Do all NASCARs have the same engine?

No—the engines are not all the same across NASCAR. In the modern era, the NASCAR Cup Series runs manufacturer-specific V8s built to a common rulebook, the Xfinity Series uses a mix of open (OEM-built) and spec engines, and the Craftsman Truck Series predominantly uses a single spec engine supplied by Ilmor. Within each series, NASCAR tightly regulates architecture and performance to keep parity, but the engines are not identical across the sport.

What “the same engine” really means in NASCAR

From the grandstands, NASCAR engines can sound and perform similarly because rules enforce common architecture and power targets. That said, “same” doesn’t mean identical: different series use different engine programs, and even within a series, manufacturers or suppliers build their own approved designs under strict limits.

Here are the core traits many top-tier NASCAR engines share, which can make them feel alike to fans despite being different in origin or details:

• All are naturally aspirated V8s with pushrod (two-valve) architecture.
• Displacement is regulated (Cup and Xfinity are centered on 358 cu in), with power managed via spacers and other rulebook tools.
• Engines are designed for durability at high RPM over long green-flag runs.
• Electronics and fuel systems are standardized by series (e.g., electronic fuel injection in Cup; Xfinity largely remains carbureted).
• Parity mechanisms (inspection, dyno checks, mapping limits, and part approvals) keep competition close.

These commonalities deliver a consistent NASCAR identity in sound and speed, but they don’t make the engines interchangeable or identical across series.

How engines differ by series

Each national series takes a distinct approach to engines, balancing cost, parity, and manufacturer involvement. This breakdown highlights who builds the engines and how closely they’re standardized.

• NASCAR Cup Series (Next Gen era): Manufacturer-specific 358 cu in, naturally aspirated pushrod V8s from Chevrolet (R07), Ford (FR9), and Toyota (TRD). Electronic fuel injection, single-source ECU, and power targets typically around 670 hp at most tracks and around 510 hp at superspeedways via tapered spacers. Engines are built by approved builders (e.g., ECR, Roush Yates, TRD) under a tight rulebook.
• NASCAR Xfinity Series: 358 cu in, naturally aspirated pushrod V8s using a mix of “open” (OEM-style, team-sourced) engines and NASCAR-approved spec engines from designated suppliers. The series has historically retained carburetors, with parity managed through rules and spacers; teams choose based on budget and performance strategy.
• NASCAR Craftsman Truck Series: Predominantly uses the Ilmor NT1 spec V8 supplied and supported by Ilmor Engineering for cost control and parity. OEM-style engines are permitted by rule but are rarely used; EFI and standardized electronics are mandated.
• ARCA Menards Series (NASCAR-sanctioned context): Widely uses the Ilmor 396 spec engine alongside legacy open engines, illustrating NASCAR’s broader use of spec programs outside the Cup/Xfinity/Truck ladder.

The takeaway: NASCAR doesn’t mandate one universal engine. Each series has its own engine model, ranging from manufacturer-built in Cup to predominantly spec in Trucks, with Xfinity in between.

Inside the Cup Series: similar on paper, different by brand

Manufacturer-built but tightly regulated

In the Cup Series, Chevrolet, Ford, and Toyota each field their own purpose-built 358 cu in V8 designs. While the architecture is fixed (pushrod, two-valve, naturally aspirated) and performance is boxed in by rules, the engines differ in block, head, and internal designs, as well as cooling and lubrication strategies. A single-source ECU, standardized sensors, and tapered spacers are used to hit NASCAR’s horsepower targets and maintain parity. Despite past experimentation and industry chatter about hybridization, the Cup field continues to race conventional naturally aspirated V8s in the current Next Gen era.

Are engines interchangeable between makes?

No. Chevy, Ford, and Toyota engines are distinct designs with different parts, calibration, and integration details. Teams typically lease engines from their brand’s approved builder, and engines must pass NASCAR tech and, when required, dyno verification to ensure compliance.

Why NASCAR blends spec and open engines

NASCAR uses different engine approaches to balance three priorities. Cost control encourages spec options (notably in Trucks) that reduce development expenses. Competitive parity keeps racing close via standardized electronics, spacers, and inspections. Manufacturer relevance allows brands to showcase engineering in the Cup Series while staying within guardrails that prevent runaway spending.

Quick answers to common follow-ups

Can teams freely modify engines?

No. Engine builders operate inside a detailed rulebook with sealed components, approved parts lists, and strict inspection. Penalties for violations can be severe.

Is hybrid or electric power coming soon?

NASCAR has explored alternative and hybrid technologies in testing and demonstration contexts, but as of the current Next Gen era, no national series races with hybrid assist in points events. Any shift would be formally announced well in advance.

Summary

NASCAR does not use one uniform engine. The Cup Series runs brand-specific V8s under tight rules, the Xfinity Series blends open and spec options, and the Craftsman Truck Series largely relies on a single Ilmor spec engine. Common architecture, electronics, and parity tools make performance comparable, but engines differ by series and, in Cup, by manufacturer.

What engine was banned from NASCAR?

NASCAR has banned several engines throughout its history, but two prominent examples are the Ford 427 SOHC Cammer due to its advanced single overhead camshaft design, and the Chrysler 426 Hemi because of its overwhelming dominance, which led to fears of uncompetitiveness. Additionally, the engine in the 1969 Chevrolet Corvette Grand Sport was also banned, not due to rule-breaking, but because GM corporate policy prohibited its factory entry into the competition.
 
The Ford 427 SOHC Cammer

• What it was: A high-performance V8 engine with single overhead camshafts (SOHC) and electronic fuel injection, designed to compete with Chrysler’s Hemi. 
• Why it was banned: NASCAR banned overhead camshaft (OHC) engines, making the Cammer ineligible for stock car competition. 
• Aftermath: Ford shifted its focus to drag racing, where the engine became a legendary and dominant force. 

This video explains why the Ford 427 SOHC Cammer was banned from NASCAR: 38sRare Car StorysYouTube · Feb 12, 2025
The Chrysler 426 Hemi 

• What it was: An incredibly powerful and compact engine that quickly achieved a high level of success in NASCAR. 
• Why it was banned: The Hemi’s dominant performance was so overwhelming that it was banned to “level the playing field” and restore unpredictability to races. 
• Aftermath: The ban wasn’t permanent, and the Hemi was allowed back into NASCAR after rules were revised to ensure its availability in production cars. 

You can watch this video to learn about the history of Hemi engines in NASCAR: 55s4 Wheels ChroniclesYouTube · Sep 23, 2023
Other Notable Banned Engines 

• Smokey Yunick’s “Mystery Motor”: This advanced Chevrolet engine was banned by NASCAR before it ever raced, though not for breaking rules but due to the potential for it to completely rewrite the sport’s history.

Why is Dodge not allowed in NASCAR?

Ultimately, Dodge chose to withdraw from NASCAR, citing the inability to secure a partnership with a team that met its high standards for competitiveness and technological innovation.

What engine is Toyota using in NASCAR?

Toyota NASCAR engines are purpose-built TRD (Toyota Racing Development) 5.9-liter, 358-cubic-inch pushrod V8s, designed for their Xfinity Series and Cup Series stock cars. These naturally aspirated V8s, built by Joe Gibbs Racing in the Xfinity Series and TRD in the Cup Series, produce around 650-700 horsepower in their standard configurations.
 
Engine Type and Performance 

• Engine Type: TRD V8 (pushrod, overhead valve engine)
• Displacement: 5.9 liters (358 cubic inches)
• Horsepower: Approximately 650-700 hp, depending on the series and restriction package.
• Aspiration: Naturally aspirated
• Fuel Delivery: Carburetor

Development and Manufacturing

• TRD: Toyota Racing Development (TRD) designs and builds the engines for Toyota’s NASCAR Cup Series cars. 
• Joe Gibbs Racing: Joe Gibbs Racing (JGR) builds the engines for Toyota’s Xfinity Series cars. 
• Secrecy: TRD maintains high secrecy surrounding its engine designs and development, which helps give their cars a competitive edge. 

Comparison to Production Engines

• Purpose-Built: Unlike older engines based on production models, NASCAR engines are entirely purpose-built racing engines, not modified street car engines. 
• Performance: They are designed to maximize power without mufflers or catalytic converters, allowing for higher output compared to street-legal engines. 

Do Chevy Nascars use Chevy engines?

The Chevrolet engine in Cup is called a R07. 2. That’s a 5.8L two-valve per cylinder V8. Its roots are in the small block Chevy era from 50-plus years ago.