9 Speed Secrets Behind the 6.2 Hemi Dodge Challenger SRT Demon
What they don’t tell you about the 840-HP 6.2 Hemi in the Dodge SRT Demon
Updated October 3, 2018
The 2018 Dodge Challenger SRT Demon equipped with 6.2 Hemi is officially the fastest street-legal car ever built, and it’s available directly from the factory. Not wasting any time, the SRT Demon has already set multiple speed records. It takes just 2.1 seconds to reach 60 mph, and just another 2.8 seconds to reach 100 mph. That makes it just slightly slower than the powerful Saturn V rocket that took man to the moon. On the drag strip, the Demon is truly in its element. In fact, Dodge has made it abundantly clear that their goal was to create a drag monster – not a track day car (unless your track is Pomona or The Strip at Vegas).
(Not) Legal for NHRA Competition
Capable of a 9.65 second quarter-mile at 140 mph, the Demon is faster than NHRA’s stock limit, so it’ll require you to earn an NHRA license and install a full roll cage to drag race. That’s what the fuss is all about when you read “banned from NHRA competition.”
Rev ‘er up
The Demon has a 300 rpm higher rev limit than the Hellcat. By analyzing Hellcat dyno data, those additional rpm alone could add as much as 40-50 horsepower to the engine, which are reflected in the serious internal upgrades the Demon features to allow the 6.2 Hemi to handle the extra force as well as spin faster.
On each power stroke the piston and rods are loaded with 11 tons of force, with every combustion stroke, 50 times a second at 6300 rpm.
While the increased 14.5 psi of boost (versus 11.6 psi in the Hellcat) sounds cool, it has its negatives. In fact, it’s quite hot. That level of boost will raise the temperature of the intake air by 190F degrees. On an 80ºF day, 270ºF air is coming out of the supercharger (not good for making power). Which is why SRT developed the Power Chiller, which connects the A/C system to the intercooler in order to further reduce intake air temperatures (IATs).
A Key to the Lock that Opens the Power
Not all of the Demon’s 840 horsepower is on tap all of the time. Not only do you need to feed the 6.2 Hemi 100 octane unleaded race gas, but you need to plug in the special control module and a dash-mounted button included in the Demon Crate that’s shipped with the car.
Full Fuel Flow
The fuel pumps are impressively capable. In fact, it can fill an average-size bathtub in about 4.2 seconds. Each injector nozzle sprays enough 100 octane that it would completely fill the cylinder of a mid-sized sport bike.
More Intake Air Requires a Bigger Filter
The stock, EPA-approved filter likely doesn’t draw enough air to satisfy the 6.2 Hemi during all-out drag strip performance. Thus, within the Demon Crate lies a larger conical filter (along with a hydraulic jack, front drag wheels, torque wrench, and passenger mirror block-off plate among other quarter mile-eating necessities) similar to what you’d find on many high-powered drag vehicles. While it’s probably not street-legal, the supercharger undoubtedly satisfies the Demon’s supercharger, allowing it to reach full stride quickly.
Seating for One
In order to hit the numbers on the drag strip that the SRT engineers have accomplished, it takes more than brute horsepower. Roughly 200 pound of interior was shed. This was achieved while maintaining a factory-like feel within the cabin, minus the obvious removal of seating. That’s the way the car is delivered – with only the single driver’s seat — unless you pay $1.00 to have each the other seats reinstalled.
Roll Your Own
If you’re so inclined as to want to bolt-in a harness bar, they’re available through a third party aftermarket companies. All mounting points for the bar are easily accessible.
A Blink of an Eye
When Drag Mode is selected, the 8-speed automatic transmission changes gears in 400 milliseconds, or four-tenths of a second. That’s how long it takes to blink an eye!