V10 Drag Pack
Last update, March 23, 2017
Dodge chief Tim Kuniskis wrote, “The Dodge Challenger SRT Demon is conceived, designed and engineered for a subculture of enthusiasts who know that a tenth is a car and a half second is your reputation.”
Dodge stated that the Demon is “not intended for a road course; rather, each customer can decide at the time of order, or once they own the car, or even on a moment’s notice that they want their car to favor street performance, drag strip performance or something in between.”
Numerous hints suggest that it will be rated at 757 horsepower. One video showed a best recorded 0-60 of 3.0 seconds and 0-100 of 6.08, with a quarter mile of 10.5 at 129 mph — but this may just be artistic license.
The new Challenger Demon wide-body is laser clearanced, and the entire chassis is e-coated for durability before final assembly.
This week’s 2018 Dodge Challenger SRT Demon teaser might be one of the most exciting thus far: the upcoming Mopar muscle car will be the first ever road-going car equipped with a TransBrake.
That’s right – the new Demon is going to come from the factory with a TransBrake built into the 8-speed automatic transmission, allowing it to get away from the line harder and more consistently than when launching strictly with the brakes.
When a driver launches the average automatic-transmission car at the drag strip, they pull into the staging beams, holding the brake pedal down with their left foot and easing into the throttle with their right foot to increase engine speed before the launch. This method has been used by most drag racers since the dawn of the automatic transmission, but it has its shortcomings.
The biggest issue is that as you add power to the rear wheels, you increase the chances of spinning the rear tires in place or of overpowering the front brakes, pushing the car through the staging beams with the front tires locked. This is especially true of high performance cars with skinny front tires, like the 2018 Challenger Demon, since those narrow front tires have such a small surface contact area on the ground.
Most racers get around this is by installing a transbrake, which essentially “traps” the engine power in the transmission so as they increase engine RPM, there is no power working to spin the rear wheels or push the front wheels with the brakes locked. When the transbrake is released, all of that power is instantly sent to the rear wheels and the car rockets out of the hole with far more force than launching with the ol’ two-foot method.
The Demon can launch at 2,350 rpm without touching the brakes, while increasing launch boost pressure by 105% and launch torque levels by 120%. This system provides Demon 40% more torque on launch than trying to launch the car with skinny front tires using only the brakes. It works with the anti-lag system.
When this system is activated, the driver holds down the left shift paddle on the steering wheel, engaging the TransBrake, locking the output shaft, and allowing the driver to increase engine RPM and boost while the car stays stationary – all without touching the brakes. When the driver is ready to launch, they let off the shift paddle and all of the Demon’s power is sent to the rear wheels in roughly 150 milliseconds, which is quicker than the delivery in a car being launched with the two-foot method, for improved track times in every metric.
The Demon TransBrake has a unique preloading feature which applies a moderate amount of power to the drivetrain, but not enough to risk spinning the tires or moving the car. That helps protect the driveshaft, the rear differential and the axle shafts, but and also allows the power delivery to happen so quickly.
The teaser image came with more mystery math on the Demon’s license plate and this time, we get the equation of 8.3+317=534…and your guess is as good as ours when it comes to deciphering any of these numbers.
Many race cars have an electric cooling system which keeps the coolant moving through the engine and the fans on, after the engine is shut off. That way, the engine is cooled for the next run. The 2018 Dodge Challenger SRT Demon has a similar system, but rather than the traditional cooling loop, the “After-Run Chiller” pushes air through the intercooler cooling loop, with the electric fan lowering the temperatures of the intercooler as quickly as possible. As a result, the Demon will be cooled down and ready for the next run more quickly than, say, the Hellcat Challenger or the Camaro ZL1.
The Demon’s After-Run Chiller is controlled from the infotainment system; it turns itself off when the target temperature is reached, and the driver can monitor the temperatures via the Performance Pages.
The 2018 Challenger SRT Demon Performance Pages also have a real-time horsepower graph, timers for 0-60, 0-100, eighth mile and quarter mile, a G-force meter and a full suite of auxiliary gauges which display everything from boost pressure and intake air temperature to oil pressure and engine horsepower. The system lets the driver set up the Line Lock, Launch Control, and gear-by-gear shift light systems.
The Demon also comes with a line lock system to do better burnouts at the track without chewing up the rear brakes; it locks up the front brakes at the push of a button.
The Demon will also be the first production road car to come with a “torque reserve” system – or what racers commonly call an anti-lag system. As Dodge wrote, “it lets more air flow through the engine before launch, allowing for increased supercharger rpm without torque overwhelming the brakes and spinning the rear tires.”
Normally, there is a lag between the time you first hammer the throttle to the time when you reach full boost, because the engine has to rev to build pressure in the supercharger. The torque reserve (or anti-lag) system closes the supercharger bypass valve, so boost pressure rises faster; and the engine computer briefly deactivates alternating cylinders to spin the engine faster, while keeping power output low.
On launch, the Demon will leave the line at a higher engine speed and a higher boost level, a performance edge; and it’s a little easier on the drivetrain components when preparing to launch. A byproduct is a unique exhaust sound — the alternating cylinder deactivation creates a distinctive “stutter.”
Finally, there is more mystery math in the license plate.
Like the Hellcat, the Demon has the driver’s side “Air Catcher” headlight, but it also has the Air Catcher treatment on the passenger’s side assembly – like the new Challenger T/A, and unlike the current Hellcat.
The Demon has a much wider and taller “scoop” at the front of the hood, measuring 45.2 square inches, making this the biggest hood scoop inlet on any production car in America. It sends air through a channel in the underside of the Demon’s aluminum hood to a larger air box which, when the hood is closed, does not draw any air from the hot engine bay. This new system is called the Air Grabber.
The Air Grabber name is from B-body cars of the late 1960s and early 1970s, which had a manual control knob; the new system is always open, and lowers the intake air temperature by a whopping 30°F. Cooler air leads to more power.
Like the modern Shaker hood, the new Demon Air Grabber with have a unique logo under the hood to go along with the unique air intake setup and the duct in the hood.
232 pounds were cut from the Challenger SRT Hellcat.
One video and press release showed how.
A unique steering column assembly is four pounds lighter; the parking sensor system was cut to trim two pounds. The brakes have smaller rotors (from 390mm to 360mm) and calipers (6 pistons to 4) to eliminate 16 pounds.
New wheels cut 16 pounds, and various noise/vibration parts were taken out to slash 18 pounds. Lightweight suspension components cut 19 pounds, taking out the spare tire and other trunk materials gained 20 pounds of loss, and a scaled down audio system cut 24 pounds.
The Demon doesn’t come from the factory with a rear seat (cutting 55 pounds) or a passenger seat (cutting 58 pounds). That’s the biggest factor in the 232-pound diet: 113 pounds of seats.
The 2018 Dodge Challenger Demon comes with “eighteen components that maximize the Challenger SRT Demon’s flexibility, exclusivity, and future collectability” — Direct Connection performance parts, Demon-branded track tools, matching spare wheels, and the Demon Track Pack System.
The plaque suggests that the crate will be paired with each car. The serial number is 0757; you have to wonder if perhaps that isn’t another subtle clue, along with the VIN ending 1121.
The spare wheels have a similar design to the 18x11 wheels on the Challenger SRT Demon – except they appear to be much narrower. These might be “drag skinnies” — narrow wheels wrapped in narrow tires to reduce front end weight and aerodynamic drag, solely there to allow the driver to keep the car straight.
The company also released what may be a second and unrelated box, cobranded with Snap-On, including a hydraulic floor jack, cordless impact wrench, torque wrench, tire pressure gauge, fender cover, and tool bag.
The press release claims, “All come crated with a dozen more parts, including Direct Connection Performance Parts, matching Demon-head logo’d wheels and the Demon Track Pack System.”
The new Demon will be the first ever regular-production, road-legal car to come with drag radial tires— the Nitto NT05R, 315/40R18. Those drag radials are mounted on lightweight 18 inch by 11 inch wheels; with the flared fenders, they make the Demon 3.5 inches wider than the Challenger SRT Hellcat.
These tires were specifically designed for the Demon, with a unique rubber compound and construction, so they should work better than other drag radial tires on this monster Mopar muscle car. With this extra grip, Dodge is putting more power to the wheels, with a new set of 3.09 rear gears.
The Hellcat Challenger automatic comes with 2.62 rear gears, so the new gearing will transfer 18% more of the engine torque into wheel torque, for quicker quarter mile times. The 3.09 gear swap has been popular with existing Hellcats.
The Demon will also have a new torque convertor, which is also to yield 18% more torque multiplication.
That means 35% greater launch force than the Hellcat – before any potential power increases are factored in.
Adding to the grip is a specially retuned adaptive and adjustable suspension. Drag racers used to set up their suspensions to transfer weight to the rear wheels for better traction, with soft springs and dampers up front, and stiffer dampers in the rear. The front end comes up and the weight of the car pushes down on the rear wheels as the rear shocks help keep the wheels down for the best launch. The downside is decreased handling in normal driving, so while a car with the drag-strip suspension might get off of the line much quicker, a stock car would handle a turn better.
Engineers used the Hellcat Challenger’s mechanical/electronic adaptive and adjustable suspension to work around the problem by adding “Drag Mode.”
The front springs have a 35% lower rate (than the Hellcat), the rear springs with a 28% lower rate; the front sway bar has a 75% lower rate, the rear sway bar has a 44% lower rate, and new drag-tuned Bilstein adaptive damping shocks are included.
When the new Drag Mode is engaged, the suspension enables better weight transfer to the rear wheels for better launches. Otherwise, the driver can engage a street-friendly mode for stronger cornering and ride quality.
The software mystery is being discussed in the Allpar forum, and likely refers to the compression and rebound rates of the dampers in Drag Mode under wide open throttle (WOT) and normal acceleration, with firm compression and firm rebound for the rear dampers and firm compression with soft rebound for the front dampers.
The software “code” below might be explained by suspension engineer and race specialist Ian Sharp’s words: “It is related to torque split and/or torque vectoring, either front to rear or front side to side, and diagonally on very sophisticated systems. This is probably related to how power is delivered, whereas electronic stability control is somewhat the inverse as it relates to how each individual wheel brake is applied to maintain dynamic stability.”
Drag racing tends to break driveline parts, especially the driveshaft, rear differential, and the axle shafts; so the 2018 Challenger SRT Demon team has beefed up each one, compared with the Hellcat.
The driveshaft is of high strength steel, with tube walls 20% thicker than the normal Hellcat’s, and it can safely send 15% more torque to the rear wheels.
The rear differential is stronger inside and out, with a case of heat treated A383 aluminum alloy and higher strength internals, to handle 30% greater torque levels.
The half shafts have 41 splines made of a high strength alloy that can handle 20% greater torque levels.
Next, engineers turned their attention to wheel hop, with a new Launch Assist that uses the wheel speed sensors to pull some power from the wheels when needed, to prevent damage and traction loss.
Finally, to make it easier to install a racing harness, there will be an optional four-point safety bar which bolts in behind the front seats without cutting or drilling.
During the last few seconds of a March video, a spread of screens for the Demon’s Performance Pages system flash across the screen. This quick glimpse might unlock all sorts of answers to this new Challenger’s greatest mysteries, but I think that much of the information included is nothing more than random information added for display purposes.
This first screen is likely one of the configurable gauge screens (above), showing the horsepower, the g-forces, the boost pressure and the gear selection – none of which have any key numbers in this shot.
The second screen shows the dyno graph which debuted on the Durango SRT. During the course of the video, we see the line climb a bit, but that portion ends before we see any significant numbers.
The third screen in the Demon Performance Pages video shows auxiliary gauges. The most significant numbers are the 0-60 or 3.0 and the 0-100 or 6.08. The Hellcat Challenger gets from a stop to 60 in the mid 3-second range and 100 in the 7-second range, so with the new Demon, those numbers seem very possible.
The fourth screen shows the performance timer readout, with strangely blurry numbers where they matter the most. Most of these seem possible for a car which is a quicker version of the Hellcat Challenger, but the speeds don’t make sense. The times could prove to be legitimate, but the trap speeds don’t seem right.
The fifth and sixth screen both show more auxiliary gauges without any significant figures.
The seventh, eighth, ninth and tenth still images of the 2018 Challenger SRT Demon Performance Pages show graphs which could be revealing key information, but the line in the graph remains the same in every image! While the numbers on the side change, the line remains the same in every graph, so it’s most likely that a random line was added to make the graphs more interesting.
There is almost no way that the new Demon could be experiencing this numbers. For instance, the Intake Air Temp gauge is hovering around 125 degrees and it spikes to about 225 degrees.
On the Boost Pressure screen, there is a Demon logo blocking out the peak, but it looks like it tops out somewhere around 15psi based on the other graphs.
On the Air/Fuel Ratio screen, where the line reaches its highest point, the car would be far too lean to be safe for the engine.
Finally, the IC Coolant Temp levels spike in an unusual manner – leading me to believe that this isn’t a line graph which we would see in a properly-tuned, supercharged Dodge Demon.
The eleventh image from the Demon Performance Pages video shows the G-meter, with 1.45g of launch forces— reasonable for a high performance muscle car with sticky tires.
The twelfth screen shows the dyno graph screen. The scale on the left tops out at 700 and it climbs by hundreds, and it appears as though both horsepower and torque top out around halfway point between 700 and where 800 would be. Combine that with the fact that the time on all of these screens is 7:57, and we have to wonder if the rumors of the mid-700hp range might be true.
The next three screens show the various settings of the Demon’s Drive Mode setup screen and there is nothing huge to be learned from these.
Take special notice of the fact that the “Power” numbers have been removed, but in each of the screens, we see different variables representing the numbers. We see XXX, XYZ and YYY – leading me to believe that the Demon might have three different power settings rather than two.
We can also see the mention of the Red Key, suggesting that the Demon will use a multi-key setup, and we can see that there is a Valet Mode and an Eco Mode – for those folks who want to get great mileage on the way to the track.
Finally, the last image of the Demon Performance Pages application shows some of the drag race options, already discussed.
The original Demon was a version of the 1971 and 1972 Dodge Dart, based on the Plymouth Duster. It came with a choice of slant sixes, a 318 V8, and the potent 340 V8, which accounted for roughly 1/8 of sales — but the image that endures is the Demon 340.
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