A British company selling a replica of the Jaguar XJ13 four-cam V12 car.

Building The Legend, a British company that sells highly accurate replicas of the Jaguar XJ13, has developed a custom-built, period-inspired V12 engine that makes the project car truly concours-worthy.

Called the "Tera," the engine was unveiled at Race Retro in the UK on February 21 and is available in a variety of configurations, from street setup to race. Various configurations are available, from street to race.

Its design was inspired by the 5.0-liter, 60-degree V-12 developed by former Jaguar engineer Claude Bailey for the XJ13, matching the original double overhead cam. Jaguar's own V-12 engine, which eventually went into production, was replaced by a simpler single-cam design. It is also a thing of beauty in its own right, and that is before considering the performance offered.

According to the spec sheet, the engine can be ordered in 6.1- or 6.8-liter displacements, with a safe rev limit of 8,000 to 8,500 rpm, depending on configuration. It is also a distributor-less design with a compression ratio of 11.7:1. Maximum output is 650 hp and 600 lb-ft of torque.

Only a few companies are currently building replicas of the XJ13, and not all of them have the blessing of Jaguar as Building the Legend has. Building the Legend has received guidance from some of the existing XJ13 teams. Incidentally, the first XJ13 replica that Building the Legend unveiled in 2016 was powered by one of the three prototype V12 engines that Jaguar developed as part of its XJ13 program.

For readers unfamiliar with the XJ13, it was developed in the 1960s as a contender in the 24 Hours of Le Mans. However, due to regulation changes in 1968, only one car was built, and it never raced on the circuit as intended in 1969; in 1971, the car crashed during testing, but fortunately was fully repaired after the accident.