Below are the 1.6lD / TD camshaft specifications, from the 1.6lTD SAE paper. I hope this information does the trick for calculating the optimal intake manifold runner length:"The intake valve has a maximum valve lift of 8 mm. Intake opening is at 5 degrees aTDC and intake closing at 14 degrees aBDC where both timings are rated at 1 mm of camlift. The maximum valve lift of the exhaust valve is 9mm, with opening and closing at 27 degrees bBDC and ~ degrees bTDC respectively. Intake valve clearance is 0.2 to 0.3 mm, and exhaust valve clearance is 0.4 to 0.5 mm. All these geometrical dimensions are identical with that of the 4-cylinder naturally aspirated Diesel engine."If more information is necessary, I might also have a plot of the cam displacement vs rotational angle as well (IIRC, such a plot exists in the original 1.5l VW Diesel SAE paper.)