[Flieger]

The 2,3 and all of the other ST engines were Magnesium crankcase.

They had Biral cylinders until the 2,5 liter with 66mm stroke was introduced as the very last variant. This was made possible by the 89mm Nickasil cylinders. The 66mm stroke revved faster and lessened the vibration problems in the crankshaft on the 70.4mm stroke crankshaft, which had caused flywheels to come loose.

ST engines all had 10,5:1 compression ratios, though there may have been some special factory cars (916 engine?).

According to Paul Fere's Porsche 911 Story:

911/20 and 911/22: 2,247cc (85mm bore x 66mm stroke)
power: 230 PS @ 8000 rpm
valve diameter intake/exhaust: 45mm/39mm
valve lift intake/exhaust: 12.1mm/10.5mm
911/20 = injected 911/22 = Webers

911/21: 2,380cc (87.5mm bore x 66mm stroke)
power: 250 PS @ 8000 rpm
valve dia. intake/exhaust: 45mm/39mm
valve lift intake/exhaust: 12.1mm/10.5mm
injected

911/70: 2,494cc (86.7mm bore x 70.4mm stroke)
power: 275 PS @ 8000 rpm
valve dia. intake/exhaust: 46mm/40mm
valve lift intake/exhaust: 12.1mm/10.5mm
port diameter intake/exhaust: 41mm/41mm
injected

911/73: 2,466cc (89mm bore x 66mm stroke)
power: 275 PS @ 8000 rpm
valve dia. intake/exhaust: 46mm/40mm
valve lift intake/exhaust: 12.1mm/10.5mm
port diameter intake/exhaust: 41mm/41mm
injected