Quote:
Originally Posted by teoman
Indeed, you are really missing the idea though.
It is a quick test, filter will not collapse unless you use significant rpm * throttle. And you will know if humidity has an effect on « perceived » octane rating of fuel.
Forget the air filter, install soaked and non restrictive rag in filter box.
The objective is to determine if water (humidity) has an effect on fuel economy. If it does, then more elaborate non-temporary solutions can be devised.
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When I had my diesel it had crossed my mind once or twice to make a "swamp cooler" somewhere in the engine bay that would feed the intake with cool moist air. The idea was I wanted to see if I could take the car to an emissions testing facility and see if I could bring NOx down. Apparently NOx is heavily influenced by both temperature and humidity. By decreasing temperature and/or increasing humidity NOx should be able to be reduced to a mere fraction.
I also thought of it as a way to make high octane engines need less octane. But I decided that it was not worth the effort due to the greater space needed. (The car I have now has so little space under the hood that Toyota put the 12V battery in the trunk!) Also because it wouldn't work well in the winter. (It hit 0° F last night and snow has stuck to the ground without melting since Sunday.)
The thing is that it would likely have a greater effect at full throttle than at part throttle. At full throttle is when you really benefit from having enough octane or detonation resistance. So the rag would have to be made to allow full throttle air to pass through.
At part throttle the extra humidity and cool air could actually increase fuel consumption. A really cold and humid intake charge should have a harder time burning up all the fuel than a warm one. So you get more HC emissions that have to be burnt up in the catalytic converter.
These effects are basically what water injection research has also supported, which is basically the same thing only more controlled. When I was working on my Air Cooled Super Beetle one guy that raced them said he started getting great fuel mileage on his turbo setup during races when he added water injection to his turbo charged engine. He was able to lean out the air/fuel mixture and advance the timing and he got more power at the same time and his engine ran much cooler with the water injection. So much so that the stock VW cooling system was plenty to keep it cool.
So there is some truth behind adding humidity or water to the intake. But the only thing that engines will likely control in response is the timing. Modern cars won't lean back the rich air/fuel ratio at high load and also can't increase their CR, things that could be done on a dedicated engine. Also you would probably have to "turn it off" at low loads and startup's. And then there's the freezing weather problem.