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Post-race inspection process explained

June 24, 2014, Staff report, NASCAR.com

Car and engine teardown take place at NASCAR R&D Center in Concord, North Carolina

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While six-time NASCAR Sprint Cup Series champion and first-time Michigan International Speedway winner Jimmie Johnson and the No. 48 team were celebrating their Quicken Loans 400 victory, NASCAR.com prepared the car for a unique ride.

A camera was mounted on the No. 48 Chevrolet SS to follow it from Victory Lane through final inspection at the NASCAR Research and Development Center in Concord, North Carolina.

Check out these answers to questions about the process as you watch the video.

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Q: What's involved in the at-track post-race inspection?

A: In addition to the standard, thorough inspection that regularly takes place, additional at-track post-race inspection varies. It can be weighted toward the most relevant race car performance elements for a specific venue, i.e. expanded, aerodynamic-related inspections at high-speed tracks and mechanical traction at short tracks.

Q: What is the white-light 3-D scanning process?

A: This process inspects and verifies that a body surface complies with NASCAR rules. White-light 3-D scanners capture a digital 3-D scan of a physical object. In this case, it's the race car body. The car is coated with a special powder and then a series of targets/dots are applied to the surface of the body. The 3-D scanner directs a series of reference patterns onto the car. The light deflects onto the car's surface. The 3-D scanner captures these images to calculate the object's depth and surface information. From this data, a computer recreates a super-accurate 3-D replica of the race car body surface. NASCAR then compares this body surface with the NASCAR-approved computer aided design (CAD) and the original equipment manfacturer's (OEM) body surface. This NASCAR-OEM approved body surface is referred to as the "Gold Surface."

Q: What's involved in the overall teardown at the R&D Center?

A: In addition to the engine being measured on the NASCAR dynamometer and then completely disassembled and inspected, the transmission is disassembled; the gear ratios are verified; components are measured and weighed; drive shaft, rear suspension components are checked for proper dimensions, construction and weight. The rear end, rear gear, differential and axles along with the shocks are completely disassembled. The fuel cell is completely disassembled. Exhaust, air ducting, all electrical components and wiring are removed and checked. A complete safety audit is conducted and cataloged. The front sway bar along with the upper and lower control arms are removed, measured and inspected for compliance. Springs -- both front and rear  -- are inspected for height, dimensional correctness and linear compliance.

Q: What's involved in the engine teardown?

A: The engine is removed from the car and moved to the engine inspection area where it is disassembled by the team. Once disassembly is complete, NASCAR inspectors begin the process of measuring, weighing and checking the material of individual components of the engine i.e. throttle bodies, intake manifolds, cylinder heads, connecting rods, pistons, lifters, intake and exhaust valves. The bore of the cylinder block is measured to ensure it is at or less than the maximum. Bore size and crankshaft stroke are also measured. Using a calculation of those two measurements -- bore and stroke -- the total cubic inches of displacement is determined. Piston and cylinder-head chamber volumes are measured to determine the compression ratio. NASCAR has a minimum and maximum rule for cubic inches of displacement as well as a maximum compression ratio. Templates are installed on the cylinder head to check valve location, intake and exhaust port height/location. The throttle body's venturi and throttle bore sizes are checked and installed on a flowbench to measure the airflow rate in cubic feet per minute, or CFM. Manifolds are put on a fixture and compared to the OEM-submitted manifold to ensure that the externals of the manifold have not been altered.

Q: Why are cars other than the No. 48 in the post-race teardown video?

A: Following a NASCAR Sprint Cup Series event the winning car, second-place car and a random car are brought back on the NASCAR transporter to the R&D center in Concord, North Carolina for post-race inspection. To maintain a level of transparency in the inspection process, the teams' cars are positioned side-by-side in the inspection bay at the R&D center.

Q: What is the mechanical arm seen toward the end of the video?

A: It is a digitizer, a portable computer-aided measurement system. It's extremely accurate -- to within .001 thousands of an inch -- and it takes the place of conventional mechanical measuring instruments like a micrometer, caliper, height gauges and tape measures. NASCAR uses this computer-aided measuring system to inspect and verify that the body, components and chassis are all assembled in the correct NASCAR-approved locations and in the correct relationship to one another.

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