An illustration of Bosch WaterBoost technology inside an engine.
Water injection sounds like the stuff of science fiction: squirt a jet of vapourised water into the engine to get more power!
In reality, that’s a pretty apt description.
But not every car has this technology. In fact, only the BMW M4 GTS in recent memory appears to have this tech.
It’ll take a few years for it to trickle down to our bread-and-butter models, so let’s take a look at what benefits it brings.
What is water injection for my engine?
Water injection – also called “anti-detonant injection” – is a technology that is claimed to reduce both fuel consumption and CO2 emissions while boosting engine performance.
It has its roots in World War 2 fighter aircraft. The P-47 Thunderbolt and P-51 Mustang both had water injection to briefly increase their power outputs.
In modern cars, water injection won’t necessarily help you get out of a dogfight-slash-traffic light grand prix, but it can give you a more reliable engine.
In a car, water injection happens right before the intake valve.
That cools the intake air, making it denser (higher volumetric efficiency), preventing knocking, or premature detonation of fuel.
What are the advantages?
Having a denser air-fuel mix enter the combustion chamber translates to increased performance.
As a reminder, internal-combustion engines love sucking down cool, dense air because it reduces the likelihood of knocking.
The BMW M4 GTS is so far, the only production car to make use of water injection.
For the same compression, it nets you a more complete burn and therefore reduces the pollutants coming out from your engine.
Also, it means that you need to burn lesser fuel to get the same power output, translating into better fuel economy.
What are the limitations of water injection?
Firstly, technology like this can’t simply be retrofitted to any engine.
That’s because your engine is programmed to run on a specific air-fuel ratio, so introducing water injection will likely mean reprogramming your motor.
That involves a lot of time in getting it right, otherwise you negate the benefits of water injection.
In addition, the water tank must be topped up every 3000km or so, so you must keep an eye on it.
Also, engine damage can occur if too much water is pumped in.
Too much water in the cylinder could result in blown heads, shattered pistons and a very, very bad time for you.
The future
As car engines get smaller, automakers will want to eke out more gains from them.
Every little bit helps when engines downsize.
In this case, water injection could give a big boost (pardon the pun) to those efforts.
If this technology can trickle down to the cars you and I drive every day, bring it on we say!
