1.8 Prius gets 74 kW @ 5.200 rpm with linear interpolation 3.7 "Prius" engine would get only 263 kW @ 9.000 rpm, but then again Prius engine runs at extreme 8:1 effective compression and 13:1 expansion ratio.
I still think as I said earlier it could be that 17:1 is not the effective compression ratio but it's still must be high (16:1) to get that power. I don't know at what point you can call an engine "atkinson" cycle engine.
Maybe next year they come up with 5.0 L engine
but then they will face engine overweight and they will have to go with lighter hybrid system.