NASCAR Engine Explained: Why a Cup V8 Still Uses Pushrods

Welcome to the Happy Hour Racing Wednesday Tech Breakdown - where we take one confusing part of NASCAR and make it make sense. No engineering degree required.

The Short Version

Every NASCAR engine in the Cup Series is a 358-cubic-inch V8 with no turbo and two valves per cylinder. It opens those valves with pushrods, a layout that goes back generations. NASCAR sets the power by track type, from 750 horsepower at short tracks down to as low as 465 at Daytona. The biggest reason to care: more power is not the hard part. Making that power last is, because an engine has to survive pretty much at least two races.

What Is Actually Under the Hood

Displacement is the total space inside all the cylinders, and Cup caps it at 358 cubic inches, or 5.86 liters. Three makes race: the Chevrolet R07, the Ford FR9 and a Toyota built by Toyota Racing Development. ECR Engines and Hendrick Motorsports build the Chevys, and Roush Yates builds the Fords.

There is no turbo or supercharger. The engine is "naturally aspirated," which means it breathes only the air it can pull in by itself. It drinks Sunoco Green E15, a 98-octane race fuel. And it has only had fuel injection since the 2012 Daytona 500. Before that, Cup ran carburetors for more than 60 years.

How a Pushrod Engine Works

Every cylinder needs a door to let air and fuel in and a door to let exhaust out. Those doors are the valves. A Cup engine has two per cylinder, so 16 in all. Something has to open each one at exactly the right moment, and that job starts at the camshaft, a spinning rod with egg-shaped bumps on it.

On most modern street engines, the camshaft sits on top of the engine, right over the valves. In a Cup car it sits down in the middle of the block, a long way from them. So it needs a messenger. Here is the chain:

Think of the rocker arm like a playground seesaw. The pushrod shoves one end up, the other end goes down, and the valve opens. A spring then snaps it shut. All of that happens thousands of times a minute. Cup engines have been reported running above 9,000 rpm for an entire 500-mile race, a speed well beyond what a typical street V8 ever sees.

Why NASCAR Engines Still Use Pushrods

Mostly because that is the formula. The 90-degree pushrod V8 has been a fixture in the sport since the rules tightened up decades ago, and every team and engine shop is built around it. The layout also keeps the engine compact and its weight low, because no camshafts sit up on top.

The catch is that the street car world has moved on, and that shapes NASCAR's future. Elton Sawyer, NASCAR's competition boss, has called a V8 pushrod engine "a dealbreaker" for manufacturers thinking about joining. RACER reported in January that the answer on V8s is probably changing if NASCAR is serious about adding a brand. Others point the other way, noting General Motors is spending $888 million on next-generation V8s in Buffalo, New York. For now, a pushrod V8 is what races for the title Sunday at Homestead.

One Small Part Sets the Horsepower

A Cup team does not get to pick its power. NASCAR sets a target by track type, then controls it with a tapered spacer, a block with holes in it that sits on top of the intake and limits how much air gets in. Bigger holes, more power. That is how the 750-horsepower change happened for 2026.

So why stop at 750? NASCAR President Steve O'Donnell said going past it would cost the industry $40 million to $50 million. NASCAR's John Probst said higher numbers start crossing into "very short-mileage engines."

Why Every Engine Has to Last

Here is the part most fans miss. It is not the spacer holding the number down. It is the engine-use rules, which ask an engine to run pretty much at least two races. FOX's Bob Pockrass laid it out:

On DaleJr's podcast, O'Donnell said going to more than 750hp would be a significant cost. It isn't that the tapered spacer is issue; it's with engine-use rules of pretty much at least two races per engine, that durability of the parts/pieces comes into question with more hp. https://t.co/5FvTGWAbSh

- Bob Pockrass (@bobpockrass) October 8, 2025

You can see the stakes when one lets go. At New Hampshire in August, Ross Chastain lasted just 41 laps and finished 36th. His explanation: "There was oil coming out of the exhaust pipe."

NASCAR also checks these engines closely. In 2024, Toyota's engine shop rebuilt Denny Hamlin's race-winning Bristol engine before NASCAR could tear it down and inspect it. Toyota reported the mistake itself and still called it "grievous." It cost Hamlin 75 points and 10 playoff points, and crew chief Chris Gabehart was fined $100,000.

What to Watch for Sunday

Homestead-Miami is exactly 1.5 miles, so it is not on the 750 list. The title cars will run the 670 target. When you see a car puff smoke and hear the driver report a loss of power on the radio, you now know what is going on inside: one of those fast-moving parts, or the oil that protects them, has quit. One bad part can undo a whole season in a single lap.

The Bottom Line

A NASCAR engine is an old idea pushed unbelievably hard. Finding more power is the easy part. Making it live for two races is the real engineering.

If you like knowing what is going on under the hood, you are our kind of fan. Browse our driver collections and pick up something to wear on Sunday. New tech breakdowns drop every Wednesday, and if you want to see where all that power ends up, read our transaxle breakdown next.

Gear for the engine shop crowd:

• Denny Hamlin 2024 Bristol Race Win T-Shirt - the win behind the engine teardown story, and the featured pick above.
• Ross Chastain #1 Melon Man Mesh Hat - for the Melon Man fans who felt that New Hampshire one.
• Kyle Larson #5 HendrickCars Uniform Pit Hat - a Hendrick car with a Hendrick engine.
• William Byron #24 Raptor Uniform Pit Hat - same engine shop, same pit road look.