Many owners want more power from their late-model muscle car, and electronic tuners can be a simple, cost-effective way to unlock it. But tuners can deliver performance gains that go far beyond the headline horsepower number – gains that will make a huge difference to the feel of the car every day, from sharper throttle response to faster shifts.
To explore the performance gains in more detail and demystify a tuning process that can sometimes seem like a black art, we caught up with Michael Litsch, DiabloSport’s senior product manager for domestic tuning.
Litsch says that an electronic tuner can commonly add 25 to 30 horsepower to a modern, naturally aspirated, V8 muscle car running on premium fuel. The increases are typically greater for boosted motors like the Hellcat.
Making muscle-car horsepower through electronic tuning follows the same principles that engine builders have long used to chase power: optimizing timing and fueling to find the perfect balance of power, safety, and performance. These adjustments will be familiar to anyone who’s ever turned a fuel screw on a carburetor, changed a fuel jet, or played with mechanical advance curves and a distributor. And as with a carbureted motor, optimized timing will also help with throttle response.
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“Through the fine adjustments available in the powertrain control module (PCM), we have full access to the timing maps and fueling controls,” Litsch explains. “We make sure that the fuel comes in at the right place and that the correct amount of fuel is being used in all scenarios, optimizing the air-fuel ratios for maximum power. And then we start altering the timing. On a simple level, you keep increasing the timing until the power stops going up. That’s the motor telling you it’s where it wants to be.”
Bumping up the shift points in the automatic transmission can be another way to increase power, depending on the motor. “The Coyote Mustangs are a great example of that,” he observes. “Most of our tunes for 2011-and-newer Mustangs might only add 200 to 300 rpm to the shift points, but the power curve is still climbing, so there’s a benefit to be had.”
Even when the headline horsepower gain from electronic tuning may not seem huge, the power is typically more usable than before, so the customer immediately feels the benefit. Litsch says that oftentimes, a new engine calibration will involve liberating the horsepower that’s already there, not just adding ponies, even if that’s how the result feels to the owner behind the wheel.
“As with many modern muscle car applications, you can expect a tuner to gain you around 25 horsepower on 2005-10 Chargers,” he offers as an example. “Chargers respond so well to tuning because they’re saddled with so much torque management. OEMs are sometimes over-aggressive with it as a method of keeping parts alive, regularly limiting torque output to far less than the transmission can handle. In my experience, tweaking the torque management can convince drivers that the car has picked up 20 horsepower.”
As with horsepower, an electronic tuner can not only enable the motor to produce more torque but also allow the driver to enjoy more of the torque it’s already producing. In fact, if you notice that the vehicle is “making more power” after a tune, chances are you’re feeling the torque, not the horsepower.
“Torque is a function of timing,” says Litsch. “In many cases, optimizing the timing will increase the torque. But in a lot of situations the vehicle has the capability to make more torque than it does, simply because the torque management doesn’t allow it, especially at lower engine speeds. You’ll never experience that unless you have a manual transmission but 90% of late-model muscle cars have automatics.
“Increased torque – or simply unleashing the available torque by reducing torque management – is what gives you that seat-of-the-pants feel,” he continues. “It’s what defines a muscle car according to the template set down by the Big Block cars in the 1960s. Once you’ve tuned the motor, it can put whatever it’s capable of making to the ground, as opposed to losing it through the transmission, or at the rear end, or having it limited at the throttle. We can control many ways to improve torque output that are not always obvious to people.”
Throttle response is another great way to change the feel of a muscle car, even without increasing its power output. By-wire throttles enable fuel-economy-minded OEMs to dilute the feeling when you push the pedal to the floor, so an electronic tuner has plenty of scope to improve muscle-car throttle response, providing a more immediate ‘tip-in’.
“We encounter many scenarios in modern muscle cars where literally nothing happens when you push the throttle to the floor,” says Litsch. “The PCM decides when the throttle body moves. In Camaros and Corvettes, for example, GM limits the throttle-opening up to 3,500 rpm. As a result, you’re missing power down low, but we can change that variable to 100% throttle across the board. The car will feel like it picked up 30 foot-pounds low down, without affecting timing or fueling. There are many neat benefits like that available in our calibrations.”
In a similar vein, ’99-’02 Camaros and C5 Corvettes have a power enrichment (PE) delay. When you floor the pedal, the air-fuel ratio remains at 14.9:1, so the car makes no additional power for a specified PE delay of around 1.5-2.0 seconds, during which time it’s slowly ramping in fuel. “Set that delay to zero, and the change is astonishing,” he adds. “Suddenly it’s blowing the tires off when you floor it. You didn’t add any power, just removed the limitations.
“If you only adjust timing and fueling, but don’t address the throttle openings and torque management, you’ll never notice any of that power,” Litsch continues. “It must all tie together, which is why we refer to it as a calibration, not just a tune. It’s an engineering process to understand what and where the limitations are.”
DiabloSport tuners for GM and Dodge muscle cars also have a Throttle Boost parameter that enables further adjustment of the electronic throttle pedal.
“If it’s adjustable in the calibration, we will increase the sensitivity by 10 to 15% in our tunes,” Litsch relates. “We would always urge people to drive it before you adjust it further. But if you feel like you want more sensitivity, we give you an option to add another 20%, which will make it really snappy. “Standalone, inline throttle boosters are a huge market, but they’re artificial,” he expands. “It’s a different experience anytime you do something inline and trick the computer, versus reprogramming right inside the PCM, as we do. It gives you a more linear and realistic throttle feel than some inline throttle boosters.”
We’ve already seen how delaying the shift points sometimes helps an engine to make more power. Electronic adjustments to transmission shift pressure are another way to boost muscle-car performance. This too, is an area where OEMs calibrate the hardware to perform well below its capability, whether to make the car easy and comfortable for inexperienced drivers to handle, or as a means of differentiating between Normal, Sport, and Track modes. This inherent potential enables tuning companies like DiabloSport to unlock more performance, all of the time.
“It can be tough to visualize, but, for example, a GM transmission might have a table of values for shift pressure populated with values of 700 psi for a nice, firm shift,” Litsch shares. “But the stock transmission only shifts at 250 psi because elsewhere in the transmission controls, the shift pressure is limited by a scalar of 250 psi. Raise that single value to 700 and suddenly, the transmission can use every value that was populated in the table. You now have firm shifts without having changed any of the shift pressures in the calibration.”
Transmission tuning can deliver performance even where fueling and timing changes cannot. An engine tune on Litsch’s own Coyote Mustang, for example, gained him only 15 horsepower at 7,000 rpm – not an improvement you’re likely to feel on the drag strip. But bumping the shift points by 300 rpm and speeding up the shifts knocked three-tenths off his ET in the quarter-mile.
“Fifteen horsepower was worth maybe a tenth at best,” he assesses. “The other two-tenths came from non-power-adding adjustments like shifting more firmly, getting into the next gear quicker, and applying the power more quickly.”
According to Litsch, faster shifts not only improve performance, but also benefit transmission longevity. Slow shifts that slip the transmission build heat – an automatic transmission’s number-one enemy.
“Firming up the shifts will reduce the heat buildup, which in turn reduces the wear and tear on the clutches, which will extend the life of your transmission. It’s a win-win. Our torque-management reductions also keep things within the limit of where the factory transmission is happy.”
And finally, if you’ve got eight cylinders, you’ll likely want to use them all the time. Both GM and Dodge muscle cars deploy fuel-saving, cylinder-deactivation technologies like Active Fuel Management/Dynamic Fuel Management (AFM/DFM) and the Multi-Displacement System (MDS). The performance hit is obvious – even the best throttle response is hampered by the need to refire the dormant combustion chambers – not to mention some of the unwanted sounds you could hear through an aftermarket exhaust system.
Any Diablo-supported vehicle that has AFM/DFM or MDS, can have it switched off in the tune, ensuring that the full V8 is always available to optimize the throttle response.
To finish, Litsch notes that the performance gains for a particular vehicle model are available to every customer, no matter which DiabloSport device they choose to tune it with – inTune i3, Predator 2 (pictured above), PredatorX or Trinity 2. Not all electronic tuners are available for all vehicles, however: ’15 and newer Dodges don’t use the Predator 2, while the PredatorX is currently still GM-only.
Looking ahead, in 2025 a new muscle car is joining the party in the form of the Dodge Charger. DiabloSport has already launched a Pulsar Cat6 inline tuning model for the similarly Hurricane-powered Rams and Wagoneers, and the plan is to have that device available for the Charger as soon the car as it reaches its first customers.
For more information on DiabloSport tuners, go to https://www.holley.com/brands/diablosport/
