After having withdrawn from Formula One on the quit of the 1962 season, Porsche targeted once more on sportscar racing. The 904 debuted past due in 1963, for the 1964 racing season, as a successor to the 718, which have been delivered in 1957. Porsche designed the GTS variation to compete withinside the FIA-GT elegance at numerous worldwide racing events. The street-criminal model debuted in 1964 for you to observe institution three appendix J homologation guidelines requiring a positive range of road-going versions be offered via way of means of the factory. Porsche produced one-hundred and 6 904s at 4 or 5 an afternoon with a listing rate of US$7245 (FOB Stuttgart). Orders a ways surpassed the only hundred vehicle requirement to fulfill homologation regulations and greater automobiles might have been offered. The 904 marked the start of a sequence of sportscars that culminated withinside the dominant 917.
Engine
Begun because the Type 547, its improvement started in 1953, while the preceding VW-primarily based totally 1,one hundred cc (sixty seven cu in) flat-4, used withinside the present day 356 and rated at 38 hp (28 kW), hit the restrict of its potential. Porsche found out it wanted some thing all-new. The brainchild of Ernst Fuhrmann, later technical director, it became was hoping to reap an "unheard of" 70 hp (fifty two kW) in line with 1 l (sixty one cu in), counting on hemispherical combustion chambers (which might be known as hemis withinside the U.S.) and forty six mm (1.eight in)-throat 46IDA2 two-choke Weber carburetors to generate 112 hp (eighty four kW) from the 1,500 cc (ninety two cu in) 4-cam engine. The 1.five liter weighed 310 lb (one hundred forty kg) dry, ultimately generating a hundred and eighty hp (134 kW). A complicated layout that proved "very taxing" to construct and assemble, however very durable, it became utilized in 34 one-of-a-kind models, consisting of 550 spyders, 356 Carreras, and F2/1s.
Chassis
The 904 became the primary Porsche to apply a ladder chassis and fibreglass frame, acting greater like a consultant racing vehicle than the changed sports activities automobiles ordinary on the time, and became painted white. The fibreglass frame became bonded to its metal chassis for added rigidity, and done a drag coefficient of 0.34. While many German race automobiles had used unpainted aluminium our bodies for the reason that well-known 1934 Silver Arrows, maximum 904s had been painted silver, the contemporary-day German countrywide racing color. Unusually for Porsche, the two-seater our bodies had been supplied via way of means of contractors, which might later grow to be general exercise amongst race vehicle builders. The 904's fibreglass frame became made via way of means of spraying chopped fibreglass right into a mold, the quantity sprayed frequently numerous in thickness over the form of the automobile and as a end result the burden of the numerous automobiles became extremely inconsistent. Race-organized 4-cylinder 904s weighed in at about 1,443 pounds (655 kg) and the low weight gave the 904 the capacity to boost up to 60 mph (ninety seven km/h) from a standstill in much less than six seconds (the usage of the same old rear gear, which became ordinary at Sebring) and to attain a pinnacle velocity of one hundred sixty mph (260 km/h) (with the three.362 ratio). Frontal region became best 14 sq ft (1.three m2).
Suspension
The Porsche 904 rode on coil springs (the primary Porsche now no longer to apply trailing arm the front and swing axle rear suspension), with unequal-period A-hands in the front. The wheelbase became 90.five in (2,three hundred mm) (via way of means of contrast, the Corvair's became 108 in (2,seven-hundred mm)), music the front and rear 51.7 in (1,310 mm), peak forty two in (1,one hundred mm), and floor clearance of 4.7 in (one hundred twenty mm) on 15 in (380 mm) wheels. Brakes had been 275 mm (10.eight in) discs on the the front and 285 mm (11.2 in) on the rear.
