The E31 BMW 8 Series is a legend in its own right. It’s the successor to the original E24 6 Series, and the progenitor of the 8 Series Coupe we know today, chassis code G15. It even shared an engine with the legendary McLaren F1 – well, sort of anyway. The limited production 850CSi saw a version of the McLaren’s legendary S70 engine under the hood. But what if you wanted something even more special?

Custom builds are great because they, hopefully, bring a vision to life. And that’s exactly what the wrenches at REYN Speed Shop and Precision Sport Industries (PSI) – and automotive artist Jon Sibal – did with their 858 CSL project. If you were anywhere near social media over the Legends of the Autobahn weekend – and have a BMW-tuned algorithm – you undoubtedly noticed the wild silver 8 Series in your feed. Here’s all the details on the only 858 CSL you’ve ever seen.

V10 S85 Engine Under The Hood

Let’s start with arguably the most exciting part of the custom-built 8 Series. The factory powerplant has been ejected in favor of a 5.0-liter V10 lifted from an E60 M5. The S85 engine has been stroked to 5.8 liters by none other than CarBahn. In case you forgot, that’s the Euro-centric speed shop founded by Steve Dinan, BMW tuning wunderkind. The engine touts Eventuri air intakes, imposing carbon fiber funnels extending from each side of the V10’s manifold. It’s still RWD, and the engine pairs up to six-speed manual. Power isn’t disclosed, but Carbahn’s race-tuned 5.8-liter produced 720 horsepower on a dyno circa 2018, according to their Facebook page. The tuner quotes 620 horsepower for the street version.

Retro and Digital Interior

The 858 CSL dons black Nappa leather inside, with “vader” seats lifted from an E36 M3. Most of the cockpit’s switchgear and instrumentation is yoinked straight from the E60 M5, and the car even features a push-button start and iDrive screen in the dash. Tuner shop PSI handled the manual swap, but they also ensured the car retained BMW OBD2, CAN, and MOSTBUS functionality. The car even has functional DSC and ABS. In fact, you could theoretically roll up to any BMW dealership and get the vehicle serviced like a normal production vehicle. REYN says that all the regular E60 modules and diagnostics are maintained as factory. The best part is that, just like in the original interior, everything is tilted clearly towards the driver.

Lots of Performance Parts

The 858 CSL isn’t your typical E31 8 Series and that’s glaringly obvious from one look. The car sits on a Moton four-way suspension, and REYN Speed Shop ALP-001 wheels hide Brembo GTS calipers with carbon ceramic rotors. The wheel design is also interesting. Custom-made in house, the wheels took inspiration from the E46 M3 CSL, 850CSi and from the iconic ALPINA wheels. LED exterior lights – also courtesy of REYN – give the car a unique tuner look that complements the gorgeous carbon fiber body panels. Designed by artist Jon Sibal, it emphasizes and amplifies the vehicle’s natural curves. You’ll note dramatically enhanced rear fender flares, a curvy CSL-esque trunklid, bespoke front clip, a carbon fiber diffusor, and other details.

The 858 CSL is cool, that’s for sure. And it better be – the project took four years to complete. As mentioned, the car functions as a factory 858 CSL would if BMW built one, thanks to mostly stock computer bits. REYN says that serviceability was a key goal in the build, as the owner intends to drive the car long distances. Here’s hoping it takes less than four years to see it out and about again.

[Photos: Dan Levins @klapped.media]