Pictured: The last production-model 8.4L V10. Next year's will go up nearly 21 cubes (8.7L) and significantly more horsepower without the use of a supercharger.

There’s no love lost between the two remaining American supercars. Undoubtedly, Corvette’s halo car, the 638hp supercharged 376cui (6.2L) ZR1 is truly a force to be reckoned with, and has been the only game in town – as far as “new” production cars go – for over a year. The final Viper SRT10 ACR-X rolled off the assembly line some time ago, and while last year’s Vipers are yesterday’s news, they continue to set records time and time again.

With a larger plant, top-of-the-line engine management software and a desire to stamp the ZR1 into the mud, the '13 Viper has all the makings of a 650-to-675HP monster.

So with the new ’13 Viper quickly approaching, Corvette has something to start worrying about. While leaks pertaining to how the ‘Vette will deal with the “Viper Problem,” the mad scientists in Auburn Hills are letting more details on the new snake slip.

Allpar was recently informed that the ’13 Viper would be powered by an 8.7 liter version of the V10 engine, replacing the smaller 8.4L V10 from 2010. While this might not sound like a significant jump, the last production 8.4L produced 600HP, while the last run of ACR-X Vipers cranked out 640-naturally aspirated-ponies.

That’s a step up from 510 cubes to an estimated 531 cubic inches, making it the largest engine ever used in a Chrysler production car; the previous being the venerable Magnum and Super Commando 440 V8 found in some of Mopars most iconic classic muscle cars.

The ’13 Viper is expected to start production in the fall of 2012 as a 2013 model, which – unfortunately – negates previously leaked mid-summer release dates.