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View Full Version : Simple WI For increased fuel mileage??


eliTDI
25-05-2008, 01:51 AM
Hi,
I am new to this group, and have some questions. I have been to a few sites talking about a water system you can make yourself, in order to improve fuel mileage. One of these says that you take something like a windshield washer jug, fill it 3/4 full, then put a hose on the bottom, and run it up above the jug. On the top of the jug (like in the cap) you put a second hose in there (not submerged in the water) and the other end of the top hose is inserted into the intake tube after the air cleaner, but not too close to where the tube attaches to the intake of the motor. It supposedly creates a venturi effect with the air passing the hose, which in turn sucks air in thru the tube hooked on the bottom of the water jug, which bubbles the water, and in turn creates an overly humid condition in the upper hose, where the water vapor is sucked into the air intake tube. Supposedly, this water vapor expands in the combustion chamber, and takes up some of the room that the fuel normally would, in turn saving fuel, along with the steam cleaning of the combustion chamber. They also claim an increase in torque due to the rapidly expanding water vapor.
I have a 2004 Jetta PD TDI, and if this sounded plausible to you guys, I thought about giving this a try. I know for a fact that when it is fairly cool and humid outside, I tend to get the best mileage.

Sorry the post is a bit long-winded, but any input/advise would be appreciated. The car is due to be chipped in a few weeks, and I think that will be plenty of power for what I need. I drive about 100 miles a day round trip to work, so any fuel savings is money out of the oil companies profit, which is a good thing!


Thanks, Eric

nutron
15-01-2009, 12:22 PM
Well firstly, there is no such thing as suction. The absense or reduction in pressure in the intake line allows the pressure in the line from the water tank to disipate into the intake. The reduction in pressure in the vessle containging the liquid if sufficient could cause the liquid to boil at a much lower temperature, i.e. what ever temperature it is outside. In practice you would not get sufficient vacuum in the vessle to cause water to boil. Both water and methanol will evapourate at room temperatures normally and with that method they will evapourate faster but the tiny amounts of vapour being inhailed by the engine would be insignificant.

So no, it's rubbish. Using just plain water injection though can decrease emissions output, increase torque and improve fuel economy.

Dust
19-01-2009, 08:30 AM
If you are on tdiclub.com, there are several threads about gas mileage and water injection with TDIs, and tuning suggestions too.