Driving in rain or to work on early mornings I had noticed my fuel economy improved by a small amount. Could it be the higher water vapour content in the air? Via research I came across an old technique called water injection used in the world War 2 era. Basically a fine mist water is introduced into the air intake manifold and this is burnt in the combustion Chambers.
The water mist is converted to steam which increases the compression ratio of the engine. The steam also cleans the built up carbon in the cylinders and also the oxygen sensor.
One month after implementing my own blend of water injection (water induction), I gained an extra 40km on a full tank of gas! The original stock range on my lev civic was a pitiful 290km. Four years after implementation of water injection, I typically get 460km. On consecutive long drives I will get over 560km per tank.
This project works reasonably well on cars without a catalytic converter. I have tried this on a car with its cat still installed and the project was a failure. Also, the needle valve used to control the flow of water into the intake manifold is critical in its percent open state: even a little too much water and the engine will splutter so its very important to use the smallest possible flow of water to achieve misting.
Now let me Show you what I did to obtain these results and it cost me less than 100TT dollars.
Step 1: Vacuum Line to the Air Intake Manifold.
I used the vapour line that pulls gasoline vapours stored in a charcoal canister. Years ago the rollover valve in my gas tank got stuck in the closed position. As a result I condemned that vapour line and removed the fuel vapour recovery hardware. The vacuum line as a result was available for my use to get a controlled amount of water into the air intake manifold. In the pic that's the hose with the copper tubing link.
Please note that if you introduce water mist before the air intake throttle you will sieze up your intake air control valve (and the electronic throttle if you have that) . Water mist must be introduced downstream of these devices for a reliable solution.
Step 2: Valve to Control the Water.
Using a brass needle valve for water control, I connected to the vacuum line. A very small amount of water is needed as even a little too much will cause the engine to cough and stall! If that happens it will need water removal from the air intake manifold and lots of heavy revving to start back.
Using a quarter inch inner diameter tubing, my flow is approximately 20mm travel of water in 15 seconds. I made a red mark to know how much to turn from the lock off position.
As water becomes mist via this valve, it gets really cold. Small scale refrigeration! This is a future project I will try to tap into.
Step 3: Water Reservoir .
Any bottle will work. Just have the tubing inserted and that's it. My bottle there gives me a month's supply. The water required is very small and it is only sucked into the engine when the throttle is closed (strongest vacuum at that position).
Important to note is I had removed my Catalytic converter. It was over ten years old at the time and past its service life. I used this water injection technique on another car without a Catalytic converter and it got much better fuel economy. I tried on a vehicle with a converter and that vehicle experienced the opposite!
When I start my car, steam exits the exhaust and carbon residue is deposited on the inside of the tailpipe. I no longer get the typical gasoline car exhaust smell. It smells much cleaner however I don't go sniffing that tailpipe for the good vibes.
This has been one of my most successful hobbies and literally pays for itself.
Step 4: Exhaust Debris.
As shown on the pics, Steam condenses to form a small quantity of water on the tail pipe. Carbon from inside the engine has been deposited due to the cleaning action of the steam. My Tail pipe is always cool to touch thanks to this effect.
Step 5: Side Effect: Refrigeration
I added a small radiator and separate water bottle with needle valve to test a theory. Under the pull of vacuum line, liquid water become water vapour much easier. To become vapour it needs to absorb thermal energy. This is why the vacuum line became so cold when the car starts. I have decided to use this phenomenon to produce low level air conditioning.
The temperature difference measured was greater than 14C. The radiator got cold enough to form condensation on a hot day in Trinidad.
I will make use of the refrigeration side effect to further another project.