Even if the hellcat happens to get more hp than the Viper its not like Dodge cant give the Viper more. The 8.3 is barely working to get the 640hp out of it at 77 hp/L. The Porsche 911 GT3 for example makes 125 hp/L.

 

77 hp/l is probably the upper limit in terms of two-valve pushrod technology. Maybe a bit more but I wouldn't expect to see the big V10 in emissions and OE durability compliant form with much more than that and certainly no where near the GT3's 125 hp/l


2 valve and 4 valve engines can generally flow in the same neighborhood when it comes to peak flow but a 4 valve engine absolutely smashes its 2 valve counterpart (all things equal such as bore size) in the low to mid lift range while requiring less valve timing and less aggressive cam lift rates.


That said, I have no doubt the aftermarket could get the 8.3 well over 100 hp/l.

 

I'm chomping at the bit to see what the SRT 8 version will hold.
I love the new Challengers, inside and out. They did a GREAT job.