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Old 04-05-2008, 06:10 PM   #10 (permalink)
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Join Date: Feb 2008
Location: Italy, Morbegno (SO)
Posts: 151

tigra AERO - '96 opel tigra
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Originally Posted by lovemysan View Post
Last august I made a trip to georgia. Before I left I fabbed up this airdam. It gave 5.5" of ground clearance. It was made from 26 gauge HVAC sheet metal. The first 3 hours of the trip netted excellent results(tailwind). Upon turning south mileage plummeted. I put 750miles on it with worse than usual mileage. I did some early morning 60-30mph coast down test. The results were very close but the without the airdam I got a very light improvement. This confirmed my suspicions that it was indeed hurting performance. The airdam certainly had its advantages, the A/C worked as good as stock at highway speeds. The added high pressure on the cars nose made for excellent cooling properties(Which was nice for a trip to Georgia in august). It also just looked cool. I couldn't have gotten more looks if I was driving a hot pink pantera. It was however impossible to live with. Even the most gently graded driveway would defeat it. Gravel is the enemy of any airdam. It wouldn't last 20 minutes on an icy winter day. The presence of mind required to prevent its destruction was mentally draining. I think for proper performance in my case the airdam and belly pan must be integrated together.
I am not surprised from your results.
with your airdam, you have added more frontal area, and because your car (with many aero mods) it is very efficient, your have gotten worse the things.
If I just remember, your car is equipped with full bellypan.
You can try to reduce central height of airdam, this, reduce the FA, and permit to pass the air under your car.
Look, the example opel calibra.
Calibra equiped with engine undercover, use an airdam tested in windtunnel.
After many tests, Opel are deliveryd an airdam shaped with raised central area, and high at the side.

look the image below:

It permit to deviate the air from wheels and the suspension arm.
I do not have any report, but in my car, I am insirated me to Opel for my front deviator
if you try it, tell us the change.
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