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.

 

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!

 

A more or less stock bodied Z will never see the speeds to make a wing actually create any type of down force that would affect handling.

 

Oh, well nevermind then...

 

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.

 

I wish I could find a video but I couldn't. try watching Sebring this weekend and if its raining or when a prototype car gets in a dirty track watch the rooster tail that gets created over the top plane of the rear wing. That will illustrate what TK is explaining here. Per Schroeder's BM car at the last event was smoking and you could clearly see the exhaust smoke being run up to the wing from the ground behind the car.

 

rrrrrrrrrrrrrrrrrrrrrrrrrright...............

 

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

 

That's one! I was actually hoping for, "Unless you are making over 500hp, the wing will have no effect". lol

 

I couldn't believe it took till page 2...

 

Anyone know of the place to get the CFD info on the Nismo package (350 or 370)? Just curious about the effectiveness on the Nismo rear ends.

 

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!

 

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

 

I already had T2 spring I believe are 700 lbs. Before the wing I had a very loose car over 90. With the wing at all the way up. Keep in mind the back of our car has a tilt back. I think you will like the results.

 

I have mine set at the most aggressive setting and there is no loose feeling in the rear. Was just running at 135 yesterday and feels very planted. Expect some drag though.

 

That's what the NOS stickers are for- enough power to overcome the drag! ;-)

 

Of course! As long as it makes at least 500hp.

 

Sigh... I'm gonna need bigger stickers then.

 

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)

 

Multiply any Newton(N) number by 0.3 to get approximation in pounds.