Water injection

[NorPug]

Have anyone knowledge about water injection on the N9T. They say that it's "healty" for the engine and prevent knocking.

I found this link for a cheap selfbuild system:

www.dawesdevices.com

Looks easy, but what size of injector-nozzel and where's the best place to put it...

Any suggestions

[Bean]

I've never had water injection on my cars - but I worked on one that did. It was a very simple system that used the ECU to trigger the sprayer at a given temp and/or boost. Simple pressure/temp switches could do the same.

There wasn't a whole lot of technology to it - but the sprayer was located just after the throttlebody. Ideally it has to be far enough away that the water properly vaporizes, and that it mixes thoroughly into the itake charge.

I'd say to put it right after the TB, but make sure to choose a nozzle that has a really good spray pattern. You'll pretty much have to do some testing to get the right nozzle, but I'm sure you can do some research to get an idea of what to run as a starting point.

Water injection is definitley something I'd consider doing as well - but not till it's at a point that it needs it. Doing it for everyday driving isn't going to be a good thing - but it'll definitely help in extreme conditions such as racing. It also ensures the engine is making the appropriate heat - if that water doesn't vapourize then bad things can happen...

[Toni Lindroos]

How about just spraying water on IC's surface to cool it down in hot conditions? I think some cars actually use water spraying that way?

[webmaster]

Welcome NorPug!

Your right Toni! I think the new Subaru WRX STi has a intercooler spray switch.

Are ralley cars still using water injection?

I think it's a great idea, but probably hard to tune / get just right.

[Bean]

Yep - rally cars still use water injection...

The car that I worked on (RS200 at Pike's Peak) also had external spraying to cool the intercooler. Initially he had it set to go with boost, but I convinced him to change it to intake air temp and boost based since the intercooler has a tendency to heat soak - it made more sence to activate it by temp as well.

The internal spray system used the same temp/boost engagemet, but used a separate pump and resevoir.

It would be neat to set up a system that had a variable voltage feeding the 12V pump so that you could size it for full boost at 12V, and it would then vary the amount going in at lower boost. Problem is setting it up properly - but most people just spray in a modest amount. It still helps - but it's not perfect. $$$ to go from OK to perfect though. Full injections systems have been set up just like fuel to do it properly - but that RS200 had a very basic system and it worked fine.

Geoff was the guy who built it and he said it racing conditions you don't need the fine control since the car is driven at the edge the entire time. Peak heat and peak boost almost always...

Like it was mentioned - tuning would be difficult - but if you just had on on/off switch - you could just turn it on when the car was going to play. Set it up with a modest injection rate and you'd have a very effecting intake charge cooling system.

A friend just set up a ghetto system on his supercharged Scirocco and he said the difference was amazing. He just bought a selection of nozzles and kept upping the size until he didn't notice a difference, and then he went down one from there. Seems to work great for him.

[JunktionFET]

I have a friend that once put a bag of ice on his intercooler and noted a nice boost in power for a few moments. It was a hot summer day, and it made the car behave as though it was winter... albeit briefly.