The BMW Z4 M Roadster (E85) came from the factory with with a 3.2 L S54 inline-six making 338 horsepower and 269 lb-ft. However Manhart calls this roadster a “MHZ4 600” because of the increased power from a powertrain swap. Instead it’s powered by a 5.0 L S85 V10 from E60 M5 stroked to 5.8 liters making 630 PS (621 hp) and 640 Nm (472 lb-ft) of torque. Power is sent through a M3 E92 six-speed manual gearbox with a sintered racing clutch to a E60 M5 differential. The 1450 kg (3196 lb) roadster rides on Bilstein B16 PSS10 coilovers, Brembo six-piston calipers with 380×34 rotors in front, and E60 M6 brakes in back.
Source: Manhart Performance FB page, Topgear, and Autoblog
That V10 looks completely stock in that Z4 like it was meant to be there. Super clean swap.
BMW made the Z cars with bigger engines in mind than those that you could buy them with. The Z3 was actually tested in a V12 configuration.
I’m upset that someone stole this idea straight from my mind. I’ve been looking for this exact build and imagining it for years. It’s perfect.