Water Injection on a NA motor. BS?

[Guest Andrew240z]

Greetings,

 

I believe my title pretty much explains what I am trying to get to the bottom of. I have an individual who has been claiming for years that water injection on a normally aspirated motor will give performance improvements. So far, I have only found that it may allow you to run a lower octane gas, and nothing further. I have repeatedly asked him for a pre/post dyno readout from one of his cars, or from ANYWHERE that shows any performance gains. Can someone kindly direct me in the right direction? Thanks!

[datsunlover]

I'll have to ask my friend for the web site, but hes considering a water/meth injection system for his turbo Volvo. From what he's researched, it DOES work on N/A engines, but the gains are very small compared to using it on a turbo setup. Makes sence to me as the more boost you push in, the more heat is generated therefore warenting the water/meth injection to cool the intake charge. I can't really see the intake air in a N/A engine getting to those temperatures to begin with, so...

[Pop N Wood]

David Vizard had a good write up on water injection in his old, old, old book about building performance motors with economy. What water injection does is allow you to run more timing or compression in an engine that would otherwise detonate without it. It was really huge back in the 70's for guys who had the old high compression muscle cars who suddenly found 100 octane gas unavailable. Without the water injection they had to serious retard engine timing and THAT caused a significant power loss.

 

So the water injection doesn't increase power, but the tuning you can do as a result of it does.

 

It is definitely not BS. WWII fighter planes all had water injection in the later part of the war.

 

In a modern engine with a computer controlled knock sensor and variable boost, I would think water injection would allow the computer to automatically dial in more boost/timing. Vizard also pointed out that WI is typically not needed while cruising. It is only needed during periods of heavy throttle.

[Guest Andrew240z]

I realize that it is effective on WWII fighters. They used to have a throttle break seal, that the pilots could push the throttle past,and get additional power. Breaking the throttle seal also meant that the motor would have to be torn down after the flight was completed. But, this was also at very high altitudes on supercharged jet motors. Not exactly your run-of-the-mill toyota 4 cylinder. I also realize the benefits on a turbo motor. But, in a semi-humid climate such as Missouri, I just cannot see the benefits of this on a car. Maybe in Nevada, or another dry climate?

[Guest boosted]

An old timer told me stories about WWII planes using water injection during take off only. Water injected to raise compression increasing power output to get the plane off the ground .

Also heard that this was not a good idea in the L series aluminum heads.?

weather or not it actually causes any damage I do not know. Off the top of my head I cannot remember if it was the water or the meth that wasnt any good for the head.

[Bernardd]

http://www.myo-p.com/

[dr_hunt]

I ran the Edelbrock Vari-jection for years on a 406 NA sbc that had 11:1 comp in my 4wd truck. The Edelbrock unit had a vacuum setting and an rpm setting to start the injection. I had to repair the ecu several times and as far as I know edelbrock quit making it. It helped curb detonation.

 

Water injection just uses the latent heat of vaporization to cool the intake charge. The water also cleans carbon deposits from the combustion chamber. As for performance increase, I doubt it. If you really look at it there is no energy (BTU) in H2O to be released in the combustion process and it actually takes energy to break the H2O bond, so the answer to power should be NO! However, cooling the intake charge, makes for more air in the cylinders, but the increase would probably be miniscule at best.

 

IMHO

[datsunlover]

Now that someone has said something about the WWII fighters, I remember something about that too.. An 'old timer' told me about it too.. Something about how they used it while in flight as a 'boost' for sudden bursts in speed (for getting away or around and enemy fighter). And yes, the principal was, that water does NOT compress as the air/fuel mix does therefore, in effect, it rasied compresion slightly, making more power. I would agree with the rebuilding beeing necesary after this type of.. abuse of an engine.. I'm thinking this is similar to what has been posted about the 'throttle seal' thing..

[SpeedRacer]

DR_Hunt has it right. “Water injection just uses the latent heat of vaporization to cool the intake charge.†The latent heat effect is the same thing that makes air conditioning work. Although water injection is much more beneficial on turbo and supercharged engines it does provide for increased horsepower on a naturally aspirated engine.

 

As the water changes from a liquid to a vapor it absorbs a huge amount of heat which cools the incoming charge, (BTW, the water turns to vapor so it does not increase the compression ratio). For a carbureted engine the rule of thumb is that, for every 13 degrees cooler the incoming charge is, there is a 1 percent increase in horsepower. Most water injection systems recommend you use an alcohol solution to reduce the possibility of freezing. Also, alcohol provides for an improved latent heat effect, since it evaporates at a lower temperature, and it does in fact burn.

 

In general, today’s fuel injected engines tend to see even more improvement in horsepower because most of the on board computers can make adjustments to the air/fuel ratio and timing to take advantage of the denser charge.

 

The "13 degrees cooler/1 percent increase in horsepower" is also the reason why you want to duct fresh outside air to the air cleaner instead of the hot under hood air. It's not unusual for there to be 80-100 degrees difference in the temperature.

[Pop N Wood]

No no no no no! Water injection does not increase HP. It does allow more boost-timing-compression without detonation. It is the added boost-timing-compression that adds power.

 

WW2 fighters had a "war emergency power" rating. They also had variable boost and nitrous. Break the lock wire on the throttles, jam it to WEP, boost goes up, water injection comes on and in many cases so did the nitrous. After 10 minutes the engine needed a complete overhaul.

 

If your car runs fine the way it is, water injection will probably decrease your HP. It is only when you change the boost-timimg-compression that WI helps.

[MikeJTR]

When I was in college (1984), my senior project was a water-injection system.

To make a long story short, the water injection provided minimal power gains on an engine using fuel with a lower than required octane. The car required 87 octane, and 80 octane was used on the test vehicle.

 

The water injection eliminated the pinging when injected into the intake system. The latent heat of evaporation (going from a liquid (water) to a gas (steam)), reduced the temperature in the cylinders, and prevented detonation (pinging).

 

After road testing the car and adjusting the system to eliminate pinging, the car was put on a chassis dyno, and lost 20% of its initial horsepower.

If I remember correctly (for my particular project), the system was tweaked for maximum power, and it allowed the engine to produce about the same power on 80 octane, as it did on 87 octane (without water injection).

 

Most cars already use a form of "liquid" injection to reduce pinging under high loads. The fuel-enrichment system at full power dumps extra fuel into the combustion chambers, lowering the temperature of the fuel-air mixture, and reducing pinging.

In my opinion, fuel enrichment is simpler, and cheaper than water injection.

[Moridin]

I ran the Edelbrock Vari-jection for years on a 406 NA sbc that had 11:1 comp in my 4wd truck. The Edelbrock unit had a vacuum setting and an rpm setting to start the injection. I had to repair the ecu several times and as far as I know edelbrock quit making it. It helped curb detonation.

 

Water injection just uses the latent heat of vaporization to cool the intake charge. The water also cleans carbon deposits from the combustion chamber. As for performance increase' date=' I doubt it. If you really look at it there is no energy (BTU) in H2O to be released in the combustion process and it actually takes energy to break the H2O bond, so the answer to power should be NO! However, cooling the intake charge, makes for more air in the cylinders, but the increase would probably be miniscule at best.

 

IMHO[/quote']

 

I read somewhere, that the water reacts with the gasoline during combustion (I'm not 100% sure about this) to add more energy to the process, thus adding more chemical power - this is beside the cooling effect.

[dr_hunt]

Ok, I asked my uncle, retired AF colonel, who was a WWII fighter pilot, korea (jet age), and Vietnam (jet age), although in Vietnam he flew B52 missions out of alaska.

 

He said irregardless of whether the plane had water injection or nitrous, the engines had to be rebuilt if the throttles had been pushed beyond a certain point, due to overrevving. He said the H2O injection rarely worked since it would freeze in the winters of England and, but rarely used NOS since they needed every plane they had intact and not down for repairs. He said it was a hell of a plane and the H2O injection wasn't that critical to the planes performance as was the NOS and his understanding from briefings was that the H2O was for suppressing detonation. He also said he personally never needed or used the NOS.

 

Stoichiometrically, would somebody show me how water reacts with gasoline in a controlled combustion to increase HP!

 

I thought it was like this;

 

C8H18 + 12.5O2 --> 8CO2 +9H2O

 

Correct me if I'm wrong here but if you add H2O to the left side then to balance you add H20 to the right side as well, however you are adding (L)H2O to the left and the product on the right is (G)H20 resulting in a net loss of energy from the equation, subsequently you have less BTU given off because it was used in converting the liquid H2O to gaseous H2O. So any benefit has to be from denser inlet air temperature and nothing else. Water does not react with gasoline, never has and never will.

[Moridin]

It was something during the combustion process and I haven't had enough college level chemistry to prove it. I'm trying to remember back, but it was to do with CO2 and water. I didn't believe it myself, but the guy proved it. I'll see what I can dig up on these forums from my previous posts.

[SpeedRacer]

Yes, Yes, Yes, Yes - water injection does increase HP.

 

Please check out this SAE (Society of Automotive Engineers) Document:

 

SAE Technical Paper 1999-01-2568

“Water Injection Effects In A Single-Cylinder CFR Engineâ€

 

Excerpts –

 

“Early designs of high compression ratio aircraft piston

engines employed a water vapour induction system to

increase the fuel anti-knock rating and engine output.

With 10% injection of water1, during intake stroke fuel

octane rating is boosted about 2 to 4 units with simultaneous

increases in the engine output of 30 - 50 % [2, 3].â€

 

“Early designs of high compression ratio aircraft piston

engines employed a water vapour induction system to

increase the fuel anti-knock rating and engine output.

With 10% injection of water1, during intake stroke fuel

octane rating is boosted about 2 to 4 units with simultaneous

increases in the engine output of 30 - 50 % [2, 3].â€

 

“All observations are attributed to a cooling effect due to

the high latent heat of vaporisation of water and to a

water induced slow-down of the combustion process.

Direct test evidence on latent heat effects and on water

induced changes in combustion rates does not yield

homogeneous results, owing to various typologies of the

engines used for experiments.â€

 

The fact that you can increase compression and timing further increases the HP. Fortunately, many computer controlled cars have knock sensors so they can do that today. This is why your car runs better and faster on a cool damp morning than a hot dry afternoon!

 

And last, but not least, all WWII aircraft that used water injection generally used a 50/50 alcohol/water mixture. Not because England was cold but because, even in the summer, once you were above 15,000 feet it was almost always below zero.

[dr_hunt]

My quote was "Water injection just uses the latent heat of vaporization to cool the intake charge." It was a response to the question as to whether or not water injection adds HP. Increasing compression and timing are other factors I never mentioned but are the centerpiece of the article. I'd like to see a dyno test where timing and compression were left constant in a normal NA automobile engine and water injection added 30-50% more HP. Holy smokes if that papers claims are correct, it's as good as nitrous for less than 100 bucks! Ten percent water is alot of water, but would be worth it to get 520HP or even 600HP if it is as claimed. The fact that it didn't yield homogenous results is rather alarming though.

 

The statement from Moridin was quote; "I read somewhere, that the water reacts with the gasoline during combustion (I'm not 100% sure about this) to add more energy to the process, thus adding more chemical power - this is beside the cooling effect."

 

Fact: The internal energy of water in BTU/lb mass is 0.00 in a liquid state and -143.34 if in a saturated vapor at the same temperature, taken from Fundamantals of Classical Thermodynamics, 3rd ed, Wiley publishing, pg 619-633. So, after the water went through the carb venturi, we have to assume that it is in the same state as the fuel, vapor, it would then slow the combustion process down by removing heat, which would slow the pressure rise, since the pressure in the combustion process (P1*V1/T1=P2*V2/T2) is inversely proportional to the temperature, and the heat is lost to raising the temp of the water in lb mass, which in this case is 10% of fuel, so it would be significant. Bottom line, acts like octane!

 

Your talking a different kettle of fish pardner as evidenced in the paper!

Quote; "Early designs of high compression ratio aircraft piston

engines employed a water vapour induction system to

increase the fuel anti-knock rating and engine output."

 

Key point here is the words "Water vapour" and the evident fact that they were detonating engines because they didn't have enought octane and using water injection to overcome the limitations of high compression air cooled engines. That's the point, if your running on the edge, yup, you'd be loosing HP, alot of HP, detonation kills and 30 to 50% gains would be practical and realistic if you were running on the edge, however not on a normal NA engine.

 

Quote; “All observations are attributed to a cooling effect due to

the high latent heat of vaporisation of water and to a

water induced slow-down of the combustion process.

Direct test evidence on latent heat effects and on water

induced changes in combustion rates does not yield

homogeneous results, owing to various typologies of the

engines used for experiments.â€

 

However they don't state what the "various typologies" are that were used in the experiments. I'd like to call a duck a duck and a goose a goose, so it would be beneficial to know engine particulars so we don't categorize all engines as being the same, because they are not. Which is why the KB hemi makes 8,000 HP out of 500 cubic inches and that is why they are not using blown 500 inch BBC's or Fords.

 

Primary effect was latent heat of vaporization, secondary was delaying the combustion process effectively the same as increased octane. There is no mention of reacting with gasoline on a chemical basis, adding more chemical power or adding more energy to the process.

 

I'd bet that if you research that paper alittle more they are specifically referencing very, very early high compression air cooled engines. Advances in NA aircraft engine design today are kin to the automotive world and would be like a comparison of the LS1 to the Ford flathead of the 30's.

 

Gather some more details and let's see what that paper is all about so we don't get all hyped up on your claims of 30 to 50% more HP.

[Guest 240zJake]

Thought I'd let you guys in on what Sport Compact Car has to say about the water injection system they installed on their Z:

The article http://www.sportcompactcarweb.com/projectcars/0102scc_proj300zx/

 

Water Injection

In an effort to run more boost without having to resort to running race gas full time' date=' and to help keep our engine cool during extended high-speed runs such as hot lapping, we installed an ERL Aquamist competition water injection system. Unlike the crude windshield washer pump-based systems of old, the Aquamist system uses a sophisticated, solid-state, piston-type pump that pumps the water at 125 psi. At this high pressure, there is little likelihood that boost pressure can reduce water flow significantly. A windshield washer pump, by contrast, can only run 10 to 20 psi. If you only have a 10 psi water pump and are running 20 psi of boost pressure, you will end up reverse-flowing boost pressurized air throughout your water injection system.

 

Water injection relies on water's naturally high specific heat, which means it requires a lot of heat to change liquid water into water vapor (steam). The high specific heat is one of the reasons why water is an excellent coolant. When injected into an engine, water does several things. When it is first injected, some of the water vaporizes absorbing heat from the incoming intake stream. This helps cool the hot intake charge in much the same way nitrous oxide injected into the intake of a nitrous-equipped car does. Since the Z's stuffy engine compartment and intake tract suffer from heat soak, we will really need this intercooling effect.

 

Once inside the combustion chamber, the water is fully vaporized into steam. This vaporization absorbs a tremendous amount of heat from the combustion reaction, helping cool the engine internally to prevent glowing hot spots (areas of self-ignition where detonation propagates). The heat absorbed from the water's phase change also acts to buffer the combustion event, slowing it down. Thus, the water helps regular pump gas behave much like slow, controlled-burn, high-octane race gas.

 

The superheated steam also acts like a powerful steam cleaner inside of the engine, removing compression-raising, hot-spot-propagating carbon deposits from the combustion chamber and spark plugs. This is a pretty cool side benefit of water injection.

 

Since water absorbs power-producing heat, it does not produce quite the same horsepower per psi of boost as race gas does, but it does allow quite a bit of additional boost. Because of its cooling and combustion buffering effects, water also goes a long way to eliminate engine-damaging detonation.

 

The Aquamist water injection system uses a unique proprietary atomizer nozzle to introduce the water to the intake air stream. The nozzle produces a range of droplet sizes from a fine fog to a coarse mist. This helps the water work more efficiently. The fine water fog vaporizes almost immediately, helping reduce the intake air temperature by about 20 to 30 degrees. The larger droplets do not vaporize until they reach the combustion chamber where they can perform their internal cooling and combustion buffering duties. All of the droplets are small enough where the even distribution of water throughout the manifold plenum is assured. Since most modern fuel injected cars have manifolds that are designed to flow dry air only, not a mixture of liquid and air, the maintenance of correct water droplet size is critical for even cylinder-to-cylinder water distribution.

 

Since we first tried the Aquamist system, we have had nothing but success with water injection for both increasing power and getting more reliability out of heavily boosted engines.

 

The Aquamist system works so well that almost all of the psycho turbocharged Group-A rally cars in Europe use this exact system with up to 3 bar of boost. Some rally cars use two pumps with multiple nozzles for even more water flow. In fact, the European-market Ford Sierra Cosworth uses this system as original equipment from the factory! This alone speaks highly of the system's reliability and performance.

 

In previous testing, the Aquamist system was able to keep a turbocharged SE-R's engine from getting coolant temperatures above 200 degrees during hard track lapping on a 100-degree day. Stock SE-Rs will normally overheat under these conditions, no less turbocharged. This is a strong testament to the ability of water injection to keep an engine from overheating under extreme conditions. Since the Z's tight engine compartment suffers from poor air circulation and the Z is also prone to overheat under track conditions, the Aquamist system is going to be one of our strategies to help keep the engine cool and in one piece at the track.

 

The Aquamist system can be tuned using different sizes of jets ranging from 0.40 mm to 1.0 mm. We opted for twin 0.5 mm jets, treating our engine as two, small 1500-cc three-cylinder engines. We used the Z's rear-mounted windshield washer reservoir as the water holding tank for the Aquamist system, since the Z is so tight that there was no place else to fit an additional water tank. Because of the Z's lack of space, we were forced to mount the Aquamist pump to the backside of the front bumper support. This sounds less than ideal, but because space goes for such a premium in a Z, this was literally the only place we could find!

 

To partially offset the power-reducing, internal-quenching effect produced by the water, a leaner fuel-air mixture and more ignition advance can be run. Advancing timing on a turbocharged engine that has been retarded to avoid detonation will not only increase power output, but also reduce exhaust gas temperature--a good thing. JWT will program a special ECU that has a special map to complement the water injection system once we get close to getting our engine running.

 

The water injection system is almost like having a perpetual tank full of race gas--without the $5-per-gallon cost. After all, water is cheap. For once in the history of hot rodding, something can be done for nearly nothing. As an interesting side note, water injection also reduces toxic oxides of nitrogen emissions by reducing combustion temperatures. All of these advantages and cleaner air to boot!

 

[/quote']

 

Jake

[Moridin]

I started to find some of the things I was reading at one point. I did this before I had little to know clue what I was reading. I'm a little better now, but still not great. Here's the link: http://www.pollutionengineering.com/CDA/ArticleInformation/features/BNP__Features__Item/0,6649,134644,00.html

 

A few of the things I was pointing to had to do with the reduction of NOx gases which frees up more O2 for more power and a more complete burn of the hydrocarbons in fuel.

 

I'll keep doing more research until I can find the article I orginally talked about.

[Pop N Wood]

Yes' date=' Yes, Yes, Yes - water injection does increase HP.

[/quote']

 

No no no no! Read what you posted more carefully. Your article is worded ambiguously, but it doesn't say WI increase HP by itself. It talks alot about preventing detonation and says it raises the octane rating of the fuel by 2 to 4 points. And everyone knows that saying putting 93 octane gas in a car that only needs 87 octane will NOT increase HP. Doesn't work that way.

 

Look at one of the later posts that stated

 

Since water absorbs power-producing heat, it does not produce quite the same horsepower per psi of boost as race gas does, but it does allow quite a bit of additional boost

 

This is what Vizard stated in no uncertain terms. Building an engine that needs WI to run without detonation will produce less HP than running the same engine on the proper octane gasoline. Read MikeJTR's posting. He got almost the same HP using 80 octane as the base engine using 87 octane once he retuned

 

I stand by what I repeated from Vizard.

[dr_hunt]

What was the title of this thread? NA I think!