A useful YARN.. aerodynamic testing on the cheep.

[wayne petty]

http://www.autospeed.com/cms/A_111110/article.html?popularArticle



read linked article above before reading my thoughts below.

this might be a great use for those gopro cameras or mounting a quality cell phone camera or small high def video camera on a bracket off to the rear or side of the car..  something tubular and out of the air stream..

and finding some place to get the car up to speeds..


i thought up a hollow spoiler for the rear deck that the upper surface mounts to the horizontal deck surface and the rear layer mounts to the vertical surface.. with vertical bracing inside.. openings along the gap to allow air to be pulled out the back of the car..  an adjustable rear side panel... so you could adjust the amount of siphon effect on the top edge of the spoiler by the air flow..


and since i am blowing in the wind on this one..

a few of you are aware that Most OBD2 cars have 3 wire fuel tank pressure sensors that are very accurate and sensitive in both positive and negative inches of water column..  i don't know what the total range is.. but that would be easy to figure out..   some techs have rigged these to an extra radiator cap adaptor and a 9 volt battery .. wiring to their very expensive digital storage occilloscopes.. to look for combustion leaks in cooling systems by looking at the tiny pressure changes in the cooling  while cranking or idling with the water pump not spinning.. .  yep.. sensitive..  these could be used to monitor the pressure above the rear of the car... and below the car... to see/warn the driver if the pressure below the car becomes greater than the pressure above the car..  indicating the car is about to lift at speed..

one wonders if extending the rear of the front wheel wells downward with something like a mud flap off a truck.. but positioned at an angle.. kicking more air out from under the car.. in the middle of the car..  in addition to the front air dam.

[enjenjo]

That spoiler is not legal in most places as you describe it.

What does the pressure sensor look like? So I can recognize one when I see it.

[wayne petty]

What does the pressure sensor look like? So I can recognize one when I see it.

this is what the GM fuel sending unit mounted version looks like..  there are dozens of different shapes and styles.. including some that are remotely mounted and use a vacuum hose to connect to the tank vent lines..

http://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/SU1390/image/4/

[1800guy]

Wow! Great reference.  As soon as the weather permits I have to try this out.  I did go to Part One first as instructed, and now I can check if my home-brewed induction mods really worked.  I've also been wondering about the tail-end of my car, which is really square - a classic 3-box design.  I was thinking maybe a discreet lip on the deck-lid would help - this will be the way to know for sure.  Thanks a lot for passing this along.

[Bruce Dorsi]

Thanks for the link, Wayne!

There's some interesting stuff at that AutoSpeed site.