nnorris7413

iTrader: (5)

here's a rough draft of my research paper on water injection that i wrote for english class



Water Injection and Turbocharged Engines

The idea of injecting water into an engine to increase the engine’s power output first came up during World War II. The cooling of the combustion chamber by the injected water suppresses knock, which allows the boost pressure or compression ratio to be raised. In addition to the power gains that water injection can achieve, it also reduces a car’s emissions and increases its fuel economy. Water injection has come a long way since World War II and is now put to use on modern day street cars and race cars. While water injection systems are a cheap and easy way to get more power out of an engine, the consequences of a system failing are fairly extreme. Water injection is a cheap and practical way to get more power out of an engine, and, in spite of the possible consequences, it would be worth the risk to install a kit onto a car to achieve the incredible performance gains.
Water injection first came around during World War II when a demand for more horsepower out of already built engines arose. The task was given to Frank Weber of Pratt & Whitney. He came up with the idea of injecting a small stream of water just before the combustion chamber of the engine. This would result in the water cooling the combustion chamber, which would ultimately suppress knock. This suppression of knock would allow the boost pressure on the turbocharger to be raised exceptionally. “The maximum manifold pressure ever recorded was a staggering 150 inches of mercury (inHg)! This was up dramatically from the 49-inHg maximum manifold pressure originally…” (McCutcheon, 9). The original output of the engine was 2,000 horsepower, but after the addition of water injection, the power output was raised to 2,800 horsepower. Water injection was immediately applied to each of the planes in the fleet, and it may very well have been one of the main reasons for the Allies winning the war. It was not until 1964 when Pat Goodman decided to design and install a water injection system onto his Porsche racecar that water injection finally came to cars. This gave Goodman’s Porsche a great advantage, so “the racing organization responded by banning his device . . . it made the vehicle too fast!” (Water Injection Wizardry). Since then water injection has found its way onto countless street and race cars.
Water injection works because of water’s extremely high latent heat. When water evaporates it absorbs a great deal of heat. This means that it is absorbing heat from the combustion chamber, which results in cooler chamber temperatures. This increases the likelihood of the fuel burning too early, so knock is suppressed. "The conversion of water to steam consumes heat (at a rate of about 1,100 calories per gram of the liquid) at a very critical instant. This absorption of heat prevents the temperature of combustion from rushing to a sharp peak (as it does in a standard engine) and then dropping rapidly off. Instead, the car's heat increases more slowly, reaches a lower peak, and descends much more gradually," (Water Injection Wizardry).
Since the chance of detonation is greatly reduced, this means that the boost pressure can then be turned up. Raising the boost pressure increases the pressure in the combustion chamber which, in turn, increases the heat. Without water injection it would not be possible to raise the boost pressure past a certain point because the increased temperatures would eventually make the fuel ignite too early. Since the water cools the engine, more boost can be run safely. More boost means more air getting to the engine. More air getting to the engine means more fuel is needed to react with that air. More fuel in the engine means a bigger combustion. And a bigger combustion means more power being transferred from the engine to the wheels.
Water injection can be fairly unsafe, and as a result of this, many people are opposed to using it. It allows a car to run past its limit of detonation, but because of water injection it does so safely. If the system were to fail; however, the result would be catastrophic damage. The engine would knock incredibly since there is no more water being injected to cool the combustion chamber, and this would result in a blown engine. In order to reduce the risk of a blown engine, a good failsafe is a requirement. . “One word of warning, a water injection with good failsafe capabilities must be your first priority when you are choosing one,” (Water Injection Basics). Failsafes can be fairly expensive since they monitor many different aspects of an engine and the water injection system. As soon as the smallest problem is recognized (and with a very good, expensive failsafe a problem can be detected before it happens) failsafe immediately puts the car into safe mode, which usually involves the boost pressure being dropped to the minimum allowed by the wastegate and the car will run very rich to avoid even the slightest chance of knock occurring. A good, safe tune coupled with a good failsafe equipped with a water injection system can make a car basically bulletproof.
Water injection not only adds power to an engine, but it also increases a car’s fuel economy and reduces its emissions. By increasing a car’s power output less throttle is needed to travel at the same speed. Less throttle used means less fuel is being burned. “More power means that less throttle can be used to travel at the same speed. That efficient gasoline use translates to better mileage . . . as well as a boost in performance,” (Water Injection Wizardry). A car with a water injection system is capable of being tuned for either maximum power or maximum fuel efficiency. Tests have proven that there can be “approximately 20% MPG improvement by installing a water injection system on your stock engine,” (Water Injection Wizardry). This means that for every five tanks of gas put into a car you are getting the equivalent mileage of six tanks of gas. Over time this savings adds up and that can pay for an extremely good failsafe, and over time the water injection system itself will be paid off. Another effect of water injection is that the fuel burns much cleaner, which greatly reduces emissions. "This ethanol boosted engine concept uses a small amount of ethanol to increase the efficiency of use of a much larger amount of gasoline by approximately 30%. Gasoline consumption and the corresponding CO2 emissions would thereby be reduced by approximately 20%," (Cohn, 2).
In this test, ethanol was injected into the engine instead of water, but the same concept was used: the ethanol would cool the chamber temperatures which allows for the boost pressure to be raised. With that big of a decrease in emissions it is truly a surprise that manufacturers do not install water injection systems on production cars.
While not very complex, a water injection system greatly increases a car’s performance and efficiency and decreases its emissions. The cooling of the combustion chamber by the water increases an engine’s knock resistance. If tuned properly, an engine can take advantage of this suppression of knock and gain a great deal of power by increasing the boost pressure from the turbocharger. Water injection is an extremely effective and fairly inexpensive way to get the best performance out of an engine. Although an improperly setup or poorly monitored system can easily destroy an engine, a properly maintained water injection system is a practical modification to perform on a street driven car.

nnorris7413

iTrader: (5)

Sources used:

Bromberg, L., D. R. Cohn, and J. B. Heywood, comps. Calculations of Knock Suppression in Highly Turbocharged Gasoline/Ethanol Engines Using Direct Ethanol Injection. 23 Feb. 2006. Massachusetts Institute of Technology. <http://lfee.mit.edu/public/LFEE%202006-01%20RP.pdf>.

Georgallides, Tryphon. "How a Water Injection System Works." Rallycars.Com. 1996. <http://www.rallycars.com/Cars/WaterInjection.html>.

"Water Injection Wizardry." Mother Earth News Sept.-Oct. 1979. <http://www.motherearthnews.com/library/1979_September_October/Water_Injection_Wizardry>.

"Water Injection Basics." Alcohol-Injection. 11 Oct. 2005. <http://www.alcohol-injection.com/forum/showthread.php?t=217>.

Cohn, D. R., L. Bromberg, and J. B. Heywood, comps. Direct Injection Ethanol Boosted Gasoline Engines: Biofuel Leveraging for Cost Effective Reduction of Oil Dependence and CO2 Emissions. 20 Apr. 2005. Massachusetts Institute of Technology. <http://lfee.mit.edu/public/LFEE_2005-001_RP.pdf>.

McCutcheon, Kimble D. "Frank Walker-"What Can I Do About This Problem?"" <http://enginehistory.org/Frank%20WalkerWeb1.pdf>.

"Subaru World Rally Car Engine." Race Engine Technology.

Hendricks, R. C., D. T. Shouse, and W. M. Roquemore, comps. Water Injected Turbomachinery. Mar. 2005. NASA. <http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050175876_2005173637.pdf>.

Lanzafame, R., comp. Water Injection Effects in a Single-Cylinder CFR Engine. Mar. 1999. Society of Automotice Engineers.

SlowCar

iTrader: (4)

"This increases the likelihood of the fuel burning too early, so knock is suppressed."
~increases = decreases

~maybe by converting the inHg to psig:
~49 inHg = 24 psig
~150 inHg = 73.7 psig
~a more familiar unit will make more impact to the reader
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“One word of warning, a water injection with good failsafe capabilities must be your first priority when you are choosing one,” (Water Injection Basics). Failsafes can be fairly expensive since they monitor many different aspects of an engine and the water injection system.
~not expensive compared to a blown engine. a few have learnt it the hard way.......and more will

nnorris7413

iTrader: (5)

Thanks for those!