Why Did Caterham Need a New Engine for the Seven?
If you’ve followed Caterham for any length of time, you know the Seven is a legend—raw, simple, and utterly focused on driving fun. But even legends hit a crossroads. For years, Caterham relied on Ford’s Sigma and Duratec engines to power its featherweight machines. The Sigma, a 1.6-liter, was the heart of the Academy race cars, while the 2.0-liter Duratec kept the road and track versions lively. The problem? Ford stopped making both engines years ago.
Caterham did what any resourceful company would: they stockpiled blocks and parts, building engines as long as they could. But the writing was on the wall. With Sigma supplies nearly gone and Duratec stocks dwindling, the company faced a real dilemma: how do you keep a classic alive when its beating heart is no longer in production?
What Makes the Academy Series So Important to Caterham?
You might wonder why Caterham prioritized the Academy car for its engine search. The answer is simple: the Academy is the gateway for new racers. Every year, 34 to 40 fresh-faced drivers build and race their own Caterhams, learning the ropes and joining a community that’s seen more than 1,400 people become racers over the past three decades. These cars aren’t just track toys—they’re road-registered, home-finished, and a rite of passage for enthusiasts.
Keeping the Academy alive means keeping the spirit of grassroots motorsport thriving. It’s not just about selling cars; it’s about nurturing the next generation of drivers.
How Did Caterham Find the Right Engine Partner?
Finding a replacement engine wasn’t as easy as picking one off the shelf. The new powerplant had to fit the Seven’s compact frame, be light enough to preserve its nimble character, and offer bulletproof reliability. Oh, and it couldn’t break the bank. Not a small ask.
Enter Horse—a joint venture between Renault and Geely. Horse isn’t a household name yet, but with the capacity to build over three million engines a year, they’re a serious player. Caterham zeroed in on the HR13DDT, a 1.3-liter turbocharged four-cylinder already found in cars like the Renault Megane, Nissan Qashqai, and Mercedes A-Class. This engine isn’t just proven—it’s guaranteed to be available well into the next decade.
What’s Special About the HR13DDT Engine?
Let’s get nerdy for a second. The HR13DDT is a modern marvel: 1332cc, an aluminum block and head, direct injection, twin cams, and a lifetime timing chain. One standout feature is its mirror bore coating—a technology first seen in the Nissan GT-R—which reduces friction and saves weight. The result? The HR13 is about 35kg lighter than the old Duratec, and at least 15-25kg lighter than the Sigma, even after accounting for the added intercooler.
Power output is flexible. In production cars, it ranges from 115 to 160bhp, but Caterham’s prototype is tuned for 130bhp at around 5750rpm, with a broad, flat torque curve that makes it feel eager from as low as 2000rpm. That’s the kind of usable grunt that makes the Seven so much fun, whether you’re carving up a track or blasting down a back road.
How Did Caterham Adapt the Seven for the New Engine?
Swapping engines in a car as tightly packaged as the Seven is never straightforward. The HR13 mostly fits, but there are quirks—like a fuel pump and rail that poke up higher than the old engines, requiring a new bonnet design. Some teams considered modifying the pump, but with it pressurizing fuel to 350 bar, the consensus was to leave it as is for safety.
The prototype I drove at Brands Hatch was built on the wider SV chassis in left-hand drive, giving engineers more room to work. The exhaust and catalytic converter, for instance, would interfere with the steering column in a right-hand-drive car, so those details are still being ironed out. A second prototype, based on the narrower Series 3 chassis and built for right-hand drive, is already in the works.
What’s It Like to Drive the Caterham Seven with the Horse Engine?
Let’s cut to the chase: the new engine feels right at home in the Seven. It’s not a fire-breather, but it’s honest, responsive, and eager. There’s a touch of turbo lag if you’re really looking for it, but in a car this light, it’s barely noticeable. From 2000 to 5000rpm, the engine pulls with real enthusiasm, and the power delivery is linear and progressive—just what you want for a car that’s all about driver engagement.
Caterham’s engineers have worked to make the turbocharged engine feel as naturally aspirated as possible. There’s even a symposer—a tube with a vibrating membrane—to enhance the induction noise, giving the engine a satisfying growl without resorting to artificial tricks.
Gearbox-wise, the new setup uses a six-speed Mazda MX-5 unit, which is a bit heavier than the old five-speed but paired with a lighter, bespoke limited-slip differential. The result? The overall weight stays about the same, preserving the Seven’s legendary agility.
How Will This Change Affect Caterham’s Lineup?
For now, the Horse engine will be exclusive to the Academy cars. Entry-level 170s will continue with Suzuki power, and other models will stick with the Duratec until supplies run out. But let’s be real: Caterham didn’t sign up for a new engine just to build 34 cars a year. With its flexibility and tuning potential, the HR13DDT is poised to become the backbone of the Seven lineup in the years ahead.
One important note for purists: if you want a naturally aspirated Seven, now’s the time to act. The new engine is turbocharged, and while it’s been tuned to feel as NA as possible, the era of high-revving, naturally aspirated Sevens is drawing to a close.
What Does This Mean for Future Caterham Owners and Racers?
The switch to the Horse engine is more than just a technical update—it’s a lifeline for the Seven’s future. With a secure supply of modern, efficient engines, Caterham can keep building cars that deliver pure driving joy, while meeting ever-tougher emissions and reliability standards.
For Academy racers, the new engine promises the same accessible, rewarding experience that’s made the series a launchpad for amateur motorsport careers. And for road car buyers, it means the Seven will remain relevant, reliable, and—most importantly—fun.
The Bottom Line: The Seven’s Spirit Is Alive and Well
Change is never easy, especially when you’re dealing with an icon. But Caterham’s careful, thoughtful approach to finding a new engine shows real respect for what makes the Seven special. The HR13DDT may not have the cachet of a classic Ford lump, but it delivers where it counts: lightness, reliability, and a driving experience that’s as grin-inducing as ever.
If you’re a die-hard Seven fan, rest easy. The future looks bright—and fast.