The Nissan RB26DETT Engine Manual. Nissan debuted the RB26DETT engine in 1989, packing it inside the newly reborn Skyline GT-R (R32). Since then, it has firmly established itself as one of the world’s most legendary tuner engines. Even detractors admit the RBDETT’s great power, high revving, solid reliability, and just wonderful sound. Nissan stopped producing the RB26DETT in 2002, and NISMO has only lately begun producing RB26DETT parts again.
The RB26 was released just a few years before Toyota launched their JZ engine series in the A80 Supra, and the RB26 vs 2JZ argument has raged ever since. While the Supra is a fantastic car, the RB series has long been the preferred powertrain. Though, unlike the 2JZ, the RB26 was never sold in the United States, it still has legions of American fans.
This book will cover all you need to know about the magnificent RB26DETT engine found inside the R32-R34 Skyline GT-R, beginning with a brief history of the engine before delving into technical specs, engine specs, typical problems, and, most importantly, performance and modifications.
History of the Nissan RB26DETT Engine
The RB26DETT was first seen beneath the hood of the 1989 Skyline GT-R (R32). The GT-R had been out of production for more than a decade since the early 1970s, and Nissan brought it back to compete in Group A road racing as a more powerful version of the Skyline GTS-R, powered by the 2.0L RB20DET, which Nissan stroked and bored to create the 2.6L RB26DETT for the GT-R.
The RB26DETT engine was produced until 2002, when it was replaced by the VQ and, subsequently, VR Nissan engine series. The RB26 was primarily utilised to power the GT-R Skyline (R32-R34), but it was also used in Autech tuned versions of the Stagea 260 RS (WC34). Tommykaira, a well-known Japanese tuner, also used a highly tuned version of the RB26DETT in his Tommykaira ZZII concept car. However, after the design was purchased by AutoBacs Seven, he never released the ZZII to the public.
In the United States, the RB26DETT
Nissan never offered the RB26DETT in the United States, and its popularity in the country can be traced entirely to media appearances. JDM manga comic books such as “Initial D” and “Wangan Midnight” were popular, as were video games and movies. RB26DETT-powered Skyline GT-Rs were prominently featured in early “Gran Turismo,” “Need for Speed,” and “Forza” video games. Films such as “Fast and Furious” featured Skylines, including Paul Walker’s renowned R34 GT-R, and there were rumours among car aficionados about the secretive “Mid Night Club” street racing club in Japan that featured GT-Rs.
RB26-powered Nissans are finally legal for import into the United States, some two decades after their initial heyday. Anything built before 1997 is legal as of 2022, and there are already hundreds of RB26 Skylines tearing around the states. Only more will follow, especially when the legendary R34 GT-R becomes available in 2024.
Technical Data for the Nissan RB26DETT
Vehicle Applications for Nissan RB26
The Nissan RB26DETT engine was found in the following vehicles:
- Nissan Skyline GT-R (E-BNR32) 1989-1994
- Nissan Skyline GT-R (E-BCNR33) 1995-1998
- Nissan Skyline GT-R (GF-BNR34) 1999-2002
- Nissan Stagea 260 RS (WC34) (Autech Tuned Version) 1997-2001
Engine Specifications for the Nissan RB26DETT
The Nissan RB26DETT engine is a 2.6-liter inline-six twin-turbocharged engine. RB – “RB” engine series; 26 – 2.6 l displacement; D – Dual overhead camshafts (DOHC); E – Electronic fuel injection (EFI); and TT – twin turbochargers.
The RB26 is built with a cast iron block and an aluminium alloy head. The valve train is a DOHC with twin cams and four valves per cylinder, giving the engine a total of 24 valves. The RB26 lacks variable valve timing (VVT), which Nissan did not include in their engines until the early 1990s. The intake cams have 8.55mm (0.338″) of lift, and the exhaust cams have 8.28mm (0.326″). They both have a 240° intake duration and a 236° exhaust duration. Nissan provided sodium-filled exhaust valves for cooling and solid lifters for actuation on the RB26.
Nisan thoroughly designed the engine to compete and comply inside the FIA requirements for Group A racing. The size and stroke are 86mm x 73.7mm (3.39′′ × 2.90′′), making it a big bore yet short stroke engine. This enables a roaring high-rev 8,000 RPM red line, which sounds absolutely fantastic when struck.
Nissan equipped the RB26 with hypereutectic aluminium alloy pistons and forged steel I-beam connecting rods. To prevent excessive heat, the RB26 incorporated piston-cooling oil jets as well as oil cooling ducts under the piston crown. The turbos are parallel, rather than sequential, and are built of ceramic by Garret. The compressor is housed in a T3 housing and has an A/R of 0.42. The turbine is a T-25 with a ceramic wheel and an A/R of 0.64.
Throttle Body RB26
The throttle body configuration on the RB26DETT is unusual. Throttle body is usually located between the intercooler and the intake manifold in turbocharged engines. The throttle body, on the other hand, is located between the intake manifold and the cylinder head on the RB26DETT. The RB26 really has six throttle bodies rather than one. Throttle bodies are divided into three groups of two assemblies each, and they are all linked together. They are 45 mm in length.
On higher horsepower RB26DETT engines, a common mod is to replace the individual 45 mm throttle bodies with a single 90 mm throttle body located between the intercooler and manifold. This has been shown to boost torque over the power spectrum without sacrificing peak power. It’s really only helpful on higher-powered setups, although it can have some amazing consequences.
The N1 and DE variants of the RB26DETT
The NISMO RB26DETT N1 is a high-performance variation of the RB26. It shared many of the same components as the normal RB, but with a few power and performance enhancements. The T-25 turbos were modified from journal bearing to ball bearing and were capable of producing 14 PSI of boost. For further strength, the ceramic wheels were converted to steel. Nissan also made some changes to the pistons to boost cooling.
Nissan designed the N1 block to be slightly different from the conventional RB26 block, and it is labelled with a 24U instead of a 05U to distinguish it. They upgraded the oil and water passageways for better cooling and to decrease overheating, which was a common complaint with normal RBs. Nissan also reinforced the rods and pistons to withstand the extra power required for FIA competition.
Nissan introduced the naturally aspirated variation of the RB26 in 1992, giving it the engine designation RB26DE. The RB26DE debuted in the 1992 Autech tuned Skyline model, with “specially-made Autech intakes, exhausts, camshafts, pistons, etc., and a specially tuned control computer.” To compensate for the lack of turbochargers, Nissan increased compression on the naturally aspirated RB26 to 10.5:1. The RB26DE’s power output was reduced to 217 horsepower and 181 pound-feet of torque.
Nissan RB26DETT Reliability and Common Issues
Even when tuned or modded, the Nissan RB26DETT has always been renowned for its above-average dependability. These engines will easily exceed 100,000 miles with regular care and mild improvements. While it’s unusual for any performance engine to last beyond 200,000 miles without being rebuilt, the RB26 is capable of doing so.
The RB26DETT’s principal flaws are widely regarded as bad pistons, a horrible oil pump, high-RPM misfiring, and faulty Air Flow Metres (AFM).
Pistons and Rods for RB26
The factory pistons are made of hypereutectic aluminium alloy and frequently exceed 400 horsepower. They are by far the weakest internal component of the RB26, and are frequently upgraded as one of the first parts of any RB build. Aftermarket forged pistons are a quick and straightforward solution to this problem.
The connecting rods are generally regarded to be good up to 450 horsepower before they fail. Some people have run much more on the stock rods, but if you plan on pushing big power, it’s a good idea to upgrade them. Despite the fact that the OEM rods are forged steel, they do not stand up consistently on higher power builds. A stronger set of aftermarket forged rods will perform far better and cost far less than a potentially snapped rod.
Misfires and problems with the RB26 oiling system
The main issue with the RB26, and indeed with the RB series in general, is oiling, both supply and recovery. The issue is primarily with pre-1992 RBs and is caused by the oil pump. It is primarily an issue at higher RPMs and is caused by the way Nissan designed the oil pump and crankshaft.
Essentially, Nissan designed the crankshaft oil pump drive with an excessively short drive portion, which frequently leads to early failure. Nissan fixed the problem on post-1992 RB26s, albeit RBs in general leave plenty to be desired in terms of oiling systems. On stock or moderate builds, the most common fix is to install an upgraded and ported wet sump oil pump from Tomei or HKS, along with a larger oil pan. Installing the Kiwi CNC billet dry sump pan and modular front differential is a good option for builds with more than 700-800 wheel horsepower.
Misfiring is another prevalent RB26 issue. Typically, the issue occurs between 4,500 and 5,500 RPM, and the engine stutters/hesitates/misfires. Almost always, this is due to faulty coil packs or, on rare occasions, faulty spark plugs. Changing out coil packs is usually enough to remedy the problem. High performance engines, such as the RB26, require spark plug and coil pack replacements significantly sooner than standard engines. If you frequently operate at high RPMs, you should easily change your plugs every 10,000-20,000 miles.
RB26 AFM Issues
Faulty Air Flow Metres (AFM) are another rather prevalent problem with the RB26. The most common issue with AFMs is dry solder joints, which occur when the solder dries and leaves no connection. This usually results in the car running excessively lean or rich, or in the car struggling to idle and not revving past 2,500 RPM. The solution is to either purchase an improved AFM part or just re-solder the joints for a better connection.
That covers all of the issues that the RB26 is commonly associated with. Overall, it’s a powerful engine that lasts a long time. Proper maintenance is essential, but with it, you can expect your RB26DETT to last a long time.
Performance and Upgrades for the Nissan RB26
The Nissan RB26DETT’s reputation did not emerge from thin air; it is capable of some serious performance. Though Nissan listed the rated horsepower of the RB26-equipped GT-Rs as 276 horsepower and 260 lb-ft of torque, that has always been regarded as a low estimate.
Because to the “Gentleman’s Agreement” that the main Japanese automakers signed, Nissan, Toyota, and Honda all pledged to keep their engines under 280 horsepower. They did this to discourage manufacturer horsepower battles, which are typical in America.
However, most manufacturers were known to disregard this, and several models are thought to far exceed the stated 280 hp limit. One of them was the RB26-powered GT-Rs, which were expected to produce more over 300 horsepower in the R33-R34.
Top 6 RB26DETT Modifications
Even at 280-300 horsepower out of the box, the RB26 has plenty of power potential. The following are the top six RB26DETT Performance mods:
- Downpipe
- Intake
- Boost Increase/Turbo Upgrade
- Intercooler
- Tuning
- Larger cams and the HKS V-Cam
RB26 Intake and Exhaust Upgrade
Upgrading the downpipe is one of the quickest, easiest, and greatest mods you can perform on the RB26. A complete 3″ downpipe will boost torque and horsepower while also allowing you to increase turbo spool. That means you’ll be boosting faster and harder, causing the RB26 to really pull in the lower RPM range. Obviously, you’ll want to keep Low Speed Pre-Ignition (LSPI) in mind with any small-displacement turbo engine, but the RB26 is quite capable with a downpipe.
A better intake will also add 5-15 horsepower. Larger cone or pod style filters (pods are most popular) can be used to replace the factory airboxes. Keeping the airbox in its original placement or shifting the filters even further to the side will give the coldest air possible.
Turbo Upgrades for the RB26
The next stage is to increase the boost on the OEM turbos or replace them with larger ones. The stock turbos are set to 10 PSI (14 PSI on the N1), but they can be boosted by 3-5 PSI for greater power. Another popular alternative is to replace the N1 turbo on stock RB26s.
The HKS 2510, HKS GTSS, HKS2530, and Garrett 2560r are all popular bolt-on turbos. All of these are normal bolt-on replacements that produce 350-450 horsepower and have a rapid spool. If you want to push more than 450-500 horsepower and use pump 91 or 93 fuel, you’ll probably have to forego the twin-turbo arrangement in favour of a massive single-turbo.
Intercooler Upgrade for the RB26DETT
If you’re increasing the boost pressure or installing a new turbo, you should inspect your intercooler. The intercooler is generally thought to be good until roughly 350 horsepower, at which point it becomes overworked. The ideal solution is to install a larger core intercooler with larger boost tubes. If you intend to run a huge turbo, you’ll need a larger and more efficient intercooler to prevent detonation and pre-ignition.
HKS V Cam System RB26DETT
As previously stated, the RB26DETT lacks VVT because Nissan did not launch it until the early 1990s and never included it in the RB26 series. HKS, on the other hand, devised a solution known as the V Cam system. The V Cam system adds VVT to the RB26, although it only works on the intake side.
The HKS V Cam system is available in three configurations: Step 1, Step 2, and Step Pro. The cams gain lift and duration with each stride, resulting in increased power. It is compatible with factory pistons for Step 1, but it is recommended that you update those anyhow if you plan on going to Step 2 or higher power levels. See the dyno graphic from HKS below, which compares their Step 1 V Cam System to the OEM cams.
Tuning the RB26DETT ECU
ECU tuning is our final recommended improvement for the RB26. While the stock system can handle an upgraded intake and exhaust, once you start cranking up the boost, you’ll want to get it tuned to keep your air-to-fuel ratios safe. The RB series of engines is prone to detonation, and you don’t want to blow up a beautiful setup due to a lack of tuning.
The A’PEXI Power FC, a standalone engine management system that is fully adjustable for the RB26, is by far the most common system for RB26DETT tuning. It comes pre-programmed with multiple base maps that may be used as is or adjusted for increased power.
Related : The Honda B18 Engine Manual
Supporting Mods for RB26
If you intend to build your RB26 via the aforementioned build method, you will undoubtedly require some supporting mods. At the very least, you should replace the water pump and oil pump, as well as install an oil cooler. Overheating and oil problems are the most common causes of RB series engine failure, and you should solve them first.
The next steps will be mostly determined on your build level. Anything over 300 horsepower will require larger injectors and a larger fuel pump. Pump petrol may generally be set at 1050 cc injectors on many builds, but if you want E85, you’ll need to pump that up past 2000 cc on big builds.
The pistons are reliable until about 400 horsepower, when they are known to break. The connecting rods survive a little longer, up to 450 horsepower, but they are just as likely to fail after that. On larger builds, forged pistons and stronger forged rods are the way to go.
When running higher than factory boost levels, you should consider updating the head gasket. there will leak sooner or later, and there is a simple fix that may be done to avoid future problems. After 400 horsepower, you’ll need a beefier clutch and flywheel. The factory clutch will not survive long, and you’ll need something to handle the GT-R’s notoriously violent AWD starts.
Legacy Nissan RB26DETT
Overall, the Nissan RB26DETT engine is one of the best Nissan has produced since the 1990s. It’s dependable, works admirably, and powered one of the most iconic JDM vehicles of all time. Though it is not the easiest engine to obtain in the United States due to the fact that it was never sold here, anyone who has imported an RB26 will tell you it is well worth the effort.
