There were two basic generations of the 16-valve 4A-GE motor. They are most easily distinguished by the intake manifolds and are referred to by the biggest change made during the revision, which was the size of the intake ports in the cylinder head.
Pre-1990 4A-GEs had larger ports and are thus referred to as "bigports." They used the Toyota Variable Induction System (TVIS) which had two runners going to each port and butterflies to close one runner at low RPMs. The normally aspirated intake manifold has a plate that says "TVIS" on the top.
In 1990, the TVIS system was dropped and the intake ports made smaller. Each port now had only one runner. The intake manifold on normally aspirated motors now has no markings except for several lengthwise ridges. Smallport motors received higher compression ratios and more power for both normally aspirated and supercharged versions.
It should be noted that supercharged motors of the same version, bigport or smallport, have the exact same cylinder head and ports as the corresponding normally aspirated version. It should also be noted that no supercharged motors had TVIS, and the only way to distinguish bigport supercharged intake manifolds from smallport is by the port sizes (no smallport SC manifolds had EGR, but no Japanese bigport SC manifolds did either). It should also be noted that ALL USDM motors used the flapper-door airflow meter (smallport, bigport, supercharged) for load sensing and all overseas motors used the MAP sensor.
Several very minor revisions happened inside the bigport and smallport versions, but all of the important changes happened at the smallport revision.
112HP (bigport NA pre-1987)
115HP (bigport NA 1987-1989)
130HP/140PS (smallport NA 1990+, )
145HP/PS (bigport SC, all)
165PS (smallport SC, 1990-1991, not sold in US so no HP rating)
170PS (smallport SC, 1992-1994, not sold in US so no HP rating)
9.4:1 (bigport NA)
10.3:1 (smallport NA)
8.0:1 (bigport SC)
8.9:1 (smallport SC)
Engine per model:
Bigport: ALL AW11 NA, ALL AE86 GT-S, USDM AE92 GT-S pre-1990, Corolla FX16
Smallport: 1990+ USDM AE92 GT-S, Levin/Trueno AE92 1990+, USDM Geo Prizm Gsi
The 20-valve cylinder head variant had a completely different cylinder head and intake manifold with individual throttle bodies and was only sold in 1992-1994 AE101 and 1995-1998 AE111 Levin/Trueno models sold overseas. It should be considered the "third" version of 4A-GE.