wow....

wow....

+1, whew thats alotta math stuff. lol

wow....

+1, whew thats alotta math stuff. lol

i failed math, but damn....


i don't think r33 kit is doing anything.....lol

Most of aerodynamic systems will only affect the vehicle in race conditions as the times will depend on it.
The aerodynamic effect on the vehicle is actually not just simple forces applied. There is actually a cloud of aerodynamic forces surrounding the vehicle, with positive pressure on the front of the vehicle, and negative pressure aft of the vehicle.

Everything you modify for vehicle exterior geometry will affect the car’s attitude on the track.

So there is many questions you must ask yourself. Why do you want a body kit on your ride ? most of import tuners will say honestly just for plain look and to add this ‘in your face’ look. If it’s just for looks, than science doesn’t have anything to do. Only tastes. And tastes is not arguable  so we will suppose it is for race purposes.

This is a relatively subjective description of aerodynamic influencing devices so I invite you to actually correct me if I’m wrong and if you think something else is needed. Basically, you will influence the aerodynamics for either closed circuit racing or for drag.

The worst enemy for the aerodynamic drag of a vehicle is possibly the ground effect, which is a layer of air on the ground that does not have the same aerodynamic effect as air in altitude. This air has more lift for aircrafts, so it’s a good thing for aircrafts, but since it has more lift, and cars tend to have more downforce (because they’re grounded lol), this makes an increased value of drag. A good way to prevent this is to reduce the amount of air going under the car with lowered suspension and lip kit. The advantage is reduced drag (and more top speed) and the inconvenient is less ground clearance. 

If you build for drag, you want to minimize the aerodynamic forces. And you don’t really care about down force as the car does not need to turn. As long as it won’t lift, you want to reduce downforce to decrease aerodynamic drag.
So to minimize drag, you will want to lengthen and streamline the body, lower the stance and add a spoiler that will contain the negative pressure aft of the vehicle, or even better, streamline the vehicle in the shape of an ellipse. You will also want to funnel what little air goes under the car to actually direct the aerodynamic forces in a more streamline manner than actually having the air hit every single mechanical part protruding from the under body of the car.

The other effect is the drag of the wheels induced by the swirl effect of spinning wheels. This is why there is a lot of drag race cars built with wheels offset in the inside of the vehicle. The more you actually spin wheels, the more some sort of distorted aerodynamic vortex actually mixes with the outer air stream, thus increasing the turbulence of surrounding air, thus increasing the drag.


For closed circuit purposes, it is a fine balance between front down force and rear down force (excessive front downforce will make the car oversteer in turns and rear down forces induces understeer). It is pilot required adjustements depending on each track, track conditions etc. So you do want to have downforce in closed circuits to increase the weight of the vehicle in the corners (and increase the static friction force laterally).

This is more complicated than drag machines since the track changes, the driver changes, weather etc. So really design in a wind tunnel and on track is necessary to make good technical decisions. It takes also a lot of skills,  a lot of man hours and obviously $ as anything else in automotive.

An example of aerodynamic device applied on a nascar where the is a fence on the roof of the car. A fence, used in aircraft wings, actually reduces the amount of air slipping from the top of the car to the side of it.
As far as I’m concerned, there is not a lot of body kits available for the b15 chassis and I would suppose that the best looking, more aerodynamically significant kit is the lip designed by www.onderground.com. It actually deflects air from under the vehicle to the sides.


I don’t think you will notice the effect on a street ride, but on a closed circuit track it might shave off some time.

Another body kit I like is the buddy club kit as it actually retains the orginal body lines while reducing the stance and scooping up air to direct it into radiator systems


Actually some body kits such as the r33 has many openings which you could use for either oil cooling or brake cooling. It doesen’t improve the vehicle aerodynamics though. It simply helps cooling of engine bay and doesen’t really reduce the drag coefficient (which is all we want from aerodynamic systems)

Does the Nismo lip for the sentra do any good? I mean its engineered for our cars right?