The Comprehensive RB26 engine guide

"RB26DETT and N1 Tuning"

The RB26 engine came into production in 1989 until 2002 and was fitted to the GTR R32. The RB26 was homologated for GroupA Touring cars, so they have decent crank and rods and overall the design lends itself nicely to tuning and upgrades.

It has become a firm favourite for tuners today, a reputation earned in part thanks to it's solidity and high revving nature. We get many questions and enquiries for tuning the RB26 so we've collated our replies, suggestions and recommendations from our readers into this article.

Interestingly the RB26DETT often finds its way into other cars such as the Silvia, 300zx and 350Z.

Nismo took an RB26 and tweaked this to a 2.8 and extracted an impressive 510 bhp and 540 Nm (400 lbft) of torque

Thankfully there are lots of performance parts and upgrades around today for it. The primary aim for RB26 tuning is to get the power on early in the rpm band.

The RB26 was a logical advancement to the RB25. The longer stroke of 2mm makes an extra 0.1 liter of displacement. They also generally rev happily to higher RPM's thanks to the solid lifters as apposed the Hydraulic ones on the RB25, The RB26 is also better designed to resist detonation (piston ring location.)

The Gold top, N1 edition of the RB26DETT was introduced to make more power and is generally considered the best base to work on in your tuning project.

It used a Garrett M24 Turbo and had cylinder block improvements particularly better cooling and oil delivery. The N1 has a much better water and oil pump which make good upgrades to the standard RB26 engines if you are on a budget but ideally you should look to aftermarket part suppliers namely, Tomei, Jun and Greddy for oil and water pumps.

The rods and pistons were stronger on the N1 so you have a better base to work from.

There are so many options for the RB26DETT you need to decide your power target first and plan from there.

The standard engine is very well built and unusually for a production car engine you can see around 600bhp reliably if the supporting engine components can deliver enough fuel and air to attain this level of power.

We are often asked whether to go MAP or AFM, we find the AFM's can be a pain and generally see much better results with a MAP sensor.

When tuning over 340bhp the standard turbos can struggle. The N1 again offers an upgraded turbo which can provide more air helping you push power levels to 400.

The HKS 2510 or 2530, Garret T3 are good options for a power boost on daily driver thanks to the low lag they offer.

Extending exhaust or intake durations can alter the bhp band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

Please watch our video which covers the 9 best mods for tuning your RB26 Engine. Be sure to keep up with our latest YouTube content and subscribe.

Best Engine Mods for your car

  1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

Typical stage 1 mods often include: Remaps/piggy back ECU, Intake manifolds, Panel air filters, Sports exhaust header/manifold, Fast road camshaft, drilled & smoothed airbox.

Typical stage 2 mods often include: high flow fuel injectors, induction kit, fuel pump upgrades, Ported and polished head, Fast road cam, Sports catalyst & performance exhaust.

Typical stage 3 mods often include: Engine balancing & blueprinting, Adding or Upgrading forced induction (turbo/supercharger), Crank and Piston upgrades to alter compression, Competition cam, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves).

A triple plate clutch is also a good investment as this will ensure that power is not lost through clutch slip.

Be prepared to set aside a full years salary to fund your RB26 tuning project beyond the 400bhp level. Cutting corners will cost a fortune in repairs and redoing modifications to a higher standard.

Engine management is an essential in any tuning project and our in house RB26 fans always suggest a Link G4+ (or a G4 with an external knock control unit) or Syvecs ECU (the upgdated data logging feature is extremely useful).

RB26 DETT Turbo upgrades

Big upgraded turbos will usually suffer low end lag, and little turbos spool up quickly but don't have the high rpm engines power gains.

the market of turbo units is always increasing and we commonly find variable vane turbo units, where the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbo units divert the exhaust gases into 2 channels and push these at differently angled vanes in the turbocharger. They also increase the scavenging effect of the engine.

You'll commonly see there's a limitation in the air flow sensor AFM/MAF on these engines when a lot more air is being pulled into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting power at a much lower level.

Big turbo or twin turbo?

The debate rages on. Having installed a modern GTX large turbo with billet turbo which was setup to produce similar boost to the stock setup we can confirm it outperforms the stock twin turbo setup throughout the entire rev range. Be careful with the top end though if you're running stock internals, a big turbo makes much more power.

The newer and better twin scroll turbos from Borg Warner (EFR's) are absolutely stunning and deliver power right across the rev range.

Note we are here comparing a cutting edge modern big turbo, with the latest flow optimisations and characteristics with 20 year old twin turbo technology.

If you compare a modern big turbo with a modern twin turbo you'll blur the advantages. Stick with stock internals then we'd say go with a twin turbo setup. If you are chasing bigger power and are prepared to do strengthening work then a big turbo wins hand down.

Big single turbo conversions are worth doing as an upgrade on all RB26's in our opinion, the designs are quite modern and you get good low down power and massive top end potential. On the high revving stock engine internals you should only reliably run low boost (around 9psi).

Uprate the internals and you can safely use the top end from the bigger turbos.

The twin turbo design works well and has a logical upgrade path allowing you to hit much higher power figures without the lag you get with some older large turbo setups.

Currently (2017) the choice turbo for an RB26 is a Borg Warner EFR. The way the RB26 engine fires makes a twin scroll turbo intake a solid bet for upgraders.

On the twin turbo exhaust gases  is fed from the alternate cylinders so one uses 1,2 and 3 and the other is fed from 4,5 and 6. This smooths out the uneven exhaust pulses and when you upgrade to a big single turbo you really want the turbo to spin smoothly.

A twin scroll turbo feeds the exhaust flow evenly into the turbo intake, and the turbo turbine profile is further tuned for each scroll.

This is why the twin scroll headers look so complicated but all of this combines to help smooth out the exhaust flow and gives a fast spool up and smooth power delivery. The manifold lengths into the turbo are carefully designed and shaped to aid a smooth flow of exhaust at the correct time.

400-650 bhp tuning tips

Going over 400 bhp requires some serious turbo upgrades. The GT2530 was a popular option for large power gains but we recommend the newer and better twin scroll Borg Warner EFR 8174 or the larger EFR 8374 (good for 500-800bhp).

You'll need to upgrade your brakes, suspension and clutch when tuning a car. We see too many projects that focus on power gains and ignore handling and power delivery.

For larger power gains to around 650 bhp we would recommend a 1.2mm metal head gasket, NGK heat range 8 Sparkplugs when running 1.4 boost or more. It makes sense also to fit race spec main bearings and a progressive boost controller.

An aftermarket ECU is harder to setup but gives better performance and helps you optimize the timing and fuelling to a fine degree of accuracy - we suggest you go for the Link G4+ (or a G4 with an external knock control unit) or the better but more expensive Syvecs ECU (the upgraded data logging feature is extremely useful).

Add in a high performance fuel rail, some 1000cc injectors and the EFR8374, GT2860-5 or GT2871R turbo with a good fuel pump (you should spec for around 280 litres per hour for this.)

Cams will make a large difference to the power band and should be considered if you are building a track day car, but for a road car don't go too aggressive with the cam profile.

Tuning to the 600-900 bhp mark will take some serious investment

For a little bit more power you could specify a HKS T04Z, or T88-34D turbo or preferably the Borg Warner twin scroll EFR 9180, fit a stroker kit which will take the RB26 to 2.8 litres and matched to a suitable flowed and ported cylinder head and forged internals will take power levels up to around 800bhp safely. RB30 is the next step for a large power project car.

Add in race spec wastegate, 3 layer radiator and intercooler, race spec head studs and big valve head conversion to stretch power towards the 870bhp levels.

Some of our members and RB26 owners have pushed around 800bhp on standard internals. We would recommend forged parts, and balanced parts for these higher power figures.

The engine does love to rev compared to many other high power engines and it would be a shame to restrict the rpm range because of weak or unbalanced internals.

RB26 DETT weak spots.

The weak spots, the oil pump was prone to fail under heavy load causing oil starvation. When you need oil more than at any other time this can cause significant damage to an engine.

The later N1 was fitted with an uprated oil pump which avoids this problem but there are better aftermarket oil pumps around from Tomei, Jun and Greddy.

Ignition coils can fail, evident as a misfire or flat spot. Replace these with higher spec parts should they start to fail.

The engines require regular servicing and fully synthetic oil of the correct grade if you are serious about maintaining it in good condition.

Please use the comments box below to add your tips and suggestions, we never consider our articles to be final and complete, and we are very grateful to readers for their suggestions, tips and comments to help keep us at the cutting edge and up to date.

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