Nissan S110 Silvia RS and S12 RS-X Silvia (Gazelle)

Nissan decided that it would not be cost effective to only fit the FJ20 into DR30 Skyline's. 
So the Naturally Aspirated FJ20E was fitted to the S110 RS Silvia Hardtop Coupe. Due to the huge popularity of the FJ20 in Japan the turbo charged FJ20ET version was fitted to  early model S12 RS-X Gazelle and Silvias in both hatchback and coupe models. 

The FJ20ET found in the S12 RS-X used a different intake/exhaust manifold than the DR30 to fit in the Gazelles smaller engine bay. Factory Torque/power is slightly less than in the DR30 FJ20ET. 
The rocker cover is also visually different than the S12 FJ20ET, having an indent around the oil filler cap rather than the flat design found in the Skyline.
Later model S12 Gazelles came fitted with the turbo intercooled 1.8L 4cyl. 16valve DOHC CA18DET engine.