I read somewhere years ago that there's a reason for the taper. Seems that Autodelta, after qualifying a 1600 GT, tore down the engine to freshen it for the race. After blowing every car into the weeds and winning the race with new found horsepower, the team discovered that the engine assembler installed the wrong intake manifold. Instead of using the straight bore 1600 manifold, the mechanic installed a taper bore 1300 manifold. Seems velocity, and not volume, is the key. Production intakes have been tapered ever since.turbolarespider said:
Due to the casting method used on the intake, there is a significant taper at the end of the manifold (not the throttle body part), which on my GTV was about 2-3 mm smaller.
Came across this passage on page 44 of John Tipler's book 'Giulia Coupe GT & GTA'.papajam said:Seems that Autodelta, after qualifying a 1600 GT, tore down the engine to freshen it for the race. After blowing every car into the weeds and winning the race with new found horsepower, the team discovered that the engine assembler installed the wrong intake manifold. Instead of using the straight bore 1600 manifold, the mechanic installed a taper bore 1300 manifold. Seems velocity, and not volume, is the key.
JoeCab said:
In a sense, what Autodelta found regarding the smaller intake manifold and intake ports can be extrapolated to porting a head. It is important to maintain velocity......