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Discussion Starter · #1 ·
I was just under my Viggen yesterday when my mechanic was installing a downpipe for me. I was happy that there was way less rust than I expected, but I noticed that there seems to be nothing preventing air from catching on the rear bumper as it flows under the car.

It looks to me like some type of airfoil could be fabricated to guide most of the air under the bumper and reduce drag. I know some hondas as well as some sports cars come with such a piece.

Has anyone tried this on their Viggen, or another Saab? Could this actually end up having a negative effect such as instability at speed?
 

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The engineers spent a lot of time working the Viggen bodywork to reduce the CoF by about 20%. I doubt that they missed anything that glaring. There's also the possibility that a ramp back there would actually increase lift (they may have even tried it).

I would tend to leave it as is.
 

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Discussion Starter · #3 ·
Good point. That's why I'm hesitant to be the guinea pig. But I'd love to hear about it if anyone else has tried... and lived to tell the tale :cheesy:
 

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The engineers spent a lot of time working the Viggen bodywork to reduce the CoF by about 20%. I doubt that they missed anything that glaring. There's also the possibility that a ramp back there would actually increase lift (they may have even tried it).

I would tend to leave it as is.
oonly the front end was worked for the drop in CoD
 

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^ I don't think so. The side skirts were obviously worked to help with the CoF, they blend to the rear bumper, and the engineers specifically highlighted all the time spent on the rear spoiler design to reduce lift. Seem unlikely that they would have spent all that time on the spoiler on top of the rear end and ignored the bottom. Unless you have some statements from the factory somewhere that back up your suggestion, the evidence is pointing the other way.
 

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yes, the whole car was re worked for aero. BUT, only front end changes effect the CoD because thats what has to be slippery and punched through the air (its only 8% better than, not 20%). the spoiler, skirts, rear are for extra lift that was created. skirts stop air from rushing in under the sides etc.

Aerodynamic Exterior Design
The 9-3 Viggen's aggressive front spoiler, rocker panel extensions, rear bumper cover and rear wing aren't just stylish - they serve a purpose. Fully integrated into the already sleek shape of the Saab 9-3, these elements give the Viggen dramatically improved aerodynamic properties. The Coupe and 5-Door Viggen's coefficient of drag (Cd) has been decreased a full 8% to 0.31 Cd, and Saab engineers have managed to reduce lift forces at the rear wheels by 60%
a properly designed undertray front and/or rear will absolutely make the car more slippery as long as you make sure all pockets are well covered. testing on evos showed something like 3mph increase in 1/4 mile traps from a smooth front tray alone.
 
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