2nd Generation Group 5 - .22Sports Cars.22 .281970 to 1971.29 Group 5 (racing)

group 5 porsche 917 competing in 1970 international championship makes

for 1970 season, fia applied group 5 classification sports car class had been known group 4 sports cars. minimum production requirement remained @ 25 , engine capacity maximum @ 5 litres had applied in superseded group 4. group 5 sports cars contested fia s international championship makes in 1970 & 1971, alongside 3 litre group 6 prototype sports cars.

during 1970 fia decided replace existing group 5 sports car category when rules expired @ end of 1971 season, big 917s , 512s have retired @ end of year. surprisingly, ferrari decided give official effort 512 in order prepare new 1972 season regulations. many 512s still raced private teams, of them converted m specification. result of rule change, sports car racing popularity suffered , did not recover until following decade, advent of group c incidentally forced out of competition in favour of 3.5 atmo engine formula, reminiscent of events nineteen years previous.

background 5 litre sports car category

in effort reduce speeds generated @ le mans , other fast circuits of day unlimited capacity group 6 prototypes such 7 litre fords, , entice manufacturers of 3 litre formula 1 engines endurance racing, commission sportive internationale (then independent competition arm of fia) announced new international championship makes run group 6 sports-prototypes limited 3 litre capacity 4 years 1968 through 1971.

well-aware few manufacturers ready take challenge, csi allowed participation of 5 litre group 4 sports cars manufactured in quantities of @ least 50 units. targeted existing cars aging ford gt40 , newer lola t70 coupe.

in april 1968, csi announced that, there still few entries in 3 litres group 6 prototype category, minimal production figure compete in group 4 sport category of international championship of makes reduced 50 25 starting in 1969 through planned end of rules in 1971. allow homologation in group 4 of cars such ferrari 250 lm , lola t70 had not been manufactured in sufficient quantities qualify (unless, in case of lola t70, open can-am cars counted well).

starting in july 1968, porsche made surprising , expensive effort take advantage of rule. rebuilding race cars new chassis every race or 2 anyway, decided conceive, design , build 25 versions of whole new car sport category 1 underlying goal: win first overall victory in 24 hours of le mans. in ten months porsche 917 developed, based upon porsche 908, remarkable technology: porsche s first 12-cylinder engine, , many components made of titanium, magnesium , exotic alloys had been developed lightweight hillclimb racers. other ways of weight reduction rather simple, gear lever knob made of balsa wood.

when porsche first visited csi inspectors 3 cars completed, while 18 being assembled , 7 additional sets of parts present. porsche argued if assembled cars have take them apart again prepare cars racing. inspectors refused homologation , asked see 25 assembled , working cars.

on april 20 ferdinand piëch displayed 25 917s parked in front of porsche factory csi inspectors. piëch offered opportunity drive 1 of cars, declined.

during june 1969, enzo ferrari sold half of stock fiat, , used of money porsche did 6 months earlier 917, build 25 cars powered 5-litre v12 in order compete against them. financial of fiat, risky investment made, , surplus cars intended sold racing customers compete 1970 season. within 9 months ferrari manufactured 25 512s cars.

ferrari entries consisted of factory cars, tuned spa sefac , there private cars of scuderia filipinetti, n.a.r.t., Écurie francorchamps, scuderia picchio rosso, gelo racing team , escuderia montjuich not receive same support factory. considered field fillers, never candidate win. @ porsche, however, jwa gulf, kg salzburg replaced martini racing following season, received direct factory support , privateers aaw shell racing , david piper racing received better support ferrari s clients.

the 917 instability problem resolved revised rear hatch, called 917k (kurzheck). there long tail version known 917lh (langheck). towards end of 1970 season, ferrari entered races new version of 512, 512m had revised bodywork