Everything You Need To Know About Harley-Davidson's Most Powerful Motorcycle Engine

Harley-Davidson's reputation for extremely powerful motorcycles has grown steadily with each new model release. Revealingly, the "hog" moniker started as a nickname dubbed by journalists reporting on the Wrecking Crew motorcycle racers, a Harley-exclusive team whose mascot was a piglet. But the name likely stuck due to the motorcycles' large size, roaring sound, and powerful engines.

The Screamin' Eagle Stage IV Performance Crate Engine is, in Harley-Davidson's own words, "the biggest, most powerful street-compliant crate performance engine Harley-Davidson has ever created." And the specs don't lie. Announced in 2023 as the newest edition to the Screamin' Eagle line of engines, this beast boasts a whopping volume of 135ci or 2,122cc. That's over four pints of fuel and air, or over two liters, in the cylinders at any given time.

If the numbers don't mean much to you, you might have to head to a Harley dealership to experience its power. Of course, as a flagship build, it runs smooth as butter. But crank the throttle, even when in park, and you'll realize just how much juice this thing can generate. Right out the gate, it pumps out 143 lb-ft of torque to the rear wheel. Compare that to rival Indian Motorcycle's most powerful engine, and the Screamin' Eagle surpasses it by quite a bit.

The Stage IV is a V-Twin engine, meaning it has two pistons arranged at a 45-degree angle. This is the standard for Harley V-Twins, and it's what gives them their distinct sound. However, the 135ci volume is far from standard.

Adding to the high performance are 6.8g/sec fuel injectors, which are more than fast enough to reach high speeds in seconds. It also has 4.31" steel sleeve cylinders. They're so finely tuned that Harley took out a patent on them. Those fancy cylinders are topped with another Harley-brand part, the Screamin' Eagle Extreme CNC-ported cylinder heads.

It's designed for a "wide open throttle," which means you can crank it to accelerate in a flash. It makes passing on highways safer and easier. The rotational speed can deliver 130 hp at 5,500 RPM.

For perspective, the first Harley-Davidson model had bicycle pedals for adding human power should the 24.74ci, 3hp engine struggle on steep hills. But that was over 100 years ago, and times have changed. 

Let's get the price out of the way. The Screamin' Eagle Stage IV Performance Crate Engine costs about $8,000. You also might end up shelling out more should you choose to get it retrofitted. But for those buying a new bike, you can request the Screamin' Eagle at the dealership before you pay for an engine you won't use.

It's compatible with equipment-style 2021-and-later Harley-Davidson Touring models, which means there's no need to customize the engine mount. It bolts right on. You can use the Harley website to check which version, the oil-cooled or Twin-cooled, fits your bike. It also has a tool for searching your local dealerships to make sure they have your Screamin' Eagle in stock.

One of the biggest reliefs for Harley owners looking to upgrade their engine is the available two-year manufacturer's warranty. It's only an option when a certified dealer performs the installation, but that's to be expected. If you prefer to install it yourself, Harley provides a technical guide to walk you through it, and we here at Slash Gear have a guide to motorcycle customization types. 

For an expert installation, you can schedule an appointment with your local dealership to get the most powerful Harley engine to date.