Bobby’s search led him to a nice example of the less rare, but still valuable, 1989 Turbo Cabriolet. Coincidentally this car was black-on-black, just like his original Speedster. From there, the road map to his ultimate Speedster was laid out over the course of the next five years.
He contacted Dave Bouzaglou at TRE Motorsports in Van Nuys, California, who set out the mechanical specification for the car. Dave agreed to manage the project in conjunction with a small handful of trusted local specialists for the custom bodywork, paint and interior trim.
The heart of any car is its motor, and Bobby and Dave even discussed swapping out this one’s for a later 3.6 biturbo. In the end Bobby went for Dave’s suggestion to take the original motor’s displacement out to 3.4 liters and fit twin turbochargers as part of a full engine rebuild that would also be the safety check for many more years of faithful service.
The displacement bump comes from a set of 98mm JE pistons married to the factory crank and rods, with all the reciprocating parts checked for wear and balanced as a matter of course.
To improve breathing and optimize gas flow, the cylinder heads were swapped for 3.2 Carrera units, which have larger ports to start with. Some machining work was done to further improve flow, and a pair of high-lift camshafts with matching valve springs was installed.
One of the great things about the air-cooled Porsche flat-six is the vast interchangeability of parts. With its enlarged displacement and twin turbos, the engine needed a much deeper breathing intake and exhaust, so Dave ditched the Turbo’s original Bosch K-Jetronic CIS setup and the stock exhaust.
A gas-flowed Carrera 3.2 intake manifold and enlarged throttle body, working in conjunction with a custom Promotive ECU and fuel pressure regulator, now looks after the intake side of the combustion process.