Yahoo Autos This Shop Building the 560-HP 4.5-Liter Cayman GT4 Porsche Won’t
On paper, the original Cayman GT4 is perfect. A mid-engine Porsche with an engine from the 911 Carrera S, front suspension from the GT3, and a proper six-speed manual gearbox. It’s enough to make any enthusiast swoon. But when Rick DeMan, founder of DeMan Motorsport, got behind the wheel, he wasn’t impressed.
“I bought a GT4 in 2015, and my first test drive left me very disappointed,” DeMan told me during a recent visit to his Blauvelt, New York workshop. “The chassis was gorgeous, as beautiful as any other GT car Porsche has made. But the engine was anemic.”
Not satisfied with Porsche’s approach to the ultimate Cayman, DeMan set out to perfect the GT4. He and his team have spent the past five years modifying the car’s drivetrain to create more power, and deliver a more visceral experience. The result is a 560-horsepower weapon that outshines anything else with a GT badge on its bumper.
DeMan is a mid-engine P-car veteran. He made a name for himself racing 914s from the late Nineties into the early 2000s, dominating club events both regionally and nationally. His shop has been a go-to for Tri-state Porsche owners for years, offering everything from basic maintenance to race prep on a wide range of models. His facility, a 25,000-square foot warehouse tucked in a Rockland county industrial park, is a candy shop for Porschiphiles. The front is a showroom that’s been turned into a makeshift storage area, packed to the brim with various race cars, including an IMSA prototype. In the main workroom, there are shelves stacked four stories high with brake calipers, suspension pieces, exhaust systems, and flat-sixes. There’s even a paint shop and a dedicated engine-building room where DeMan’s crown jewel, the 4.5-liter flat-six, is assembled.
The 4.5-liter engine upgrade package started out as a passion project for DeMan, seeking to bring his personal GT4’s engine up to match the sublime chassis, and his customers quickly took interest. It started out with a displacement bump to 4.0 liters, with the package growing to 4.25 liters, and eventually, 4.5 liters.
The engine is the result of some skillful old-school hot-rodding techniques and years of development. DeMan takes the original 3.8-liter engine from the car being upgraded, and sends it to a machinist to increase bore from 102 mm to 108 mm. Mahle racing pistons, Carrillo connecting rods, and a crankshaft from the 991-generation 911's flat-six are added to increase stroke. Those are just the basics. There are lots of other changes DeMan declined to share, in the interest of keeping his discoveries secret from competitors.
DeMan has built over 24 big-displacement GT4 engines for customers. Most are in street cars that see regular track use, though a few have found their way into race cars. Many of his customers are U.S.-based, though clients send their engines from as far as Thailand and Australia to have the package installed. During my visit, a Boxster Spyder on Belgian plates was waiting for its upgrades.
And what of the gearbox? One of the GT4’s few widely agreed-upon flaws is that the six-speed, while fantastic to use, is geared very long (second gear tops out at over 80 mph). DeMan has a solution for that as well. “After building 914s for years, we knew gearing was important,” he told me. “Gearing selection was always one thing we did in the race cars, and we were really good at it.” He made connections with several manufacturers, and now custom-orders ratios for gears two through five, specifically designed to work with the 4.5-liter’s power delivery. It’s just one of several additional mods you can add on when ordering your engine package.
