Hopefully this thread will be taken serious and not become a flame fest.
In preparation for the 2013 season i have been pouring over the 2013 February GCR for a few days. I keep reading on Apexspeed that diffusers allowed in 2012 F2kCS will not be legal in SCCA Club in 2013.
Seriously, can somebody elaborate?
Is it 9.1.1.4.c the language i colored red?
Based on the language in 9.1.1.6.e., it would appear that all diffusers as we know them are illegal. SInce it doesn't exempt FC diffusers...
If you answer, please include page number, section number, etc. so it will be clear and concise. Please, no opinions, without reference to applicable rule and verse.
Below are all the rules i could find that apply to FC diffusers:
9.1.1.4. Bodywork (page 260)
9.1.1.4.c Bodywork and rear spoiler(s) and any attached components except for suspension components shall not exceed a maximum width of 95cm (37.40 inches). No part of the bodywork, rear spoiler or exhaust system shall extend more than 100cm (39.37 inches) FF; 80cm (31.50 inches) FC behind the centerline of the rear axle nor exceed in height a horizontal plane 90cm (35.43 inches) above the ground with the car as qualified or raced with the driver on board. The safety roll bar/roll cage, fairings, and engine air box are not included in these restrictions. Bodywork shall not increase in width behind the centerline of the rear axle in any horizontal plane. Allowances shall be made for radius of bodywork along primarily horizontal surfaces in this area. Undertrays and floorpans may extend laterally past cockpit sides, sidepods, and engine compartment enclosures,
9.1.1.4.d. Diffusers and undertrays shall not exceed a maximum width of 95 cm (37.40 inches). No part of the diffuser or undertray shall extend more than 80 cm (31.50 inches) behind the centerline of the rear axle nor exceed in height a horizontal plane 90cm (35.43 inches) above the ground with the car as qualified or raced with the driver on board. (page 260)
9.1.1.5. Control of Undersides Shaping (page 261)
It is the intent of these rules to minimize (not eliminate) the use of “ground effects.”
a. A reference area is defined
Formula F: by the full width of the lowest surfaces of the car licked by the air stream between the front bulkhead as described in B.3.a above and the rear of the rear tires.
Formula Continental: by the full width of the lowest surfaces of the car licked by the air stream between the front bulkhead as described in B.3.a above and the front edge of the rear tires.
These surfaces may include the floor pan, undertrays, diffusers, side pod bottoms and any essentially horizontal bodywork that is included in the lowest surfaces licked by the air stream. Within this reference area, the lowest surfaces licked by the air stream must be flat with a total vertical tolerance of 25.4mm. An undertray beneath the engine, bell housing and/ or gearbox is not required.
1. Mirrors and any primarily vertical bodywork (e.g., cockpit/radiator sides that are oriented 45 degrees or greater relative to the ground) that extend laterally past the outer edges of the floor pan and/or undertrays are not subject to the reference area restrictions.
2. Fairings for streamlining suspension pickups are not subject to the reference area restrictions; however, such fairings shall be symmetrical about their horizontal axis.
3. The perimeter of any reference area surface that transitions upward to any bodywork may use a maximum 1 inch radius and shall be included in the reference surface measurement.
b. Measurement for compliance of the defined area shall be performed as follows:
1. A non-flexible straight-edge bar shall be placed against the lower surface of the reference area in a suitable section (unworn and flat enough to prevent rocking of the bar) from which the bar can be oriented to measure all parts of the reference area. The competitor shall be responsible for the availability and condition of such a surface. The bar shall be of sufficient length to reach all portions of the reference area from that surface.
2. All measurements shall be taken vertically from the bar to the reference area surfaces. The total maximum vertical distance (additive upward and downward) from the bar to any part of the reference area surfaces shall be 2.54 cm. Skid blocks and or rub strips are not included in this measurement.
c. No aerodynamic devices (e.g., skirts, body sides, skid “planks”, undertrays, skid blocks, etc.) may extend more than 1 cm (.394 inches) below the reference area.
6. Aerodynamic Aids (page 262)
9.1.1.6.e. Shaping of the lower surfaces to create “venturi” type tunnels is prohibited. An example of venturi tunnels is shown in the following figure. (page 262)
***** a picture I can’t attach to a post ****
9.1.1.6.j. (FC only) Diffuser undertrays, to the maximum allowed bodywork width are permitted, but any portion within the reference area (B.5) must comply with the reference area measurement rules. (page 263)