As I mentioned before, the goal of this build is to build a car that meets the regulations of group 5 while implementing modern technology to make it faster. A set of the rules is located at https://argent.fia.com/web/fia-public.nsf/whistj?open . The specific rules im following are the 1976 versions since that is the year of my car. I will cover in brief the simplified versions of the rules as i have read them. I would ask if you have time please read them as well to make sure i haven't misinterpreted anything.
The Main rules are in articles 268 and 269
Part A states the minimum acceptable weights as a dry weight(actually at end of race but lets add a safety factor)
Part B ) The shape of the body must be retained but sections can be removed for weight savings. The Doors, hood and trunk may be made of different material but cannot change shape.All but windscreen material can be replaced. The Fenders are open but must retain the wheel arch shape and cover at least 180 around the tire and the full width of the tire. The interior is open but the driver should remain in the same area of the vehicle, with no sharp edges present.
Part C) The block must be same as the original vehicle with displacement open. It must also be in the same orientation as the production vehicle.
Part D) Gearbox and diff are open but should remain in same location in the vehicle
Part E) The suspension type should be the same type as the production vehicle but points can change location
Part F) Steering system is open
Part G) Widths should match chart based on displacement
Part H) Brakes are open
Part I) There must be a safety cell. It may not be in drivers compartment or engine compartment.
Part J) Aero Devices may not protrude out past the frontal projection of the car. Front splitter may not be longer than 10% of the wheelbase as measured from the furthest forward point on the original bodywork. It must also be installed below the plane of the wheel hub. The rear wing may not exceed 20% of the wheelbase as measured from the outermost part of the bodywork
There are more rules in the earlier sections regarding cage material layout and size but that's a bit too technical for this post.
Now time for me to explain the game plan. I have taken lots of inspiration from articles and pictures i have found on the internet. The most helpful was a speedhunters article on the Zakspeed Capri. It had great explanations as well as great pictures of the car less bodywork. http://www.speedhunters.com/2013/02/fire-breathing-neck-snapping-the-ultimate-capri/
Chassis - The main frame structure will rely on a 4130 Chomoly tube frame structure that will include all the major mounting points. This means both front and rear sub-frame structures disappear in order to reduce weight. Also the whole front clip will be removed. This frame structure allows for easier repair and modification to meet the needs of the car. It also increases the structural rigidity of the vehicle. This frame structure will also replace the rear of the car and provide safer mounting for the Rear wing and fuel cell.
Suspension - Both ends of the car will have the original parts replaced by custom structures in order to reduce weight and have better kinematics since point dictation is free. Both ends will receive coil-overs with external reservoirs. Hubs will be upgrades to a modern 5 lug BMW setup in order to easier obtain aftermarket big brake kits and for easier choice of rims. Rims will stay a traditional 3 piece but with turbine fans in order to aid under-body air extraction. These wheels will be complimented with modern race rubber. Steering will be converted to forward mount Rack and Pinion Setup(I work for a steering company, its easy to get a spare one)
Driveline - The Motor will stay an M10 Block but the head choice hasn't been finalized. The plan is to sleeve the engine down to 1.6 liter or a similar size that allows an already in production race piston. which will be paired to a lightweight con-rod. AS with the spirit of Group 5 the car will have a nice healthy turbo mounted to it. The goal is for around 450HP at the crank. The exhaust will have a side exit just before the passengers door. The Motor will also be equipped with a dry sump system and an external electric water pump. The Radiators will be moved rearward to in front of the rear wheels. This is because the front will have an oil cooler and intercooler. The transmission will be a 6 speed sequential that can either be set up for lever or paddle actuation. The rear differential will be from a newer BMW that can handle the power. The engine itself will be shifted back in the car balance out the weight and to reduce the rotational moment of inertia.
Aero - The front will include a larger front spliter with side shields in order to maximize the available front downforce. This will transition into 2 small tunnels that open to the suspension area. The Front fenders will vent on top and out the back and include wing elements before the wheel to produce extra downforce. The side of the car will have large sideskirts in order to minimize air bleed over. The underside will be flat bottom until after the rear diff where a diffuser will be located. The diffuser will extend past the bodywork slightly to help with downforce. The rear fenders will house the radiators so they will have a forward intake and the air will be routed to vent in conjunction with the rear wing. Extra winglets will be mounted on the fender behind the wheel as well as the lower section of the fender will be used as a smaller diffuser section. The rear wing will be mounted with large endplates and in a location as to balance out the aero. All bodywork will be replaced with fiberglass except the roof. The doors hood and trunk will only change material not shape.
Other - For safety and easy of use an airjack system will be mounted in the car. Also a fire suppression system will be mounted in the engine compartment. The dash will be replaced by a digital readout. The engine will be controlled by an aftermarket ECU from MOTEC. The race seat will be a proper FIA approved seat.
The car will most likely look like Formula SAE met Group 5 which is basically whats happening. Let me know what feedback or questions you have about my plan. I haven't covered everything and there is still plenty of time to change things.