What does water injection actually do?

[thexav]

I've been wondering about water injection.

People add it to their projects, but what does it do? Surely water doesn't mix well with fuel or even burn?

I can see why you'd spray it on an intercooler for example but why on earth would you inject water into your engine?

 

[Lunchmoney]

I've not heard of injecting into the engine. Why would anyone do that?!

 

[obi_waynne]

Benefits and drawbacks of engine water injection systems

We look at the pros and cons of water injection systems and the effect this can have on a highly tuned engine. When you are running with high compression ratios as a result of forced induction or an engine rebuild water injection has many benefits.

www.torquecars.com

It is a thing @Lunchmoney

Water injection slows down the burn, so it can reduce the risk of knock in highly tuned engines. It's similar to running higher octane fuel in it's effectiveness.

In my opinion it is a bodge, a good knock sensor, setting the correct compression ratio and adequate boost.

If you are injecting water and methanol it makes sense as this can help raise power, again you need to keep the mapping spot on.

 

[TCJBOLDIE]

IMO water injection can be dangerous IF there is a leak in the system or if it became faulty over time and failed to switch off or leak when parked as we all know water can't be compressed and could lead to costly repairs.