Can you tell the difference?...
Can you tell the difference? The car on the left is a short-track car, and the car on the right is a superspeedway car.
On the superspeedway car,...
On the superspeedway car, race teams often will use thinner rotors to lessen the rotating mass. Even the wheel-bearing grease is sometimes substituted with oil to help reduce friction.
There are many changes in...
There are many changes in a superspeedway car. Here, two of the most visible ones are the smaller wheel opening and the smaller air intake on the superspeedway car (right).
(above and below) The decklid,...
(above and below) The decklid, quarter-panels, and spoiler are moved back and down within rule limitations to keep the spoiler out of the airflow as much as possible to reduce drag.
You cant always tell...
You cant always tell by looking, but the race teams attempt to lay down (flatten) the windshield to reduce wind resistance and increase cowl pressure.
From the grandstands, race cars may look the same regardless of the track. But a closer inspection reveals that teams build cars for certain styles of tracks, such as short, intermediate, road course, and the superspeedways of Daytona and Talladega.
Perhaps the most effort goes into the cars that will race at Daytona and Talla-dega. Teams must find ways for cars to go faster and offset rules that greatly reduce horsepower. These speedway cars are more than just a particular chassis setup. They are purpose-built cars with one functionto go fast at only those two tracks.
Speedway cars are distinct from cars that run on tracks of intermediate size because of two basic elements of racing: aero-dynamics and downforce. Aerodynamics, or aero, is how the air goes over, under, and around the car at speed. Downforce is how that air pushes the car to the track, increasing traction and handling.
A car built for intermediate tracks wants downforce. But, as ARCA crew chief Bill Kimmel says, At Daytona and Talladega, you dont want downforce. You want to be as slick as you can be. You dont want any drag whatsoever on the car. It takes a completely different race car. Air plays the biggest part.
The body receives extra scrutiny when building speedway cars. Teams will spend hours in the wind tunnel looking for ways they can massage the body to improve its aerodynamics.
NASCAR requires the rear spoiler to be at 70 degrees so that it acts like a wing to catch air and slow the car. To counteract the spoiler, teams actually drop the back end of the car out of the air as much as they can. Remember those shocks from a few years ago and how they made the cars look as if they had two flat rear tires?
Builders take advantage of the small tolerances in body specs and lower the rear of the cars body as much as they can and still meet all of NASCARs templates, but the back end is lower. If a rule says the tolerance is 1/8 inch, builders will take it because it all adds up.
The rest of the body gets equal attention. The wheel openings are the smallest seen on the cars, and youre lucky if you can get your fingers between the tire and the fender on speedway cars. They are so tight that if a driver doesnt point the wheels straight during a pit stop, they wont come off. By comparison, short-track cars have a little more breathing room because of contact and less of a need for aerodynamics.
All of the glass in a speedway car is painstakingly fit to the body, and gaps are virtually nonexistent. The gaps on the hood and deck lid are precise, too. Even the paint, including primer, is as thin as possible.
You want to make sure the front end stays as narrow as it can, Kimmel says. Every dent in the car is like a place to catch air.
Chassis and Motor
While the bodies are different, chassis setups for speedway cars are close to some intermediate tracks such as Atlanta Motor Speedway. Spring rates and other chassis settings are not what they used to be. At Daytona, with less downforce, softer setups help maintain and increase speed.
In the past when speeds were up, stiffer springs, especially the right front, were needed to offset centrifugal forces. As the cars became more aerodynamic and got through the air easier, springs were softened and actually increased handling.
Kimmel keeps his cars extremely easy to roll. You can put oil in the bearings instead of wheel-bearing grease, anything that would enable the car to roll easier, he says. We look under the car and try to keep all sharp edges off the front. We might use a little wider gusset on our exhaust pipes to keep air from getting up inside the car. Anything we can possibly do to make the car slicker.
Even brakes are a factor. A lot of people run the .810 rotor or a smaller rotor all the way around just for less friction, says Joe Dan Bailey, the crew chief for Shawna Robinson in ARCA.
But there are two rules of thumb on that, Bailey says. On the one hand, its less weight to get up to speed. However, heavier rotors, once theyre going, generate momentum to keep the wheels rolling harder. So youre not going to lose momentum because youve got that carrying your wheels.
As for motors, NASCAR does rule. A restrictor plate, a thin slice of aluminum reducing the intake of air and fuel to the engine, keeps power and speed down. Motors have only between 425 to 450hp instead of the more typical 800.
Engine builders spend countless hours trying to find 1 or 2 hp at a time in other areas of the engine while still using the plate. Those who stumble across something, just like discoveries by fabricators and chassis men, can help keep their car out front.