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.