The whole 392 thing was a total coincidence. So says Dodge Challenger chief engineer Tom McCarthy. In 2009, McCarthy and his team were discussing a punch-out of the Challenger SRT8’s rather peaky 6.1-liter V-8 for more midrange torque.
“I always thought that engine was tuned to the horsepower number,” says McCarthy, meaning that to reach the 425-hp benchmark engineers tuned the engine for revs to the detriment of usable torque. McCarthy and his team settled on giving the big-block a 0.9-mm increase in bore to 103.9 and a 3.6-mm stretch to the stroke to 94.5, for a total of 6410 cc. The 2011 Challenger SRT8 391.15, base price around $46,000 makes 470 hp at 6000 rpm and, perhaps more important, 470 lb-ft of torque, a gain of 50 lb-ft. The torque peak is lower, too, at 4200 rpm versus 4800 in the old 6.1. And, yes, the engine is still painted Hemi Orange.

Dodge Challenger SRT8