Interesting Aero Data - Fuel Economy, Hypermiling, EcoModding News and Forum

dremd · 11-16-2009, 07:43 PM

I have some interesting first hand aero data on a lowered MKIV Golf that may be of use to someone here (maybe even me).

!!Please do not ask for the source of the data, I do realize that here is not the place for such things, but data is Data!!

At ~ 110 MPH the windshield washers begin spraying a noticeable amount of fluid on to the windshield, and by 125 MPH the flow is up to approximately 1/2 of what the pump outputs.

I am not sure if this is due to a low pressure at the base of the windshield, or high pressure at the tank, or a combination of the 2.

Any Ideas? Thoughts?

Cd · 11-16-2009, 08:23 PM

Yikes !
Just curious if you had a scanguage hooked up. I'd be interested to see the mileage drop at that speed.

No idea what was happening with the water at the base of the windshield. If you really want to see a good SAFE example of the airflow around the base of the windshield ( or anywhere else on the car for that matter ) you could create either do some tuft testing or do an ink test.
( For the ink test, run a length of flexible tubing out the window, tape it to the side of the car near the area you want to test, making sure that the tubing is mounted in such a way that it does not cross in front of the area that you want to test.
Fill the tube with a solution of food coloring and olive oil ( thicker than water, won't evaporate and non toxic like transmission fluid or other substances ) Connect a hand pump to one end, and at the appropriate testing speed, squirt the fluid onto area being tested.
Once the test is done,it will leave markings that show the direction of the airflow. If you have a dark colored car, or have trouble seeing the results ... or just want a clean car .... tape a piece of paper where you want to test ( but keep it as flush with the body of the car as possible so it does not blow in the wind )

And um... I wouldn't do the ink test on the windshield ( AHHHHH !!!!! CAN'T SEEEE CRRAASSSHHH )

dremd · 11-16-2009, 08:28 PM

ScanGauge was connected. Indicted Fuel Economy at 125MPH was between 30mpg and 35 MPG. I make no claims as to the accuracy of ScanGauge in a TDI Golf.

I was thinking about a Tuft test, but have no plans on additional testing at speeds anywhere near this.