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Demon power curves and video

by Patrick Rall on

Last week, Dodge offered up a video of the supercharged Hemi of the 2018 Challenger SRT Demon on an engine dyno.  Understandably, that video has become quite popular: it lets us  watch the exhaust system glow bright red at wide open throttle, while showing the horsepower and torque levels at a variety of points in the powerband.

There is also the beautiful sound of the newest Mopar muscle car engine in action, which is more than half of the allure of this video.

The problem is that not everyone understands exactly what is going on with the Dodge Challenger SRT Demon engine on this dyno. Some people are watching this video and pointing out that the slow run-up to peak power leads to a lower-than-actual number. Those folks point out that a “normal dyno run” at their local performance shop only really takes a few seconds and that if this engine was tested in the same manner, it would yield much higher numbers.

Dodge Challenger Demon power curve

Those people might be right, but the point of this video is that the engine in action is going through the SAE power validation process. The SAE system requires the test engineers to gradually bring the engine up to peak power, stopping along the way at a set of designated rpm points. At each rpm point, the engineers and the SAE official on hand for the validation process wait for the power number to level out and when it does, that horsepower and torque output become SAE certified.

The goal with this process is to measure the sustained power at the various points, which is a far more accurate measure of real world power output, rather than testing to see what the absolute peak horsepower is during a hard spike.

The entire SAE process takes more than 5 minutes, but the folks from Dodge have sped up the video to make for easier viewing. During the run, we see the rpm point along with the horsepower and torque levels at each. The video also includes interesting notes about the testing process of the Demon’s supercharged Hemi, giving us all something to read while waiting for the 840 horsepower peak.

So, for those of you insisting that this video is proof that Dodge is sandbagging by using this power measurement method – you are right that this engine might make more power under different testing methods, but you are wrong in suggesting that Dodge is doing anything wrong. This is the method required by the Society of Automotive Engineers (SAE) for their uniform testing standards, and it is this process which led to the 840 horsepower output of the new Demon.

Check out the video for a look at the power levels of the new Dodge Challenger SRT Demon engine at each designated rpm point, gradually ramping up to the 840 horsepower peak at 6399 rpm.

Patrick Rall was raised a Mopar boy, spending years racing a Dodge Mirada while working his way through college. After spending a few years post-college in the tax accounting field, Patrick made the jump to the world of journalism and his work has been published in magazines and websites around the world.


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