The CTR was an abbreviation for 'Group C Turbo Ruf' and was based on the 1987 Porsche 911 Carrera 3.2. It was chosen over the factory turbocharged Type 930 because the 3.2-liter version weighed less and had a more desirable drag coefficient. The factory doors, hood, engine cover, and body panels were removed and replaced with aluminum, helping to shed an additional 440 lbs of the factory curb weight. Fiberglass was used for the bumpers. The rain gutters were removed to help reduce drag. A pair of intake ducts were added to the rear flares to help channel air to the intercoolers.

The engine received several modifications which included an uprated Bosch Motronic 2.1 fuel injection system. An ignition setup originally designed for the Porsche 962 race car was added, and the cylinders were bored out to 98 mm, increasing the displacement from 3.2 liters to 3.4 liters. Large twin-turbochargers and twin intercoolers were added to the engine, helping boost output to 463 bhp and torque to 408 ft-lbs. The sound of the blow-off valve was similar to the chirp of a canary, thus leading to the nickname 'Yellowbird.'

The engine was mated to a five-speed transmission of their own design, which allowed them to add their own customized gear ratios. The suspension system was upgraded, 330 mm diameter Brembo brakes installed, and 17-inch Ruf Speedline alloy wheels with Dunlop's Denloc system performance tires were added to all four corners.

The Ruf Yellowbird CTR made its debut near the close of 1987 and had a price of $223,000. Production lasted until 1996 with 29 examples built from scratch. Around 20 or 30 examples were built from customers' Carreras.

by Dan Vaughan