BMW Water Injection: A New Spin on Old Hot Rod Trick

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Daniel Gray

September 20, 2016

Daniel Gray

September 20, 2016

Water injection technology dates back about 100 years. It works by cooling the cylinder, preventing premature ignition and engine knock. A cooler cylinder allows for a leaner fuel mix, a higher compression ratio, and more advanced timing. It’s a must if you want to make more horsepower on a tight budget. BMW utilizes the strategy with its limited-edition 2017 BMW M4 GTS—marking the first time that water injection has been used in a production vehicle, via a BMW M engineered system with Bosch components. Only 700 M4 GTS will be built.

The M4 GTS is factory-rated to sprint from zero to 62 miles per hour in 3.8 seconds, with a speed-limited top end of about 190 mph. The M4 GTS’s twin-turbocharged 3.0-liter inline six-cylinder engine pumps out 500 horsepower and 442 pound-feet of torque. That beats the conventional M4’s 425 ponies, and even the M4 Competition, with its rating at 444 horsepower.

Water injection is not just about making more horsepower. BMW also expects a four percent gain in fuel economy overall, with a 13 percent improvement while driving at highway speeds or during spirited acceleration.

The water injection system in the M4 GTS features an innovative tank setup. Water flows back into the tank when the engine is shut down, to avoid freezing in cold weather and is thawed when the engine is restarted. The tank is designed to hold enough distilled water for nearly 1,900 miles of travel.

The system is designed so that the port-injected water evaporates prior to combustion and is flushed out of the cylinder with the exhaust gases. Nothing is left behind to cause rust.

If you want to make big horsepower with water injection, you don’t have to fork over a suitcase full of cash for a brand new M4 GTS. eBay Motors lists a number of water injection products - opens in new window or tab., including Snow Performance’s system, which can be added to a wide range of engines in less than four hours. Prices for a Stage 1 Boost Cooler start at $400.

70 More Horsepower for the Taking

Matt Snow dove into the world of water injection in 1998. He was running a supercharged 5.0-liter V8 in his Mustang and the engine had a nasty habit of blowing head gaskets. At the time, Snow was the lead technician on a diesel fuel injection project at Sturman Industries in Woodland Park, Colo. When one of his engineers heard about the head gasket problem, he suggested that Snow try water/alcohol injection. “I was able to leverage a lot of engineering and technical expertise,” said Snow.

That led to Snow building a one-off system that solved the head-gasket dilemma and helped add an extra 70 horsepower to his Mustang. When word got out about the water/alcohol injection setup system, folks clamored for the system. Snow Performance, also based in Woodland Park, was launched in 2001. The system quickly gained fans, with sales doubling every year for the first four years.

In 2014, Snow Performance became a second-tier supplier of components for the BMW M GTS effort. “This is a huge step forward for the technology,” Snow explained. “With BMW M and Bosch championing it to the auto manufacturers, it legitimizes it at a time when smaller turbocharged engines need to run leaner in the high engine load states as well as have more power to satisfy the market.”

Snow Performance offers water/methanol injection kits for gasoline-powered and turbo diesel engines. While forced-induction engines offer the most potential for horsepower gains, naturally-aspirated engines benefit as well. The 50/50 methanol mix (aka common windshield wiper fluid) raises the octane level and reduces air inlet temperatures. This allows for more boost and advanced timing. It can also be used along with high-octane race gas or E85 for an extra cushion of safety.

The company builds all of its systems in the US. Snow Performance - opens in new window or tab. offers bolt-on kits for a wide range of vehicles including Mustangs, Camaros, Challengers, Chargers, Evos, STis, BMWs, and EcoBoost F-150s, as well as Cummins, Duramax, and Powerstroke turbo diesels.

About the author

Daniel Gray

Daniel Gray is a best-selling tech author, trail-blazing blogger, recovering road-test editor, OG automotive YouTuber, and semi-retired delivery driver. His latest project, “The Last Mile Is the Front Line,” explores the over-hyped promises and unseen challenges of grocery delivery, where sustainability is paramount.

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This article is meant to provide general guidance only. Automotive maintenance, repair, upgrade, and installation may depend on vehicle-specifics such as make and model. Always consult your owner's manual, repair guide for specific information for your particular vehicle and consider a licensed auto-care professional's help as well, particularly for advance repairs.