This Tiny Four-Cylinder Engine Revs to 10,000 RPM

It produces 324 horsepower and weighs 187 pounds.

Boreham Ten-K 2.1-Liter Four-Cylinder Engine

Photo by: Boreham Motorworks

Anthony Alaniz

By: Anthony Alaniz

Nov 14, 2025 at 4:37pm ET

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Combustion engines are far from dead, and they could be in production well into the next decade—and beyond. In the last year, we’ve seen automakers recommit to production gas engines alongside a series of others that push the boundaries of the technology.

The latest innovative engine is from Boreham Motorworks, which is showing off its new Boreham Ten-K naturally aspirated 2.1-liter four-cylinder engine. It produces 324 horsepower at 10,000 rpm and weighs 187 pounds (as pictured), which is light compared to others of similar sizes, especially for road cars.

This one will power the brand's reborn Ford Escort Mk1 RS. The engine features individual throttle bodies, a belt-driven twin cam, and lightweight internals and billet components, including the crank, rods, cradle, dry sump, and cam cover. It features Formula 1-inspired port geometry and modern electronics.

Boreham Motorworks says it saved weight by utilizing thin-wall 3D printed casting technology, which "enables a sculpted engine block, formed closely around the internal components."

Boreham Ten-K 2.1-Liter Four-Cylinder Engine

Photos by: Boreham Motorworks

Boreham Ten-K 2.1-Liter Four-Cylinder Engine

Photos by: Boreham Motorworks

The engine is undergoing dyno testing and calibration, and according to the company, "exceeding development goals for performance" with power and rev limit already above initial targets.

Other companies are also pushing the boundaries of internal combustion engines. Omoda & Jaecoo introduced one with 48 percent thermal efficiency, which could translate to roughly a 2.5 percent reduction in fuel consumption.

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Horse Powertrain, a global supplier of powertrain systems, has introduced a family of range extenders, including a hybrid version that operates on both gas and liquid petroleum. If current trends continue, we expect to see more innovative combustion engines.

Automakers have also recommitted to producing them well into the next decade despite earlier promises to quickly shift toward building only battery-electric vehicles. Adoption has been inconsistent, so automakers are producing what buyers want, and that means the combustion engine continues to dominate.

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