930 Turbo 4-Speed Gearbox. These photos show the modifications required to adapt a 930 Turbo 4-Speed gearbox to a mid-engine Porsche 914 including the machining of the case, inverting the "ring & pinion", shortening the main shaft, etc., etc. This particular gearbox will be installed behind a 475 H.P. Aluminum V8 engine. The 930 Turbo transmissions are very strong indeed and were designed for turbocharged racing engine applications where output often exceeds 500 H.P.