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Old 06-20-2009, 07:12 PM   #8 (permalink)
Deezler
Master EcoModder
 
Join Date: Apr 2008
Location: Michigan
Posts: 259

Bio Deezler (sold) - '03 Volkswagen Jetta GLS TDI
90 day: 50.78 mpg (US)

The Beast. - '03 GMC Sierra 2500HD SLT
90 day: 12.86 mpg (US)
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Quote:
Originally Posted by ConnClark View Post
I have to wonder if you could use fewer VGs and get close to the same improvement. Your original air flow near the sides of the rear window was pretty well attached.
Yeah I wondered that too right after I stuck the last VG on. doh. I am contemplating pulling the very outer ones back off. As you say the airflow out there was already fairly well attached, so VGs out there can only be causing extra drag...

As per the deck lid extension, well, I guess I'm not so sure. But the CFD pics above were done with NO vortex generators. I pleaded with Trebuchet to run some of those in a simulation but his interest waned before it happened. Not sure whether the CFD could properly model those, but it would be interesting.

Only got one rainy day of commuting with these on, but the drive to work was my best ever scan gauge reading. Also a downpour that forced slower driving. Drive home was clear, and only average mileage. Have not noticed any less wind noise, but seems like that would only be noticeable in the back seat anyway, since my airflow up front is unchanged.
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