The RB engine is an oversquare 2.0–3.0 L straight-6 four-stroke gasoline engine from Nissan produced from 1985 to 2004. The RB followed the 1983 VG-series V6 engines to offer a full, modern range in both straight or V layouts. It was part of a new engine family name PLASMA (Powerful & Economic, Lightweight, Accurate, Silent, Mighty, Advanced).

The RB engine family includes single overhead camshaft (SOHC) and double overhead camshaft (DOHC) engines. Both SOHC and DOHC versions have an aluminium head. The SOHC versions have 2 valves per cylinder and the DOHC versions have 4 valves per cylinder; each cam lobe moves only one valve. All RB engines have belt driven cams and a cast iron block. Most turbo models have an intercooled turbo (the exceptions being the single cam RB20ET & RB30ET engines), and most have a recirculating factory blow off valve (the exceptions being when fitted to Laurels and Cefiros) to reduce compressor surge when the throttle quickly closes.

The RB engines are derived from the six-cylinder L20A engine, which has the same bore and stroke as the RB20. All RB engines were made in Yokohama, Japan where the VR38DETT engine was also made. Some RB engines were rebuilt by Nissan's Nismo division at the Omori Factory in Tokyo as well. All Z-Tune Skylines were rebuilt at the Omori Factory.

Since 2019, small-scale production of the RB26 blocks and heads are currently being produced as part of Nismo's Heritage Series.

Bore and stroke All Nissan engines follow a naming convention, identifying the engine family (in this case, RB), displacement, features present—see the list of Nissan engines for details.

The stock dimensions for the Nissan RB Engine: RB20 - , bore x stroke: RB24 - , bore x stroke: RB25 - , bore x stroke: RB26 - , bore x stroke: RB30 - , bore x stroke: "D" indicates a dual overhead cam as opposed to a single overhead cam "E" indicates the individual engine ports are electronically fuel-injected 'single-cam' "S" indicates the engine is carbureted "T" indicates the engine has a factory installed turbocharger "TT" indicates the engine has factory installed twin turbochargers "P" indicates the engine runs on LPG (liquefied petroleum gas)

RB20 (2.0L I6)

The first RB20ET/DE/DET engines were fitted to the HR31 Skyline and the Nissan Fairlady 200ZR (Z31 chassis), produced from August 1985. The early twin cam engines featured the NICS (Nissan Induction Control System) injection system, while the later twin cam engines used ECCS (Electronic Concentrated Control System). Later versions which used ECCS engine management, discarded the twelve tiny runners for six much larger ones (though they retained twelve ports on the head, so there was a splitter plate). It was also fitted to the A31 Cefiro, C32 and C33 Laurel. The Fairlady 200ZR was fitted with an intercooled NICS type RB20DET.

The first RB20E engine was used in the C32 Nissan Laurel, produced from October 1984.

Laurels, R32 Skyline and Cefiros used the second (1989–1993) series RB20E/DE/DET. This had an improved head design, and used the ECCS injection system. These later motors are known as "Silver Top" engines.

The RB20DET-R was used in the Nissan Skyline 2000GTS-R (HR31) and was limited to 800 units.

There were a variety of 2.0 L RB20 engines produced: RB20E single-cam Power: at 5600 rpm Torque: at 4000–4400 rpm Camshaft duration: 232° intake; 240° exhaust Camshaft lift: 7.3 mm intake, 7.8 mm exhaust RB20ET single-cam, turbocharged Power: at 6000 rpm Torque: at 3200 rpm RB20DE twin-cam Power: at 6400 rpm Torque: at 5600 rpm Camshaft duration: 232° intake, 240° exhaust Camshaft lift: intake, exhaust RB20DET twin-cam, turbocharged Power: at 6400 rpm Torque: at 3200 rpm Camshaft duration: 240° intake, 240° exhaust; 248° intake, 240° exhaust ("Red Top") Camshaft lift: intake, exhaust; intake, exhaust ("Red Top") RB20P single-cam, 12 valves, autogas LPG Power: at 5600 rpm Torque: at 2400 rpm RB20DET-R twin-cam, turbocharged Power: at 6400 rpm Torque: at 4800 rpm RB20DE NEO twin-cam Power: Torque:

RB24S (2.4L I6)

This is a comparatively rare engine, as it was not produced for the Japanese domestic market. These were fitted to some left hand drive Nissan Cefiros exported from Japan new. Mechanically, the RB24S combines an RB30E head, RB25DE/DET block and RB20DE/DET crank with 34 mm height pistons. The resulting bore and stroke combined to form a inline-six engine.

This engine used carburetors instead of the Nissan ECCS fuel injection system. It is able to rev higher than the RB25DE/DET (as it has the same stroke as the RB20DE/DET) as well as being almost the same displacement as the RB25DE/DET. A common modification is to fit a twin cam head from other RB series motors while retaining the carburetor set-up. The standard single cam form produced at 5,000 rpm and of torque at 3,000 rpm.

RB25 (2.5L I6)

The RB25 series of engines was first introduced in the R32 Nissan Skyline GTS25 sedan and coupe models in 1991. The RB25DE (naturally aspirated) and DET (turbocharged) variants produced from August 1993 also featured NVCS (Nissan Variable Cam System) for the intake cam. This gave the new RB25DE more power and torque at lower rpm than the previous model. From 1995 (series 2 engines), both the RB25DE and RB25DET had a revised electrical system and the turbocharger on the RB25DET(S2) had a ceramic turbine wheel rather than aluminium. The most obvious change to the system was the introduction of ignition coils with built in ignitors, therefore the coil ignitor that was on previous models was not used. Other changes were a different air flow meter, ECU, cam angle sensor and throttle position sensor. Mechanically the series 1 and 2 are very similar, the only mechanical difference would be the camshafts as the series 2 cam angle sensor's shaft that goes into the exhaust cam is slightly different. Early series 2 featured the traditional Mitsubishi CAS which was later swapped for the Black Hitachi CAS which used a grooved shaft because of a half circle positioning tooth which occasionally broke off when removing CAS.

In May 1998 a NEO head was fitted, which enabled the engine to be classified as a low emission vehicle (LEV) engine due to their lower fuel consumption and emission output. The NEO head featured solid lifters (needing adjustment over time) rather than hydraulic (self adjusting), revised camshafts (higher lift lower duration to complement smaller ports and torque), with on/off solenoid variable VCT, used a hotter thermostat, model-specific coil packs and a revised inlet manifold (the runner diameter is reduced from to increase air velocity and low end torque) in particular the RB25DE NEO which had two inlets going into the inlet manifold. The combustion chamber of the head is smaller so model-specific pistons are used to compensate. The turbo received the larger OP6 turbine wheel, while some came with an aluminium compressor and super alloy turbine wheels, others had the nylon plastic compressor wheel and ceramic turbine wheel. Turbo engines were upgraded to use GT-R spec connecting rods. Some also used an N1 type oil pump and had the oil pump drive collar on the crank revised to help cope with the breakage problems associated with fast, high revs. All in all they are quite a different engine in their own right — a culmination of 20 years of Nissan RB engine building rolled into one.

The non-VCT, non-turbo RB25DE was fitted to the R32 Skyline, the VCT turbo and non-turbo was fitted to R33 Skylines and the WNC34 Stagea and the Laurel C34. R34 Skyline, C35 Laurel and later Stagea (WGNC34) models use the NEO RB.

The 2.5 L RB25 engine was produced in four different forms:

RB25DE twin-cam, non-turbo with 10:1 compression ratio Power: at 6000 rpm Torque: at 4000 rpm RB25DET twin-cam, turbocharged (T3 Turbo) with 9:1 compression ratio Power: Torque: RB25DE NEO twin-cam, non-turbo with 10:1 compression ratio Power: at 6000 rpm Torque: at 4000 rpm RB25DET NEO twin-cam, turbocharged (T3 Turbo, "45V3" with OP-6 compressor) with 9:1 compression ratio Power: at 6400 rpm Torque: at 3200 rpm)

RB26 (2.6L I6) RB26DE The RB26DE is a naturally aspirated variant of the RB26DETT made specifically for the 1992 Nissan Skyline Autech Version GTS-4 (HNR32) sedan. Mechanically, it is similar to the RB26DETT as it uses the same cylinder head, bore and stroke () and individual intakes as the RB26DETT, minus the usage of a parallel twin-turbo system. The engine and ECU (engine control unit) were tuned by Autech and S&S Engineering to make at 6,800rpm and at 5,200rpm. It also has a higher compression ratio than the RB26DETT, at 10.5:1.

RB26DETT

The RB26DETT engine is a twin-turbo inline-six engine manufactured by Nissan, for use in the 1989-2002 Nissan Skyline GT-R. The RB26DETT engine block is made from cast iron, while the cylinder head is made from aluminium alloy, which contains DOHC 4 valves per cylinder (24 valves in total) setup. The intake of the RB26DETT varies from other RB-series motors in that it has six individual (3 sets of 2 throttle assemblies that are siamesed together) instead of a single throttle body. The engine also uses a parallel twin-turbo system, using a pair of T25-type ceramic turbochargers set by the wastegates to limit boost pressure to , although the Skyline GT-R has a built in boost restrictor to keep boost under .

The first 2.6 L RB26DETT was rated by Nissan at around at 6,800 rpm and at 4,400 rpm. By the end of production, power levels had gone up to around at 6,800 rpm and at 4,400 rpm, not only because of developments and modifications to the engine, but also because of the "Gentlemen's Agreement" made between automakers at the time to limit the "advertised" horsepower of any vehicle to . While the published figures from Nissan were as quoted above, it has been known among enthusiasts that the car actually had a factory power output closer to the figure. The RB26 is widely known and became quite popular for its strength and power potential thanks to its iron block and forged internals, making it a modification friendly platform for tuners and aftermarket modifications in general.

Duration Lift Camshaft Intake Exhaust Intake Exhaust RB26DETT (05U) 240° 236° RB26DETT N1 (24U) 240° 236° Some factory features of the RB26DETT: 6 throttle body intake Solid lifter valve actuation, shim under bucket Belt driven cams CAS (crank angle sensor) driven off exhaust cam, tells ECU (engine control unit) crank/cam position water cooled, oil pressure lubed turbos OEM cast pistons have cooling channels under the crowns (extra oil cooling to keep piston temperatures down) Piston oil squirters Sodium filled exhaust valves 8 Counter weighted crankshaft 'I' beam connecting rods

There is a common oiling problem with the pre-1992 R32 RB26 motors, as the surface where the crankshaft meets the oil pump was machined too small, eventually leading to oil pump failure at high rpm. This issue was resolved in later versions of the RB26 with a wider oil pump drive, which is found in all Series 3 R32 and onward RB26 motors. Aftermarket performance parts makers also make oil pump extension drive collars to rectify this problem. More recently a spline drive solution has been developed by an aftermarket tuner Supertec Racing who moves away from the OEM flat drive system and uses splines to drive the oil pump gears in the same way as the Toyota's 1JZ-GTE engine found in the Toyota Supra (MK3). This kit is available for most uprated RB26 oil pumps including Nissan's own OEM, N1 and Nismo parts, although most high HP RB-series engines all over the world have been proven to be reliable without spline driven oil pumps when built and tuned correctly.