Understanding NASCAR Engines

From the front air splitter to the rear deck-lid wing, a stock car is packed with innovative engineering. Interestingly, one of the most complex parts of the car is often hidden from the public eye—its engine.

Beyond assembling a skilled team, one of the key factors in winning NASCAR races is building or acquiring a powerful and reliable engine. While adjustments to aerodynamics and suspension can offer an advantage, almost everyone in NASCAR agrees that the engine is the true heart of the race car.

In NASCAR's Sprint Cup Series, engines are rated at nearly 800 horsepower. Since the introduction of the Car of Tomorrow body style in 2008, engine power has risen to approximately 850 hp. These engines are so potent that NASCAR limits horsepower on certain tracks to prevent cars from reaching speeds over 200 mph, which could cause debris to fly into the grandstands in the event of a crash.

What makes NASCAR engines truly unique? Can you simply drop one into your Monte Carlo and call yourself the King of The Road?

This article will explore the complexities of NASCAR engines and the considerable effort and finances involved in their creation. NASCAR engines come at a steep price, with owners often spending $50,000 or more for just one engine to stay competitive. When you factor in a fleet of over a dozen cars, as most top teams have, the costs rise exponentially.

For that hefty investment, these teams receive a finely tuned, meticulously engineered machine crafted from the most exotic and costly metal alloys available. Additionally, teams may employ PhDs in engineering to squeeze every ounce of potential horsepower from the engine. As you might expect, thorough design and rigorous testing are standard when crafting a critical component like the engine for a stock car.

At this point, you might be thinking, 'If everyone else's engines can only generate 800 or 850 horsepower, why don't teams just build engines with 900 or even 1,000 horsepower? Let's address that next.

NASCAR Engine Rules

In NASCAR, technology is like an ongoing arms race. Teams are always on the lookout for innovations that will make their cars faster and more competitive. However, if one team gains too much of an advantage and starts winning too easily, it makes racing predictable and dull for fans. Bored fans lead to empty seats in the grandstand, which results in a drop in revenue.

To keep things fair, NASCAR takes extreme measures. After a race, you might see the winning driver celebrating with champagne and a quick on-camera interview, but the day isn't over for the team. NASCAR officials will roll the winning car away for a teardown, a complete disassembly of the car, including the engine and suspension. This is done to check for any irregularities, such as illegal parts or measurements, that could unfairly boost performance.

Teams do have some flexibility with engine design, but NASCAR enforces strict rules. For example, the engine must be a carbureted V-8 with an iron block. There are also strict limits on how much the engine cylinders can be bored, or enlarged by removing material. Additionally, NASCAR mandates that teams use blocks, cylinders, and intake manifolds made from castings by approved manufacturers. The standardized Car of Tomorrow body style further tightens these rules.

These rules are clearly outlined in NASCAR's regulations, but disputes often arise between teams and officials over the interpretation of these rules. Teams are often inventive in finding ways to work around these restrictions, only for NASCAR to respond with even more specific language to eliminate any advantage [source: Martin]. This is why stock cars are so similar in size and shape, with bodies designed to conform to templates mandated by NASCAR. NASCAR also provides a detailed list of required interior features for safety and to ensure a level playing field.

Now that we've covered some of the essential rules, let's take a look at the technologies that make NASCAR engines the powerful machines they are.

What Sets NASCAR Engines Apart

You may have heard people in racing talk about "blowing an engine." This term refers to a situation where a critical component is damaged to the point where the engine is no longer usable for the rest of the race. Blowing an engine can range from something fixable, like breaking a connecting rod or damaging a piston, to something catastrophic, such as cracking the engine block or melting a part of it. This raises the question: How can something made of cast iron, reinforced steel, and exotic metal alloys break?

The answer is surprisingly straightforward: Expose the engine to intense heat and pressure. Over the course of a race, which can cover hundreds of miles, engines endure numerous cycles of extreme heat and pressure. Certain racetracks, such as the tri-oval-shaped Pocono Raceway in Long Pond, Pa., are particularly challenging for teams due to their layout and the risk of engine failure. The unique track configuration requires substantial deceleration followed by rapid acceleration in the turns, putting a great deal of strain on the engine. This quick shift in performance demands can lead to engine fatigue [source: Martin].

Inside a NASCAR V-8 engine, temperatures can soar to 2000 degrees Fahrenheit, with pressures reaching up to 1500 psi—more than 100 times the normal air pressure we encounter daily. To withstand these conditions, NASCAR engine components are heavily reinforced. In other words, they are designed to be larger, stronger, and thicker than those in less powerful vehicles. Nearly every moving part of the engine, from the crankshaft to the valves, valve springs, and pistons, is fortified to handle the extreme stresses involved.

Some engine components that are exposed to the most intense heat are made from special metals to prevent them from melting or bonding with other parts. For example, valves are crafted from titanium. Titanium offers the highest strength-to-weight ratio of any metal, is highly resistant to both heat and corrosion, and is much more expensive than typical metals and alloys. The engine blocks themselves are constructed from cast graphite iron. Adding graphite to iron improves its molecular structure, making the resulting alloy stronger and more heat-resistant [source: Leslie-Pelecky].

While some teams manufacture and maintain their engines in-house, others reduce costs by leasing engines from external providers. Hendrick Motorsports, a prominent engine supplier, builds more than 700 engines annually for both their own race teams and external clients.

NASCAR engines have been continuously refined over the years to maximize performance from what many consider to be traditional engine technology. However, the most groundbreaking advancements in NASCAR recently have been in non-engine areas, including aerodynamics and safety.

As NASCAR teams continue to push the limits of racing technology, the cars have progressively become faster and more powerful. In fact, they reached speeds so high that NASCAR officials began to worry about the safety of both the drivers and the fans.

Restrictor Plates

NASCAR speeds can reach extreme levels. In 1987, driver Bill Elliott set an incredible qualifying lap speed of 212 mph at Talladega Superspeedway. However, during the race, Bobby Allison's car suffered a tire blowout and was sent airborne into a retaining fence, narrowly avoiding a disaster that could have seriously harmed the driver and spectators behind the fence. As a result, NASCAR decided to introduce restrictor plates to slow the cars down for safety reasons.

On high-speed NASCAR tracks like Talladega, teams are required to use carburetor restrictor plates to reduce their engines' power. A restrictor plate is simply an aluminum piece with four holes, designed to limit the flow of air and fuel into the engine.

The fuel and air mixture passes through the four small holes before entering the four larger holes in the carburetor, and eventually the engine. It's similar to the difference between sipping a drink through a normal straw versus using a tiny coffee stirrer straw.

To ensure fairness, NASCAR has a strict procedure for selecting restrictor plates. A team member reaches over a barrier to randomly pick a plate. The official then raises the plate for spectators to see and uses a pole to measure the diameter of the holes, each roughly the size of a quarter, give or take a fraction of an inch. The plate is then installed on the engine and sealed with a NASCAR sticker to prevent tampering [Source: Martin].

A restrictor plate can cut horsepower by as much as half, reducing power from about 800 hp to 400 hp. Interestingly, many drivers argue that the tight racing caused by restrictor plates often leads to more accidents. When one driver loses control, the close proximity of the cars can trigger a chain reaction of crashes, famously referred to as "The Big One" [Source: Busch].

When it comes to building powerful and durable engines, NASCAR stands among the top-tier leagues. Achieving greatness in this field requires talent, dedication, and years of experience, just like in any elite sport.

Building Engines for NASCAR

To truly understand the skill required to build a NASCAR engine, watch the MAHLE Engine Builder Showdown (formerly the MAHLE Clevite Engine Builder Showdown). In this televised challenge, two-person teams of professional engine builders compete to assemble a fully operational 357-cubic inch Ford Sprint Cup engine in the fastest time possible.

In 2008, the competition took place at the NASCAR Technical Institute in Mooresville, N.C., which specializes in training technicians for the unique demands of NASCAR. The contest aired on the SPEED Channel's "Two Guys Garage" show. Dennis Borem and Darrel Hoffman from Pro Motor Engines won, completing their engine in an astonishing 15 minutes and 59 seconds, setting a new record and improving their previous year’s time by almost thirty seconds [source: MAHLE Clevite].

In addition to grasping the mechanical engineering concepts behind engine functionality, you'll also need to master advanced diagnostic skills. This often involves connecting the engine to computerized tools designed to optimize performance. A well-known tool for this purpose is the engine dynamometer (engine dyno), which provides digital displays of critical data such as torque, rpm (revolutions per minute), and horsepower.

Many engine-building teams, whether independent or part of larger programs, employ individuals with doctoral degrees. These experts may specialize in fields such as fuel atomization and the behavior of combustion 'flame kernels.' Some elite engine builders come from careers in major automotive companies, but all share the specialized knowledge necessary to thrive in the demanding world of NASCAR.

To explore more about NASCAR engines and other related topics, take a look at the links provided below for further insights.