Z Racers, learn me some aero!
03-19-2010, 06:27 PM
#21
OK, so I am running some NASA stuff this year in TTB, and all the really fast guys at Road Atlanta this last weekend were running big aero. I'm thinking there must be something to this. I have a few questions for those of you who have knowledge on such matters.
I have just enough points left to add a big picnic table-style wing on the back, or a splitter or something up front (with a point left over in that case). My instinct is that adding downforce to one end without doing it to the other will create an imbalance, but I saw many cars out there doing exactly that and turning some very fast laps. So, Z peeps, anyone tried just a big wing on the back without upgrading the front? And what did you think about the changes it brought? Was the car easier or harder to drive? Did it net you faster lap times? What other changes, if any, did you have to make to the car with the additional downforce?
My other question regards the wings themselves- an admittedly quick perusal seems to show the APR GTC-300 to be a favorite choice, but the damn thing is $1500! I might could swing it if I stopped paying alimony for a few months, or started selling counterfeit Sharif-autographed Forged Performance man thongs on eBay again, but otherwise, that's a little steep for my budget. Anyone have any slightly more economical suggestions?
Thanks in advance for any helpful answers or amusingly smartass retorts.
I have just enough points left to add a big picnic table-style wing on the back, or a splitter or something up front (with a point left over in that case). My instinct is that adding downforce to one end without doing it to the other will create an imbalance, but I saw many cars out there doing exactly that and turning some very fast laps. So, Z peeps, anyone tried just a big wing on the back without upgrading the front? And what did you think about the changes it brought? Was the car easier or harder to drive? Did it net you faster lap times? What other changes, if any, did you have to make to the car with the additional downforce?
My other question regards the wings themselves- an admittedly quick perusal seems to show the APR GTC-300 to be a favorite choice, but the damn thing is $1500! I might could swing it if I stopped paying alimony for a few months, or started selling counterfeit Sharif-autographed Forged Performance man thongs on eBay again, but otherwise, that's a little steep for my budget. Anyone have any slightly more economical suggestions?
Thanks in advance for any helpful answers or amusingly smartass retorts.
A large enough wing can help extract air from underneath the car. Probably not to the extent of a LMP, but definitely measurable. It's efficiency however will be largely determined by how "sealed" the underneath of the car is.
The front undertray/diffuser, can help flow under the car, but won't be able to generate the sheer amount of net downforce as a rear mounted wing. The effect of the diffuser at the front will have a minimal effect on the pressure acting on the top side of the vehicle. It's "downforce" comes from decreasing pressure underneath the car and although this will have an overall net gain downwards, the wing can do both more generally.
The wing can enlarge the depression behind the car, which could in turn help increase flow underneath the entire car(small but measurable), and it's effect as an aerofoil will generate pressure acting down.
This is my understanding of it.
03-19-2010, 06:42 PM
#22
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Wow, very interesting T K! It may take me a few (dozen) reads to wrap my mind around that. Thanks!
So what's your take on the performance increase from the NOS stickers that were recommended to me, if I add those too? I hear they are even more effective if I refer to them as "NAWWWZ!" in a loud, annoying voice?
Seriously, thanks for the info!
So what's your take on the performance increase from the NOS stickers that were recommended to me, if I add those too? I hear they are even more effective if I refer to them as "NAWWWZ!" in a loud, annoying voice?
Seriously, thanks for the info!
03-20-2010, 09:28 AM
#25
Don't know that I agree with this statement. At a track like Big Willow or California Speedway's Roval, a stock-ish Z can enter the faster turns upwards of 120-130 mph. To say that aero is not important is probably off. Granted this may hold true on some of the other portions of the track, in the race against the clock every little bit matters.
03-20-2010, 09:33 AM
#26
Aero parts don't work in a vacuum(no pun intended). I believe what you're seeing with those other cars is the effect of increasing the low pressure directly behind the car with the use of a wing. Any device that will increase this area of low pressure, no matter how small, will have an effect on all the flow in front of it.
A large enough wing can help extract air from underneath the car. Probably not to the extent of a LMP, but definitely measurable. It's efficiency however will be largely determined by how "sealed" the underneath of the car is.
The front undertray/diffuser, can help flow under the car, but won't be able to generate the sheer amount of net downforce as a rear mounted wing. The effect of the diffuser at the front will have a minimal effect on the pressure acting on the top side of the vehicle. It's "downforce" comes from decreasing pressure underneath the car and although this will have an overall net gain downwards, the wing can do both more generally.
The wing can enlarge the depression behind the car, which could in turn help increase flow underneath the entire car(small but measurable), and it's effect as an aerofoil will generate pressure acting down.
This is my understanding of it.
A large enough wing can help extract air from underneath the car. Probably not to the extent of a LMP, but definitely measurable. It's efficiency however will be largely determined by how "sealed" the underneath of the car is.
The front undertray/diffuser, can help flow under the car, but won't be able to generate the sheer amount of net downforce as a rear mounted wing. The effect of the diffuser at the front will have a minimal effect on the pressure acting on the top side of the vehicle. It's "downforce" comes from decreasing pressure underneath the car and although this will have an overall net gain downwards, the wing can do both more generally.
The wing can enlarge the depression behind the car, which could in turn help increase flow underneath the entire car(small but measurable), and it's effect as an aerofoil will generate pressure acting down.
This is my understanding of it.
Last edited by DmanG281; 03-20-2010 at 09:34 AM.
03-20-2010, 09:40 AM
#28
One thing I found on APR's website is the CFD info and just for reference, the GT 200 wing creates approximately 180 lbs of downforce at 120 mph and the GT 300 creates approximately 345 lbs at 120 mph at thier flatest setting.
http://www.aprperformance.com/index....d=33&Itemid=45
http://www.aprperformance.com/index....d=33&Itemid=45
03-20-2010, 11:56 AM
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Well I stumbled upon a used APR GTC-300 wing some guy had JUST posted on eBay, at a good price (about half of new retail 
). I pulled the trigger on it, so I guess we'll see! Wonder if anyone can give me any insight as to how much to go up on rear spring rates and what sort of attack angles to set the wing initially? I'm waaaaaay beyond my pay grade here!
). I pulled the trigger on it, so I guess we'll see! Wonder if anyone can give me any insight as to how much to go up on rear spring rates and what sort of attack angles to set the wing initially? I'm waaaaaay beyond my pay grade here!
03-20-2010, 12:26 PM
#33
Well I stumbled upon a used APR GTC-300 wing some guy had JUST posted on eBay, at a good price (about half of new retail ). I pulled the trigger on it, so I guess we'll see! Wonder if anyone can give me any insight as to how much to go up on rear spring rates and what sort of attack angles to set the wing initially? I'm waaaaaay beyond my pay grade here!
). I pulled the trigger on it, so I guess we'll see! Wonder if anyone can give me any insight as to how much to go up on rear spring rates and what sort of attack angles to set the wing initially? I'm waaaaaay beyond my pay grade here!http://www.aprperformance.com/index....sk=view&id=181
03-20-2010, 12:50 PM
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Use the link to get more clarification on the data, but the AOA references Angle of Attack and is pretty interesting.
http://www.aprperformance.com/index....sk=view&id=181
http://www.aprperformance.com/index....sk=view&id=181
03-20-2010, 04:42 PM
#39
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350Z Nismo aero pacakge (on the actual Nismo) adds an additional 71lbs of downforce at 73 mph (Source below). Wasn't joe bob and his fishing scale...
Good thing to keep in mind that it does take high speeds (60+) to make wing effective and you pay a drag penalty (downforce=drag) so unless you've got long sweepers, its just an anchor. It takes a MONSTER wing to generate downforce at <50mph, just take a look below at Autocross classes with wings, they're HUGE and HIGH. The bottom two photos run here in Colorado so I see them regularly. I've heard the Nismo kit adds an extra .1 the 0-60mph time. Again, sorry no sources off hand but you can see the higher drag coefficent below.
=========
Got the downforce source:
http://grassrootsmotorsports.com/new...an-nismo-350z/
Skepticism is our reflex whenever we see crazy body work, but Nissan assures us that these pieces are functional. Where a standard Nissan 350Z generates about nine pounds of lift up front and 18 pounds of lift in the rear at 73 mph, the Nismo add-ons flip that to 11 pounds of downforce at the front and 33 pounds of downforce out back at the same speed. This is accomplished without screwing up the coefficient of drag too badly, as the Nismo cuts the air with a Cd of 0.339, just 0.028 off the base Z.
(11+9+18+33=71 lbs)
Good thing to keep in mind that it does take high speeds (60+) to make wing effective and you pay a drag penalty (downforce=drag) so unless you've got long sweepers, its just an anchor. It takes a MONSTER wing to generate downforce at <50mph, just take a look below at Autocross classes with wings, they're HUGE and HIGH. The bottom two photos run here in Colorado so I see them regularly. I've heard the Nismo kit adds an extra .1 the 0-60mph time. Again, sorry no sources off hand but you can see the higher drag coefficent below.
=========
Got the downforce source:
http://grassrootsmotorsports.com/new...an-nismo-350z/
Skepticism is our reflex whenever we see crazy body work, but Nissan assures us that these pieces are functional. Where a standard Nissan 350Z generates about nine pounds of lift up front and 18 pounds of lift in the rear at 73 mph, the Nismo add-ons flip that to 11 pounds of downforce at the front and 33 pounds of downforce out back at the same speed. This is accomplished without screwing up the coefficient of drag too badly, as the Nismo cuts the air with a Cd of 0.339, just 0.028 off the base Z.
(11+9+18+33=71 lbs)
Last edited by NismoZ_840; 03-20-2010 at 05:17 PM.
03-21-2010, 12:30 AM
#40
Use the link to get more clarification on the data, but the AOA references Angle of Attack and is pretty interesting.
http://www.aprperformance.com/index....sk=view&id=181
http://www.aprperformance.com/index....sk=view&id=181