Nissan RB26DETT Engine Guide

In 1989, Nissan introduced the RB26DETT engine to the world and packed it inside the freshly resurrected Skyline GT-R (R32). Since then, it has firmly established itself as one of the most legendary tuner engines in the world. Even critics acknowledge the RBDETT for making incredible amounts of power, revving high, having solid reliability, and sounding absolutely amazing. Nissan discontinued production on the RB26DETT in 2002, and only recently has NISMO started to produce RB26DETT parts again.

This guide is here to cover everything you need to know about the mighty RB26DETT engine inside the R32-R34 Skyline GT-R. We’ll look briefly at the engine’s history, before digging into the technical specs, engine specs, common problems, and most importantly, performance and upgrades.

Engine History

Nissan first brought out the RB26DETT under 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 ‘70s, and Nissan brought it back to compete in Group A road racing as a more powerful version of the Skyline GTS-R. The 2.0L RB20DET powered the GTS-R, which Nissan stroked and bored to create the 2.6L RB26DETT for the GT-R.

The RB26DETT lasted until 2002, when it was succeeded by the VQ and eventually VR Nissan engine series. Nissan mainly used the RB26 to power the GT-R Skyline (R32-R34), but they also put it in Autech tuned versions of the Stagea 260 RS (WC34). Famed Japanese tuner Tommykaira also put a highly tuned version of the RB26DETT in the Tommykaira ZZII concept car. However, he never released the ZZII to the public after the design was bought out by AutoBacs Seven.

Technical Specifications

Engine	RB26DETT
Model Years	1989-2002
Displacement	2.6 Liter (2,568 cc)
Aspiration	Twin-Turbocharged
Configuration	Inline-Six
Compression Ratio	8.5:1
Bore and Stroke	86mm x 73.7mm (3.39″ x 2.90″)
Valve Train	DOHC 4v/cy, 24 Valve total
Fuel System	Electronic Fuel Injection (EFI)
Head/Block Material	Aluminum/Cast Iron
Horsepower Output	276 horsepower (stated)
Torque Output	260 lb-ft of torque (stated)

Vehicle Applications

• 1989–1994 Nissan Skyline GT-R (E-BNR32)
• 1995–1998 Nissan Skyline GT-R (E-BCNR33)
• 1999–2002 Nissan Skyline GT-R (GF-BNR34)
• 1997–2001 Nissan Stagea 260 RS (WC34) (Autech Tuned Version)

Engine Specifications

The Nissan RB26DETT is an inline-six, twin-turbocharged engine with a displacement of 2.6 liters. The engine code RB26DETT can be broken down as follows: 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 has a cast iron block with an aluminum alloy head. The valve train is a DOHC with twin-cams and 4 valves per cylinder for a total of 24 valves on the engine. The RB26 does not have variable valve timing (VVT), which Nissan wouldn’t introduce in their engines until the early-‘90s. The intake cams have 8.55mm (0.338”) of lift, and the exhaust cams 8.28mm (0.326”) of lift. They both have an intake duration of 240° and exhaust duration of 236°. Nissan gave the RB26 sodium filled exhaust valves for cooling and solid lifters for actuation.

Nisan designed the engine extensively to compete and fit within the FIA regulations for Group A racing. The bore and stroke are 86mm x 73.7mm (3.39″ x 2.90″), and it is generally considered a big bore but short stroke engine. This allows for a screaming high-rev 8,000 RPM red line – which sounds absolutely glorious when it’s hit.

Nissan gave the RB26 pistons made from hypereutectic aluminum alloy, and I-beam connecting rods made of forged steel. The RB26 had piston-cooling oil jets to reduce excessive heat, as well as oil cooling channels under the piston crown. The turbos are set up as parallel, rather than sequential, and are ceramic and made by Garret. The compressor has a T3 housing with an A/R of 0.42. The turbine is T-25 with an A/R of 0.64 and a ceramic wheel.

The RB26DETT N1 and RB26DE Variants

NISMO created a high-performance variant of the RB26, known as the RB26DETT N1. It had a lot of the same parts as the standard RB, but with a few upgrades for power and performance. The T-25 turbos were upgraded from journal-bearing to ball-bearing, and ran 14 PSI of boost. The ceramic wheels were also upgraded to steel for increased strength. Nissan also made some improvements to the pistons for better cooling.

Nissan made the N1 block slightly different than the standard RB26 block, and is marked with a 24U instead of 05U to differentiate it. They gave it improved oil and water passages for better cooling to reduce overheating, a common complaint on the standard RBs. Nissan also strengthened the rods and pistons to handle increased power for FIA competition.

In 1992, Nissan released the naturally aspirated variant of the RB26 and gave it the RB26DE engine code. The RB26DE appeared in the 1992 Autech tuned Skyline variant, and had “specially-made Autech intakes, exhausts, camshafts, pistons, etc., and a specially tuned control computer.” Nissan raised the compression on the naturally aspirated RB26 to 10.5:1 to accommodate for the lack of turbochargers. Power was down on the RB26DE to 217 horsepower and 181 lb-ft of torque.

Common Problems and Reliability

The Nissan RB26DETT has long been praised for its above-average reliability, even when tuned or modded. In general, with proper maintenance and moderate upgrades, these engines will easily push past 100,000 miles. While it’s atypical for any performance engine to be strung out past 200,000 miles without a rebuild, the RB26 is capable of lasting for a very long time.

The main weak points of the RB26DETT are commonly considered to be weak pistons, terrible oil pump, high-RPM misfiring, and faulty Air Flow Meters (AFM).

Pistons and Rods

The factory pistons are hypereutectic aluminum alloy, and often let go past 400 horsepower. They are by far the weakest part of the RB26 internally, and people commonly upgrade it as one of the first parts of any RB build. Aftermarket forged pistons are a pretty quick and easy fix for this problem

The connecting rods are generally thought to be good to around 450 horsepower before they become compromised. Some people have run much more on the stock rods, but it’s a good idea to upgrade them if you plan on pushing big power. Even though the factory rods are forged steel, they do not hold up reliably on bigger power builds. A stronger set of aftermarket forged rods will do much better, and are much cheaper than a potentially snapped rod.

Oiling System Issues and Misfires

The biggest issue on the RB26, and really the RB series in general, is oiling, both in terms of supply and recovery. The problem is mainly related to pre-1992 RBs, and is due to the oil pump. It mainly is an issue at higher RPM, and is due to how Nissan designed the oil pump and crankshaft.

Basically, Nissan made the crankshaft oil pump drive with too short of a drive section, which often leads to premature failure. On post-1992 RB26s Nissan corrected the problem, though RBs in general leave something to be desired oiling-system wise. The most common fix on stock or moderate builds is going to be getting an upgraded and ported wet sump oil pump from Tomei or HKS, along with a larger oil pan. For builds above 700-800 wheel-horsepower, installing the Kiwi CNC billet dry sump pan and modular front differential are good options.

Another common RB26 problem is misfiring. Usually, the problem will occur between 4,500 – 5,500 RPM and the engine stutters/hesitates/misfires. Almost all of the time people find this turns out to be faulty coil packs, or occasionally faulty spark plugs. Usually, swapping out coil packs is enough to solve the problem. High performance engines, like the RB26, need spark plug and coil pack changes much sooner than normal engines. Especially if you like operating in the high RPM often, you’ll want to be changing your plugs every 10,000-20,000 miles easily.

AFM Problems

Another somewhat common issue for the RB26 are faulty Air Flow Meters (AFM). The problem with most AFMs is dry solder joints, as the solder dries up and leaves no connection. This generally results in the car either running very lean or rich, or the car will struggle to idle and won’t rev past 2,500 RPM. Either buying an upgraded AFM part is the solution, or simply re-soldering the joints for a better connection.

Those are really all of the problems the RB26 can be said to be commonly associated with. Overall, it’s a very stout engine that lasts a very long time. Proper maintenance is key, but with that you can expect long life from your RB26DETT.

Performance and Upgrades

The Nissan RB26DETT did not get its reputation out of nowhere, it is capable of some serious performance. Though Nissan listed the rated horsepower of the RB26-equipped GT-Rs at 276 horsepower and 260 lb-ft of torque, that’s always been considered a low estimate.

Due to the “Gentleman’s Agreement” that the major Japanese auto manufacturers engaged in, major companies like Nissan, Toyota, and Honda all vowed to keep their engines below 280 horsepower. They did so as to discourage horsepower wars between manufacturers – like is commonplace in America.

However, most companies were known to be ignoring this, and several models are thought to greatly exceed the stated 280 hp limit. One of them was the RB26 powered GT-Rs, which most estimate to make north of 300 horsepower in the R33-R34.

Top 6 RB26DETT Mods

Still, even with 280-300 horsepower stock, the RB26 still has some serious headroom for power. Here are the top 6 RB26DETT Performance mods:

• Downpipe
• Intake
• Increasing Boost/Turbo Upgrade
• Intercooler
• Tuning
• HKS V-Cam and larger cams

Upgrade Intake and Exhaust

One of the quickest, easiest, and best mods you can do on the RB26 is upgrade the downpipe. A full 3” downpipe will increase torque and horsepower, while also allowing for increasing turbo spool. That means you’ll boost quicker and harder, making the RB26 really pull in the lower-RPM range. Obviously, on any small-displacement turbo engine you’ll want to keep Low Speed Pre-Ignition (LSPI) in mind, but the RB26 is pretty capable with a downpipe.

An upgraded intake will also add about 5-15 horsepower. The factory airboxes can be replaced with larger cone or pod style filters (pods are most popular). Keeping the factory location of the airbox or moving the filters even further toward the side will provide the coldest air possible.

Turbo Upgrades

The next step is increasing the boost on the factory turbos or upgrading to larger ones. The factory turbos run 10 PSI (14 PSI on the N1), but can be increased 3-5 PSI for more power. Also, swapping out the N1 turbo on the standard RB26s is another popular option.

Popular bolt-on turbos are the HKS 2510, HKS GTSS, HKS2530, and Garrett 2560r. All of these are standard bolt-on replacements that will make between 350-450 horsepower with a quick spool. If you’re thinking about pushing more than 450-500 horsepower, and you’re using pump 91 or 93 fuel, you’ll probably have to ditch the twin-turbo setup and go with a big single-turbo.

Intercooler Upgrade

If you’re increasing the boost pressure, or adding a new turbo, you’ll want to take a look at your intercooler. Generally, it’s accepted that the intercooler is good until around 350 horsepower, at which point it becomes overworked. Getting a larger core intercooler with larger boost tubes is the best way to handle the problem. Especially if you plan on running a big turbo, you’ll want a larger and more efficient intercooler to prevent detonation and pre-ignition.

HKS V Cam System

As we mentioned earlier, the RB26DETT does not have VVT, as Nissan did not introduce that until the early-‘90s and never put it in the RB26 series. However, HKS developed a solution known as the V Cam system. While it only works for the intake side, the V Cam system adds VVT to the RB26.

The HKS V Cam system comes in three options, Step 1, Step 2, and Step Pro. With each step, the cams get more lift and duration, equating to more power. It is compatible with stock pistons for Step 1, though it’s a good idea to upgrade those anyways if you plan on Step 2 or above power levels. See the dyno plot below from HKS showing their Step 1 V Cam System vs the stock cams.

ECU Tuning

Our final suggested upgrade for the RB26 is ECU tuning. While the stock system can take an upgraded intake and exhaust, once you start turning up the boost you’ll want to get it tuned to make sure your air-to-fuel ratios are staying safe. The RB series of engines is susceptible to detonation, and you don’t want a beautiful setup to get blown to bits due to a lack of tuning.

By far the most popular system for RB26DETT tuning is the A’PEXI Power FC. The A’PEXI is a standalone engine management system that is fully customizable for the RB26. It comes pre-programmed with several base maps that can either be run themselves or tweaked for more power.

Nissan RB26DETT Legacy

Overall, the Nissan RB26DETT engine is one of their finest creations since the 1990s. It’s reliable, performs incredibly, and powered one of the most legendary JDM cars of all time. Though it’s not the easiest engine to get in the US, because it was never sold here, anyone who has imported an RB26 will tell you it’s worth it.

If you’re lucky enough to drive an RB26DETT powered vehicle share your story with us in the comments below!