The 33 Stradale is one of the first production vehicles to feature forward-hinging butterfly doors. The 33 Stradale also features windows which seamlessly curve upward into the 'roof' of the vehicle. The car has aluminium body on aluminium tubular chassis. As a result of being built by hand, each model differs from the others for some details. For example, the first two cars had twin headlights, replaced for later cars by single headlights. The position of the windscreen wiper, and even the number of them, is another thing that differentiates each example from the others. Also the late models have vents added behind both the front and rear wheels to allow hot air from the brakes to escape. The car has 13-inch Campagnolo magnesium wheels, the front wheels eight and the rear wheels nine inches wide; the brakes used are disc brakes by Girling, the rear ones are inboard. The suspension system of the car is directly derived from the race cars of the 1960s with upper and lower control arms in front and double trailing arms in the rear, along with substantial antiroll bars. Engine and transmission The race-bred engine bore no relation to the mass-produced units in Alfa's more mainstream vehicles. The engine is closely related to the V8 of the Alfa Montreal, albeit with smaller capacity and in a much higher state of tune. Both engines were derived from the 33 racers' but differed in many details. Both engines had chain driven camshafts as opposed to the racers' gear driven ones, but the Stradale kept the racing engine's flat plane crankshaft, whereas the Montreal engine had a crossplane crank. Race engineer Carlo Chiti designed an oversquare bore x stroke of dry-sump lubricated all-aluminum V8 engine that featured SPICA fuel injection, four ignition coils and twin spark plugs per cylinder. The engine used four chain-driven camshafts to operate the DOHC 2 valves per cylinder valvetrain and had a rev-limit of 10,000 rpm with a compression ratio of 10.5:1, producing at 8,800 rpm and at 7,000 rpm of torque in road trim and in race trim. Because every Stradale is hand built and unique the power levels can vary by car, used rpms etc., for example the first production Stradale (No. 750.33.101) has a factory datasheet that claims at 9,400 rpm with a "street" exhaust and with open exhaust. As on the racing car, the transmission was a six-speed