To make the 956 eligible under the new IMSA regulations, Porsche extended the 956's wheelbase to move the front wheels ahead of the pedal box. A steel roll cage was also integrated into the new aluminium chassis. For an engine, the Porsche 934-derived Type-935 2.8L flat-6 was used with air cooling and a single Kühnle, Kopp und Kausch AG K36 turbocharger instead of the twin K27 turbochargers of the Group C 956, as twin-turbo systems were not allowed in IMSA's GTP class at the time.