SiR uses a cable tranny- 5th gens are hydraulic
SiR has a lower compression ratio, 10.2:1 and makes 160hp
A2/A3/SiR II have a higher compression ratio at 10.4:1 and make 160hp (A2/A3) or 170hp (SiR II)
A2/A3/SiR II motors have a better cam profile
A2/A3/SiR II have better oiling functions, keeping things better lubricated
SiR has cast aluminum oil spray bars while the A2/A3/SiR II are made of extruded aluminum.
A2/A3/SiR II have a single- 4-wire O2 sensor instead of 2-single wire O2 sensors
A2/A3/SiR II MAP sensor is an integral part of the throttle body, not an external one with a tube.
A2/A3/SiR II harnesses are grey. SiR has cream colored ones.
SiR is PGM-F1, clearly labeled on the intake manifold, andA2/A3/SiR II are MPFI
SiR valve covers have "DOHC" written in a larger font size than "VTEC"
A2/A3/SiR II valve covers have "VTEC" written in a larger font size than "DOHC"

Additional Information

88-91 B16A's are known as the SIR 1. It uses OBD0 Ecu's, and cable tranny's. The engine serial number is usually 1xxxxxx.
92+ B16A's are known as the SIR 2. It uses OBD1 or OBD2(2b), and hydraulic trannys. The engine serial number is usually 5xxxxxx
The #'s at the end of the block code tell where the engine originated from. The Americas, Europe, Austraillia, etc.....
ALL Japanese engines, generally do NOT have a number after them.
SO, if you have a B16A1,2,3,4, or 5. It is usually NOT a true JDM engine. Don't mistake a B16A1 as being a cable unit, because it could be a hydraulic.