The most power I could do in demo.
Power: 646,5HP
Torque: 686,7Nm
Can you make it any better? If so, post your engine as a reply 
5.4L 16 Valve DOHCRev0.lua (25.2 KB)
I might look at it but I am building like F1 engines in the game atm so I am tied up
Veni, Vidi, Vici, here you have it. 
Could need möre pöwer though
5.4L 20 Valve DOHCRev4.lua (25.2 KB)
Man I can beat you with your own engine
5.4L 20 Valve DOHCRev0.lua (53.6 KB)