Nissan's original aim for the engine of the 300ZX was 250-300 bhp but with ample torque in the low and medium speed range and excellent throttle response and smoothness. They thought that was best achieved by a three litre V6 engine equipped with twin turbochargers. A V6 rather than a V8 would also allow for a very low front nose.

They started with the V6 engine used in the previous ZX - a 60 degree unit with an iron block and aluminium heads - but it needed to rev higher than before to achieve the required output.

They decided that the engine should have four valves per cylinder and two camshafts per bank. To give the engines the flexibility they desired, variable valve timing was introduced: NVCS (Nissan Valve Timing Control System). The variable valve timing system is simpler than those used by other manufacturers such as Honda and Mitsubishi. Only the inlet valve timing is altered. This is achieved by using a special sprocket attached to the inlet camshaft. The camshaft timing belt rotates this sprocket in the normal way, but at engine speeds below 3000RPM , oil from the main oil gallery is fed into the sprocket itself, via the camshaft, to operate a spring loaded gear. This gear then advances rotation of the sprocket by 10 degrees relative to the camshaft, thereby altering inlet valve timing and increasing low end torque. The 300ZX engine thus produces 222 bhp normally-aspirated or 280hp (automatic) to 300 bhp (manual), 280 bhp in European spec, turbocharged at 6 400 rpm. These power outputs are with the exhaust system and catalytic converters.

ECCS, standing for Electronic Concentrated Control System is the engine management computer that controls the valve timing along with the fuel injection and Nissan Direct Ignition System, NDIS which provides a separate coil atop each spark plug. The two turbochargers mounted on cast-iron exhaust manifolds either side of the engine are Garrett T2/T2.5 hybrids. The boosted air passes through intercoolers mounted in the nose. The pipe runs are complicated as inlet air has to go back from the air cleaner to the turbos, forward to the intercoolers and back again to the inlet manifolds. Inlet and exhaust systems are dual throughout, though incoming air feeds the opposite cylinder bank through what Nissan call a cross-ram manifold.

The normally aspirated and turbocharged engines are mostly alike internally, the turbo version has different pistons and aircraft-grade exhaust valves. Camshaft timing profiles are all identical except for the automatic turbo model.

For a summary of engine specifications, see the sample specification later in the article.