Top up or down
Joined: Jan 2006
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From: San Francisco
Originally Posted by VitaRenovatio' timestamp='1333597521' post='21577568
For race tracks, definitely more drag with the top down. It's been tested and proven in a high speed track in SoCal (Willow Springs International Raceway).
For autocrosses, I don't think the drag really plays a role. It would move the center of gravity a negligible amount lower and to the rear.
For autocrosses, I don't think the drag really plays a role. It would move the center of gravity a negligible amount lower and to the rear.
Huh? I said there's more drag with the top down. More drag means lower top speed and also a less efficient wing.
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Joined: Aug 2011
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I noticed less wind resistance by running top down windows up too on a road course. I prefered running top down simply because with a helmet on I don't want anyone creeping into the horrible blind spots we have.
Thread Starter
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Joined: Apr 2011
Posts: 801
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From: Southern Indiana
https://www.s2ki.com/s2000/topic/671..._fromsearch__1
https://www.s2ki.com/s2000/topic/384...op+drag+tunnel
https://www.s2ki.com/s2000/topic/821...#entry19621344
https://www.s2ki.com/s2000/topic/663...#entry15143350
https://www.s2ki.com/s2000/topic/246...1#entry4641476
https://www.s2ki.com/s2000/topic/101...1#entry1312826
https://www.s2ki.com/s2000/topic/384...op+drag+tunnel
https://www.s2ki.com/s2000/topic/821...#entry19621344
https://www.s2ki.com/s2000/topic/663...#entry15143350
https://www.s2ki.com/s2000/topic/246...1#entry4641476
https://www.s2ki.com/s2000/topic/101...1#entry1312826
Joined: Apr 2009
Posts: 2,521
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From: Renton, WA
You're not going fast enough in autox to get any drag reduction benefit with running top up.
Someone needs to time some 60-90mph acceleration runs top up and top down to see what the speed differences are.
Someone needs to time some 60-90mph acceleration runs top up and top down to see what the speed differences are.
Joined: Jun 2010
Posts: 1,881
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From: Near Philadelphia
top up or down in autocross will not make a difference, but it's a freaking convertible and I want to get my money's worth so top down is better 
By the way, the thing that they don't tell you in school is you'll never have those drag coefficient numbers in real life. Maybe some kind of very broad approximation could be done empirically, but I doubt anyone's done it.
By the way, the thing that they don't tell you in school is you'll never have those drag coefficient numbers in real life. Maybe some kind of very broad approximation could be done empirically, but I doubt anyone's done it.
Thread Starter
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Joined: Apr 2011
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From: Southern Indiana
Yeah thats what i figured... I thought that if i could get some rough drag coefficients for my car I could actually act like I care more haha. Does anyone know what the stock drag coefficient is (base number that they hand out)?
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Joined: Apr 2011
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From: Southern Indiana
http://ecomodder.com/wiki/index.php/...t_of_Drag_List
nm Looks like 0.33 is the magic mysterious number
nm Looks like 0.33 is the magic mysterious number
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Actually the correct value of Cd for the S2000 is more like 0.37-0.38 with the top up. With the top down, it's around 0.42. The rationale for this is clear, as a convertible designed for maximum chassis stiffness and roll over protection, the a pillar is quite steep and therefore the windshield is high angle as well. The back transition of the top towards the trunk is also quite a bit rough due to the hardware and has a big angle as well. Not necessarily great for keeping flow laminar. With a hardtop, the Cd is more like 0.34-5
