As promised, here are the sections I referred to in post #2, from the 2011 rulebook.
4.CC STREAMLINING:
Any device which has the apparent purpose of directing, limiting, or controlling air flow around or within the car and is not a part of the original body will be considered as streamlining.
Removal of certain devices may also be considered streamlining; axle and header configuration will not. Any streamlining devices will be considered as part of the body for classification purposes, see 2.J. The types of streamlining devices listed below are allowed in some classes:
4.CC.8 Spoiler:
A device on the upper portion of the body for the purpose of spoiling lift. The spoiler shall be mounted in the rear portion of the body behind the rear axle centerline. Two different designs can be used but not mixed together, see Figures 9 and 10.
Design one-
The spoiler must have a single surface no wider than the outside edge of the rear tires. The maximum chord measured on the top surface at the center of the car can be 10 in.. A 1 in. tab or hinge can be added to the leading edge of the spoiler for mounting purposes only. A spill plate on each side of the spoiler is allowed and must be flat on both sides and parallel to each other vertically and horizontally. It can extend forward to the rear axle centerline. Spill plates are allowed to be 8 in. above and below the forward mounted position of the spoiler when laid flat and extend 2 in. max. past the end of the spoiler. No appendages or holes that direct air are allowed on/in the spill plates. Gurney flaps are allowed but cannot extend above or behind the spill plates. The spoiler is allowed to fill in the horizontal gap between the leading edge of the spoiler and the body with a plate no farther forward than the centerline of the rear axle.
Insert Fig 9(same as 2010)
Design two-
The spoiler must have a single surface with no side plates. Maximum spoiler chord measured on the top surface is 10 in. from the trailing edge of the body. A 1 in. tab can be added to the leading edge of the spoiler for mounting purposes only. The ends of the spoiler must follow the contour of the body and shall not extend beyond the outside edges of the body at any point. When laid flat the width of the spoiler can be a maximum of 16 in. wider than the outside plane of the rear tires. No other aero devices or Gurney Flap are allowed with this design.
Insert Fig 10(same as 2010)
4.CC.12 Wings:
Wings are a special class of aerodynamic devices intended to provide down-force, which are allowed ONLY on Streamliners, Lakesters, Modified Roadsters and Production bodies which had the wing as an option. For classification purposes, the wing is not considered as part of the body.
4.KK OEM Body Kit:
Body kits produced by a recognized automobile manufacturer for a specific year vehicle must be used as a complete package. 500 kits for the same model were/are required to be for sale to the general public meets the production requirements. Mixing and matching pieces from different years or not using the complete kit will be considered streamlining.
DW
