Different combinations respond differently to different power management techniques, and as a result, the MSD 7531 box offers several methods to optimize traction. The rev limit curve, often referred to as “riding the dots”, allows racers to limit engine rpm in 100-rpm increments based on time. It’s programmed using MSD’s easy-to-use tuning software in which rpm is graphed on the vertical axis and time is on the horizontal axis. Let’s say you want to leave off the transbrake at 5,500 rpm and shift at 7,000 rpm, but you’re spinning the tires coming out of the hole. With the “dots” feature, you can set up the Digital 7 to limit engine rpm to 4,000 rpm a few tenths of a second into the run, then ramp the rpm back up to 7,000 after two seconds, once the tires have had a chance to hook. For the ultimate in precision, you can set the dots as close as 0.001 seconds apart. To establish a baseline curve, you can record a run using the Digital 7’s data logger, copy and paste the rpm off that run into a new map, and fine-tune it from there.
The slew rate control offers a way to maximize traction without relying on a driveshaft rpm sensor to detect wheelspin. Instead, users can set the maximum acceleration rate of an engine in rpm per second. The nice thing about slew rate control is that it provides a rate of acceleration control for each gear, so if you’re spinning the tires after shifting into Second gear, you can set it up to limit wheelspin. The slew rate control even has features that account for crank flex and other mechanical variables within the engine. Perhaps the simplest way to enhance traction with the MSD 7531 is with its time-based launch retard. With this feature, you can pull out timing at launch, then progressively ramp it back. For example, if your engine has 36 degrees of total ignition advance, the launch retard feature allows retarding the timing coming out of the hole up to 15 degrees, and ramping it back in from 0 to 2.5 seconds into a run.
The Power Grid is the next generation in programmable ignitions and offers several updates over the Digital 7. It has a faster, more efficient microprocessor along with an all-new Windows-based software system. The Grid has many features that racers have asked to be improved, including timing by time cylinder timing alterations and other improvements. The Power Grid consists of two pieces: the ignition side (PN 7720)—the brawn—and the Power Grid controller (PN 7730)—the brains of the system. It may seem counterintuitive to separate the two systems, but this arrangement has a few advantages. First, it eliminates the need to offer four different part numbers to have legal systems in all of the different racing classes. Second, it allows racers to install the 7730 Power Grid controller to an existing ignition system, such as an MSD 8 or Pro Mag, and step up to computer programming capabilities. Being able to connect the Grid controller to an existing MSD ignition box will save racers money simply because they do not need to buy an all-new system to gain access to the increased control that the Power Grid offers. If a racer is building a new car or upgrading the engine to the point where increased spark energy is really needed, they can upgrade to the Power Grid ignition as well as the Power Grid controller. One advantage the Power Grid ignition does have is higher output than standard programmable MSD boxes. However, if a racer is happy with their tried-and-true 7AL-2, but wants to be able to control the timing of each cylinder, adding the Power Grid control module (PN 7730) is the most cost-effective route.