Has anyone done this BASIC water injection thing?

[nimblemotors]

My thoughts are to use water injection along with raising the compression ratio to a much higher value. This would normally cause detonation, but the water injection would prevent it. And also as you said, using a custom EFI system, you could run a very lean mixture at cruise speed and use the water injection to prevent overheating of the cylinders.

I think the downside (besides the added complexity for probably a small gain), is having to add the weight of the water and/or refill it often.

[EdKiefer]

Originally Posted by nimblemotors

My thoughts are to use water injection along with raising the compression ratio to a much higher value. This would normally cause detonation, but the water injection would prevent it. And also as you said, using a custom EFI system, you could run a very lean mixture at cruise speed and use the water injection to prevent overheating of the cylinders.

I think the downside (besides the added complexity for probably a small gain), is having to add the weight of the water and/or refill it often.

2 things to watch out for is running empty of water . though if you use a tank with a level sensor you could have a light lite up to show low water level,,needs filling.
The other is keeping the water jet clean and stop any build up , I never went into depth trying to find solution here , I just ended up checking it every 6months or so but maybe there some additive that would help there .

[ConnClark]

Originally Posted by nimblemotors

My thoughts are to use water injection along with raising the compression ratio to a much higher value. This would normally cause detonation, but the water injection would prevent it. And also as you said, using a custom EFI system, you could run a very lean mixture at cruise speed and use the water injection to prevent overheating of the cylinders.

I think the downside (besides the added complexity for probably a small gain), is having to add the weight of the water and/or refill it often.

I found one paper on using water injection to up the compression ratio in the past and have never been able to find it again. The critical thing to making this work is ensuring all the water gets out of the cylinder between cycles(not all of it turned to steam). Water in the oil was another problem. I remember in the paper they used a flat 6 cylinder engine and had the exhaust valves on the lower side which helped in solving the evacuation of water problem.

[ShadeTreeMech]

I suspect micromanaging the water flow would be another solution. Keep the flow to the absolute minimum necessary for engine conditions. This would make it most water efficient and make certain all the water turned to steam. If there was water getting into the oil, it sounds like there was uneven/overabundant water flow.

Some sort of management system using exhaust gas temps as the input and water flow the controlled output would be ideal.

[cafemyk]

It occures to me that there are a number of issues with water injection. I think that it's advantages are proven in piston engines. The expansion of steam due to heat is greater than the other gasses produced in the combustion process. Therefore the heat lost from the combustion gases is more that made up for by the expansion of the water.
But this is to a point. There will come a point where the volume of water will be too high and hinder the combustion process.

To use water in the combustion process as an expansion aid will require the carrying of a large volume, perhaps up to a quarter of the volume of fuel. This will add weight which is then to be carried, perhaps off setting a portion of the fuel economy gained.

I thought perhaps instead of trying to inject water or to suck with a vacuum line that the use of a Carburetor with finer jets than used for fuel could be employed to accurately meter the dose of water into the engine. Even though most vehicles use fuel injection systems, they still employ a throttle assembly as a primary means to control air flow into the engine. If this were replaced with a Carburetor that added water vapour a good result might be achieved.

If hot water is desired, this could be achieved by pre-heating it by passing a pipe through the top of the radiator.

[oil pan 4]

Water injection - EcoModder