Homemade Water Injection for Auto Engines

Also known as an ADI, or anti-detonant injection, system, this type of cooling system is most often used with forced-induction engines, or those employing the use of such air compressors as belt-driven superchargers or exhaust-driven turbochargers. Such engines often use air-to-air cooling systems known as intercoolers to cool the superheated air charge, but intake temperatures are still high and risk pre-detonating the fuel before it is fully compressed in the cylinder.

ADI systems inject an atomized mist into the intake charge before the cylinder. As the mix of water, methanol, air and gasoline enter the piston, the heat created from compression vaporizes the water rather than heating up the cylinder walls. The methanol burns like gasoline, but does so at higher pressures, so the effective octane of the gasoline is increased.

When used alone, ADI systems have negligible effects other than cooling the engine down. In reality, the true benefit of an ADI system is potential, especially in forced-induction engines. With a higher effective octane and cooler air charge, the system allows the car tuner to electronically increase the compression inside the engine and use more aggressive ignition timing, thus dramatically increasing the power output of the engine. The more favorable operating temperatures allow the engine to operate farther under its threshold, thus increasing the longevity of the engine.

Vehicles utilizing ADI systems are unlikely to see better fuel economy. The engine will burn cooler, which may leave some fuel unburned in the exhaust. This may create a dark smoke from the exhaust, depending on the application of the system.

ADI systems are widely available for retail and are usually relatively inexpensive compared with more intensive engine and transmission upgrades. After purchasing, you must choose which ratio of water to methanol is most desirable in your driving conditions as well as how much will actually be injected into the intake charge. Higher ratios are more conservative, and lower ones allow for more aggressive engine management. It is recommended to have your vehicle professionally tuned so the engine can adjust to the new fuel mix, especially under higher loads. Water injection in conservative driving situations is more likely to drown the engine than enhance its performance.

Of course, the water and methanol do not spontaneously appear, so they must be stored in tanks, which are most often installed in the trunk or rear hatch (assuming the car has a front engine).