The Ariel Atom 4RR is a street-legal go-kart with 525 horsepower.

      Ariel Motor Company

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      This year marks the 25th anniversary of the Ariel Atom, a milestone that makes it easy to overlook just how remarkable this vehicle is. To remind us, Ariel is introducing a more extreme version, the Atom 4RR, which boasts greater power than any previous Atom.

      The 4RR is designed to commemorate the Atom's quarter-century presence and features a significantly enhanced Honda K20C 2.0-liter turbo-four engine. Similar to the engine found in the latest Civic Type R and Integra Type S, it generates 525 horsepower and 405 lb-ft of torque in its most spirited of three performance maps, with additional options for 500 hp/331 lb-ft and 400 hp/280 lb-ft.

      To achieve this power, Ariel has modified or upgraded nearly every component. The engine features closed-deck sleeves, Ariel-spec forged pistons and connecting rods, revised cylinder head and port geometry, upgraded alloy valves with stronger springs and guides, new camshafts, a larger turbo capable of producing a peak boost of 1.7 bar, and 1,400-cc fuel injectors to support it. The engine breathes through a carbon fiber intake suitable for an F1 machine and expels exhaust via a titanium exhaust system, while a gated oiling mechanism and high-flow pump ensure proper lubrication under rigorous track conditions.

      Power is delivered to the rear wheels via a Quaife six-speed sequential transmission with pneumatic paddle shifters. The clutch is only needed for starting from a stop, and an auto-blip feature assists with downshifting. Coupled with a lightweight of just 1,474 pounds, the 4RR can accelerate from zero to 62 mph in just 2.4 seconds and reach 100 mph in 5.1 seconds, making it the fastest production Atom to date, as per Ariel. Its top speed is 175 mph.

      The distinctive Atom exoskeletal chassis is equipped with adjustable twin-tube Öhlins dampers. Braking is managed by AP Racing two-piece ventilated rotors paired with four-piston calipers, featuring driver-selectable ABS with 11 settings (including “off”). The 12.2-inch rotors are the largest compatible with the Atom’s staggered wheel sizes (16-inch front and 17-inch rear), using Yokohama A052 tires sized 195/50R16 at the front and 255/40R17 at the rear.

      Carbon-fiber side pods are inspired by those created for the Atom 4R but now include additional cooling channels for the engine and transmission. A substantial rear wing and other aerodynamic components, along with mud guards (designed for road use despite its track-oriented character), are also fashioned from carbon fiber. Special 25th anniversary graphics complete the design.

      In its home market, the Atom 4RR is priced at 208,000 British pounds, which is approximately $280,000 based on current exchange rates, provided Ariel allocates any production slots for the U.S. The cars will be available to order "in extremely limited quantities," according to the company, but it is hoped that there will be enough units produced to satisfy demand.

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