The Nissan RD engine series is basically a Nissan RB engine design, except that it is only a single overhead cam six-cylinder diesel engine. It was the successor to the Nissan LD and SD six-cylinder engines and was joined by the six-cylinder Nissan TD engine. From 1997 onwards the turbocharged versions were fitted with electronic fuel injection. The turbodiesel version known as the RD28T (or RD28ET with electronic fuel injection) and were also fitted to the Nissan Safari (also known as the Nissan Patrol) off-road vehicle. Since the Nissan RD engine is based on the Nissan RB engine, they have many similarities and many parts are interchangeable. The engine block was similar to the RB30 engine except it had more material, was heavier and had 85mm bore vs the 86mm bore of the RB30 and a 83mm stroke vs 85mm stroke. One issue is that the stronger vibrations from the diesel engine can loosen the crank/harmonic balancer bolt (originally from the RB engines) and in turn become loose or fall off causing major engine damage. It is recommended to use thread locking fluid when installing. The cylinder head was of a non-crossflow design, meaning that the exhaust and intake ports were on one side of the cylinder head.

RD28

RD28 Series 1

94 PS at 4,800 rpm 18 kgm at 2,400 rpm No PCV on the tappet cover.

RD28 Series 2

100 PS at 4,800 rpm 18.2 kgm at 2,400 rpm

RD28E

100 PS at 4,800 rpm 18.2 kgm at 2,400 rpm Vacuum pump located on tappet cover.

RD28T

125 PS at 4,400 rpm 26 kgm at 2,400 rpm Nissan Safari Spirit series Y60 2-door soft-top 1996–1997 Nissan Civilian Bus

RD28ETi1

135 PS at 4,000 rpm 29.3 kgm at 2,000 rpm Nissan Safari Spirit series Y61 2-door soft-top 1997–1999 (automatic transmission)

RD28ETi2

145 PS at 4,000 rpm 26.6 kgm at 2,000 rpm