stone guard protected the power-train and a stone shield did the same for the front of the car. The GT cars received stronger lower front A-arms, and anti-roll bars were fitted front and rear. Ground clearance was reduced to . Brakes front and rear were upgraded to the same components used on the racing 911S model. Fiberglass panels for the front and rear bumpers, front and rear deck lids, and left and right rocker panels replaced the original steel parts. The rear air intake grille was doubled in size. An inlet in the front bumper admitted air to a new supplementary oil cooler in the nose. The car's nose compartment was nearly filled by a fuel tank. The car weighed ready to race. The engine remained at 2.0 litres displacement with Weber carburetor induction, but was extensively upgraded otherwise. New cylinder heads with larger valves topped aluminum cylinder barrels with chrome-plated bores. A dual-ignition system fired two spark plugs per cylinder. High compression pistons and forged steel piston rods were borrowed from the 911S. A special crankshaft was added. Camshafts and rocker arms came from the 901/20 in the Carrera 6. Power output was up to at 8000 rpm. Although the factory campaigned the car in rallying, it was more successful in road racing. In the United States the Porsche+Audi distributor called the car the 914/6R. M471, kits To qualify for SCCA homologation, 500 copies of a car had to be built. It is estimated that Porsche built fewer than 40 GTs with the full race engine. To add to the total, an additional 11 cars were equipped with the Competition Option Group M471 package that included the GT's steel fender flares, rocker panels and nose piece as well as wheel spacers, a set of 6-inch wide Fuchs wheels, and 185/70VR15 tires, but did not include the enhanced engine from the GT. Similar appearance-only kits were also supplied to dealers, totaling about 400 units. Porsche's application for homologation was successful, but instead of being added to the C Production class, the SCCA put the 914/6 GT into the more competitive B Production class. 914/8 Two prototype 914s, dubbed 914/8 generally and called 914/S'' by Porsche, were built during 1969. An orange 914/8 was the first constructed, at the instigation of Ferdinand Piëch (then head of the racing department), to prove the concept. Powered by a Type 908 flat-eight racing engine,