| Water |
| Steam |
| SuperCarb |
| Mixture |
| Products |
Admitting liquid water into a vacuum
line doesn't work. The resulting droplets are way too large and rough running
will result. The exception to this is in a turbo vehicle with the water
admitted before the inlet turbine. The high speed turbine blades chop the
water into a fine mist. This is not recommended though because the turbine blades
can be rapidly eroded.
The water injection systems that do work
are expensive. They comprise an electronic controller, a high pressure
pump and various sized nozzles. These systems are designed for turbo vehicles
and are only operated once the boost exceeds a preset level. They are not
used for cruising conditions but rather for racing. The flow rates are
very high, >150 ml per minute and this is of no use in a family vehicle.
Steam injection is what we have had the most success with. You can inject useful amounts of water as steam, without the problems associated with large water droplets. Exhaust manifold heat is used to boil water which is then admitted to the inlet manifold. The key principle here is that the steam, upon mixing with the cooler air and fuel mixture, will condense into a dense fine cloud prior to entering the cylinders. Being so fine it can mix and distribute evenly. Another benefit is the condensing steam liberates heat which helps to vaporize the liquid fuel droplets. Since we are boiling the water under quite high vacuum, the temperature doesn't have to reach 212 degrees F / 100 C to begin boiling. Our test setup In developing our system our key
policy was that the system we chose should be simple and non-invasive,
no drilling and no welding. The car was to remain stock standard, with
the add-ons able to be disconnected simply if need be.
The copper tube is about quarter inch diameter
 It is essential to include a strainer on the water pickup. The metering valve has such a small orifice that it will clog very easily. It is imperative that the system function reliably, because it is the steam or water injection system that prevents damage to the engine when we apply other mileage improving devices. |
The
system is very simple in principle using a reservoir of water, aquarium
hose and valve, copper
tube for a boiler and a T piece to tap into the PCV hose.
We also included a 
and 10 feet long. This is coiled tightly around the exhaust manifold close
to the engine with about a foot each end to attach our hoses to. Seen here blackened by the manifold heat. Use soft
annealed copper tube and wind it as tightly as possible. It is quite difficult
to do and maintaining intimate contact over the full length is virtually
impossible but not really necessary anyway. Our coils fit entirely under
the existing heat shield and look very neat.
Aquarium air hose runs from the reservoir through a hole drilled in the
lid, to an air valve close to the copper tube. The valve must be at the
copper tube end, not the reservoir end because the plastic tube will collapse
under vacuum. The valve is adjusted to control the water flow rate. You
can use plastic hose and fittings on the cold water side of the system
but you must use metal fittings on the hot side. Use hose clamps and lengths
of heater hose to connect the copper tube to the T piece in the PCV hose.
Remember to check for vacuum leaks. In operation the hot end of the tube
can get very hot, so make certain it is clear of any wiring.