BMW has found some life in water, too, squirting the stuff into the intake plenum of the M4 GTS’s S55 twin-turbo inline six-cylinder engine to make more power.
Water injection isn’t a new technology, even for production cars. More than 50 years ago, General Motors offered a water-injected turbocharged engine in its 1962–63 Oldsmobile Jetfire. If you never heard of that one, it’s probably because most were converted to use conventional carburetors after the secondary injector system dried up when owners didn’t refill the tank of “Turbo-Rocket” fluid, as GM called its methyl-water cocktail.
Any liquid, as it transitions from a liquid state to a gaseous state, can do this magic. The evaporation process converts some of the unwanted heat into harmless humidity. Lowering the intake temperature prevents engine knock and the unwanted detonation of fuel, and it also allows the turbos to produce more boost—21.6 psi versus 17.2 in the regular M4—and the electronics to advance the timing. The result in this case is a 49-hp bump from the 444-hp Competition Package M4, to 493 horsepower.
Check out the video here to watch the GTS running a 7:27.9 lap of the Nürburgring Nordschleife, quicker than that of a Ferrari 458 Italia:
front-engine, rear-wheel-drive, 2-passenger, 2-door coupe
ESTIMATED BASE PRICE:
twin-turbocharged and intercooled DOHC 24-valve inline-6, aluminum block and head, direct fuel injection, port water injection
182 cu in, 2979 cc
Power: 493 hp @ 6250 rpm
Torque: 443 lb-ft @ 4000 rpm
7-speed dual-clutch automatic with manual shifting mode
Wheelbase: 110.7 in
Length: 184.6 in
Width: 73.6 in Height: 54.4 in
Passenger volume: 54 cu ft
Cargo volume: 11 cu ft
Curb weight (C/D est): 3550 lb
PERFORMANCE (C/D EST):
Zero to 60 mph: 3.4 sec
Zero to 100 mph: 8.1 sec
Standing ¼-mile: 11.5 sec
Top speed: 190 mph
EPA city/highway driving: 16/23 mpg