The Three Things You Need to Do to Your Modern Challenger First

If there’s one modern coupe that personifies modern muscle, it’s the Dodge Challenger. 2018 marks the 10-year anniversary of the car’s reintroduction to the automotive world after a hiatus that spanned nearly three and a half decades (sorry, that rebadged Mitsubishi Galant coupe from the late 1970s doesn’t count), and Dodge’s series of updates to the modern Challenger have ensured that the latest iterations are more capable than ever.

While there’s no doubt that enthusiast-focused models like the SRT Hellcat are a blast to drive right out of the box, there’s plenty of ways to hone its performance even further. Image: FCA

That doesn’t mean there isn’t room for improvement though. Like any production car, the Challenger is built not only to a price point, but with the assumption of varied use by a wide range of customers with different expectations in terms of fuel economy, ride quality, operating costs, and so on. Those design compromises typically affect enthusiasts the most, whose top priority is usually performance rather than frugality or NVH.

So for gearheads looking to get more out of their late-model Mopar coupes, we’ve assembled this trio of “Day Two” modifications that can help elevate the capability of these LX platform beasts with minimal hassle and expense.

Unlocking Powertrain Potential

Whether we’re talking about an SXT or a Demon, for many Mopar gearheads it’s only a matter of time before the urge to add more horsepower strikes. Like most modern vehicles, unlocking additional horsepower in LX platform vehicles requires interfacing with the ECU. Not only can this allow you to install an aftermarket “tune” in place of the factory-installed engine software. It can also provide access to various engine and transmission system parameters, diagnostic codes, and other features that are otherwise inaccessible to owners.

Offering 485 and 707 horsepower respectively, the 6.4-liter Apache Hemi and 6.2-liter Hellcat Hemi aren't lacking for grunt in stock form. However, their relatively conservative engine tunes from the factory do leave some additional power on the table. Images: FCA

“The OEMs have to develop one set of maps that work for everyone in every driving situation at any temperature you might encounter,” says Matt Barker of DiabloSport.

“And it has to have lots of room for variables and fuel types that the OEM doesn’t have control over. So their tunes have to be extremely generic, whereas we can have something that works on a wide variety of vehicles, but they’re more purpose-built tunes. So for example, when we design a 93 octane tune, we are making the assumption that performance is a priority, and we can cater the tune to that a bit more, make it more responsive, develop more power, and take advantage of the higher octane fuel. When it comes to gas vehicles, we build our tunes around the octane, so we have 87, 91, and 93 octane tunes (depending on which application you have), and we can make adjustments to the timing and fueling systems that really maximize the potential of the vehicle.”

The Mopar way of doing things is a bit different than what you’d encounter in a newer GM or Ford product though, so there are some factors to consider before diving directly into the project, particularly for vehicles built within the last few years. “While Gen III Hemis aren’t necessarily any harder to tune than their GM and Ford counterparts, the biggest hurdle is the factory powertrain control module encryption used on 2015 and newer models,” explains Barker. “But we have ways to circumvent that, either with our PCM swap process, or with what we call our DiabloSport Modified PCM program, where the customer sends in their PCM and we unlock it.”

By unlocking or replacing the PCM, Diablosport’s handheld programmers like the Trinity and InTune can then access the vehicle’s software and apply tunes. “Our PCM swap is a one time cross-shipment of an unlocked computer that’s built into the cost of the product,” says Barker.

Along with its tuning capabilities, the DiabloSport Trinity also offers a number of cool real-time performance data features.

“With our PCM swap process, you go to a section on our website and enter your VIN and Calibration ID off of your factory computer. We take that information and load that into an already unlocked computer matching your same model and year and ship it out to you with a return shipper label so you can send us back your core after you’ve swapped them in the vehicle. The great thing about this method – and what kind of sets it apart from any other solutions in the industry really – is that it allows you to tune these late-model vehicles without ever having the vehicle in an inoperable state while you wait for a new PCM to be shipped to you.”

The great thing about this method – and what kind of sets it apart from any other solutions in the industry really – is that it allows you to tune these late-model Mopars without ever having the vehicle in an inoperable state while you wait for a new PCM to be shipped to you. – Matt Barker, DiabloSport

It’s a factor many might not consider when looking to tune their 2015 and newer Mopar car, truck, or SUV – when the PCM’s out of the vehicle, that ride is effectively disabled until another PCM is installed in its place.

It’s worth noting that on 2014 and older models, this PCM-related step is not needed – you can simply purchase a tuner and get started applying new software tunes, as these vehicles do not utilize the encryption found in the 2015 and newer Dodge, Chrysler, Jeep, and Ram vehicles.

And while pre-installed tunes included on tuners like Trinity and InTune can provide noticeable improvements in horsepower, torque, throttle response and even transmission behavior in stock and mildly modified vehicles, devices like the Trinity also provide the capability of installing fully customized tunes for modified builds, which can be tailored specifically to that vehicle’s setup.

The location of the PCM varies among the different Hemi-powered FCA vehicles, but on the Challenger and Charger it’s tucked away under the cowling on the passenger side of the engine bay between the firewall and the shock tower.

“When it comes to highly modified vehicles, our CMR custom tuning software has the ability to allow customer tuners to build their own third-party tunes for a specific vehicle’s configuration,” Barker says. “So if you’ve got a supercharger, aftermarket cam, and headers, and you want the most power out of that setup possible, this customization allows the tuner to make the changes necessary.”

But the engine tune is only one piece of the powertrain puzzle, as modern automatic transmissions play an equally important role in properly utilizing the power generated by the engine – particularly when it comes to off-the-line acceleration. In that regard, getting both the engine software and the transmission software on the same page is also crucial.

“Any 2015 or newer vehicle equipped with the 8-speed transmission uses the ZF transmission controller,” Barker notes. “Our devices now come pre-programmed with adjustments for the ZF 8-speed, which dial in its behavior to work best with the modifications we’re making in the engine calibration.”

Diablosport hasn’t forgotten about the enthusiasts whose rides are equipped with the 5-speed automatic either, though. “We are very close to having our EGS53 transmission tuning options available,” says Barker. “We’re just in the final stages of testing now, and they should be available in the next month or so as part of the CMR custom tuning software.”

As far as tuning tips for folks familiar with the custom tuning process, Barker offers a bit of insight into how the modern Hemi engines differ from other American V8 mills. “One of the main things we’ve discovered is that the modern Hemi doesn’t like to run lean like an LS, LT or Coyote engine,” Barker explains. “So you can target an AFR in the low 12s, where these engines tend to make the best power. It really just comes down to becoming familiar with some of the characteristic details of each type of engine.”

Barker also points out another piece of factory software that is worth some tuning attention as well – the torque management system. “As the name implies, this factory system automatically makes adjustments to the tuning to try and reduce the strain on the drivetrain,” he says.

“That system will try and reduce the load on the drivetrain and compensate for any engine tuning that might’ve been done, reducing responsiveness in the process – whether you’re using factory or aftermarket engine tunes – by doing things like changing the throttle position and making other adjustments to limit the aggressiveness of the drivetrain load. If you make a custom tune that does not make adjustments to the torque management system and the vehicle detects that you’re being too aggressive with the drivetrain in certain circumstances it can make some changes to compensate.” That’s one of the areas where the custom tuning available from the CMR software can make a real difference beyond not only the stock tune but the pre-installed octane tunes as well.

Tightening Up The Chassis

This is another aspect of factory car set up where a significant amount of inherent compromise is built into the design, not only in terms of cost-saving measures but to keep the widest swath of buyers happy with the ride quality and NVH characetistics. That leaves a lot of room for improvement for enthusiasts at a fairly low cost, particularly on vehicles without active suspension.

Since swapping sway bars has no effect on spring rates or damping characteristics, the only real change in overall ride quality is found in the stiffer bushings used here to reduce deflection. Image: Mopar Performance

Though it’s tempting to go straight to lowering springs or a coilover setup right out of the gate, if handling is your top priority, we’d suggest looking at the sway bars first. Bars like these from Mopar Performance come straight from the OEM, ensuring factory-like quality and compatibility.

Stiffening up the sway bar setup not only reduces body roll, it also alters the handling characteristics to a tangible degree. Most factory setups are designed to understeer at the limit unless coaxed by the throttle. Bars like these will bring the car’s at-limit behavior into more neutral territory, making it easier to rotate the vehicle and predict what it will do when weight starts transferring around aggressively, making this a great low-cost upgrade for enthusiasts looking to hit up the autocross course, track days, or just have some fun out on a good back road – and it comes at a very minimal cost to ride quality versus the factory stuff.

For those who want to go a step further, adjustable bars like the ones offered by Whiteline allow you to fine-tune the vehicle’s understeer/oversteer tendencies a step further by increasing or reducing the length of the lever arms, which allows the roll stiffness to be tuned for different situations without replacing the entire bar.

Aftermarket springs are an easy way to add some visual drama while lowering the car's center of gravity. It's important to consider how far you're dropping the car though - go too low and you'll change the suspension geometry, which can reduce handling performance. Images: FCA

It’s also no big secret that lowering the center of gravity will provide better handling as well. Mopar Performance’s Stage 1 springs will do just that, dropping the car by up to 1.25 inches versus stock, depending on the model. Beyond bringing the vehicle’s center of mass closer to the ground, it also improves brake dive and acceleration squat tendencies as well, giving the suspension a more responsive feel overall and reducing body motion when you’re pushing the car. It also doesn’t hurt that dropping the stance tends to give the vehicle a more dramatic look, too.

Chassis rigidity is another area worth checking out as well. The more rigid the chassis, the more effectively the suspension can function as the suspension’s geometry will change during at-limit driving, and how much it goes out of spec has a lot to do with how rigid the chassis is. Front strut braces tie the two sides of the front suspension together, thus improving rigidity and allowing the chassis as a whole to share more of the work during cornering.

Mopar Performance offers some great looking bars that dress up the engine bay while doing their job, but it’s also worth checking out some of the offerings from companies like Speedlogix and Petty’s Garage, as they offer a wider range of aesthetic customization. And if you’re willing to sacrifice a bit of trunk space, a rear strut brace provides similar rigidity improvements to the rear suspension too.

Getting Some Grip

While it might not be the sexiest mod, dollar-for-dollar tires are the most effective mod you can make to your car. They dictate not only off-the-line grip, but braking and cornering capability as well.

With a treadwear rating of 00, the Nitto NT05Rs that were specially developed for the SRT Demon might not last too long, but they’ll provide a huge improvement in grip versus a standard 300 treadwear summer tire. Image: FCA

Outside of the Challenger SRT Demon, all the factory-supplied tires have some concession to tire life, meaning there’s a significant amount of grip still on the table for enthusiasts who prioritize performance over tire longevity, particularly in drier climates where wet weather handling is also less of a concern.

As the supplier for the Demon drag radials, Nitto Tire is a great source for compounds that are significantly more performance oriented than the stock stuff. The 200 treadwear NT05 will offer substantially more grip than the factory Pirelli rubber installed on SRT, T/A 392, Daytona 392, and Scat Pack models with the Dynamics Package and they’re available in the factory size (275/40R20, excluding the Widebody Hellcat).

For those looking to go a step further, the drag-racing focused NT05R and the D.O.T. compliant NT01 road course performance tires are an option too, along with competition tires like the Toyo Proxes R888R, but it’s worth noting that none are offered in the aforementioned tire size, so you’d likely need to switch to an aftermarket wheel in order to get the most benefit from these options.

The Nitto NT05 and NT01, seen here respectively, use tread patterns and compounds that are focused specifically on delivering maximum grip in performance applications. Compared to a standard summer tire these won't fair as well in bad weather and are more finicky about temperatures, but at the track they'll pay dividends in your ETs and lap times. Since they're both D.O.T. legal, you also won't have to swap them out for a set of street tires once it's time to head home. Images: Nitto

It’s also important to point out that the speed rating of these tires is usually lower than the factory rubber on 392 and Hellcat models, so if you’re looking to do half-mile or mile-long drags, you should probably seek out a tire with a “Y” or “(Y99)” speed rating (which means they’re safe to a maximum of 186 mph or in excess of 186 mph, respectively) rather than the 168 mph max speed rating of W-speed rated tires.

Of course this is just scratching the surface of what’s possible with these highly capable modern Mopar machines. But each of these mods establishes a great foundation to build on, and will provide a greater benefit to any upgrades added further down the line. So what’re you waiting for? Get wrenchin’!

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About the author

Bradley Iger

Lover of noisy cars, noisy music, and noisy bulldogs, Brad can often be found flogging something expensive along the twisting tarmac of the Angeles Forest.
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