The 2018 Dodge Challenger SRT Demon was officially released to the public in a highly anticipated media event in New York City, and news of the new car—the first production car ever to do a wheelie—was all the automotive media could talk about in the weeks that followed. Since then, we’ve been learning more about the car as Dodge has released more detailed information it in carefully timed press conferences. Car Craft was invited to a recent one: a technical discussion about the Demon’s powertrain, and we were impressed by how passionate the SRT engineers are about this vehicle. One of the main goals was to build a car that ran 9s off the showroom floor and could pull the wheels while doing it. They met that goal, of course, and photos of wheelie heard ’round the world crisscrossed web servers on a global scale. Getting a car to do a wheelie is a relatively simple exercise of torque and weight transfer. Doing a wheelie in a car with a full factory warranty that passes federal emissions is a much more daunting challenge. Here’s a little about how Dodge did it.
Induction and Boost
Where your ordinary Hellcat makes due with a 2.4L supercharger, the Demon ups the ante with a 2.7L twin-screw supercharger, and maximum boost was increased from 11.6 to 14.5 psi. During a full-throttle quarter-mile pass, the Demon’s engine will ingest 173 cubic feet of air, so to meet that demand, the induction system draws outside air from the Air Grabber hoodscoop, the driver-side headlamp, and a third inlet near the driver-side wheel liner. Combined, the induction system can flow 1,150 cubic feet of air per minute, and it does so while still passing stringent drive-by, noise-level requirements.
Fuel
The Demon is the first production car designed to run on 100-octane gasoline. Even with tepid 91-octane, the engine will still make 808 hp and 717 lb-ft of torque and run 9.90s. A full tank of undiluted 100-octane unleashes the full 840 hp and 770 lb-ft, which is good for a 9.65-second quarter-mile pass.
Rotating Assembly
More than just a Hellcat with a bigger supercharger, SRT engineers took pains to point out that more than 65 percent of the engine’s components are changed or upgraded. The crankshaft, connecting rods, and pistons are better a stronger alloy than Hellcat. The engine block was modified to provide 50-percent greater volume of oil to the piston oil squirters, and the connecting rods are reinforced around the pin bosses. The main bearings and piston-ring clearances are optimized for greater boost and higher engine speeds, high-tensile rod and main cap bolts are used, and the engine blocks are torque-plate honed before assembly.
Valvetrain
To accommodate the maximum engine speed increase to 6,500 rpm, the valves were redesigned with single-groove keepers for greater high-rpm stability. The valvespring rate is increased and the oiling system delivers 30 percent more oil to the springs to keep them cool at sustained high-rpm operation.
Transmission
The 8HP90 automatic is the only transmission offered for the Demon and sees several improvements over the Hellcat version of that gearbox, namely a higher-stall torque converter and the incorporation of a transbrake feature in the transmissions programming. When activated, the transbrake essentially holds the driveline stationary, loading the torque converter and allowing the engine to build boost. Once underway, each gear change is accomplished in only 400 milliseconds, so there is very little interruption of power.
Driveline
The driveshaft, differential, and axles are under a tremendous amount of load, as the 4,250-pound Demon is capable of generating 1.8 g from a standing start. Therefore, everything aft of the transmission has been strengthened or reinforced. The driveshaft is made of high-strength steel and sees a 20-percent increase in wall thickness over the Hellcat. The 41-spline axleshafts are also thicker and incorporate eight-ball CV joints, while the ring-and-pinion and differential housing are made with heat-treated upgraded alloys. The standard-equipment 315/40R-18 Nitto drag radials are also a first for a production car, and their sticky compound and soft sidewalls also help enable the insane, wheels-up launches and 9-second e.t.’s. It’s an amazing time to be a muscle-car enthusiast.
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