Introduction: Water Injection – Stage 1

Water Injection, also known as Wa-i

It may be a bit strange to hear, injecting water into engine combustion chamber ... hmm.
But it turns out that this method gives many benefits.

Wa-i is not a new innovation; even it has been applied in fighter planes during the World War 2 to improve the engine power during the attack.
Heat is a major issue in machine, and may cause rapid damage to engine components resulting in lower performance of the engine itself. Heat on the engine combustion chamber can reach 1100º C (2200º F)! Moreover if the machine uses Turbo or Supercharger
Wa-i works by lowering the high temperature in the combustion chamber when the air sucked into the machine gets cool as it mixes with cold water mist, thereby slowing down the burning of gasoline. It can be equal to consuming high-octane gasoline of equivalent of RON 113
This would be advantageous as the ignition timing could be more advance without having knocking symptoms, and the engine power increases. Theoretically, fine water droplets will split into mist in hot temperature of the combustion chamber, it generates additional extra power for the engine.

Benefits of Wa-i:
- Enabling to set gas mixture as efficient as possible (LEAN)
- Enabling to set ignition timing to move forward (ADVANCE) to get larger torsion.
- Keeping the combustion chamber to remain clean, as it always rinses by water vapor.
- Preventing carbon buildup in the combustion chamber.
- Keeping the engine temperature stability.
- Preventing engine Knocking/Pinging.
- Reducing NOx pollution level thanks to low temperature in the combustion chamber.
- Can consume Premium (Ron 88 fuel) without knocking.
- Can be mixed with alcohol / methanol to obtain a higher RON.

Negative impact …
- As the engine does not Knocking / Pinging, it would be difficult to detect fuel quality.
-. More attention should be given to muffler form corrosion possibility.
- Service contract for new car under warranty may be void
-. Extra work to constantly monitor the condition of the water tank is required

Common question: Could this cause Water Hammer?

Discharge of the injected water is very small, in the form of water droplets. When it goes into the combustion chamber, water droplets will break into water vapor at high temperature, hence it is not in the form of water
In other words, Wa-i does not cause Water Hammer.
In a joke of senior colleagues who have applied Wa-i since 2002 in various cars ... "water hammer occurs when the machine rotates at high rpm and a bucket of water is poured through carburetor.. BAMMMM ".. and. the machine will be jammed.
Water for Wa-i is REFINED WATER, or distillated water. Do not use mineral¬-contained water such as well water, tap water or bottled water as it will corrode.

For more powerful engine, refined water may be mixed with Alcohol / Methanol at a mixture of 1:5 to 1:3
On this occasion, I try to apply it in my car. And at this point I refer it to as Stage-1 Wa-i.
At Stage-1 Wa-i, the water stream is regulated by regulator and screened by One Way Filter, then flowing as a subtle splash of water through a syringe, then the water is channeled in through the hose into the existing vacuum in the carburetor or Plenum intake.
I use vacuum hose from Plenum Intake to Fuel Pressure Regulator, then it is distributed through Tee join to supply the Wa-i.


Components for Wa-i are quite cheap and easy to obtain, among others:
1. Aquarium Suction Filter
2. Water Regulator
3. One Way Filter
4. 24G syringe
5. Aquarium Tee join
6. One Way Filter


The picture is the Stage-1 Wa-I diagram:
1. Suction Filter
2. Water Regulator
3. One Way Filter
4. 24G syringe
5. Aquarium Tee join
6. One Way Filter

As the engine character varies, the syringe to be used may vary (24G, 25G, 26G, 27G, etc), depending on the need of water debit of your car engine..

To assembly the syringe with the hose and One Way Filter, you need to be accurate. Make sure that these components are glued with super glue.

Next is to make Water Tank.
Water tank could use various media, for example 2.0 l plastic jar that can be bought at supermarket.


After all components having been neatly assembled, install it to the engine.

From the running test, the power being generated is quite different.
The traction of the engine is light and long, starting from the bottom up to the Redline RPM it passed smoothly without knocking even it consumes RON 88


After having a running test, it was found that creating a branch of the vacuum to Fuel Pressure Regulator is not right.
The result was, at high RPM, FPR does not work optimally to maintain the fuel pressure as the pressure of the Vacuum was split by Wa-i.

Therefore, it has to make a new vacuum line, which is turned out that the line has been ‘provided’ by the engine component.
Later, the Wa-i will be moved to the new line.

See table of Emission Test with or without Water-Injection
  • Wa-i application on my engine not make any significant change (normal condition)
  • There are increasing value of HC (Hydro Carbon), maybe caused of too much water mixture.
  • Wa-i application can decrease CO value on idle, but increase CO at high rev, but still in normal range.

Good luck.


Translated by Taufik Masjhur
This post was originally published on in Bahasa Indonesia language.

References: mailing list
CRC Handbook of Chemistry and Physics,77th Edition, CRC Press, 1997, ISBN 0-8493-0477-6.
Improve energy efficiency in vehicles –
Water Injection Thermodynamics by Eric Fahlgren, 19 September 2003
Water Injection Project –, 5 February 2002
Water Injection For Your Turbo By Member David Lewis
Do-It-Yourself Water/Alcohol Injection System and Intercooler Sprayer by Dawes, 21 March 2000
Water Injection By Robert Mann, 27 September 2001, Revised 07 July 2003
Do-It-Yourself Water Injection System by Ron Novak, 1980
Nasa Water-Alcohol Injection Reports – Heinicke, Orville H ,NACA WR-E-264 NACA-MR-E5H12 , August 1945