The Engine NASCAR Banned—and Why It Matters

The Ford 427 SOHC “Cammer” engine was banned from NASCAR and never raced in Cup competition; Chrysler’s 426 Hemi was also barred for the 1965 season but later reinstated in 1966 after a street version was produced. This distinction reflects NASCAR’s long-standing rules aimed at keeping engines tied to production cars and maintaining competitive parity.

What Was Banned: Understanding the Ford 427 SOHC and the 426 Hemi

Ford 427 SOHC “Cammer”: Outright Ban

Developed by Ford in the mid-1960s to counter Chrysler’s dominant Hemi, the 427-cubic-inch single overhead cam (SOHC) “Cammer” employed overhead-cam architecture that NASCAR deemed too specialized for stock-car racing. NASCAR refused homologation, effectively banning the engine before it could compete. The series also codified a pushrod-only philosophy that remains a pillar of Cup engine design.

Chrysler 426 Hemi: Temporarily Barred, Then Reinstated

Chrysler’s 426-cubic-inch Hemi, famous for hemispherical combustion chambers and overwhelming performance, was banned for the 1965 NASCAR season on the grounds that it wasn’t yet available in production cars. Chrysler boycotted that season. When the “Street Hemi” reached showrooms for 1966, NASCAR allowed the engine back, and it went on to power some of the sport’s most iconic wins.

Why NASCAR Drew the Line

To understand these decisions, it helps to look at the principles NASCAR applied across eras. Below are the key reasons the sanctioning body has restricted or banned certain engines or technologies.

• Production relevance: Engines had to be derived from mass-produced cars, not one-off racing specials.
• Competitive parity: Prevent any single manufacturer from gaining an unassailable advantage through exotic hardware.
• Cost control: Limit expensive, exotic technology that could trigger unsustainable development wars.
• Safety and speed management: Keep power and speeds within manageable limits for tracks and tire technology.
• Rule continuity: Maintain a pushrod, two-valve-per-cylinder template that defines stock-car identity.

Together, these factors explain why NASCAR barred the Ford 427 SOHC entirely and only allowed the Hemi once it met the production-availability standard.

Key Moments in the Engine Rulebook

The following timeline highlights pivotal decisions shaping NASCAR’s engine identity—from the Hemi era to modern electronic fuel injection.

1. 1964: Chrysler 426 Hemi debuts in NASCAR and dominates marquee events.
2. 1965: NASCAR bans the 426 Hemi pending production availability; Chrysler boycotts.
3. 1965: Ford unveils the 427 SOHC “Cammer”; NASCAR refuses approval and bans OHC designs.
4. 1966: Street Hemi goes on sale; NASCAR reinstates the 426 Hemi for competition.
5. 1970s–2000s: Pushrod V8 architecture remains mandatory; forced induction and OHC remain off-limits.
6. 2012: NASCAR adopts electronic fuel injection, retaining naturally aspirated, pushrod V8s.
7. Today: Cup engines remain 358 cu in, pushrod V8s with EFI, reflecting the long-standing template.

These milestones show how NASCAR has adapted technology while guarding its core engine formula, striking a balance between innovation and tradition.

What “Banned” Really Means in NASCAR

In NASCAR’s context, “banned” can mean an engine was never homologated (Ford’s 427 SOHC) or temporarily barred until it met production and eligibility criteria (426 Hemi in 1965). The modern rule set still prohibits overhead cams and forced induction in Cup, keeping engines naturally aspirated, cam-in-block V8s designed for reliability, parity, and cost control.

Summary

The Ford 427 SOHC “Cammer” was the engine NASCAR banned outright, never allowing it to race, while the Chrysler 426 Hemi was banned for the 1965 season but returned in 1966 once a production version was available. Both decisions stemmed from NASCAR’s focus on production relevance, competitive balance, and cost control—principles that continue to define the series’ engine rules today.

Why was the Ford 427 banned from NASCAR?

This design was revolutionary. But it added weight and complexity a common misconception is that NASCAR banned the 427 sock solely because it was too complicated. And exotic.

Was the 440 faster than the 426 Hemi?

No, the 426 Hemi was generally faster than the 440 engine, especially in their stock forms, though a well-tuned 440 Six-Pack could give the 426 Hemi a strong run. The Hemi was a race-oriented engine built for high RPMs and was more powerful in stock form, while the 440 offered better low-end torque and was more practical and affordable for street use. 
Stock Performance Comparison

• 426 Hemi: Opens in new tabKnown for its high-RPM power, the 426 Hemi had a significant power advantage from the factory, dominating on the drag strip and in NASCAR due to its ability to move more air and fuel through its hemispherical cylinder heads. 
• 440 Magnum/Six-Pack: Opens in new tabWhile powerful, the 440 had more weight and a lower torque peak in the RPM range, giving it a better street-friendly feel. In some stock comparisons, the 440’s extra weight could even make it slightly faster than the Hemi in the 1/4 mile, though this was a rare exception. 

Factors Influencing Performance

• Tuning: Modifying a 440, such as with headers, could significantly boost its performance, though the Hemi’s true potential was almost limitless with proper tuning and parts like suitable cams and headers. 
• Purpose: The 426 Hemi was designed as a race engine in “street clothing” and excelled in long-distance racing. The 440 was a more affordable and practical “street brawler” that was easier to maintain and offered more mid-range torque for street driving. 
• Cost & Maintenance: The 426 Hemi was more expensive to purchase and could be challenging to keep running at its peak, whereas the 440 was significantly more affordable and easier to keep in tune. 

In summary, the 426 Hemi was the faster, higher-performance engine, particularly in its element at the racetrack. However, the 440 Six-Pack was a formidable competitor that could often beat the Hemi in shorter, stock form races off the line and on the street due to its lower-end torque.

Why did NASCAR stop using Dodge?

Dodge left NASCAR in late 2012 primarily because their sole factory-backed team, Penske Racing, defected to Ford after a disagreement over contract terms, leaving Dodge with a brand-new competitive car but no other major teams to race it. This departure was compounded by Chrysler’s financial struggles during the global economic crisis, which strained resources and led to a broader strategic reassessment of motorsports involvement. The company ultimately decided it couldn’t find a suitable team to maintain a competitive presence in NASCAR at the required level.
 
Key Reasons for the Departure

• Penske Racing’s Defection: The biggest factor was the departure of Penske Racing, their primary partner, for Ford at the end of the 2012 season. This left Dodge without their flagship team and significantly weakened their NASCAR program. 
• Financial Hardship: The global financial crisis and Chrysler’s subsequent bankruptcy strained Dodge’s ability to fund its motorsports efforts, making it difficult to support a competitive NASCAR program. 
• Lack of a Viable Structure: With Penske gone, Dodge was unable to secure other top-tier teams to fill the void. They had just introduced a new competitive car for the 2013 season, but they lacked a stable team structure to compete effectively with it. 
• Strategic Realignment: Dodge and its parent company, Fiat, were reassessing their overall motorsports strategy, which included investing more heavily in Italian-branded motorsports, potentially diverting resources from NASCAR. 

What Happened Next

• Dodge did not return to NASCAR at the highest level after 2012, despite discussions and the introduction of new cars like the Charger. 
• There has been ongoing speculation about a potential return, with NASCAR officials and sports media noting continued discussions, but no concrete plans have materialized yet. 

What motor was banned from NASCAR?

NASCAR has banned several engines due to performance imbalances and technological advancement, including the Ford 427 SOHC Cammer for its advanced overhead cam design and the Chrysler 426 Hemi because it wasn’t available in enough production cars. Other banned engines include a Smokey Yunick twin-turbo Chevrolet engine due to its extremely high horsepower and the early fuel-injected engines in 1957 because they were considered too advanced. 
Here are some prominent examples of engines banned from NASCAR:

• Ford 427 SOHC Cammer 
  • Why it was banned: This overhead cam engine was too exotic and advanced for NASCAR competition, which feared it would lead to an “arms race” and disadvantage smaller teams. 
  • Result: Ford moved the engine to drag racing, where it found significant success, and it remains legendary in automotive history. 
• Chrysler 426 Hemi 
  • Why it was banned: In its 1964 debut, the Hemi was dominant, but it was banned in 1965 because it wasn’t available in enough production cars for NASCAR’s homologation rules. 
  • Result: Chrysler protested and didn’t compete in 1965, but NASCAR revised the rules in 1966 to allow the Hemi again, and it remained a dominant force. 
• Smokey Yunick Twin-Turbo Chevrolet Engine 
  • Why it was banned: Created in 1967, this engine produced over 800 horsepower, far exceeding competitors. NASCAR officials deemed it too powerful and advanced, fearing it would make competition meaningless. 
  • Result: The ban represented NASCAR’s deliberate rejection of turbocharging technology at the time. 
• Early Fuel-Injected Engines 
  • Why it was banned: In 1957, Chevrolet offered fuel-injected engines to the public, but NASCAR immediately banned the technology, viewing it as too advanced to be used in competition. 
  • Result: The ban allowed NASCAR to maintain a more controlled level of performance and prevent rapid escalation of technological capabilities.