3S-GE Generations

Now this isn't going to be as in-depth as my article on the different 3S-GTE generations, but more basic guidelines for those who don't know a lot about the changes made to 3S-GE's in comparison to those made to the turbo models. If you have information that would be of use, please email me. The names given to the different generations are not official, but simply those commonly used to refer to them, and they are:

Gen 1: 1985-1989
As found in ST16* Celicas, Coronas and Carinas, ST17* Coronas, and probably more. Power was around 130-150hp.
Gen 2: 1989-1993
As found in the ST18* Celicas, Carinas, Coronas, SW20 MR2s (until late 1993) and probably more. 150-160hp
Gen 3: 1993-199?
As found in the ST20* Celicas, Currens, SW20 MR2s (late 93 onwards), and probably more. 175-180hp ( pic )
Gen 4: About 1998 onwards
This is the first of the "BEAMS VVT-i" 3S-GE's. Often refered to as the red-top. Found in some SSIII Celicas, and Gen 5 SW20 MR2s, and also in ST21* Caldinas (minus the red rocker cover and plenum). 190hp (auto) 200hp (manual).
Gen 5: 1998 onwards
The "black top" BEAMS Dual VVT-i motor. Found in Altezzas (and Lexus equivalents). 200hp (auto) and 210hp (manual)
So, I will now go through the various aspects of the engine and compare the differences between each generation.

Intake Manifold
Gen 1
Side entry, T-VIS (8 runner).
Gen 2
Side entry, twin plenum "ACIS" (Acoustically Controlled Intake System). This has a 3 piece intake manifold, from the head the first piece are the intake runners, then there is a plenum which is opened and closed with butterfly valves, and then more runners leading to another plenum. The intermediate plenum is opened at a certain rev point, around 4,000rpm, with the increased intake volume giving better Helmholtz tuning for the upper rev range. Intermediate Plenum ( pic 1 - pic 2 - pic 3 )
Gen 3
Appears to be very much identical to Gen 2.
Gen 4
Side entry, velocity stacks in plenum ( pic 1 - pic 2 - pic 3 )
Gen 5
Similar to Gen 4, not sure whether it has the velocity stacks, but probably does.
Exhaust Manifold
Gen 1
Uses a cast 4>2 manifold with the two outlets merging to one very quickly when it meets the exhaust
Gen 2
Uses a much improved tubular 4>2 manifold with very short secondaries. This will bolt on to Gen 1 motors
Gen 3
Similar to Gen 2 ( pic )
Gen 4 & 5
I have no knowledge of the exhaust manifolds on these so please contact me with correct information if you have it.
Engine Management Type
Gen 1
Airflow meter for fueling calculations. Normal coil and distributor ignition
Gen 2
MAP sensor for fueling calculations. Normal coil and distributor ignition
Gen 3
MAP sensor for fueling calculations. Normal coil and distributor ignition
Gen 4
Mass flow sensor (hotwire?) for fueling calculations. Direct Fire Ignition
Gen 5
Mass flow sensor (hotwire?) for fueling calculations. Direct Fire Ignition
Engine Notes:
Gen 1
The head appears to be very similar to the Gen 1 and 2 3S-GTE heads. Crankshaft an be either 6 or 8 bolt (flywheel flange). The 6 bolt is similar to a 4S-FE crank, infact it's probably the same as they have the same stroke, and the 8 bolt is the same as a Gen 1 3S-GTE crank (with a slightly smaller PCD than Gen 2 onwards)
Gen 2
The head appears to be halfway between a Gen 2 and Gen 3 3S-GTE head. It has smaller intake ports, similar to the Gen 3 3S-GTE, but still uses shim-over bucket cam followers, and has the same exhaust port layout.
Gen 3
Reports suggest the head is practically the same as a Gen 3 3S-GTE head, with the shim under-bucket cam followers and the Gen 3 3S-GTE exhaust port spacing
Gen 4
11:1 CR. This has VVT-i (variable valve timing - intelligent), which is a system that varies cam timing to suit revs and load. Operates on only the intake cam. Not sure how port sizing and spacing compares to previous generations. Interestingly the blocks on these engines had improved reinforcing around the head bolt boss in the corner by the water pump. This boss is known for breaking off the block in 3S-GTE's under high power or excessive stress. This reinforcing also occured in later 3S-GTEs, and new blocks from Toyota apparently also have the reinforcing.
Gen 5
11.5:1 CR Similar VVT-i system as above, but works on both intake and exhaust cams. Also had reinforcing around the head stud by the water pump, and the manual models had Titanium valves.

Note: most of this information, such as dates, power output etc, pertains to JDM (Japanese Domestic Market) models, which we have here in New Zealand.

Sources: My own experience with much useful input from Dave van der Haas. Horsepower figures from http://www.geocities.com/MotorCity/Pit/9975/dataBySubject/GasolineEngines.html#S-series