The likely issue is that Cosworth got ahead of Aston Martin's official confirmation of Valkyrie outputs, something we're more used to from patent offices and Chinese model makers. The question is what output is Cosworth really talking about, and which car.
All of last year, however, various reports had the street-legal Valkyrie making 1,130 hp. A Road & Track report attributed "nearly 1,000 hp" coming from the NA V12, the remaining 130 from a kinetic energy recovery system working the front axle. Hence, we're not sure if Cosworth's talking about its own engine alone at 1,130 hp, or its engine with the KERS. But then there's this: At the launch of the Valkyrie AMR Pro during the Geneva Motor Show this year, Aston Martin said the track-only Valkyrie AMR Pro would enjoy "a combined power output of more than 1100 bhp — more than the Valkyrie road car and a figure than comfortably exceeds the magic 1:1 power-to-weight ratio."
The truth's a mystery for now, which is just as Aston Martin would want it. If Cosworth's engine really does make 1,130 hp on its own, that would be monstrous, and it would mean the automaker's been playing a serious game of English understatement. Even if Cosworth included the hybrid help, however, an NA V12 with 1,000 ponies would take the crown. The only competition is the 6.5-liter V12 in the Ferrari 812 Superfast, and that's 211 horses adrift. The quad-digit figures expected from Mercedes-AMG Project One and McLaren Speedtail require turbochargers, as does the just-teased V8 going into the Shelby Tuatara.
With the first of 150 Valkyrie road car deliveries scheduled for next year, we probably don't have that much longer to wait to find out.