The 4AGE has been available in a number of forms. This is a brief run down of how to identify what engine your looking at.
The first generation 4AGE was 16V and had silver cam covers with Toyota lettering in blue or black text. This was found in the Corolla GT and came in MAP and MAF versions. The MAF engine has 112bhp and the MAP 130bhp.
The second model was released in 1988 and had a stronger block but with red or black writing on its silver cam cover. The version came in the MK1 MR2
The 4AGZE was also available from around 1988, this model was supercharged, it had no colour whatsoever on the cam cover, and this engine wasn’t available in the UK
In 1989 the 16V 4AGE model which also had a silver cam cover with red letters and many changes to the internals. This version is referred to as the red top and came in the Corolla GTi. This engine was a small port motor and went without TVIS. All the other motors were big port and had TVIS.
The 3rd generation had external oil lines from the cylinder head to the block.
In 1991 the 4AGE had 20 valves and this had silver writing in a silver cam cover and is usually called the silver top.
In the middle of the nineties an upgraded 20 valve 4AGE was released, this has slightly more power and came with a black cam cover, this is referred to as the black top.
Toyota’s TVIS system (Toyota Variable Induction System) was well ahead of it’s time. It varied the length of the intake runners depending on throttle position and rpm. Fitting individual throttle bodies makes little or now difference to power but low speed drivability does suffer.
Although the exhaust ports are the same size on the 16V and 20V the headers are not interchangeable
Cams can give around 160bhp above this the TVIS will need to be ditched in favour of throttle bodies. It’s possible to get 200bhp with uprated internals but it’s easier and cheaper to boost the motor
Raw Engineering supply a Rotrex kit for the 4AGZE which can take the silver top to 220bhp, the kit costs 3000GBP
HKS do a turbo kit for the 4AGZE which incorporates the original supercharger. Hard to get hold of now and probably a bit pricey, both to buy the kit and to install it.
For more info on the 4AGE, visit http://forums.club4ag.com/zeromain