Talk:Water injection (engine)

Air/Fuel Ratio
The typical air to fuel ratio (under higher load conditions) is typically 10.5:1 to 12:1 to cool the intake charge for as much reason as there isn't perfect mixing of the fuel and air before the combustion event--To maximize the oxygen use in the air as well as power output (and vice versa), extra fuel is used. In classically naturally aspirated I.C.E. cylinder/head design this maximum output was yielded about about a 12:1 air/fuel ratio.

In other words: Water injection doesn't typically improve the mixing before combustion as to allow maximum power to occur at stoich as opposed to a so call "rich" mixture.

Fluid composition
The following note:

"NOTE: Due to its corrosive nature, the alcohol in water injection systems cannot be ethanol. Only methanol and isopropanol are used, methanol being the more commonly-utilised form of alcohol for this purpose due to its higher availability and lower cost than isopropanol."

... from the article is not supported by most articles on this topic.

Please read "Why Not Methanol?" at the following link: http://www.drivingethanol.org/motorsports/racing_fuel_characteristics.aspx)

or...

"Methanol is also more corrosive than both ethanol and gasoline..." at http://www.klima.ph/cth/solutions/alternative_fuels/alternative_fuels.php

The "ethanol is more corrosive that methanol" statement appears to be a "talking point" that I will leave to the reader to figure out it's motivation based on the politics of each alternate fuel. Note that there are tens of thousands of E85 "flex fuel" vehicles in operation today (Brazil) that are designed to burn a mixture of 85% ethanol and 15% gasoline.

I presently use a 50/50 ethanol/water mixture in my water injection system - specifically to AVOID the corrosive nature of methanol on the fluid pump.

"But the greater effect comes later during combustion when the water takes in significant amounts of heat energy as it converts from liquid to gas (steam), increasing piston pressure (torque) "

this needs further clarification, on the face of it removing heat energy will not increase pressure or more technically the BMEF. I think its intent is to say while some heat and hence pressure is lost due to the need to vaporise the water, this is more than offset by the higher charge pressure, and hence effective compression ratio, which results in a higher BMEF.

and furthermore, the addition of the water will actually reduce the amount of work (due to lower temp increase, and hence less pre TDC cylinder pressure) required to compress the charge, so factor that in as well. —Preceding unsigned comment added by 124.188.50.48 (talk) 07:45, 20 November 2007 (UTC)

This article needs a revamp
This article seems to be lacking facts and is outright erroneous on a number of points.

"Many water injection systems use a mixture of water and alcohol (usually 50/50), partly because the alcohol is combustible, while water is not; in addition, the alcohol serves as an antifreeze for the water. Hence, water injection is also often known as methanol-water injection, owing to the fact that the alcohol mixed into the injection solution is often methanol, CH3OH."

I would like the author to cite a source for this information. AFAIK Water injection is water injection unless the author can cite an instance where Water-Alcohol injection was referred to as water injection in a technical capacity. Once you mix it with alcohol then it is no longer simply water. German engineers used Water and alcohol injection and it was named MW50 http://en.wikipedia.org/wiki/MW50

The MW50 article is far more accurate and professional than this article

I also second the point about this line "Due to its corrosive nature, the alcohol in water injection systems cannot be ethanol. Only methanol and isopropanol are used, methanol being the more commonly-utilised form of alcohol for this purpose due to its higher availability and lower cost than isopropanol."

This is outright absurd. Methanol is far more corrosive than Ethanol. In a properly designed system none of this matters though. What does matter is the latent heat properties of those three alcohols, their octane ratings, their specific energy, their stochiometric air fuel ratios, etc etc etc

None of this is mentioned, and essentially should not be in the article since it is entitled "Water Injection"

What is ironic is that the NACA reference at the bottom of this page specifically mentions using Ethyl alcohol in the first paragraph. Ethyl alcohol is Ethanol.76.176.101.124 (talk) 08:28, 15 December 2007 (UTC)

Recent edits by 75.183.72.53
There's no point in having a revert war over this. I've reverted your edits because I don't feel they add anything significant and I have doubts about the scientific correctness of them. Any statements about the composition of the fluid or the reasons for it's specific composition belong under the appropriate section. Repeatedly re-adding the same content after it is removed is pointless. We should be able to come to consensus rather than keep reverting each other's edits. Shreditor (talk) 00:37, 19 September 2008 (UTC)

Merge with MW50
There is lots of overlap here. The MW50 article is a specific description of the German water injection system, while this is a more general article. I propose that we move the relevant contents of the MW50 article in to a section in here, then turn "MW50" in to a redirect to this article. Shreditor (talk) 00:37, 5 May 2009 (UTC)


 * Support - No problem with the redirect, but any content merged here needs to be cited, as that article has no sources. - BillCJ (talk) 01:51, 5 May 2009 (UTC)


 * Weak oppose No real problem with the merge and I wouldn't oppose it if it happens, but MW50 is a sufficiently notable example that it ought to be expandable to a much better article: better refs, expansion of the list of engines / aircraft so fitted, and in particular some images. In that case, I'd think the ideal scenario is a one para precis under Water injection (engines), and a more link to MW50. Andy Dingley (talk) 09:29, 5 May 2009 (UTC)


 * Oppose -- By that logic, "M16" should be a subsection in the "Assault Rifle" article. I agree that MW50 needs to be improved, but I feel the specific German system is sufficiently notable and distinct from the abstract concept of water injection that it deserves its own article.  From reading the articles, it sounds like the physics of the MW50 system is slightly different from normal water injection in that MW50 acts like water injection but also has additional effects in the supercharger.  But I'm no expert on the topic, so maybe someone qualified can confirm or deny that.  Aubri (talk) 13:36, 15 October 2009 (UTC)


 * Oppose  MW50 is not even a subsection of water injection, it combines something else WITH it.   Continuing the above analogy, the M-16 should be made a subsection either to the Garand M-1 due to being a selfloading standard infantry weapon or to the Stg.44 for being an assault rifle postdating it...   Weird proposal. DW75 217.208.225.55 (talk) 05:41, 2 January 2010 (UTC)
 * Wierd opposition. - BilCat (talk) 11:15, 4 October 2010 (UTC)

Effects of water injection on BMEP?
Have done some calcs for a steam engine, and was somewhat surprised at the resulting BMEP. Wondering if anyone has details (power, displacement rpm) that would allow bmep figures to added for water injection to page on BMEPs.There also seems to be certain similarities between water injection and internal combustion boilers. http://www.douglas-self.com/MUSEUM/POWER/ICboiler/ICboiler.htm 82.47.136.229 (talk) 16:36, 19 November 2011 (UTC)

Maintenance tag from 2014
Since there hasn't been any effort to clean the article up and provide citations, I am going to remove all the uncited content. See more citations needed.

This is the diff of all the changes. In my experience, it is MUCH easier to start fresh with reliable sources and build content. This diff can also be used to do research for the type of content - which would likely need to be reworded based upon content from the source.–CaroleHenson (talk) 01:47, 18 February 2022 (UTC)