Despite being called stock cars, NASCAR vehicles have purpose-built engines that are very different from the ones in our everyday sedans. With a bigger size, more valves per cylinder, and way more horsepower, racing engines are super impressive compared to our stock car engine.
When deciding which engine builder to choose, racing teams have some options, but NASCAR’s regulations set a maximum size and power for all race engines.
The exact size and power of a NASCAR engine depend on which of the 3 companies that design production engines builds it. Depending on the company’s engine development philosophy, they will prioritize certain functions like cooling or torque generation and adjust the larger engines accordingly. This article focuses on the exact specifications for NASCAR motors sizes used in racing events.
What Is the Size of a NASCAR Engine?
According to the race engine spec sheet provided by NASCAR, the race engines are all V8 and can not be larger than 358 cubic inches. In general, the HP is between 700 and 800, but after the regulation engine horsepower reduction, most output is below 670 HP. The rules also outline the type of materials, like aluminum and carbon fiber, that can be used to build race engine components and when modifications like bore sizes can be made by race teams.
On oval tracks like Talladega Superspeedway, the rules force engine horsepower reduction and restrictor plates over the intake manifold limit engine to 550 HP. The larger engines need to be adjusted after the engine builder has completed the production engines to meet each track’s requirements. Tapered spaces are used to bring the engine horsepower reduction in compliance with NASCAR cup rules. Most tracks have a capped power output of 670
Production engines have a required compression ratio of 12:1 and need to contain less than seven-liter engines. The engine horsepower reduction brings the powerful V8 engines down to the power of finely-tuned six-cylinder engines like those used in IndyCar.
Even with the restricted power and tapered spacers, the high-performing coolant pumps, steering pumps, electronic fuel injection system, hybrid powertrain, supercharged catalytic converters, and precision shifting manual transmission, these racing engines blow all street legal four-cylinder and six-cylinder engines out of the water.
NASCAR Engine Types
Due to how strict and frequently updated, it is tough for race teams to develop a production engine that crushes the completion. Even so, the main differences in NASCAR engines can be found between the different NASCAR races. Only the NASCAR cup series boasts the 725-horsepower V8 NASCAR racing engines that still fit the (358 cubic-inch) engine rules. The other races have slightly fewer horsepower-generating engines but are still higher than what is allowed on the Talladega Superspeedway.
| Engine Type | Engine displacement | Power output | Fuel Delivery |
| NASCAR Cup Series – Gen 6 | 90° 5.86 L (358 cu in) pushrod (OHV) V8 | 750 hp (559 kW) on < 1 Mile ; 550 hp (410 kW) > 1 | Electronic multi-point indirect port fuel injection |
| NASCAR Xfinity Series | 5,860 cc (358 cu in) Pushrod V8 | 650–700 hp (485–522 kW) UR, ≈450 hp (335 kW) R | Carburetion |
| Camping World Truck Series | 5.86 L (358 cu in) built OR 396 cu in (6.49 L) | 650–700 hp (480–520 kW) UR ≈450 hp (340 kW) R | Carburetion (built) or throttle-body injection (optional series-spec) |
NASCAR Cup Series – Gen 6
The NASCAR cup series is the top racing event in NASCAR. It boasts the largest production engines that follow the face engine spec sheets and achieve maximum engine displacement. The Larger engine blocks and big-block seven-liter engines produce much more power than our road cars’ small-block engines. All cars have 8-cylinder engines and can reach speeds in the 220 MPH range on non-restricted tracks.
NASCAR Xfinity Series
The engine design for the NASCAR Xfinity series allows racers that cannot compete at the highest level a chance to join the sport. It gives fans more races every season and is a great way for aggressive race teams to field new talent.
Most of the races are on oval tracks, and races like the Talladega Superspeedway still require tapered spacers to keep the base engine HP at 550 or below. With smaller engines like the 340-cubic-inch (5.57-liter) V-8 engine design, these cars are still able to zip around these tracks and run better than the average engine.
Camping World Truck Series
A race category for stock cars with pickup truck bodies, this event is also very popular among race fans. While trucks are capable of housing ridiculously powerful larger engines like a 427 cubic-inch (7000cc) engine, the regulations and restrictions still keep the regulation engine size between the standard 5.86 L (358 cu in) built OR 396 cu in (6.49 L). The increased power of the trucks needs to be balanced with the higher center of gravity pickups sport which makes it an exciting race for spectators.
Who Makes NASCAR Engines?
All NASCAR cars are equipped with a V8 engine that is no larger than 358 cubic inches. The parts come from different manufacturers, and this, in turn, creates the differences that give some cars advantages and keeps the suppliers competitive.
Traditionally Ford motors, Chevrolet, and Toyota have made the engines for all the race teams since NASCAR has been around. Initially, stock engines of these cars were modified by race teams, but over time the engine developers began to design purpose-built engines specifically for NASCAR specifications.
Ford
Second generation Ford Fusion is the body design ford used for the GEN 6 version. It more closely emulates the stock cars fans can buy and encourages team and motor brand loyalty. The standard engine supplied by Ford to NASCAR is the FR9. This engine was purpose-built by Rousch Yates Engines and Ford Performance and boasts superior cooling that allows the engine to maintain maximum power at high internal temperatures.
These engines are capable of producing more than 800 HP but are restricted by NASCAR regulations based on the specific track
Chevrolet
This company uses the R07 engine model. The main advantage of this engine is that it relies on oil cooling and component damping as well as high-temperature lubrication. Instead of oil running through the system and being stored in the crankshaft, it is sucked with an oil pump to a tank to allow unrestricted airflow through the crankshaft.
This translates to an increase of 10 to 20 HP. The oil-driven cooling system can operate at 10,000 RPMs, and Chevrolet builds engines for 10 NASCAR teams.
Toyota
The only Foreign-owned NASCAR engine builder Toyota brings a unique angle to the NASCAR engine development standpoint. Capable of producing a solid 725 HP and a V8 engine, Toyota builds around 400 engines a year for NASCAR racers.
Once an engine is built per the parameters set by NASCAR’s governing body, Toyota uses a dynamometer that measures horsepower and torque and allows adjustments to increase HP, like better placement of intake valves and bore holes for increased engine displacement. These data points from Toyota’s tests check how the engine handles at high RPMs.
How Much Better Are NASCAR Engines Than Street Car Engines?
While NASCAR race cars are meant to resemble the stock car we drive on the street, they have a better engine design, engine power, and with specialized engine components much high engine speeds. Modern engines designed for stock car racing. A typical NASCAR engine can run as much as $50k.
There are no six-cylinder engines or traditional four-cylinder engines like most street cars are used in NASCAR race cars. Bigger engines are not all that makes NASCAR vehicles way better than our stock engines. Check out the info below to see why these cars are only on the tracks and not on our roads.
Engine Size
V8 and as large as 358 cu in to meet regulation provide plenty of power to hit speeds averaging 200 MPH. These builds can have as much as 800 HP and the ability to run at full power, even at high speeds. The bigger engine will get very hot and need all the fluids required to run smoothly delivered exactly where it’s needed and when it is needed. Constant maintenance keeps these beasts purring perfectly.
Lubrication System
Oil is the lifeblood of an engine, whereas fuel is the catalyst for combustion. As more speed is needed, more explosions are produced, and the engine heats up to ridiculous levels. A high-temperature rapid cooling fluid system allows the engine to maintain full performance while the internal components are red-lining. Long after our car would be spurting clouds of steam and smoke, these cars will happily zip around tracks at twice the speed we can legally travel.
High Performance Fluids
0W-5 oil is better than any high-performance synthetic oil our car dealership sells us. With the same consistency as water when superheated, this oil makes its way rapidly through the internal engine parts and keeps everything cool and frictionless. The fluids in these cars are designed to only last one race, so no preservatives or anti-corrosion additives are needed.
The fuel that NASCAR racers use is closer to jet fuel in purity than even the coveted 97 octane at our pumps. To race for hours, overtake other cars on hairpin corners, and all the other racing feats a NASCAR driver must accomplish in a typical race, the fuel needs to be the best available. Anything these automatic engines need is provided in high-quality fluids that allow these engines to run at top efficiency for hours and hours of exciting racing with the standard-size motor NASCAR uses.
