It has been said that as soon as a car starts moving, aerodynamics come into play. Although that is true, it’s nothing that you will notice at lower speeds. But aerodynamics still play a huge part on how well a car is going to slice through the wind, and while some may think that spoilers and wings create necessary downforce and aid in traction, too much wing can actually slow a car down because it creates too much drag.
Even some high-end exotics were found to be more aerodynamic sans wings, and they were able to reach a higher top speed because the of the reduced coefficent of drag (cd) without the bulky wings. Anyone who has held their hand out of the car window at 60 MPH has experienced what aerodynamics can do, and rotating your flat palm in either direction brings about a major change how your arm reacts to the way the air hits your hand.
But when you start talking four door sedans, there’s a lot more to consider when it comes to aerodynamics. Granted, the new Dodge Charger is a pretty sleek car to begin with, but when your engineers are aiming for 200 MPH, that’s entering NASCAR territory – and we’ve all seen how much they tweak the body on a NASCAR.
The engineers at SRT were doing just that with the new Charger SRT Hellcat: they were aiming for 200 MPH and spent about a 100 hours in the wind tunnel tweaking and manipulating the lines of the 2015 Dodge Charger. The Chrysler Technology Center wind tunnel in Auburn, Michigan, is where engineers spent more than a year perfecting the profile of the Charger SRT Hellcat to get to their lofty goal.
When your goal is the fastest and most powerful sedan in the world, every inch of the car is going to be a factor. Starting with the front fascia on the Charger, it was bigger than the standard Charger to accommodate the huge intercooler and to create venting ducts for the huge Brembo front brakes – also the largest brakes Chrysler has ever put on a car.
The doors and roof line remained unchanged, because it was already a very efficient design. But once the air starts moving around the larger front fascia, that’s where engineers went to work at achieving their “world’s fastest” goal.
Terry England, engineer for all SRT and Viper Vehicle Systems, said, “The low drag helps the Charger deliver such a high top speed. The Charger is low in drag to glide through the air very smoothly. In the wind tunnel, we look closely at the hood, the fascia and the rear spoiler to improve aero. As the design evolves from the studio, we provide input on wind-tunnel findings.”
With the engine already producing 707 horsepower, the most of any musclecar, that alone is not enough to push a car to this lofty top speed goal. The wind against the car creates resistance, so engineers spent time making subtle changes until they were satisfied with the way the air flowed across the Charger’s sleek profile.
“When we set the functional objectives for the car’s aero performance, we aimed to contribute to top speed and design intent alike,” said England. “Already an efficient design, we were able to enhance aerodynamic performance for the SRT Hellcat iteration. The aero team aimed for breaking 200 mph, so we were very happy to see that big number.”
But another factor also arose from all of this extensive testing: the car also had to be able to handle well at speed. Just going 200+ miles per hour isn’t enough if the car isn’t capable of maintaining its posture at those speeds. To help keep the car stable at 200 MPH, the rear spoiler was elevated slightly to increase downforce and provide a good balance between the front and rear of the car.
“As aerodynamicists, we aim to honor design and the studio’s collective vision,” said England. “We work closely with the design team from the very beginning and then adjust with small tweaks to optimize throughout the process.”
The hood of the SRT Hellcat is also modified from stock to provide for an air inlet for the supercharger, as well as a pair of venting ducts to draw excess heat from under the hood. But the design of the hood and how the air flows over it also play a huge part in aerodynamics, also. “The hood scoop created some drag, so we smoothed the radii around it,” said England. That solved the problems they were experiencing, and as a result the Charger SRT Hellcat was able to pull off a 204 MPH top speed: mission accomplished.
England summarized the project, “Charger SRT Hellcat aerodynamic performance is a contributing factor in delivering such high-performance, so crossing the 200 mph threshold was icing on the cake.” Check, and mate.