-second point.

The more complex Discreet operation can control up to 8 forward shifts by commanding an electric or CO2 solenoid through a relay or air pods on a Liberty or Lenco directly without the need for relays. The software can be triggered either through a timed basis or by an rpm trigger or as a combination of both control mechanisms simultaneously. More importantly, there is a Shift Power Management program within Shift Output that can perform an ignition cutoff or power reduction through a timing retard feature executed to control power during the shift. There is another area in Shift Output that also controls torque converter clutch management that we’ll discuss later.

As with all the V6 systems that we’ll discuss, there are various initializations and trigger mechanisms that must be enabled before the system will function and all of these must be either specified or disabled in order for the system to operate as intended. Many of these systems are put in place to operate as safeguards to prevent mistakes that could be dangerous or that could damage parts. As an example, the Shift Output operation would not occur until the minimum rpm or a specified time has elapsed.

Within Shift Output, there’s also a provision for “pedaling” where the driver may have to lift slightly in order to keep the car straight or to compensate for tire spin or shake. The pedaling function pre-configures Shift Output to either freeze the timer function when the ECU encounters less than 100 percent throttle opening (as reported by the throttle position sensor- TPS) or to continue the shift timer if that’s the primary function for the shift point. In addition, each gear is also independently configurable for either time or shift rpm.

Holley V6 Main Features

Mode Features
Shift Outputs Both 2 and 3-speed autos plus Lenco and Liberty
Converter Lockup Outputs Lock and unlock on gear change
Dump Valve 4 outputs to control converter dump
RPM Spool Assist 2 outputs to help turbo engines spool quicker

Shift Power Management

Let’s dive a little deeper into Shift Output control to investigate what Holley calls Shift Power Management. This is essentially engine power output control (or torque management) during the shift. V6 offers finite torque control through the ability to retard (or add) timing during and just after the duration of the shift. This is offered both as a control mechanism that can improve transmission durability as well as a way to manage traction upon completion of the shift.

All standard Holley ignition maps offer a two dimensional (2D) graph that plots ignition timing against time. Shift Power Management can be initialized by the ECU based on pre-selected shift control inputs. These timing changes can be as small as 0.1-degree over equally short 0.001-second time intervals. This allows the tuner to create very precise curves that are individualized for each gear. There are also delay features that can be added for each gear to offer additional options.

Engine cutout can also be initiated in this same fashion if, for example, power interruption is necessary to initiate a manual transmission shift where this is necessary to unload the gears.

There’s also an additional function called Inactive Time After Shift where adding 1-second to this function over-rides any other shift command for one second. This comes into play for example if the car creates massive tire spin hitting the shift rpm for 1 second. If this occurs, without the Inactive Time After Shift, the ECU could immediately command a shift to the next higher gear. The delay feature prevents this from occurring.

The Holley Dominator and HP ECU can directly control any device that draws 2.0 amps or less. But the majority of the control solenoids will likely draw much more than this so a relay is the best way to accomplish this.

Converter Lockup Operation

This next level of control is aimed at high horsepower cars equipped with lockup converters. In the Version 5 software, this could be accomplished by customizing an input/output (I/O) tables. Version 6 includes a series of preconfigured tables that make this easier to navigate and control. Converter lockup may involve multiple stages while offering a very sophisticated series of control parameters. To start, Version 6 offers lockup control for each individual gear. So it’s plausible that the converter could be launched, locked up and subsequently unlocked for each gear change.

Further, with the correct external components, V6 offers pulse-width modulation (PWM) control. A simplistic definition of this would be that the ECU can control the rate at which the lockup function of converter is engaged. So over a set length of time (0.50-second for example), the ECU can pulse the engagement solenoid to achieve progressive lockup. This helps minimize traction issues on lockup. This can be triggered either on a time basis or by a combination of time and/or rpm. If the “and” function is enabled and specified with an rpm, both time and rpm must be achieved before the lockup will initiate.

The pedaling feature discussed previously can also be applied to converter lockup to give the tuner wider freedom of operation. This is generally initiated by establishing a minimum TPS position. Once the converter is unlocked due to pedaling, it will then lock back up at 100 percent with no functions for PWM control.

A dump valve is an external solenoid-controlled device that diverts line pressure away from the torque converter to increase the stall rpm. Generally, these devices can increase stall by roughly 400 to 700 rpm and sometimes higher. This is accomplished by reducing the volume of fluid entering the converter, which creates cavitation. The V6 software allows control over as many as four separate valves that otherwise operate in a stand-alone condition as on-off devices. However, when the solenoids are tied into the Holley Dominator ECU, they can be more finitely controlled by the V6 software. The additional control offered by the V6 software allows the tuner to experiment beyond using these valves only on the starting line and then disabling them down track as a tuning parameter.

While normally these valves function either on or off, V6 offers PWM control for incremental increases in stall speed at any point down the track. This option functions opposite from torque converter lockup but there are applications where this could be potentially beneficial.

There are also several options for when these dump valves can be operated. For example, the dump valves could be triggered simultaneously with the engagement of the trans brake, and then disabled at a given rpm or time after the trans brake is released and the car has moved down track. Then there could be PWM control only after the car reaches a selected gear. The V6 software offers multiple opportunities to use these valves.

Spool Assist

Spool assist and converter lockup features are especially useful with turbocharged engines in managing their tremendous power output as well as allowing the turbos to spool more quickly during staging.

Along with the above contingencies, the V6 also offers a separate control feature for turbocharged applications. Once the trans brake is enabled, Spool Assist merely closes a valve once the designated boost has been achieved. So if 10 psi is selected, the output will deactivate at 10 psi and reactivate at 9 psi if the boost drops.

While previous versions of the Holley software offered significant nitrous control, V6 does adds a few new features. There is a Tuning Summary at the top of the nitrous screen that places all of the stages across the screen so they can be viewed all at once. Plus, there are new entries that allow the user to enter the size of fuel and nitrous jets used for each stage. Another plus for dry nitrous versions is a map that will track the total amount of fuel added for each stage. There’s also a new Summary map for ignition retards for each stage again to help keep track of the amount of timing changes per stage.

Finally, the Holley engineers have made some minor updates to areas including rev limiting, drive-by-wire, traction control, and data logging. As you can tell, this upgrade is really intended for the hard-core drag racing crowd that relies on sophisticated software to help manage the huge amounts of power that are now abusing tires across the country. If you’ve managed to work your way through this description and understand the parameters and the opportunities, then you are a candidate for taking advantage of what the Version 6 software has to offer. With all these additions, there’s now more opportunities for the racer to add increasingly more finite controls over the vehicle. As power continues to escalate, the tuner who can manage all that power the best will likely be the quickest competitor down the track. And that’s the name of that tune!


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