Donnerstag, 4. Oktober 2007

Camshaft Profile

To get an improved 1600cc engine for street driving an adequate camschaft profile is necessary. I've chosen a pair of cams which is quite similar to the Alfa Grp. 1 cam part no. 115010320032. From different sources (original Alfa cam data, IAP, Kent Cams, Schleicher, J. Kartalamakis, Alfa Bulletin Board, Colombo & Bariani, etc.) I have chosen a cam with these data:

- max. lift 10,97 mm
- duration 286 deg @ 0,35 mm clearance
- 243 deg @ 0.05" clearance (for those who are Americans)
- 248 deg @ 1,0 mm clearance
- timing: 110 deg lobe center (on both inlet and outlet cam)
max. valve opening overlap @ TDC 2,5 mm

To improve the profile I calculated the lobe geometry according to Benzingers Formula using smooth intersections between triangular mathematical spline formulas. These cams are regrinded from original Alfa 105480320051 camshafts by CAMPRO, Bochum/Germany. See

Valve lift (black), speed (reed) and acceleration (blue)

Valve lift curve, calculated curve (blue), Grp. 1cam (magenta)

Valve timing chart (0 deg = TDC)