Archives

I just spent some time at one of the other sites reading a thread on water injection. (I'm always looking for an excuse to mess with my car.) They were talking about "water vapor" introduced to the intake air stream increasing fuel economy. Assuming they are talking literally about gaseous water, that won't do a thing except take up more room. I guess it might displace some oxygen and cause the ECU to adjust the FI mapping down, but you're also reducing power at a given throttle position. Any potential gains using that technique are iffy at best. But that isn't the case if they were talking about water droplets in the intake stream.

Water injection has been around for a very long time on turbocharged engines. Its purpose is to cool the pressurized intake stream (remember that temp goes up when a gas is compressed) to prevent detonation in the combustion chamber. And it works well! As water droplets enter the intake stream they absorb huge amounts of thermal energy when they change state to a gas. Naturally aspirated cars don't need that because intake air temps don't get high enough under normal driving conditions to cause detonation. (IAT on my Accord hovers around ~105-110F due to the nice warm engine bay.)

But then it dawned on me: the same thing could be accomplished in a combustion chamber. If water droplets make it into the combustion chamber they will absolutely change state when the combustion event happens. This should convert more thermal energy into mechanical energy as water expands to steam, increasing the thermal efficiency of the engine. Power should increase for a given operating condition and exhaust gas temps should be lower. Improved fuel economy would be realized when the driver does not have to open the throttle as far to achieve a given rate of acceleration or a particular steady speed.

Practical considerations:
-Optimizing the water intake stream would take some care
-Using anything other than distilled water could result in a scale forming on everything that it touches.

Possible deal breaker:
-This whole thing depends on the assumption that the water->steam process does not interfere with combustion in such a way as to reduce its thermal efficiency. I am concerned that the energy used to flash the water droplets to steam might end up robbing the energy from other work-producing events. I'm going to have to think about that one and do some more research.

Thoughts?

I've heard rumors it helps. I would also be cautious of corosion from the distiled water. But I've never looked into it so it might be a irrational fear.

brick,

You have reminded me to really check my mpg on Monday's work commute. Might have heard on the weather channel that North Texas has received some badly needed rains this weekend.

I seem to get a 5-10% increase in FE just after a rain. Even wondered if installing a mister would be a good idea, but like you was afraid of doing harm. I wish the Honda engineers would go so far as to allow steam injection once the car is warmed up and err on the side of caution to avoid corrision.

When hacks like this come up, you have to figure the engineers consider it an had a reason to reject it. It could be:

it does not work
it is not legal
it could cause lawsuits
it would shorten the car's life
it is not cost effectiveIn this case, I hope they thought it's #5. I hope there is a way to be careful and make it an FE booster.

#6: The consumer has to add distilled water too often for it to be practical.

I think that a properly implemented system could be made safe for the engine. A lot of what comes out of the tailpipe is water as it is, so the real problem is preventing corrosion on the intake side. I guess my biggest concern is being able to meter it to follow volumetric flow rate. That could be nearly as complicated as a fuel injection system. RPM and vacuum ought to be enough data to get the job done but I have zero experience with microcontroller type stuff. Hmm.

I have half a mind to pursue this within reasonable limits. There might even be an inexpensive kit that I could modify. "Aquamist" comes to mind. Gotta do a google search...

**EDIT**
The aquamist kits are waaaay overkill for what we're talking about. I think that the best way to start is the simplest: a reservioir, an electric pump, a simple atomizing nozzle, and way to vary the speed of the pump manually from within the cabin. This would allow me to get up to a steady-state before switching on the pump and watching my scangauge. If it does anything I should be able to see some change in FE and fuel flow readouts as I adjust the water flow rate. If it does nothing I haven't wasted too much time/money on overcomplicated control systems :)

Brick,Delta, Tom,

I have had & used {Water-Injection} on a Kaw. 6-Cyl. Water Cooled Motorcycle. It was installed with a Turbo, Water Injection System Installed by Mr. Turbo in Chicago, IL. The reason for the Water injection along with the Turbo was to Lower the Intake Charge and keep the Engine from {Pre-Ignition} with the High-Compression Pistons that came Stock in the Bike. The Turbo was set a Much Lower Boost Level because of the Stock Compression and the {Water-Injection} kept everything in check, so as not to {Burn} a hole in the Pistons under Boost. To say that this Bike was fast was, an-understatement at Best. Exam: At like 120 MPH you could roll on the Throttle to wide open, Lean-Forward & the Bike would raise the front-tire up off the Road. I already know you find this hard to believe, but it is True-However & alot of the guys that thought at the time had Fast Bikes, Found out the Hard way what was really fast. A 1300 CC Mr. Turbo, Water Cooled, With Water Injection Kaw. Woop - E !!!!!!!!!!!!!!! Can you say? HANG-ON !!! :D

Terry
BTW,Man that takes me way back when: :D

That sounds like way too much fun :D

My first exposure to water injection was through a bunch of Volvo fanatics (no joke) who liked to crank up the boost on their ancient truck-derived engines. At 2-3 bars they didn't have a choice! That actually brings up an interesting point. I do have an old tank (85 Volvo wagon) in my parents garage waiting for a little TLC. That beast would make a pretty decent test mule for this kind of thing. 114 naturally aspirated horsepower pushing a 3400+ lb steel shoebox and I routinely saw MPG averages in the high 20s. Not bad for a car my parents bought when I was 3.

That sounds like way too much fun :D

My first exposure to water injection was through a bunch of Volvo fanatics (no joke) who liked to crank up the boost on their ancient truck-derived engines. At 2-3 bars they didn't have a choice! That actually brings up an interesting point. I do have an old tank (85 Volvo wagon) in my parents garage waiting for a little TLC. That beast would make a pretty decent test mule for this kind of thing. 114 naturally aspirated horsepower pushing a 3400+ lb steel shoebox and I routinely saw MPG averages in the high 20s. Not bad for a car my parents bought when I was 3.
brick;

Quote{ That beast would make a pretty decent test mule for this kind of thing.}

Why-Not !!!!!

Terry

Tiger,

I thought driving 113mph in an Insight was thrillseeking, but 120 on one wheel? :eek:

Tiger,

I thought driving 113mph in an Insight was thrillseeking, but 120 on one wheel? :eek:
Chuck,

I have not always been the most sensible person. Infact I guess just the opposite of that. Safe was not really a major concern back then with the extreme motorcycles or the xtreme cars I drove back then. However I will have to say that I did have alot of fun being crazy at the time. That has been many-many yrs. ago and now here I am thinking about FE and driving a HCH II.

How very interesting if one were to just stop and look back at one's past adventures.

Wild-Man;
Terry
BTW, Calm as a Kitten now though. :)

Hi Brick:

___Although these HW test reports are ancient by today’s standards; the EPA did measure FE in the vehicles of that era with the vaporization and other devices installed in a similar fashion as they do today.

Gas Saving and Emission Reduction Devices Evaluation (http://www.epa.gov/otaq/consumer/reports.htm)

___One device after another after another and the results yielded nothing … Just pick any pdf with a vapor injection like title.

___Although I hate to rule anything out and have seen a nice pick up in FE on a particular road after a rain in the Insight, it could be tens of things causing the appearance of better FE vs. what is achieved over a tank. If one were to take their automobile to the absolute limits each and ever tank and then install a water or alcohol vaporization device and actually recorded a significant change in results, there might be something to it. Every time I read a post about this or that injection HW, lubricant, fuel additive, or adjustment, I look at the posters current tank or lmpg and simply shake my head in utter amazement that they made the claim in the first place. In other words, I am not ruling out an injection mod from initial proclamation but until these guys learn how to push tanks with minimal ICE modifications first, they may as well be spitting into the wind with proclamations that in my mind mean absolutely nothing.

___Good Luck

___Wayne

Wayne, thanks for that link. For vapor injection I think the best way to analyze it is not to use a car at all. There are, indeed, too many variables to test something this complex on the road. I can probably get away with it in testing the additive, but not this. My thinking has been to design and build a simple test apparatus that measures the work produced by a single combustion event. (All it takes is a piston that is driven against known resistance, such as gravity.) That would allow me to meter air, fuel, and water under controlled conditions and repeat as many times as I want.

Of course this is all very hypothetical, but I think it would be interesting. :) You could test just about any mechanism that way.

Hi Brick:

___I would love to see the results in a device as you described. If you need any assistance, let me know what I can do to possibly help!

___Good Luck

___Wayne

Possible deal breaker:
-This whole thing depends on the assumption that the water->steam process does not interfere with combustion in such a way as to reduce its thermal efficiency. I am concerned that the energy used to flash the water droplets to steam might end up robbing the energy from other work-producing events. I'm going to have to think about that one and do some more research.

Thoughts?

I have wondered about this too. I read somewhere that steam takes up 1500 or more times as much space as water. Maybe this would overcome any losses in energy in the combustion event?

For you younger guys - I remembered that Oldmobile used a 'Water-Injection' system back in 1962. Below I pasted the paragraph talking about it but the rest of the site is pretty good reading on the evolotion of the GM V8. So as stated in other post - it is nothing new. The whole story can be found at wikipedia.org. (http://en.wikipedia.org/wiki/Oldsmobile_V8_engine)

Turbo Jetfire

In 1962 (http://en.wikipedia.org/wiki/1962) and 1963 (http://en.wikipedia.org/wiki/1963) Oldsmobile built a turbocharged (http://en.wikipedia.org/wiki/Turbocharger) version of the 215. The small-diameter turbocharger was manufactured by Garrett AiResearch (http://en.wikipedia.org/wiki/Garrett_AiResearch) and produced a maximum of 5 lb (0.34 bar) boost at 2200 rpm. The engine had 10.25:1 compression and a single-barrel carburetor. It was rated at 215 hp (160 kW) @ 4600 rpm and 300 ft·lbf (406 N·m) @ 3200 rpm. The high compression ratio created a serious problem with spark knock (http://en.wikipedia.org/wiki/Spark_knock) on hard throttle applications, which led Olds to use a novel water-injection system that sprayed small amounts of distilled water and methyl alcohol (http://en.wikipedia.org/wiki/Methyl_alcohol) (dubbed "Turbo-Rocket Fluid") into the combustion chambers to cool the intake charge. If the fluid reservoir was empty, the engine's timing would be retarded to avoid engine damage. Unfortunately, many customers did not keep the reservoir filled, or had mechanical problems with the turbocharger plumbing.
The turbocharger was offered only in a special Jetfire model, which was the first (http://en.wikipedia.org/wiki/List_of_automotive_superlatives) turbocharged passenger car offered for public sale. Only 9,607 were sold in two model years, and many were converted by dealers to conventional four-barrel carbureted form.

I realize that some time has passed here, but I have an interesting observation.

An old service trick for cars with carbon in the cylinders: warm up the engine to full temp, remove air cleaner, manually hold throttle open to about 1500 to 1800 rpm, pinch off a garden hose, then gently start a stream of water into the carb. Once the water starts, then the engine speeds up slightly. This seems to indicate that somehow the water is producing useful work.

As for injecting water, I think that a very small amount of liquid in the form of water droplets may work where water vapor, or the gaseous state, would only dilute the fuel/air charge.

I, too, have noticed slight increases in FE during or after a rain. I used to attribute that to the water acting as a lubricant for the tires-to-the-road connection, but I don't know.

Faithful and True

What i have read in the past if vaporized in the intake due to excessive heat like turbo or supercharging cools the air and combustion chamber to allow more power from the ability to add timing and more fuel.
In naturally asperated engines this is unnessary unless to much fuel,timing or there is to high compression for the octane used.
So if it ain't too hot to start then it only cools the fire resulting in lower fe

I think the main advantage of water injection is allowing a higher compression ratios while not needing high octane gas. It is the higher compression that gives the better FE.

Ever notice that when you are climbing a hill or otherwise have the engine in a high load that has the engine pinging, the pinging subsides when you lift off the gas. With water injection, the water injection could be used only under those conditions.

Water injection was used in WWII fighter plane engines under "emergency power" conditions.