The engine will likely be a twin turbocharged 1.6L 4 cylinder with Kers. The turbo boost is expected to be around 3 bar in order to reach a BHP of 500 to 550. RPM's will be limited to approximately 10,000 to 11,000. The Kers output is expected to be 112kw (150 HP) and the battery storage is expected to increase to 2200 kJ. Quite frankly, I find those storage capacities to be a bit hard to believe. I doubt that the current batteries have that kind of capacity. If true, Kers would supply 150BHP for 24 seconds. If so, the car would have a maximum combined power of around 650 to 700 BHP.
The original blog is here.