Time to dust off water injection

Time to dust off water injection

The time goes back to cool, damp autumn evening drives in my SAAB 96. The engine was a two-stroke 3 cylinder engine of 44 horse powers in a five seated car. The power output on a warm summer day was anemic to say the least, but with 100% humidity the car ran like a much stronger car. When SAAB came out with the new model 99, one of the options was a turbocharger and water injection. It worked spectacularly well, but was dropped in favor of a turbo intercooler in later models. The reason given was sales resistance to having to have a fuel tank and a water tank. In addition the water had to be mixed with alcohol (preferably methyl alcohol) in cold weather to prevent freezing.
Now the government is forcing ethanol in the fuel mixture “to save the environment”.
Ethanol in the fuel mixture is probably adding to the total carbon footprint of driving. To ferment sugar about half the weight is lost as CO2 gas and half becomes alcohol
So my proposal is to dust off the old idea of water injection and start getting the benefits of it.
These are the benefits of water injection:
1. The engine can be made smaller and lighter for a given horsepower output.
2. The water acts as a coolant to the input air, so the need for the intercooler goes away.
3. If methanol (108 octane) is added to the water it acts as an octane booster, making it possible to increase the compression even further.
4. The mixture combusts slower and when the water vapor evaporates, it occurs later in the power cycle, which gives the engine a higher efficiency, not quite as high as a diesel engine, but without the soot.
5. The NOx emissions are reduced since the combustion is running cooler.
6. There is no sophisticated mining required to produce the cars, as opposed to hybrid cars, where the energy needed to mine the materials exceeds the energy savings during the lifetime of the car.

These are the disadvantages of water injection
1. 2 fuel tanks instead of one, making for a heavier car.
2. One more thing that can go wrong.
3. A need to upgrade service stations with water or water-alcohol filling stations.

So what do you think? Government Motors just sold SAAB, but there is still knowledge about water injection for racing.


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