Archive for August 24th, 2017|Daily archive page

Demon – The SRT® Hellcat’s Big Brother

The SRT® Hellcat’s Big Brother
As if the 6.2-liter HEMI® V8 powering the SRT® Hellcat wasn’t hot enough, to ensure consistent 9-second quarter-mile performance — not occasional visits — the 2018 Dodge Challenger SRT Demon packs an 808-horsepower wallop (or 840 with 100-octane racing gas in the tank), low-drag front tires and the all-out computer calibration mode included with the Pre Stage Kit.

So how did Dodge grab all that extra power from the already-crazy-potent SRT® Hellcat HEMI engine? To find, out we cornered Dodge factory insider Jim Wilder for answers. Wilder told us: “Dodge CEO Tim Kuniskis is really the man responsible for this. At the start, we shot for low-10-second capability. That’d have made it about a half-second quicker than a Hellcat.”
We have to stop here to remember that Kuniskis is one of a rare breed of auto industry CEOs with gasoline in his veins and grease under his fingernails. While climbing the corporate ladder he owned and raced a well-respected breed of American turbo V6 muscle cars in his spare time. Wilder continues: “So we had these regular progress meetings and Tim pulls me aside and says; ‘Jim, low-10-second cars are fast … but 9-second cars are unheard of. How can we make it even faster?’ At every meeting Tim was pushing us to leave no stone unturned.”
Stones that Wilder’s HEMI V8 development crew turned include bumping the Demon supercharger capacity from 2.38 to 2.7 liters, which elevates maximum boost from the SRT® Hellcat’s 11.6 to 14.5 psi, stiffer valve springs to enable a 6,500-rpm redline (versus 6,200 for Hellcat) and the industry-first SRT Power Chiller™.

Supercharged cars like the Demon compress the incoming air before it reaches the combustion chambers. This effectively “force feeds” the cylinders a much greater volume of fuel and air than they could otherwise ingest on their own. But when air molecules get jammed together like that, the resulting friction heats them up. Ironically, this can reduce the total air volume and diminish the benefits of the supercharger.
But … if the compressed air is routed through a cooling device like an intercooler, then much of that density can be restored. For Demon, Jim Wilder and his team of engineers took a look at the on-board passenger compartment air conditioning system – which is standard in every Demon – and tapped into it to help keep the HEMI engine’s intake charge cooler, denser and more potent. Dubbed the SRT Power Chiller, the system retains the Hellcat’s twin intercoolers then adds another two air-to-glycol (liquid coolant) heat exchangers.
To activate the SRT Power Chiller, just dial up Drag Mode on the gauge cluster then sit back and relax as part of the air conditioner output is re-routed to chill the HEMI V8’s induction system. Thanks to the SRT Power Chiller, inlet air temperature drops by as much as 45 degrees F, making the age-old practice of packing the intake manifold with ice bags between races a thing of the past.
Beyond these fortifications to boost the Demon’s HEMI engine output to as much as 840 horsepower, numerous body, suspension, calibration, brake and driveline modifications were made to the Demon package to ensure Tim Kuniskis’ quest for a 9-second passenger car bore fruit. We’ll explore them in the next chapter in this series of Demon blog postings.

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