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NASCAR vs. Your Street Car: What’s the Difference?

It’s easy to pretend you’re a NASCAR driver while you hug the turns of your local expressway hurrying home from the office. But how similar is your car to those the pros drive every Sunday? What are the real differences between Brad Keselowski’s Ford Fusion race car and that 2004 Toyota Sienna sitting in your driveway?

1. The Power Generated by the Engine

The basic NASCAR engine is not that much different from a street car’s, but it’s much larger and the engine block is custom-made. NASCAR racecars use V8 engines that regularly generate a horsepower rating of 800 and above. Per this article, 37.7% of passenger cars on the road today are running a 4-cylinder engine, the most of any engine type. While there are several other factors (like piston size and overall engine size and design) that play a role in generating horsepower, an average 4-cylinder vehicle produces around 200 hp. 4-cylinder engines account for 54.2% of all new vehicles sold, which means a NASCAR engine is about four times more powerful than the one in your car.

2. The Way the Camshaft Works

The biggest difference may be the way the engine’s camshaft (or cam) operates. The camshaft controls the opening and closing of the valves, kind of like the breathing in and out of a lung, only this happens inside the engine. The cam regulates the amount of fuel/air mixture the engine can pull in and push out. The amount of fuel the engine can effectively and efficiently burn and get rid of dictates the power the engine will generate. This guy explains the concept perfectly in under two minutes.

In a race car, the cam keeps the intake valves open longer at certain higher speeds for additional airflow and peak engine performance. If you did that to a street car, the engine would be far less powerful at lower, street-legal speeds.

3. The Overall Design

Race cars are designed to be driven extremely hard for a short period of time, then rebuilt for the next race. Street cars are rarely pushed to the same kind of mechanical limits and need to run for tens of thousands of miles with minimal maintenance. The different functionality required to win a race leads to several design differences.

The chassis on a stock car must be lightweight, yet firm enough to handle high stress. A roll cage serves as a chassis and is covered by a 24-gauge sheet-metal body with a closed cockpit. For weight distribution, the heaviest parts, like the engine and transmission, are located as close to the midpoint of the car as possible, as is the driver’s seat. The deck lid (roof) and hood are made of carbon fiber, which is roughly 50% lighter than steel. The entire car is wind-tunnel designed to maximize downforce, which is downward thrust created by the car moving through the air, and which ultimately creates more grip by pushing down on the tires. This maximizes the energy generated by the engine. Aerodynamics are so significant to design and on-track performance that NASCAR has an ongoing partnership with NASA for aerodynamic testing called “Rockets to Racecars.”

4. The Tires

The tires used in NASCAR are a lot different from those generally used on a street car because the demands placed on them due to temperature and speed are so extreme. In addition to being wider and softer, they’re comprised of specialty compounds approved by NASCAR. On tracks a mile long or more, NASCAR requires both inner and outer tires. The inner tire is essentially a second tire mounted inside the first tire. It exists so that if the outer tire deflates, the inner tire remains intact so the driver can bring the vehicle to a controlled stop.

Another interesting thing is that there’s no tread on the tires used in NASCAR. The bald design actually allows the surface of the tire to be fully exposed to a dry track, maximizing the tire’s ability to grip the track.

The biggest differences between a NASCAR race car and the car in your driveway boil down to specialization. When a win for your favorite driver can be determined by a tenth of a second, the cumulative effect of all those modifications is significant.

One way your car is superior to those in NASCAR? The front lights, fog lights and brake lights are nonfunctioning decals on the race car. +1 for your ’04 Sienna.

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