Both SOHC and DOHC versions have an aluminum head. The SOHC versions have 2 valves per cylinder and the DOHC versions have 4 valves per cylinder, all cam lobes move only one valve. All RB engines have belt driven cams and a cast iron block. All turbo models have an intercooled turbo (except the single cam RB20ET & RB30ET engines), and most have a recirculating factory blow off valve (except when fitted to Laurels and Cefiros) to reduce boost surge when the throttle is closed.
Some sources indicate the 'RB' name stands for 'Race Bred', although this is disputed. The Nissan RB Engine is derived from the 6 cylinder Nissan L20A engine which has the same bore and stroke.
Bore and stroke
All Nissan engines follow a naming convention, identifying the engine family (in this case, RB), displacement, and features present- see the list of Nissan engines for detail.
The stock dimensions for the RB engines;
- RB20 - 2.0 L (1998 cc, bore: 78.0 mm, stroke: 69.7 mm)
- RB24 - 2.4 L (2428 cc, bore: 86.0 mm, stroke: 69.7 mm)
- RB25 - 2.5 L (2498 cc, bore: 86.0 mm, stroke: 71.7 mm)
- RB26 - 2.6 L (2568 cc, bore: 86.0 mm, stroke: 73.7 mm)
- RB30 - 3.0 L (2982 cc, bore: 86.0 mm, stroke: 85.0 mm)
- "D" indicates a double overhead cam as opposed to a single overhead cam
- "E" indicates the engine is electronically fuel-injected as opposed to carbureted
- "T" indicates the engine has a factory installed turbocharger
RB20
There were a variety of 2.0 L RB20 engines produced:
- RB20E - single-cam (85 to 96 kW (115 to 130 ps) @ 5600 rpm, 167 to 181 N·m (17 to 18,5 kgf·m) @ 4400 rpm)
- RB20ET - single-cam turbocharged (107 kW (145 PS) @ 6000 rpm, 206 N·m (21.0 kgf·m) @ 3200 rpm)
- RB20DE - twin-cam (110 to 114 kW (150 to 155 PS) @ 6400 rpm, 181 to 186 N·m (18.5 to 19 kgf·m) @ 5600 (and later with a NEO-Head 4400 rpm)
- RB20DET - twin-cam turbocharged (158 kW (215 PS) @ 6400 rpm, 265 N·m (27.0 kgf·m) @ 3200 rpm)
- RB20P - single-cam (94 PS @5600 rpm and 142 N·m @2400 rpm)
- RB20DET-R - twin-cam turbocharged (210 ps @6400 rpm and 245 N·m @4800 rpm
The first RB20E/ET/DE/DET engines were fitted to the R31 Skyline. The early twin cam engines are generally referred to as 'Red Top' engines because they have red cam covers. The early twin cam engines featured the NICS (Nissan Induction Control System) injection system, while the single cam engines always used ECCS (Electronically Concentrated Control System). Later 'Red Top' twin cam engines used in the R31 series Skylines from late 1987 onward use the ECCS system and a different intake manifold arrangement. The RB20E was also fitted to some Holden Commodores (the VL Commodore) sold in New Zealand, and also to the A31 Cefiro. The Z31 200ZR was fitted with an intercooled NICS type RB20DET.
Laurels, R32 Skyline and Cefiros used the second (1988-1993) 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). It is limited to 800 units.
The RB20P is the autogas LPG (Liquified petroleum gas) version of the RB20, but with 12 valves (OHC).
RB20E
RB20ET
RB20DETRB24S
This is a relatively unknown 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 it is made from an RB30E head, RB25DE/DET block and RB20DE/DET crank with 34 mm height pistons. This engine used carburretors instead of the Nissan ECCS fuel injection system. It is able to rev harder 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 carburreted set-up. The standard single cam form produced 141 PS @ 5000 rpm and 20.1 kgf·m (197 N·m) of torque @ 4400 rpm.
RB25
The 2.5 L RB25 engine was produced in three forms:
- RB25DE - NON - TURBO twin-cam 140 kW/190 PS and 147 kW/200 PS (with VCT) @ 6000 rpm, 255 N·m (26.0 kgf·m) @ 4000 rpm)
- RB25DET - twin-cam turbo (T28 Turbo) (245 to 250 hp and 319 N·m)
- NEO RB25DET - twin-cam turbo (206 kW (280 PS) @ 6400 rpm, 362 N·m (37.0 kgf·m) @ 3200 rpm)
RB25DE and DET engines 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.
In May 1998 a NEO head was fitted, which enabled the engine to be classified as a low emission vehicle engine (LEV). The non-VCT and non-turbo was fitted to the R32 Skyline, the VCT turbo and non-turbo was fitted to R33 Skylines and the WC34 Stagea. R34 Skylines also use these engines, but they are fitted with a NEO head.
RB25DET
NEO RB25DETRB26DETT
The RB26DETT engine is a 2.6L Inline-6 engine manufactured by Nissan, for use primarily in the 1989-2002 Nissan Skyline GT-R. The RB26DETT engine block is made from cast iron, and the cylinder head is made from aluminium. The cylinder head contains 24 valves (4 valves per cylinder), and uses a dual overhead camshaft setup. The engine also uses a parallel twin turbo system. The turbo system is arranged so that the front turbo is powered by the front 3 cylinders, and the rear turbo is powered by the rear 3 cylinders. The turbo chargers are of equal size, and are set by the wastegates to limit boost pressure to 14.7 psi, although the Skyline GT-R has a built in boost restrictor to keep boost under 10 psi.
It is often possible to produce 600hp without modification of the engine internals (by use of larger turbocharger, and either keeping the stock twin turbo arrangement, or using a single turbocharger). With extreme modification, the RB26 motor is capable of power in excess of 1 megawatt (or over 1,340 hp).
There is a common oiling problem with the pre-1992 R32 RB26 motors, as the surface where the crank meets the oil pump was machined too small, eventually leading to oil pump failure at high rpm. This was fixed for later versions of the RB26.
Originally the R32 GT-R was planned to have a 2.4L RB24DETT, and compete in the 4000 cc class (in Group A rules, the displacement is multiplied by 1.7 if the engine is turbocharged). This was when Nismo was going through the process of designing the R32 GT-R to be a Group A race car. But when the engineers added the AWD system, it would make the car heavy and less competitive. Nismo made the decision to make the engine a 2.6L twin turbo, and compete in the 4500 cc class, resulting in the RB26DETT known today.
The RB26DETT was used in the following cars:
- Nissan Skyline GT-R R32
- Nissan Skyline GT-R R33
- Nissan Skyline GT-R R34
- Nissan Stagea 260RS
- Tommy Kaira ZZ II
RB26DETT N1
The RB26DETT N1 is a modified version of the RB26DETT engine. Nismo (Nissan Motorsports) found that the standard RB26DETT engine required too much maintenance to use in a Group-A or Group-N race car. As an upgrade, Nismo balanced the crankshaft to a higher specification than stock, as the RB26DETT engine experiences vibrations between 7000 and 8000 rpm. The engine also has improved water channels within the engine block. The top piston rings were also upgraded to 1.2 mm. The N1 engine also received upgraded camshafts, and upgraded turbochargers.
Although all versions of the RB26DETT N1 engine use Garrett T25 turbochargers, the specification of the turbochargers changed through the 3 generations of the RB26DETT N1 engine (R32, R33, and R34). The R32, and R33 versions used Journal Bearing T25 Turbochargers. The R34 RB26DETT N1 engine used Garrett GT25 turbo chargers (which use a Ball Bearing, and has much faster response than a Journal Bearing due to reduced friction).
The biggest difference between the turbochargers used in the N1 engine, and the standard RB26DETT engine, is that the Turbine Wheels in the turbocharger are made from Steel, rather than the Ceramic used for the Standard RB26DETT turbochargers. The Ceramic turbine wheels are found to be very unreliable when used at higher temperatures (such as when the turbochargers are used at a higher boost pressure than stock).
RB26DETT Z2
This is the engine used in the Nissan Skyline GT-R Z-Tune. It uses the stronger RB26 N-1 block, modified with Nismo parts, bored and stroked to 2.8 L (87.0 x 77.7 mm). The end result was the RB28Z2, which produces 500 hp (368 kW) and 540 N·m of torque.
RB26DETT
RB26DETT Z2RB30
Three models of 3.0 L RB30 were produced:
- RB30S - carbureted single-cam
- RB30E - fuel-injected single-cam (114 kW @ 5200 rpm, 247 N·m (25.2 kgf·m) @ 3600 rpm)
- RB30E R31 Skyline - fuel-injected single-cam (117 kW @ 5200 rpm, 252 N·m (25.2 kgf·m) @ 3600 rpm)
- RB30ET VL Commodore - fuel-injected single-cam turbo (150 kW @ 5600 rpm, 296 N·m @ 3200 rpm)
This motor was produced because the Holden 202 (3.3 L) powering the Holden Commodore could no longer satisfy emissions requirements, and with all new cars required to run on unleaded petrol by 1986, a quick replacement was needed. Nissan Motor Co. sold the RB30E to Holden for the VL Commodore. The RB30E in the VL suffered from cylinder head cracking due to the radiator being fitted lower in the engine bay, causing air locks in the cylinder head. This was not as severe in R31 Skyline as the radiator is mounted higher. The engine proved to be very reliable apart from this issue. The RB30S was found in some Middle Eastern R31 Skylines and in some Nissan Patrols. The RB30E was found in R31 Skylines and VL Commodores in Australia as well as in South African R31 Skylines (with 126 kW @ 5000 rpm and 260 Nm @ 3500 rpm)
The turbocharged RB30ET (producing 150 kW) was found only in the VL Commodore (available in all Calais) and consisted of a lower compression RB30E bottom end, more powerful oil pump, T3 Garrett turbocharger, 250 cc injectors and a different intake manifold. The motor itself is still popular today (albeit in highly modified form) on the Australian Drag Racing circuit.
Nissan Special Vehicles Division Australia produced two limited models of R31 Skylines, the GTS1 and GTS2. These contained slightly more powerful RB30E engines, containing lumpier cams and better flowing exhausts.
- GTS1 RB30E - injected single-cam (130 kW @ 5500 rpm, 255 Nm (26.0 kgf·m) @ 3500 rpm) - special cam profile, special exhaust.
- GTS2 RB30E - injected single-cam (140 kW @ 5600 rpm, 270 N·m (27.5 kgf·m) @ 4400 rpm) - special cam profile, special exhaust, piggy back computer, valve porting.
RB30DE
These rare engines were used in the Tommy Kaira M30 based on the R31 Skyline GTS-R. A modified RB20DE head was bolted on to the RB30E block. It delivered 177 kW (240 PS) @ 7000 rpm and 294 N·m (30.0 kgf·m) @ 4800 rpm.
RB30DET
Nissan did not produce this engine, but it refers to a turbocharged engine featuring an RB30E block with a twin-cam head conversion. Common hybrid in Australasia using a RB30E bottom end mated to a RB25DE,RB25DET or RB26DETT cylinder head and turbo (RB20DE and DET heads are not used as the bores are different in size; RB30 86.0mm RB20 78.0mm). The RB25DE cylinder head from the R32 Skyline, A31 Cefiro or C33 Laurel can be used, and fits perfectly on (although better valve springs are required to prevent valve float when running any more than stock boost). The RB25DET (from the R33 Skyline or C34 Laurel or Stagea) head is also used, however an external oil feed must be fabricated for the variable cam timing on the RB25DET, and the galleries at the front of the engine do not line up. The variable cam timing may be disconnected altogether.
The fitment of a twin cam head from any of these engines onto a standard compression RB30E bottom end gives an ideal compression ratio for a mild to moderately modified street turbo engine, making the conversion popular amongst those who would otherwise convert their RB30E to a high compression RB30ET using original ET bolt on externals.
Although it has a larger displacement than the RB26DETT, maximum possible horsepower is less, as the RB30 block lacks the RB26 block's internal cast-in bracing, and consequently cannot rev as high due to harmonic issues at ~7500 rpm. To compensate, the RB30DET produces more torque at lower revs. There is also an 'RB30DETT' kit manufactured by OS Giken of Japan, which bolts an extension on top of the RB26 engine block, and fits liners, to give an 86 mm bore x 86 mm stroke. It is available as an assembled short block, containing billet chrome-molybdenum crank, billet chrome-molybdenum H-beam connecting rods, forged pistons, and costs ¥1,500,000.
RB-X GT2
The RB-X GT2 (also called REINIK) is an engine specially made for the Nismo 400R. The difference between this engine and a RB26DETT is that the engine is bored and stroked (87.0 × 77.7 mm) which results in 2771 cc. Engine gives out 400 PS (331 kW) at 6800 rpm and 47.8 kgf·m (469 N·m or 347 lbf·ft) at 4400 rpm. This engine comes with a reinforced cylinder block and cylinder head, metal head gasket, pistons with cooling channels, forged crank shaft, forged connecting rods, N1 turbine with reinforced actuator, high flow air cleaner, stainless down pipe, and low air resistance sport catalizer, most of which were not offered for the RB26DETT.
