fuel efficiency and humidity levels..

[PCTREE]

OK so Im a self confessed fuel efficiency nut. I have been playing with different things to make my VW TDI get better MPG. My last tank I got 57.5 MPG Anyways the last couple of days have been really damp here and I noticed on my Scan Gauge trip computer that my FE was about 5 MPG better than usual. Both days it was pretty misty but I was able to drive at my normal speed so The only variable I can see is the high humidity.

Would it be crazy to try to introduce a water mist after the air filter???

 

[Cobleskill]

Water injection was used on hi powered piston aircraft engines. It was common after the first oil embargo too. Don't know why it faded. Only thing I remember is you have to have some alcohol in it if it is going to be freezing.
'

 

[PCTREE]

Been googling it and it definately seems to work. Why dont more people do it???


Thanks for the alcohol tip, iwas worried about it freezing. Wonder if they could slap me with an open container ticket??

 

[Cobleskill]

It seems to be a no-brainer. I know I have had cars and bikes that had noticeably more pep when it was humid/raining. Water turns to steam and you have a partial steam engine/no charge.

 

[Reddog]

Why dont more people do it???

Main reason is you are raising the compression ratio. Some motors can't handle the extra stress induced long term by that.
Also there are corrosion issues from all the water vapor created.

In WWII aircraft it was limited to just a few uses per flight. On most the only way it was triggered was by fire-walling the throttles for War Emergency Power. Then methanol/water was injected in to reduce cylinder temps and spike the compression, instant 300 pony gain.
Most of the Reno racers are running water injection.

 

[lumberjack]

Inject the water after the turbo, it can cause erosion on the turbo's turbine.

 

[sotc]