Water/methanol injection has been around since the 1920s, but really didn’t have much practical use until World War II. As we know today, a fuel-rich mixture produces more power, but it’s not because that extra fuel gets burned during combustion. Rather, the excess acts to cool the mixture as it turns from liquid droplets to vapour with the heat of combustion.
Supercharged engines were common in military aircraft, so that they could fly at higher altitudes, despite the less dense air. But rich mixtures compromise the range that the plane was capable of, so substituting another liquid for aviation fuel would effectively increase the range, or allow for more power by increasing boost which would increase the altitude the plane could fly at. In the automotive world, the technology has not been ignored.
So How Does It Work?
What causes two things you never thought safe to dump into your engine to be powerful and safe? On a simple level, it’s intercooling and race gas combined. When you inject water and methanol into the intake stream, you cool the air as the liquids evaporate. When you get into the combustion chamber, it slows the flame, acting just like octane.
When trying to increase power, the hard limit arrives in the form of detonation which, if uncontrolled, will result in physical damage to the engine. Several external factors contribute to the onset of detonation, including engine operating temperature, intake charge temperature, air to fuel ratio, fuel octane level, overall fuel quality and engine ignition timing.
Beyond these, internal factors like compression ratio and carbon build-up in the combustion chamber or on pistons can have a direct effect as well. It’s a very good anti-detonation tool for boosted cars. The limitation for how much power you can make, assuming your physical structure is sound, is the octane in your fuel which limits how much boost and the timing you can run in your engine.
In the end, it’s all about cooling. Once you have a cooler combustion process running, you have options available to you. Ideally, you want to increase power again to the point just before the onset of detonation. This can be done several ways, but combining higher boost levels with ignition timing adjustment is the most common route.
Water/methanol injection can also be used on normally aspirated engines. High compression engines can use a 50/50 mix and see benefits. Even regular engines can benefit, but these most often use water only, with a lot of timing to improve fuel economy.
Check out the video below and let us have your thoughts.