Nissan RB20DET Engine Guide

Initially introduced in 1985, the Nissan RB20 series of motors has a long and storied history. Though they are not as popular as their bored out RB25 and RB26DETT siblings, the RB20 motors are still very capable. Probably the most sought out of the RB20s are the RB20DET and the ultra rate RB20DET-R engines. Nissan put the RB20DET in the Skyline from the mid-’80s to the early-’90s, while the R type was only available for a few months in 1987. For many years, the RB20DET was one of the top dogs for Nissan performance, producing just over 210 horsepower, stock.

This guide is here to cover everything you need to know about Nissan’s RB20DET engine and its variants. We’ll look briefly at the engine’s history, before digging into the technical specs, car applications, engine specs, common problems, and most importantly, performance and mods.

Nissan RB20DET Engine History

The RB series is the successor to Nissan’s L-series engine. In 1985, Nissan released the first engines in the RB20 series, and these included both naturally aspirated and turbocharged variants. The naturally aspirated variant was labeled the RB20DE, while the turbocharged variant was the RB20DET. There were also the RB20E, RB20ET, RB20P, RB20DET-R, and the RB20DE NEO variants.

Nissan first put the RB20DET in the 1985 Skyline GT/GTS/GTV/GTE (R31) and 1985 Fairlady Z 200ZR (Z31). The engine made between 180-190 horsepower, depending on the model Nissan put it in. Later, Nissan put the RB20 turbo in the Laurel and Cefiro models, too.

While Nissan ended production on the RB20DET in 1993, after introducing its successor the RB25DET, other variants still lived on. The RB20E lasted the longest, and Nissan still had it in production as late as 2002 in the Nissan Crew LS/LX.

RB20DET Engine Swaps

Following its end of production in the early-’90s, the RB20DET quickly became a popular engine for swaps. In the US, people have commonly swapped the RB20 turbo into the 200sx (S12) and 240sx (S13/S14) to upgrade the stock SR20DET and KA24DE.

It’s certainly not as popular or heralded as the RB26DETT or RB25DET, but the RB20DET still has many loyal fans and supporters. It also has a decent aftermarket community, both JDM and in the US, which is pretty incredible considering it was never offered stateside.

Nissan only sold the Skylines in Japan, and briefly in Europe and Australia, never offering them in North America. RB20s have been eligible for import into the US since 2010 though, so they have finally started to legally make their way over. Previously, the engines were typically only available as JDM/ADM imports.

Eventually, Nissan superseded the RB20DET with the RB25DET in 1993, and only the naturally aspirated variants remained in production for the next few years.

Nissan RB20DET Technical Specifications

Engine	RB20DET
Model Years	1985-1993
Displacement	2.0 L (1,998 cc)
Aspiration	Turbocharged
Configuration	Straight-Six
Compression Ratio	8.5:1
Bore and Stroke	78 mm × 69.7 mm (3.07 in × 2.74 in)
Valve Train	DOHC, 4v/cy; 24 Valve Total
Fuel System	Electronic Fuel Injection (EFI)
Head/Block Material	Cast Iron
Horsepower Output	180-215 horsepower
Torque Output	180-195 ft-lb of torque

Nissan RB20DET Car Applications

The Nissan RB20 series appears in the following cars:

RB20E (115–130 horsepower)

• 1985–1998 Nissan Skyline GT/GTV/GTE/GTS (R31; R32; R33; R34)
• 1988–1994 Nissan Cefiro (A31)
• 1988–1997 Nissan Laurel Medalist (C33; C34)
• 1994–2002 Nissan Crew LS/LX (K30)
• 1996–1997 Nissan Stagea 20 (WHC34)

RB20ET (170 horsepower)

• 1985–1989 Nissan Skyline GT (R31)

RB20DE (150-165 horsepower)

• 1985–1993; 1998-2001 Nissan Skyline GT/GTS (R31; R32; R34)
• 1988–1994 Nissan Cefiro
• 1988–1994; 1997–2002 Nissan Laurel Medalist (C33; C34; C35)
• 1997–2001 Nissan Stagea 20 (WHC34)

RB20DET (180-215 horsepower)

• 1985–1993 Nissan Skyline GT/GTS (R31; R32)
• 1985–1989 Nissan Fairlady Z 200ZR (Z31)
• 1988–1994 Nissan Cefiro (A31)
• 1988–1993 Nissan Laurel Medalist (C33)

RB20DET-R (205 horsepower)

• 1987 Nissan Skyline GTS-R Coupe
  • Only in production from May-November
  • Only on sale from August-September in Japan
  • 823 produced total, 4 of them prototypes

Nissan RB20 Engines Specifications

All of the engines in the Nissan RB20 series have straight-six configurations. The Nissan RB20 block and cylinder head are both made from cast iron, and the bore and stroke are 78 mm × 69.7 mm (3.07 in × 2.74 in). The engine code can be broken down as follows: RB – “RB” engine series; 20 – 2.0 liter displacement; D – Dual Overhead Camshafts (DOHC); E – Electronic Fuel Injection; T – Turbocharged.

Most of the RB20 series has a DOHC twin-cam valve train, with 4 valves per cylinder for 24 valves total. RB20 engines without the DOHC valve train are OHV with pushrods and only 12 Valves.

Nissan RB20E and RB20ET Engine Specs

Nissan created the RB20E as the first engine in the series, and it only made between 110-130 horsepower. The RB20E is an OHV pushrod engine, with 2 valves per cylinder, for 12 total, and has a short stroke crank.

Nissan also created a turbocharged version, the RB20ET, which bumped power up to 145-170 horsepower. It ran 7 PSI of boost and did not have an intercooler. All RB20E/T have a static compression ratio of 9.5:1.

Nissan RB20DE, RB20DE NEO Engine Specs

The RB20DE was based on the RB20E, but the valve train was changed from OHV to a twin-cam DOHC system. The cylinder head is different to accommodate the new valve train, and has dual shafts and 24 valves, compared with the single shaft 12 valve RB20E/T. The crankshaft, pistons, connecting rods, intake, ECU, and cams are all different and built for more power. Compression was 10.0:1.

The RB20DE cams have 232/240° lift and measure to 7.3mm (intake) and 7.8 mm (exhaust). These engines make between 150-165 horsepower depending on application. There is also a RB20DE NEO variant, too. Nissan gave these engines Nissan Ecology Oriented (NEO) technology on the cylinder heads to improve emissions and increase gas mileage. The NEO heads had solid lifters, instead of the hydraulic ones in the non-NEOs, and also had revised cams.

Nissan RB20DET Engine Specs

The turbocharged variant is the RB20DET, and it has lower compression at 8.5:1 to accommodate the boost. The turbo is a 16V turbo with a T3 flange and runs 7 PSI of boost. The connecting rods, pistons, crankshaft, head gasket, 270cc fuel injectors, and ECU were all different from the RB20DE.

The RB20DET from 1985-1987 is known as the Redtop model due to the red colored valve cover. These models had the Nissan Induction Control System (NICS). The NICS had a twin-runner design, with 12 individual runners for the six cylinders and used a coil-on-plug ignition system. The NICS intake manifold also uses a dual-stage induction system for better low-end torque.

The Redtop RB20DET cams had duration of 240° intake, 240° exhaust; 248° intake, 240° exhaust. The cams lift is 7.3mm intake, 7.8mm exhaust; 7.8mm intake, 7.8mm exhaust. These early RB20DET Redtops made 180-190 horsepower and came with air-to-air intercoolers.

Released in 1988, the Silvertop RB20DET switched to Nissan’s Electronic Concentrated Control System (ECCS) with a revised manifold. Most of the engine stayed the same, but a larger turbo was fitted and the ECU changed. Nissan rated the new Silvertop RB20DET at 215 horsepower, a healthy 20-30 horsepower bump.

The Ultra-Rare RB20DET-R Variant

Nissan very briefly released the RB20DET-R variant in 1987 specifically for the Skyline GTS-r coupe. Nissan specifically made this to compete under FIA rules in competition racing. Basically, the FIA changed some of the regulations for the 1987 season for “Group A” racing, but realizing that not all manufacturers would implement the changes so quickly into production models, they only required 500 “homologation” vehicles to be built that reflected the changes in order to compete that season.

500 sounds like a lot, but it was actually a substantial decrease from the normal 5,000 needed previously for homologation. Nissan specifically built the Skyline GTS-R – with the RB20DET-R – to compete in the 1987 season under FIA regulations. Since Nissan only needed to produce 500 models, production only lasted from May-November in 1987, and Nissan only made 823 total, including 4 prototypes.

They were only offered on sale from August-September in Japan, and are probably the rarest Skyline engines ever. It is similar to the standard RB20DET, but made about 205 horsepower (the normal RB20DET made 180-190 horsepower still) due to a larger T04E turbo, new tubular equal-length exhaust-manifold, unique dump pipe, larger throttle bottle, lightened flywheel, and a bigger and front mounted intercooler. The FIA competition racing versions made north of 400 horsepower.

RB20DET vs RB25DET vs RB26DETT Engines

The RB20DET is commonly compared with its larger siblings, the RB25DET and RB26DETT. The RB25DET has a larger turbocharger, while the RB26DETT has twin-turbos. Of the three, the RB20 is by far the most underpowered and least sought out. It is still a popular option for swaps, especially in Japan and Australia, but most people generally go with the larger RBs if they can find them.

Nissan RB20DET Common Problems & Reliability

Like the rest of the RB series, the RB20DET is known to be able to take some serious mileage. They can easily break the 100,000 mile (160,000 km) barrier with proper maintenance and care, and it’s not entirely uncommon for 200,000 mile (320,000 km) examples to appear.

The main thing to keep in mind on the RB20 series is going to be timely and proper maintenance. As we’ll get into, the RB series all have documented oiling issues. Making sure proper oil changes are done every 3-5,000 miles is incredibly important.

The timing belt is also known to be a weakness on the RB engines, and should be changed every 60,000 miles at the most. The RB20 is an interference motor, so a broken timing belt can have serious – and expensive – repercussions. On interference engines, when the timing belt breaks the valves do not fully close, which means the piston will run into the valve as it hits top dead center, which will bend or break the valve.

RB20 Crank Collar and Oiling Issues

The two big problems on the RB20 relate to the oiling system and crank collar. This isn’t specific to just the RB20 series, as the RB25 and RB26 have noted issues with the oil pump and oiling systems. They both suffer from this issue (early RB26 only).

RB20 Oil Control System Issue and Fix

The issue with oil control on the RB20 is that the oil pump pushes too much oil into the cylinder head in the upper RPM range. This leads to oil pooling on top and not draining back down into the oil pan because the oil return passages are too small.

While it’s not super common on street driven cars, on the track this can lead to serious oil starvation issues. Oil ends up coming out of the cam breathers and into the inlet system, taking it away from the rotating assembly which needs it.

To fix the RB20 oil control problems it takes five steps. First, you want to block off the rear oil feed gallery to prevent excess oil flowing into the head. Second, you want to add a restrictor to the open oil gallery to control the oil flow to the head better. Third, you’ll want to run an external oil line from the head to the sump for better drainage from the head. This Head Oil Drain Kit from Franklin Performance is made for the RB series.

Fourth, you’ll want to machine out the oil return galleries by 1mm for better drainage. Finally, you’ll want to machine around the galleries so they can take in the oil better (and thus drain it quicker). Additionally, after you have taken these steps, you can also run a larger sump and oil pump to increase oiling. For very high horsepower builds, a dry sump is the ultimate solution.

Here is an excellent guide with a more detailed step-by-step process to solve the problem. The guide also covers the below issue with the crank collar.

RB20 Crank Collar Issue and Fix

The problem with the RB20DET crank collar is because the part of the crank’s snout that touches the oil pump drive is too small and wears easily. Both the crank and the pump can become damaged, resulting in the oil pump gear cracking and breaking and a complete loss of oil pressure. The issue is exacerbated by repeated high RPM engagement, and as you can imagine, no oil pressure at high RPM means big problems. This is probably the most common issue on the RB20.

To fix the problem the stock crank collar needs to be machined off and a larger replacement put on that allows for more engagement of the inner oil pump gear. Here is an RB20 crank collar from Franklin Performance.

Apart from these two main issues, as long as adequate maintenance is kept up on the RB20 series will run for lots of miles.

Nissan RB20DET Performance and Mods

Stock, the RB20DET comes with 180-215 horsepower, depending on the year and model. It is very capable of upgrades and is one of the most modded Nissan motors out there. For most people in the US, their RB20DET is likely going to be swapped into an S12/13/14. In that case, you’ll definitely want to make sure you add some horsepower before putting it in. It doesn’t take a ton to make 300 horsepower in the RB20DET, and we’ll show you how below.

Nissan RB20DET Power Limits

The RB20 is considered a relatively stout engine and handles upgrades well, and it can take some serious power with minor internal upgrades, similar to its larger siblings the RB25DET and RB26DETT. The block itself is capable of well over 700 horsepower without issue and lots of boost. The pistons and connecting rods need to be upgraded at 450 horsepower. Head studs are also a good idea at those power levels, as are both the crank collar and oil control fixes listed above.

RB20DET Mod Guide

If you’re swapping in an RB20DET, 300 horsepower is a pretty safe minimum you’ll want to shoot for. Anything less and the swap probably isn’t that worth it. Realistically, a reliable RB20DET that won’t be too expensive will probably put you in the 300-450 horsepower range.

RB20DET Mods for 300-450 Horsepower

• Front Mounted Intercooler
• Full 3” Turbo-back Exhaust
• GTR Fuel Injectors (440 cc)
• GTR Fuel Pump (or Walbro 255/Bosh 044)
• GTR Fuel Lines (or aftermarket)
• ECU Tuning
• Turbo Swap

The first thing you’ll want to do is upgrade the stock side mount to a bigger front mounted intercooler and get a full 3” exhaust. Getting a larger intercooler will allow you to run more boost than stock, and will also drastically improve cooling. A full 3” exhaust, with a high-flow cat or catless dump pipe/J pipe, is needed for reduced back pressure. An intake is optional at this stage, but will add 5-10 horsepower if it’s truly free flowing.

After you’ve made these mods, you’ll want to look at upgrading the fueling. If you have access to GTR (RB26DETT) parts, those make easy swaps. If not, you’ll want parts that have similar performance. You’ll want 370-440cc injectors, an upgrade over the 270cc stockers, as well as a bigger fuel pump and fuel lines.

Next steps will be ECU tuning and a turbo upgrade. The stock turbo runs out of power at around 275 horsepower and 12 PSI, so you’ll need something bigger for 300+ horsepower. Some of the most popular RB20DET turbo upgrades  are the RB25DET stock turbo, RB26DETT T3/T28 stock turbos, VG30DET stock turbo, HKS 2530/2835 turbos, GCG high-flow turbo, Hx35 turbo, GT30R turbo, GT3037/S turbo, and Greddy TD06 turbo. All of these will put you between 300-450 horsepower, depending on other upgrades and supporting mods.

Nissan RB20DET Supporting Mods

In addition to the above mods, you’ll also want to keep these supporting mods in mind too. For starters, you will want to make sure you have taken care of the oil control fix mentioned earlier, and if you are building the engine from the start definitely get the upgraded crank collar. Besides that, you’ll want to get an upgraded water pump and larger N1 oil pump – keeping in mind the larger oil pump only helps if you have done the oil control mod. An upgraded intake is also a useful mod but not totally necessary until you get a larger turbo.

The stock internals, as we mentioned, are good until about 450 horsepower, after which you’ll want forged pistons and rods and head studs. Larger duration and higher lift cams are also a good upgrade once you start to reach the 400+ horsepower range but aren’t necessary.

Nissan RB20DET Legacy

Overall, the Nissan RB20DET engine is one of their finest creations of the ‘80s-’90s. While they might not be as heralded as the larger RB25/26, they are still fantastic motors. Stock, they provide adequate performance with exceptional reliability, and when modded they can provide some serious thrills. You can use the provided mod guide to turn your 180-215 horsepower run of the mill RB20DET into a full-fledged 300-450 horsepower beast.

Let us know about your RB20DET experience in the comments below! Also read some of our other RB engine and GT-R guides including a complete RB30 engine guide, VR38DETT engine problems, and 2JZ vs RB26.