<< Prev Page 2 of 3 Next >> The heart of the 2018 Dodge Challenger SRT Demon is the supercharged 6.2-liter HEMI Demon V-8, rated at 840 horsepower and 770 pounds-feet of torque. The red-painted Demon engine has been certified to the SAE J1349 industry standard for its horsepower and torque ratings. The engine also meets all applicable legal emissions regulations.
While the Demon V-8 shares its architecture with the 707-hp 6.2-liter supercharged HEMI Hellcat V-8, it is not simply a Hellcat engine with more boost. The Demon V-8 engine has 25 major component upgrades from the Hellcat engine, including supercharger, pistons, rods, valve train and fuel injection system.
Among the changes, compared with the Hellcat V-8, the Demon's supercharged V-8 features:
Larger supercharger: 2.7 liters versus 2.4 liters
Increased boost pressure: 14.5 psi versus 11.6 psi
Higher rpm limit: 6,500 rpm versus 6,200 rpm
Fuel: Two dual-stage fuel pumps versus one
Larger induction air box with three sources of intake air: Air-Grabber hood, driver-side Air-Catcher headlamp and an inlet near the wheel liner
In addition, the HEMI Demon V-8 includes a high-speed valvetrain, strengthened connecting rods and pistons, and improved lubrication system. The upgrades enable the engine to sustain higher output and pressures while meeting FCA US LLC's stringent durability requirements.
One key to the Challenger SRT Demon's best-ever power output is air - the supercharged Demon V-8 takes in plenty of it. The SRT Demon's Air-Grabber hood includes the largest functional hood scoop (45.2 square inches) of any production car.
The Air-Grabber hood is sealed to the air box, which is also fed from the driver-side Air-Catcher headlamp and an inlet near the wheel liner. Combined, those sources give the Demon V-8 an air-flow rate of 1,150 cubic feet per minute, 18 percent greater than the Hellcat V-8 and the largest air induction volume of any production car.
The additional air inlets help reduce the temperature of the intake air by more than 30 degrees Fahrenheit compared with the Hellcat V-8, which improves overall throttle response.
Heat is the enemy of speed at the drag strip, so Dodge//SRT engineers looked for more ways to keep the intake air as close to the optimum temperature as possible.
The innovative SRT Power Chiller is a production car first. It diverts the air-conditioning refrigerant from the SRT Demon's interior to a chiller unit mounted by the low-temperature circuit coolant pump. Charge air coolant, after being cooled by ambient air passing through a low-temperature radiator at the front of the vehicle, flows through the chiller unit, where it is further cooled. The chilled coolant then flows to the heat exchangers in the supercharger.
Every run down the drag strip generates plenty of heat. The After-Run Chiller, a factory-production car first, helps the SRT Demon get ready for the next run as quickly as possible.
When the engine is shut down, the After-Run Chiller keeps the engine cooling fan and low-temperature circuit coolant pump running to lower the supercharger/charge air cooler temperature, helping the Challenger SRT Demon minimize heat soak effects. The driver can track the supercharger coolant temperature on the 8.4-inch Uconnect touchscreen in the instrument panel, and know in real time when the supercharger is at the optimum temperature for another run.
The impact of the SRT Power Chiller and After-Run Chiller, combined, lowers intake air temperature by up to 45 degrees Fahrenheit.
The Challenger SRT Demon is the first-ever, street-legal factory-production car designed to run on 100+ unleaded high-octane fuel. That fuel is readily available at select gas stations, specialty shops and drag strips.
The keys to unleashing the SRT Demon's full performance fury are in the Demon Crate: Direct Connection Performance Parts include a new powertrain control module calibrated for the high-octane unleaded fuel and a new switch bank for the center stack that includes a high-octane button.
The SRT Demon leaves the factory with a powertrain control module configured for 91-octane premium unleaded pump gasoline, which delivers top level performance.
The switch to the Direct Connection controller enables the supercharged HEMI engine to extract the maximum power from the knock-resistant fuel at high pressures and optimum spark timing. Drag racers can anticipate improvements in elapsed times (ETs) and trap speeds with the high-octane fuel.
The Challenger SRT Demon is engineered to be able to run on a mix of 100+ octane and premium unleaded fuels without hurting the engine, but the high-octane function won't activate if the combined fuel octane is too low. A message in the gauge display tells the driver the car will use the premium fuel calibration until the engine is shut off and restarted. How does the car know? The controller monitors the engine's knock sensors.
There will be plenty of fuel available: the SRT Demon carries dual fuel pumps (versus one pump in the Challenger SRT Hellcat), larger fuel injectors and fuel lines that handle higher pressures.
Similar to the Challenger SRT Hellcat, the SRT Demon comes with two key fobs. The black fob limits engine output to 500 horsepower. The red key fob unlocks the engine's full output of 808 horsepower and 717 pounds-feet torque. With either key fob, the driver can activate Eco and Valet Modes. Eco Mode revises the transmission shift schedule to include second-gear starts. Valet Mode limits the engine to 4,000 rpm and reduces torque output.
The high-octane unleaded fuel capability with the optional Direct Connection powertrain controller boosts engine output to 840 horsepower and 770 pounds-feet of torque.
Every Dodge Challenger SRT Demon is equipped with the standard TorqueFlite 8HP90 eight-speed automatic transmission. Already a proven and robust gearbox used with the HEMI Hellcat V-8, the transmission gets some significant changes for duty in the Challenger SRT Demon.
Internal changes include an upgraded torque converter that delivers an 18 percent increase in torque multiplication. Also, the stall speed is increased 11 percent and the lockup speed is increased.
The Challenger SRT Demon is the first-ever, factory-production car with TransBrake, which locks the transmission output shaft to hold the car in place before a standing start. This lets the driver increase engine speed up to 2,350 rpm without overpowering the brakes, resulting in quicker power delivery and up to 15 percent more torque at launch.
Driver-oriented step-by-step instructions are displayed on the instrument cluster to guide the driver through the staging process and help them keep their focus on the Christmas Tree.
The TransBrake helps to improve driver reaction time and launch consistency by using the steering wheel paddle shifters as a launch trigger - a paddle launch improves reaction time by 30 percent compared with a foot-brake launch. In addition, the system enables delivery of initial torque to the flywheel as soon as 20 milliseconds after launch.
TransBrake works in conjunction with another SRT Demon first-ever factory-production car feature, Torque Reserve, to deliver increased levels of power and torque at launch.
Torque Reserve becomes active once engine speed passes 950 rpm. It does two things:
Closes the bypass valve, "prefilling" the supercharger with boost
Manages fuel flow to cylinders and manages spark advance or retard to balance engine rpm and torque
With TransBrake and Torque Reserve active, the SRT Demon has more than 8 psi of boost at launch and up to 120 percent more engine torque than without Torque Reserve. TransBrake also preloads the driveline with torque, leading to full engine torque delivery at the rear wheels 150 milliseconds after the shift paddle is released. That results in faster acceleration at launch, faster 60-foot times and an improvement of more than a tenth of a second in quarter-mile times, which can be an entire car length.
Driveline components have been upgraded to get all that power and torque to the rear wheels, on every run.
Changes include:
Upgraded prop shaft with a 15 percent increase in torque capacity. The prop shaft uses high-strength steel. Shaft tube thickness increases by 20 percent and the stub shafts are heat treated for enhanced durability
The rear differential housing has 30 percent more torque capacity. The housing is made from heat-treated A383 aluminum alloy. New material for the gear set has higher fatigue strength, with a deeper case hardening depth and two-step shot-peening manufacturing process to increase compressive residual stress
The rear half shafts are larger in diameter; use a high-strength, low-alloy steel; and have 41 splines (up from 38), delivering a 20 percent increase in torque capacity. Eight-ball joints handle more torque, while reducing operating temperatures by more than 86 degrees Fahrenheit
SRT engineers went digital to isolate and resolve one of the biggest challenges to clean launches and driveline integrity - wheel hop.
In simple terms, wheel hop happens when tires quickly slip and regain traction at launch, rapidly storing up and releasing energy in the driveline. These high torque spikes can quickly and severely damage driveline components - and up until now, the only solution was to back out of the throttle.
Not with the Challenger SRT Demon. In a first for a factory-production car, the SRT Demon's Launch Assist uses the wheel speed sensors to watch for signs that the tires are slipping/sticking. If slip is detected, the SRT Demon's control module momentarily reduces engine torque to maximize traction almost instantly - without the driver having to lift. Launch Assist reduces loads in the driveline from wheel hop by more than 15-20 percent, dramatically reducing component damage.
The Challenger SRT Demon is equipped with a set of four standard Nitto NT05R street-legal, drag-race tires, a first for a factory-production car.
The 315/40R18 tires were specifically designed and developed exclusively for the SRT Demon, with a new compound and specific tire sidewall construction. The drag radials give the SRT Demon a 15-percent larger tire contact patch and more than twice the grip of the Challenger SRT Hellcat.
The sticky drag tires are mounted on lightweight 11x18-inch wheels, with each tire measuring 12.6 inches wide. Putting full-size tires at all four corners gives drag racers an extra set of rear tires when the front tires are replaced with narrow front-runners at the track.
A unique rear knuckle reduces negative camber by 0.5 degrees, "standing up" the tire and increasing the size of the tire contact patch.
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Challenger SRT Demon
The heart of the 2018 Dodge Challenger SRT Demon is the supercharged 6.2-liter HEMI Demon V-8, rated at 840 horsepower and 770 pounds-feet of torque. The red-painted Demon engine has been certified to the SAE J1349 industry standard for its horsepower and torque ratings. The engine also meets all applicable legal emissions regulations.