How Water Injection Can Produce Big Horsepower Gains




  • In Science
  • 2019-01-12 13:00:00Z
  • By Popular Mechanics
 

From Popular Mechanics

Arguably the coolest part of the BMW M4 GTS is its water-injection system, a production-car rarity. It was a big part of how BMW was able to turn up the standard M4's 3.0-liter twin-turbo inline-six from 425 hp to 493 for the GTS. So how can a tank of distilled water create such a substantial boost in power?

As Jason Fenske of Engineering Explained details in this new video, the water-injection system allowed BMW engineers to crank up turbo boost and advance spark timing without increasing knock or decreasing reliability. A win-win.

BMW's water-injection system-which is supplied by Bosch and available to other automakers-sprays cold water into the intake plenum via three injectors. The water immediately evaporates into the air in the manifold, reducing intake air temperature and increasing the air density. Internal-combustion engines run best with cool, dense air, which helps decrease the likelihood of knock.

With a water-injection system like this, the compression ratio can also be increased, though BMW engineers opted to maintain the standard M4's 10.2:1 ratio for the GTS. It's also worth noting that the Porsche 911 GT2 RS offers a water-injection system too, though Porsche's system works by spraying water onto the intercoolers.

Water injection is actually an old-school trick for getting more power out of turbocharged engines. The 1962 Oldsmobile Jetfire, with its turbocharged V8, relied on a mixture of distilled water, methanol and anti-corrosion chemicals. Evocatively, Oldsmobile called this mixture Turbo Rocket Fuel, and it was essential, since this was years before knock sensors could prevent destructive detonation. If you didn't fill the water tank, the Jetfire's turbo was bypassed.

Saab also offered a water-injection kit on the 99 Turbo, but the development of intercoolers led OEMs away from factory-fit water injection systems, though aftermarket tuners have made big power with such devices (most of which run on a mix of water and methanol). Now, with automakers looking to extract more performance and fuel efficiency from turbo motors, factory water-injection could become common.

('You Might Also Like',)

COMMENTS

More Related News

See Photos of the New 2020 Porsche Cayenne Coupe
See Photos of the New 2020 Porsche Cayenne Coupe

Bayerische Motoren Werke AG (BAMXF) Q4 2018 Earnings Conference Call Transcript
Bayerische Motoren Werke AG (BAMXF) Q4 2018 Earnings Conference Call Transcript

BAMXF earnings call for the period ending December 31, 2018.

Auto stocks fall after BMW warns of global economic slowdown, trade trouble
Auto stocks fall after BMW warns of global economic slowdown, trade trouble

BMW executives said the industry faces a fiercely competitive environment, dogged by questions about how tariffs and trade tension between the U.S., China and Europe could affect supply chains, manufacturing and sales.

The BMW 2-series Gran Coupe Will Be a Front-Wheel-Drive "Four-Door Coupe"
The BMW 2-series Gran Coupe Will Be a Front-Wheel-Drive "Four-Door Coupe"

This new model, debuting later this year, will be BMW's answer to the Mercedes-Benz CLA.

Automakers Are Pursuing an Electric, Autonomous Future. But First: Massive Cuts
Automakers Are Pursuing an Electric, Autonomous Future. But First: Massive Cuts

BMW has announced a $13.6 billion savings and efficiency plan that is largely intended to help it invest more in technology. This is becoming a familiar story in an auto industry that's going through massive transformation. Going all-electric and embracing automated driving is an expensive business, and coming out on top seems likely to be a matter not just of superior technology, but effectively-executed restructuring too.

Leave a Comment

Your email address will not be published. Required fields are marked with *

Cancel reply

Comments

Top News: Science

facebook
Hit "Like"
Don't miss any important news
Thanks, you don't need to show me this anymore.