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Water Injection – Injector Placement & System Design

Water Injection – The Right Approach For You

There are many ways to get water injection system onto your car and the most important factor is the cost. Water/Methanol injection is a simple concept which has become very popular hobby for those who want to make something themself. However the DIY option has its drawbacks , such as increased install time, bug finding, sourcing the right parts, reliability and tuning. If however you want something off the shelf you will find dozens of kit on the market to meet almost any requirement .

Water Injection – What Do You Want?

An intercooler water sprayer is the most basic type of water injection system. If you are counting on your water injection system to let you run more timing under high boost, reliability is critical.

Water Injection – The Pump

There are kits on the market which use pumps specifically designed for injecting water into an engine that is under high boost and there are other kits that use a generic pump which was not intended for this use. The first type of kit is proven, the generic pump kits may not be so reliable.

Water Injection – Injectors.

Again, there are kits that use generic injectors and other which use injector technology specifically designed for putting water mist into the combustion temperature under boost. If your building a kit yourself you need an injector that can spray a fine mist at the pressures you are spraying at. A nozzle will have a specific pressure it is designed to work at.

Water Injection – Installation

Finding a home for the pump, sensors, the gauge, the injector, the control unit and the tank can be time-consuming. Experience fitters will fit a kit considerably faster than a first timer.

Water Injection – Tanks

If you’re using only water, then most containers will work, if you’re using methanol, be sure the tank you are using is suitable.

Water Injection – Controlling The Flow

An on-off switch is not going to cut it. You need something that will spray in proportion to the amount of boost the engine in under and the rpm it is running at that time. This is where an off the shelf kit comes into its own. If you are going the DIY route you need to look at electronic boost controllers to see if you can use the boost solenoid function to control flow of the water/methanol injector.

Water Injection – Where To Mount The Injector

Pre turbo gives by far the biggest benefit but you need extremely good control of the mist entering the compressor. Drops landing on the compressor blades can effect the balance of the turbo causing huge problems. Pre turbo water injection changes the map of the turbo making it behave like a larger turbo.

Before the intercooler is good but be wary of puddling if you don’t have a good mist forming. Pre throttle body is the most common placement and probably the easiest to fit and tune.

More on injector placement

Water Injection – Install Safety

When the system is switched of there should be no drain on the battery and it should not be possible for water to leak out of the nozzle.

Water Injection – Fail Safe

If you are using your water injection/methanol system to allow you to run more boost and more ignition advance you need fail safes in the system. You need some way to cut ignition of fuel when the tank reaches a certain level and you want a fail safe that cuts ignition or fuel if pressure to the nozzle falls below a certain level.

Ignition cut or fuel cut is only suitable for race engines. You don’t want to be left by the side of the road if you run out of water or methanol so a signal that can put your ECU onto a different map if water level or water pressure gets low is the choice for a daily driver.

more information

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This page was last modified Apr 2, 2014 @ 4:43 pm

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