The NASCAR Car of Tomorrow (COT) is an interesting concept and one that rekindles our interest in Nextel Cup for several reasons. This magazine has, as a policy, refrained from either reporting on or covering NASCAR Nextel Cup racing because historically very little of the technology developed there pertained to the short-track racer. That has all changed with the COT.
With the changes made for the COT concept, NASCAR teams have suddenly found themselves searching for usable chassis setup technology to replace aero manipulation. | 
The NASCAR inspectors have a tool that goes over the entire body to check for compliance to the strict rules governing the shape of the fenders, hood, roof, and such. There is no manipulation allowed to any part of the spec body. | 
The rear wing on the COT is closely related to the Grand Am Daytona Prototype rear wing. It's no secret that NASCAR and Grand Am are related. This wing can produce a lot of rear downforce. It's mostly unwanted at this time until the teams figure out how to make the front ends turn. In order for a wing to function correctly, the air must flow over and under it unrestricted. Note that the underside of the wing is close to the trunk lid. This makes it more of a spoiler than a wing at the center of the car. |
Before you start writing that letter to the editor, let me stress that we have not strayed in our direction here at CT by taking this look inside the COT. Rather, we see where that series is coming about full circle, back to many of the same issues that confront the average Saturday night racer. That's worth taking a closer look.
For the past eight or nine years, teams in what is often referred to as the "top stock car class" have concentrated on aerodynamic technology. They have spent hundreds of expensive hours in wind tunnels and invested thousands of manpower hours in tweaking the metal bodies into shapes that would produce more aero downforce. It was expensive and restrictive for teams just starting out with no history of aero research.
All of that has come to a grinding halt with the unveiling and implementation of the Car of Tomorrow. With the testing and racing in select events in 2007, the teams and NASCAR have decided to go full-time with the COT for the '08 season. What is the COT and how has it changed the way NASCAR teams prepare for competition? Here is a look inside the COT and an explanation of how the teams are affected, from a technical standpoint.
NO MORE AERO MANIPULATION
The COT has, by rule, a well-defined body shape and the chassis is also specified as to the exact construction layout with certain leeway for front geometry. Basically, the COT lost about 600 pounds of downforce in the front and about 300 pounds in the back of the car over the earlier model Cup car. So, it's comparatively unbalanced downforce-wise when compared with the old design.
Then, NASCAR mandated a rear wing in place of the old spoiler that's similar to the Grand Am Daytona Prototype road-racing wing. Any aero engineer worth his/her salt will tell you the spoiler produces more drag than downforce. The wing, on the other hand, produces tons of downforce and a lot less drag. The wing is adjustable within strict tolerances as to angle of attack, so the actual downforce can be adjusted somewhat.
TALLER BODY WITH A HIGHER CG
The whole COT is 2 inches taller than the old car, which raises the center of gravity. The car is wider by 4 inches, but as we discovered, the driver is not significantly closer to the centerline as previously advertised. The driver's compartment is 11/44 inch wider, which doesn't provide the opportunity to move the seat in by much.
We were told that the individual parts and pieces are heavy and the car now weighs close to the limit once completed with all of the components installed. Some teams did not have to add ballast at a recent race using the COT.
ADDED SAFETY FEATURES
A few additions were added to help protect the drivers. The left-side framerail is doubled on the COT. The floor is heavier with a choice of steel plating or honeycomb aluminum installed under the driver's seat.
The car has a driveshaft tunnel that must be installed to the specs. It is heavy gauge steel and has heavy steel strap assemblies at the front and rear. This tunnel fully encloses the driveshaft and nearly eliminates the danger of a loose shaft. It also adds a lot of weight to the car.
As for the construction of the cars, each team and/or car builder must build the chassis/rollcage assembly and submit it to a NASCAR facility, where the location of each joint, component, and measurement is recorded and a data sheet is produced by what is called a coordinate measuring system. If the car is not within a certain tolerance, it is rejected until it's brought within the specifications.
Every joint and mating of the rollcage and other components must be placed within strict tolerances according to construction plans developed by NASCAR. Once the teams figure out what is expected of them and have properly jigged their build plates, the process should improve production. | 
A steel tunnel encloses the driveshaft, and heavy strap assemblies serve to contain a driveshaft that breaks free of either the transmission or rearend. This is a heavy piece and adds a lot of weight to the car. Note that the front "strap" becomes a part of the crossmember. | 
A set of construction plans is provided by NASCAR so each car builder can see the dimensioning. The tolerances are not too strict in most cases, with plus or minus 0.250 inch allowed. That's a half-inch allowable variation. If you're out of a specific range, the car must be changed to bring it into compliance. |