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Radical Low-End SR1 Race Car Gets a Major Update With the XXR Performance Package

Care to guess what the largest race car maker in the UK is? Think all you like, but don't go squandering too much time on the likes of McLaren, Cosworth, or another worldwide-famous name. The answer is Radical. Not in the cutthroat, extremist, not-to-be-negotiated-with sense of the word; that is the company's name: Radical Precision Engineering (RPE), and they've been building track-focused machines for the past three decades.
Radical SR1 XXR 8 photos
Photo: Radical
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They started in 1997 with one chassis powered by a Kawasaki 1,100 CC engine. Now, they have a line-up of seven production models (plus another 2024-scheduled racer). From the entry-level SR1 to the extreme RXC GT3, the range meets all track requirements, from rookies to season veterans.

Radical claims they're the world’s largest manufacturer of race cars, with over 2,800 units sold in the past 26 years. They're so successful that Radical has its single-marque competition series, with ten individual Radical Cup events worldwide.

Let's put it into perspective: the first road-legal car to drop below the seven-minute mark on the Happy Hunting-Ground circuit of Nürburgring in Germany. That was in 2009, and the Radical SR8 LM reigned undefeated for eight years.

Radical SR1 XXR
Photo: Radical
The Radical SR1 is the base car of the British manufacturer, and now it got upgraded with the XXR performance package. If SR1 means nothing to you, consider it a go-kart with wheel wells. And Lucifer's hellfire in the engine. And an atomic-weapon-grade critical mass. And the responsiveness of a rattlesnake.

The XXR update is, according to the maker, the most radical (pun inevitable) received by this model in six years. Before getting into this, look at the "casual” SR1, the Radical race car introduced in 2012.

It weighs 1,080 lb (490 kilograms) and is about the size of a queen-sized bed mattress: 3,860 mm long x 1,560 mm wide x 1,020 mm tall (152 in x 61.5 in x 40 in). And yet Radical managed to squeeze two seats in this open-cockpit racer. This double-occupancy chassis architecture is a staple of the company. However, higher-end models come with seating for one, but offer passenger accommodation options.

Radical SR1 XXR
Photo: Radical
It has no roof, as I said, so the forward-facing stays and composite halo head restraints are standard (and mandatory). The most prominent feature of the fiberglass body is the downforce-generating rear wing (although the overall design leaves no room for doubt about this car's purpose in life).

The business end of the car is the four-cylinder Suzuki Hayabusa-inspired engine that outputs 199 ps and 201 lb-ft of torque (196 hp and 273 Nm) at 10,000 RPM and 7,500 RPM, respectively. The screaming four-pot motor weighs just 83 kilograms (183 lb). The six-speed sequential gearbox is controlled via the paddle shifters (and governed by an auto-blipper system).

The mid-engine, rear-wheel-drive SR1 puts the power down via a limited-slip differential. The fully adjustable Nik-link suspension features front and rear unequal-length top and bottom wishbones, fabricated uprights, and front and rear adjustable pushrods.

Radical SR1 XXR
Photo: Radical
Optionally, the SR1 can have a quiet track day silencer or a loud exhaust – depending on the occasion – LED race lights, an oil preheater, a fuel sampling/drain kit, or a brake bias adjuster (conveniently mounted on the dash).

For precise engine management, the ECU offers detailed interrogation functions (for maintenance and analysis). The Enhanced Data Pack includes a SmartyCam video system with GPS and race data logging (brake pressure and steering monitoring).

The XXR upgrade adds a stabilizing vertical fin behind the air inlet. It drastically improves (or so Radical brags) the engine service intervals. The liquid-cooled inline-four powerplant's overhaul periods are 25% longer than the previous generation, with oil change extended from six to ten operating hours. The new scavenge pump enhances the lubrication of the engine's internals; many are redesigned for better performance.

Radical SR1 XXR
Photo: Radical
Lightweight connecting rods, crankshaft pins, and ignition increase engine responsiveness and drivability without sacrificing reliability. With a reworked dry sump, cooling, coil-on-plug ignition, and a new electronic drive-by-wire, the fifth-generation engine from Radical Precision Engineering should offer more track time without scheduled maintenance interruptions.

Since its launch 11 years ago, over 200 SR1s have lined up at the start grid in Radical Cup competitions worldwide in the PRO SR1 class. The XXR upgrade keeps all the racing privileges intact, so clashes between regular SR1-equipped race teams and high-end spec'd versions are something to look forward to.

Built as an introductory track machine for beginners seeking their first taste of professional motorsport, the Radical SR1 sticks to the company ethos of lightness, aerodynamics, and powerful hand-built engines.

The SR1's XXR installment follows Radical's last few months' trends of upgrading the SR3 and SR10 race cars with the same performance package. The up-tuned SR1 will enter production this summer and is already available for order through the Radical dealership network.
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About the author: Razvan Calin
Razvan Calin profile photo

After nearly two decades in news television, Răzvan turned to a different medium. He’s been a field journalist, a TV producer, and a seafarer but found that he feels right at home among petrolheads.
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