The Boreham Ten-K: A 10,000 RPM Naturally-Aspirated Powerhouse

While less prevalent these days, it’s hard to not appreciate the sound of a high-revving naturally aspirated engine.  The team at Boreham Motorworks just pulled the cover off their new 2.1-liter, inline-four cylinder engine.  This small-displacement powerplant puts out an impressive 325 horsepower and, as the name suggests, screams all the way to an astonishing 10,000 rpm.  It may be small, but innovative engineering is significantly pushing the boundaries for what a street-driven engine can be.   

Race-Bred DNA in A Reborn Classic

The performance is certainly impressive, but the necessity for it may be even more compelling.  The purpose of designing this engine was for a “Continumod” of the Ford Escort Mk1 RS.  Although they lack the volume today, Ford has a rich history of legendary high-performance compacts.  The company will continue its legacy with this officially licensed recreation of the iconic rally machine.  Boreham’s ambitious team of engineers had to utilize advanced methods in the creation of this engine, all while still trying to maintain the coveted classic feel.  This team, which includes former Ford chief engineer Simon Goodliff, did so in spectacular fashion.  Not only does the engine produce 325 naturally aspirated horses out of just 2.1 liters, but it weighs in remarkably light at 187 pounds.  This spec was extremely critical to ensure that the Escort met its target weight of sub 1800 pounds.  In order for the team to achieve this, they’d have to rely on billet, and lots of it.  

Inside the 10,000 RPM Masterpiece

Starting with the block itself, Boreham utilized a special thin-wall 3D printed casting technology.  By doing so, the block is able to shave unnecessary weight without compromising any of its structural integrity.  For this desired level of performance, a combination like this one relies heavily on the selection of internals. To bulletproof the Boreham Ten-K, the team utilized a billet crankshaft, billet connecting rods, and an integral cradle also made of billet material. These components are certainly typical for a high-dollar track dedicated car, but are quite exceptional for street use. In addition to this stout bottom end, the package also features a billet dry sump oiling system.  This further promotes durability and ensures proper lubrication regardless of how the car is maneuvering.  

Durability and lightweight components are a great place to start, but for this kind of application, they only get you so far.  In order for the engine to make power, it needs to breathe.  For the cylinder head, the Boreham team chose a 16-valve head with ports similar in geometry to those of Formula 1.  To achieve instantaneous throttle response, each of the engine’s four cylinders uses an individual throttle body.  The combination of port design and electronic engine management are essential for maximizing volumetric efficiency.  This is critical for a high-output naturally aspirated setup. 

There’s no doubt the Boreham Ten-K is a masterpiece of modern engine building.  This powerplant is exceptional in terms of durability and performance, especially in terms of a street-driven four-cylinder.  It’s an engine that has been meticulously crafted with the performance enthusiast in mind.  This setup is guaranteed to deliver an extraordinary driving experience that is thrilling with great power across a high RPM range. 

Although the Boreham Escort Mk1 RS is only being produced in a limited run of 150 units, the Boreham Ten-K itself is a profound achievement for small-displacement naturally aspirated engines.  This design provides insight into what the future may hold for high-performance street combinations.  It shows that with the right engineering team, proper materials, and a commitment to driver experience, the possibilities are endless for builds of this caliber in years to come.  There’s no doubt that this little screaming four-cylinder will be an industry standard for street-driven performance moving forward.