Water Injection all you need to know :D
In an effort to run more boost without having to resort to running race gas full time, and to help keep our engine cool during extended high-speed runs such as hot lapping, we installed an ERL Aquamist competition water injection system. Unlike the crude windshield washer pump-based systems of old, the Aquamist system uses a sophisticated, solid-state, piston-type pump that pumps the water at 125 psi. At this high pressure, there is little likelihood that boost pressure can reduce water flow significantly. A windshield washer pump, by contrast, can only run 10 to 20 psi. If you only have a 10 psi water pump and are running 20 psi of boost pressure, you will end up reverse-flowing boost pressurized air throughout your water injection system.
Water injection relies on water's naturally high specific heat, which means it requires a lot of heat to change liquid water into water vapor (steam). The high specific heat is one of the reasons why water is an excellent coolant. When injected into an engine, water does several things. When it is first injected, some of the water vaporizes absorbing heat from the incoming intake stream. This helps cool the hot intake charge in much the same way nitrous oxide injected into the intake of a nitrous-equipped car does. Since the Z's stuffy engine compartment and intake tract suffer from heat soak, we will really need this intercooling effect.
Once inside the combustion chamber, the water is fully vaporized into steam. This vaporization absorbs a tremendous amount of heat from the combustion reaction, helping cool the engine internally to prevent glowing hot spots (areas of self-ignition where detonation propagates). The heat absorbed from the water's phase change also acts to buffer the combustion event, slowing it down. Thus, the water helps regular pump gas behave much like slow, controlled-burn, high-octane race gas.
The superheated steam also acts like a powerful steam cleaner inside of the engine, removing compression-raising, hot-spot-propagating carbon deposits from the combustion chamber and spark plugs. This is a pretty cool side benefit of water injection.
Since water absorbs power-producing heat, it does not produce quite the same horsepower per psi of boost as race gas does, but it does allow quite a bit of additional boost. Because of its cooling and combustion buffering effects, water also goes a long way to eliminate engine-damaging detonation.
The Aquamist water injection system uses a unique proprietary atomizer nozzle to introduce the water to the intake air stream. The nozzle produces a range of droplet sizes from a fine fog to a coarse mist. This helps the water work more efficiently. The fine water fog vaporizes almost immediately, helping reduce the intake air temperature by about 20 to 30 degrees. The larger droplets do not vaporize until they reach the combustion chamber where they can perform their internal cooling and combustion buffering duties. All of the droplets are small enough where the even distribution of water throughout the manifold plenum is assured. Since most modern fuel injected cars have manifolds that are designed to flow dry air only, not a mixture of liquid and air, the maintenance of correct water droplet size is critical for even cylinder-to-cylinder water distribution.
Since we first tried the Aquamist system, we have had nothing but success with water injection for both increasing power and getting more reliability out of heavily boosted engines.
The Aquamist system works so well that almost all of the psycho turbocharged Group-A rally cars in Europe use this exact system with up to 3 bar of boost. Some rally cars use two pumps with multiple nozzles for even more water flow. In fact, the European-market Ford Sierra Cosworth uses this system as original equipment from the factory! This alone speaks highly of the system's reliability and performance.
In previous testing, the Aquamist system was able to keep a turbocharged SE-R's engine from getting coolant temperatures above 200 degrees during hard track lapping on a 100-degree day. Stock SE-Rs will normally overheat under these conditions, no less turbocharged. This is a strong testament to the ability of water injection to keep an engine from overheating under extreme conditions. Since the Z's tight engine compartment suffers from poor air circulation and the Z is also prone to overheat under track conditions, the Aquamist system is going to be one of our strategies to help keep the engine cool and in one piece at the track.
The Aquamist system can be tuned using different sizes of jets ranging from 0.40 mm to 1.0 mm. We opted for twin 0.5 mm jets, treating our engine as two, small 1500-cc three-cylinder engines. We used the Z's rear-mounted windshield washer reservoir as the water holding tank for the Aquamist system, since the Z is so tight that there was no place else to fit an additional water tank. Because of the Z's lack of space, we were forced to mount the Aquamist pump to the backside of the front bumper support. This sounds less than ideal, but because space goes for such a premium in a Z, this was literally the only place we could find!
To partially offset the power-reducing, internal-quenching effect produced by the water, a leaner fuel-air mixture and more ignition advance can be run. Advancing timing on a turbocharged engine that has been retarded to avoid detonation will not only increase power output, but also reduce exhaust gas temperature--a good thing. JWT will program a special ECU that has a special map to complement the water injection system once we get close to getting our engine running.
The water injection system is almost like having a perpetual tank full of race gas--without the $5-per-gallon cost. After all, water is cheap. For once in the history of hot rodding, something can be done for nearly nothing. As an interesting side note, water injection also reduces toxic oxides of nitrogen emissions by reducing combustion temperatures. All of these advantages and cleaner air to boot!
Maybe the heat shield is resting on the prop? have a look underneath for anything that looks out of place. sticky calipers/handbrake shoes.