Mopar’s horsepower onslaught is showing no signs of letting up anytime soon, and the latest evidence of that takes the form of a rumor from Allpar.com that Chrysler’s entire lineup of Hemi V8s are expected to get an output bump, though exactly how and when are still a bit of a mystery.

Beyond the need to stay competitive with performance offerings from other manufacturers, an update to both engines would almost certainly bring with it an improvement in fuel economy as well.

The 5.7-liter mill, in particular, is in need of some mechanical updates. Making anywhere from about 360 to 390 horsepower depending on application, the smaller Hemi has not seen any significant revision since 2009 when the second generation motor debuted in the Dodge Challenger R/T.

The 6.4 is a newer addition to the Mopar roster, replacing the 6.1-liter Hemi V8 for the 2011 model year. At its introduction it made a very respectable 470 horsepower and 470 pound-feet of torque, and for the 2015 Dodge Challenger refresh, a newly re-calibrated ECU tune bumped power up to 485 HP and 475 LB-FT.

While it’s speculation at this point, moving to direct injection seems like the most likely upgrade that will be made on both motors, as doing so increases both power and efficiency, something both the government and consumers seem to like. Gains of 10-15% in output as well as a substantial bump in fuel economy are certainly within the realm of possibility, which would bring the 5.7 to well over 400 horsepower and the 6.4 to nearly 550 horsepower.

As far as the timing for those upgrades? Allpar says they likely won’t make it in time for the 2016 model year, which starts production at the end of this summer, but will almost certainly find their way into 2017 model year cars.

Rumor has it that the supercharged 6.2-liter Hellcat V8 might get an output bump at the same time as well.

Stay tuned for updates as we have them.