Why Does NASCAR Use Pushrod Engines?

NASCAR has historically used classic technology if they believe it can remain effective in both efficiency and cost. But there are a few more reasons they use pushrod engines. Since there have been advancements from their introduction in the 1950s, you may ask why NASCAR uses pushrod engines. 

NASCAR uses pushrod engines because they are more compact and more inexpensive than dual-overhead camshaft engines. They are also simple for manufacturers to design, which makes them easier for NASCAR teams to handle. NASCAR currently has no plans to use any other engine. 

Below, we will explain what pushrod engines are, how they are constructed, and their advantages for NASCAR teams. We will also cover a few disadvantages that pushrod engines might give teams and whether NASCAR will ever decide to move on from them. 

What Are Pushrod Engines?

Pushrod engines are engines that utilize pushrods that rise beyond the camshaft and over the cylinder. Here, rocker arms let them press down on an inverted valve. These engines have seen direct competition from modern-day dual-overhead camshaft engines. However, pushrod engines remain popular. 

Lincoln and Cadillac are credited with designing pushrod engines following the end of World War II. But they did not go mainstream until 1955 when Chevy debuted the small block V8 engine, around the same time Chrysler introduced its V8 Hemi, something that would eventually make its way into NASCAR in the 1960s with the Plymouth Superbird and Dodge Daytona. 

Pushrod engines are also the mainstream successor to the old flathead engines. Flatheads comprised valves beside the engine cylinders, located inside the engine block. You may be familiar with the old Ford V8 Flatheads if you are a classic car enthusiast. 

These engines did not have the best airflow. They further had issues with both thermal characteristics and combustion. This was due to the positioning of the combustion chamber, which covered both the valve and piston tops. So, when it came to designing a newer engine model, Lincoln and Cadillac’s main goals were to correct the issue of poor airflow and combustion. 

Does NASCAR Use Pushrod Engines?

NASCAR has traditionally used pushrod engines, and they continue to use them for the Next Gen car. While pushrod engines are by no means new in the world of auto racing or the automotive industry, NASCAR has never been afraid to use older technology if it continues to serve the sport well. 

NASCAR teams have long given positive feedback on the use of pushrod engines. And if both the teams and drivers are satisfied, so is the sanctioning body. 

NASCAR Engines

Contrary to popular belief, NASCAR cars are not truly stock cars. Stock cars are production line vehicles modified to drive at faster speeds. Think of them as more powerful versions of your production car. So, if you know someone who has a production car that they haul to dirt tracks as a hobby, that’s what a true stock car is. 

NASCAR engines are built specifically for NASCAR. In other words, while Chevy, Toyota, and Ford build the engines, they are not coming off of the production line. Instead, the 3 manufacturers will build the engines then ship them to the respective teams. 

While NASCAR is not a spec series, their engines have specific specs for manufacturers to follow. This further levels the playing field in NASCAR while at the same time, allowing each manufacturer to maintain a specific amount of brand identity. Therefore, prior to teams building their respective engines, they must submit a design to NASCAR for approval first. 

While it is true that these engines are old-school pushrods, NASCAR conducts sound research, testing, and fine-tuning to create the perfect engine specs for their manufacturers. This approach has helped to keep the sport competitive. 

Engine Construction 

NASCAR engines use 2 pushrods, a conical combustion chamber, and twin valves. They must also be durable, built to run at high speeds and a high rpm for the duration of a 3 to 5-hour race. Unlike dual-overhead camshaft engines, the camshafts work from below, which differs from modern-day road car engines. 

The engines are constructed from cast iron, and to prevent fuel-air mixture leaks into the combustion chamber, manufacturers fix the combustion pistons to minimal tolerances. The engines must also be coated with titanium and carbon nitride to help preserve each component. 

NASCAR cars can get notoriously hot, so manufacturers must also be mindful of the location of its lubricating oil. In these cars, you will find them in an external tank. This requires oil to drip from each rotating component cleanly. In theory, this can increase the engine’s power output by about 20%.

To further increase output, the air and exhaust valve stays open longer than seen in production car counterparts. Manufacturers will calibrate each ignitor to ideally produce maximum power. The same goes for the timing that each valve fires. 

Shorter Pushrods Are A Must

As you can see from everything written above, each action taken is geared to ensure a NASCAR engine can reach its maximal power. To create even more power, manufacturers use short pushrods. This further makes NASCAR engines different from road cars, which use longer pushrods. 

The reason NASCAR opts for shorter rods is because longer rods are prone to deflecting. If this happens during a race, it will cause a NASCAR car to lose a substantial amount of power. The downside is that such power is prone to getting out of hand on superspeedways, which is why NASCAR uses a different horsepower package at places like Daytona and Talladega. 

Power Of NASCAR Engines

While NASCAR engines are geared to hit a specific target horsepower depending on their current design, like the Generation 6 or the Next Gen, they can reach 10,000 rpm and produce 670 horsepower. Tapered spacers, and in the past restrictor plates, limit the power of these engines for safety purposes. 

NASCAR used to use carburetors. However, that changed in 2012. These days, an indirect fuel injection system provides power. As of 2022, the Xfinity Series and Truck Series continue to use carburetors. One reason for the switch to fuel injections was for NASCAR to further reduce its carbon footprint, something carburetors are notorious for. 

Cost And Craftsmanship 

No component on a NASCAR car costs more than the engine. The cost is worth it, though, for NASCAR teams, because the engines are also the most important car component. If the engine fails, then a team is going back to headquarters early. 

Therefore, close attention to detail is required when manufacturers build these engines. Because so much strain is put on the engine during a race, they must be overhauled before racing again. For this reason, NASCAR teams often rent, rather than buy, the engines. 

Manufacturers must pay close attention to detail of the engine after each race. They will break down the engine and examine every component. This allows them to thoroughly replace anything broken before they are overhauled and returned to the respective team. 

Total Costs

NASCAR engines often cost teams $100,000. But they can also cost as much as $500,000, depending on the event. Before NASCAR moved its Clash preseason race to Los Angeles, it was normal to see teams spending at least $300,000 on engines for the Clash, the Twin Duels, and the Daytona 500, with a new engine used for each event. 

Larger NASCAR organizations running 3 or 4 cars can spend even greater amounts on engines per week, sometimes pushing $1 million in engines alone. Teams like Hendrick Motorsports and Joe Gibbs Racing field 4 cars in 2022, so it is safe to say they are spending more than smaller teams like Trackhouse Racing, who field just 2 cars. 

KEY POINTS

• NASCAR uses pushrod engines and has done for many years

• The engines used in NASCAR are the most expensive parts of the cars

• They’re designed specifically for racing, and so they’re quite different from many road car engines

NASCAR Engine Specs

While NASCAR is not a spec series, the sport does have engine specifications to help ensure equal competition. For the Next Gen car, NASCAR’s specs call for a V8 pushrod engine comprising 5.86-liters (358 cubic inches) of displacement with a naturally-aspirated FR layout.  

The engine specs come with 2 packages: one for road courses and speedways. This package involves a 4-inch (10 cm) spoiler with the engine operating at 670 horsepower. The second package is used on superspeedways and in the reconfigured Atlanta Motor Speedway. It requires 510 horsepower and 7-inch (18 cm) spoilers. 

Advantages And Disadvantages Of Pushrod Engines

Pushrod engines come with distinct advantages, which is why you still see them in NASCAR, even in the Next Gen ride. Some of these advantages include better torque and combustion, and a simpler construction process. Disadvantages include lower revs when compared to dual-overhead cam engines.

While some may describe these engines as archaic, these engines have stood the test of time in the world of auto mechanics. There have been newer engine technologies developed over the decades, like dual-overhead camshaft engines. But there are many advantages that pushrod engines have as opposed to dual-overhead camshafts. 

Advantages Of Pushrod Engines

Pushrod engines provide low-end torque. This comes from improved air velocity via 2-valve cylinders. With improved air velocity comes improvements in both torque and combustion. They also contain much simpler construction, which allows engineers and mechanics to develop them at a faster rate than the overhead camshafts. The theory is that simpler engine designs are more reliable. 

One example of the pushrod engine’s simplicity comes with the location of just 1 camshaft near the crankshaft. This keeps the belt from traveling great distances to rotate the shaft. In contrast, dual-overhead camshaft engines feature 4 drive gears and camshafts, and dual chains. Such complexity could cause quite a few headaches and delays for teams. 

Pushrod engines are far more compact. Since the lone camshaft is in the engine’s center, it allows the V8 cylinders to remain smaller. The engine is also lighter, which makes it easier for NASCAR teams to package the engine before they haul the car from the race shop. 

When NASCAR unveiled the Next Gen car, their overall goal was to ensure they were giving their teams something technologically advanced where applicable, but also low-cost. By sticking with pushrod engines, NASCAR gave its teams something on the low-cost end. 

For production car automakers, they were saving up to $400 by building pushrod engines in 2004. Now, NASCAR engines cost upwards of $100,000 or more. So, by going with a pushrod engine for NASCAR standards, teams are saving even more money. 

Disadvantages Of Pushrod Engines

Pushrod engines will never rev to the same extent as their dual-overhead cam engine counterparts. While those who prefer the dual-overhead camshaft engines praise pushrods for their unique sound, simple, and compact designs, they simultaneously shun them because they must rotate through a rocker arm and a pushrod. 

To open the valves, the process described above is forced to push the springs downward, which consequently produces a lot of reciprocal mass. Eventual valve floats are inevitable since at higher rpms the spring can’t keep up with the rotation. 

These are definitely downers, but in NASCAR terms, the pushrod’s advantages far outweigh the disadvantages. NASCAR also follows the if it isn’t broke, don’t fix it mentality. Although pushrod engines are an older technology, they continue to work just fine for NASCAR teams. 

KEY POINTS

• Pushrod engines are fairly easy to build, and can save teams money vs DOHC engines

• They provide good low end torque and they’re lighter too

• Pushrod engines can’t rev as high as other engine types 

Will NASCAR Get Rid Of Pushrod Engines?

NASCAR will not get rid of pushrod engines until the sport deems them no longer fit for use. NASCAR prides itself on being able to use older car components that many think are outdated. While they ditched a lot of old-school components in the Next Gen car, they kept pushrod engines. 

But that doesn’t mean NASCAR didn’t modify the pushrods. When you look at the engines from the Gen 6 car compared to the Next Gen, you will notice that the Next Gen engines contain far more horsepower. For example, the superspeedway package for the Gen 6 design limited the cars to just 410 horsepower. But with the Next gen cars, that package increased to 510. 

This shows that instead of overhauling their engine designs and introducing dual-overhead camshafts, NASCAR are instead able to simply modify the pushrod design when necessary.

Why NASCAR Keeps Pushrods

NASCAR wants to keep costs low for its teams. They also want to keep things simple, which provides a more equal playing field for both teams and manufacturers. Given the pushrod engine’s simpler design, this is more feasible than using a more complex dual-overhead camshaft engine. 

The dual-overhead camshaft engines are also more costly. And while there are times when NASCAR will require teams to use more expensive car components, they will do so only when the benefits outweigh the costs. This was the case with the newer, thicker, single-lug nuts. While they cost more than the 5 lug nuts NASCAR used in the past, they are also more durable, cutting costs in the long run. 

Final Thoughts

NASCAR uses pushrod engines because of their low cost, simplicity, and small size. While NASCAR’s Next Gen car came with a lot of new technology, the old V8 pushrods remained. NASCAR uses older technology in many areas, and it often takes them years before they change.