24 hours of Le Mans, which went on to finish 6th, 12th and 13th overall. Also building a 924GTR rally race car, and two other GTRs (Miller and BF Goodrich). 17 (some sources say 19) Carrera GTRs were built in total. Lastly, in 1981, Porsche entered one of two specially built 924 Carrera GTPs (the "944GTP Le Mans") in which Porsche Motorsports introduced a new prototype highly modified 2.5 liter I4 engine. This engine sported four valves per cylinder, dual over head camshafts, twin balance shafts and a single turbocharger K28 to produce . This last variant managed a seventh place overall finish and spent the least time out of any other car in the pits. This new 2.5 liter configuration engine is the predecessor of the 944 platforms and the later 1987–88 944S 16V M44/40 power-plant. Production of the 924 Turbo ceased in 1982 except for the Italian market which lasted until 1984. This was due to the restrictions on engines larger than two liters, putting the forthcoming 2.5 liter 944 into a much higher tax category. 924S In 1984, VW decided to stop manufacturing the engine blocks used in the 2.0 L 924, leaving Porsche with a predicament. The 924 was considerably cheaper than its 944 stablemate, and dropping the model left Porsche without an affordable entry-level option. The decision was made to equip the narrower bodied 924 with a slightly detuned version of the 944's 163 bhp 2.5 litre straight four, upgrading the suspension and adding 5 lug wheels and 944 style brakes, but retaining the 924's early interior. The result was 1986's 148 bhp 924S. Porsche also decided to re-introduce the 924 to the American market with an initial price tag of under $20,000. In 1988, the 924S' final year of production, power increased to matching that of the previous year's Le Mans spec cars and the base model 944 (itself detuned by for 1988). This was achieved using different pistons which raised the S' compression ratio from 9.7:1 to 10.2:1, the knock-on effect being an increase in the octane rating, up from 91 RON to 95. This made the 924S slightly faster than the base 944 due to its lighter weight and more aerodynamic body. The 1988 model also gained three point safety belts in the rear seats. With unfavourable exchange rates in the late 1980s, Porsche decided to focus its efforts on its more