RB20/25/26 Engine

RB20/25/26 Engine

The RB series of engines are among the most popular and desirable engines in today's enthusiast society. There is no other engine that sounds quite like a twin cam RB. They are known for a power-band that is smooth and increases as it progresses throughout the rpm range. Because of this, the RB engine can be one of the most exciting power-plants to pilot, that came out of Japan in the 90's. 



For information on the RB30 variant go to the RB30 Engine page.

Image result for rb26dett



 
Haltech Elite Series Setting
Value
Number of Cylinders
6
Capacity
2.0, 2.5, 2.6 Liters 
Firing Order
1-5-3-6-2-4

Engine Type
Piston 4 - Stroke
Injection Mode
Sequential
Number of Inj
6
Inj Flow/Size
240cc, 370cc, 440cc
Inj Current Setting
High
Low with Resistor Box removed for the RB26
Ignition Mode
Direct Fire
Ignition Edge
Falling
Ignition Dwell Mode
Constant Charge
Trigger Tooth Pattern
6 Evenly spaced windows, All window sizes are unique, Rising edge locked
Home Tooth Pattern
360 Evenly spaced windows, Rising edge locked
ESP Trigger Pattern
Nissan RB20, RB25, RB26
TDC Angle

109 is the base but, it does have an adjustable CAS so verifying this number is a necessity. 

Trigger Sensor Type
Hall
Trigger Sensor Edge
Rising (locked)
Trigger Filter Level
0
Trigger Pullup
Strong yields the best results.
Trigger Ground Ref
-
Home Sensor Type
Hall
Home Sensor Type
Rising (locked)
Home Filter Level
0
Home Pull-up
Strong yields the best results.
Home Ground Ref
-
Home Min RPM
-
Quick Start
Disabled (pattern does not support)
Notes







Model Variants

RB20DE

1998cc, aspirated, DOHC 24V head, 10.0:1 comp

RB20DET

1998cc, turbo, DOHC 24V head, 8.5:1 comp

RB25DE

2498cc, aspirated, DOHC 24V head, 10.0:1 comp

RB25DET

2498cc, turbo, DOHC 24V head, 8.5:1 comp, N-VTC.

RB25DE NEO

2498cc, aspirated, DOHC 24V head, 10.0:1 comp, N-VTC.

RB25DET NEO

2498cc, turbo, DOHC 24V head, 9.0:1 comp, different turbo from conventional RB25DET, N-VTC

RB26DETT (R32/R33)

2568cc, turbo, DOHC 24V head, 6x throttle ITB intake, Twin Turbos

RB26DETT (R34)

2568cc, turbo, DOHC 24V head, 8.5:1 comp, 6x throttle ITB intake, Twin Turbos, red valve covers







Injection System  

RB twin cam engines all share the same basic sequential fuel injection strategy.
Some models have a ballast resistor pack that should be bypassed if the injectors are to be changed.






Recommended Haltech ECU

The R32/33 platinum pro plugin found here: https://www.haltech.com/product/ht-055101-platinum-pro-plug-in-ecu/ is a very popular unit for mildly modified engines using oem harnesses and sensors. I always suggest the Elite 2000/2500 pnp kits found here: https://www.haltech.com/product/ht-151257-elite-2000-nissan-skyline-r32-r33-r34-gt-r/ and here: https://www.haltech.com/product/ht-151357-elite-2500-nissan-skyline-r32-33-r34-gt-r/ for those with heavily modified engines and aftermarket crank and cam triggers/sensors. If on a budget, the Elite 750 and a custom premium wiring harness found here:https://www.haltech.com/product/ht-150604-elite-750/ or plug and pin kit found here: https://www.haltech.com/product/ht-030009-plug-and-pins-only-amp-34-pin-4-row/, can be very capable. You will just be limited on inputs/outputs to the most basic functions. 





Sensor Information

CAS Crank Angle Sensor

The DOHC RB models all have a cam angle sensor located on the front of the engine driven by the exhaust cam.  One major issue with this is that the drive belt and camshaft vibrate at high RPM, with higher lift camshafts performing much worse.  They are also prone to debris blocking the slots or sensor beams causing triggering issues. 

The solution for all high power RB engines is to use a crank trigger kit, of which there are many suppliers.  Virtually all crank trigger kits are supported by the Elite ECU, with only a 12x crank tooth pattern being supported on the Platinum Pro range.  It is preferred to use a missing-tooth style pattern if it is available from the manufacturer when an Elite ECU is used, and either Hall or Reluctor can be used.





OEM Sensor

R32/33 Sensor shown below:
                  

R34 Sensor shown below:
 


Nissan CAS or crank angle sensor is a crankshaft position sensor driven from the exhaust cam. The CAS, sometimes called a cam angle sensor by mistake, and has an optical wheel inside that is driven at 1/2 of the crank speed.  It has two sets of sensors and slots inside. One set is 360 one for each degree of CAS rotation (not crank rotation). The other set is 6, or one for every 120 degrees of crank rotation. The signals are typically labeled as the 1 and 120 signals.  The 120deg signal is used as the Trigger and the 1deg signal is used as the Home.







Trigger and Home Wiring Hack

A common hack to make wiring simpler is to do the following:

In the Grey shielded Trigger 4-core cable we have 12V+, Signal Ground, Trigger+, and Trigger-.   We need all of these wires except for Trigger-
In the Grey/Black shielded Home 4-core cable we only need the Home+
If we relocate the Green Trigger- wire so that instead of going to this ECU pin it instead goes to the Home+ ECU pin we now have all of the wires we require in a single 4-core cable.

For Elite 550 / 750 / 950
1. Remove the Yellow wire from ECU pin A32 and insulate it. It will not be used.
2. Remove the Green wire from ECU pin A33 and move it to A32.

For Elite 1000 / 1500 / 2000 / 2500
1. Remove the Yellow wire from ECU pin B2 and insulate it. It will not be used.
2. Remove the Green wire from ECU pin B5 and move it to B2.



Trigger Configuration

Information is the same for all RB20/25/26 models












Igniter and Coils

Early models have an external 6-channel igniter module located on the rear section of the coil cover.  There were various ignition coil types used.  All use Constant Charge with a Falling edge.

Igniter

For models that have an external igniter, the wiring for them is labelled on the igniter itself

Pin
Function
Haltech Connection
I1
ECU Signal Cylinder 1
Ignition Output 1
I2
ECU Signal Cylinder 2
Ignition Output 2
I3
ECU Signal Cylinder 3
Ignition Output 3
G
Ground To Cylinder Head
No Connection
I4
ECU Signal Cylinder 4
Ignition Output 4
I5
ECU Signal Cylinder 5
Ignition Output 5
I6
ECU Signal Cylinder 6
Ignition Output 6
E1
Coil 1 Negative
No Connection
E2
Coil 2 Negative
No Connection
E3
Coil 3 Negative
No Connection
E4
Coil 4 Negative
No Connection
E5
Coil 5 Negative
No Connection
E6
Coil 6 Negative
No Connection



Coils

Wiring details are labelled on the coil

Early Coils (RB25 Series 1 and older) use an external igniter. They CANNOT be wired directly to the ECU.

Pin
Description
-
Igniter Module Signal
+
12V+ Switched
E
Ground (to head)





Later Coils (RB25 Series 2 and newer) have an internal igniter and can be directly wired to the ECU.


Pin
Description
IB
ECU Ignition Output
G
Ground (to head)
+
12V+ Switched





Dwell

Suggested dwell time for Nissan Coils










Throttle Position Sensor

The cable connection is used for Haltech ECUs, and NOT the connection directly on the sensor.





Pin
Description
Haltech Connection
1
Power
5V+ (Orange)
2
Signal
Spare AVI (AVI-10 White)
3
Ground
Signal Ground (Black/White)











MAP Sensor

The RB series of engines do not come with a factory map sensor. They are typically fitted with a MAF sensor for airflow monitoring. With that said, we typically use the onboard map sensor or one of our many external map sensor options found here: https://www.haltech.com/product-category/ecu-inputs-and-o2-wideband-controllers/map-sensors/

Some models have a MAP sensor present but this is only used for the boost gauge on the dash and is not connected to the ECU.











Variable Cam (N-VTC)

The RB25DET motors have the N-VTC (Nissan Variable Timing Control).  This is a switched variable intake cam control system and is supported by all Haltech ECU models with the control solenoid located near the fuel pressure regulator. 

Wiring involves connecting a switched 12V+ power source, and connect any spare ECU output (except ignition outputs) directly to the solenoid.













Idle Control

The factory idle control uses a simple 2 wire idle control motor. Any of our ecus can control a 2 wire type idle motor. 
Most variants have 2x idle solenoids.  The larger solenoid is the normal idle control valve.  The smaller solenoid is a switched on/off type that is not wired to the ECU. It instead is switched on anytime the A/C Compressor is active.













Coolant Temperature



Wiring is not polarity sensitive

Calibration: Use Temperature - Nissan Skyline R32 R33 R34 Coolant Sensor.cal












Air Temperature

RB26DETT Air Temp Sensor in stock location.



The RB26DETT engine does have an air temp sensor threaded into the intake manifold near the front. This sensor is known to have a very slow response rate and prone to heat soak due to its location. For that reason, we suggest replacing this sensor with one of our air temp sensors found here: https://www.haltech.com/product-category/ecu-inputs-and-o2-wideband-controllers/air-temp-sensors/
These sensors should be installed in front of the throttle body in the intercooler piping. Wiring is not polarity sensitive.

Other RB variants do not come with an Air Temperature Sensor, and these models should have the sensor added when using a Haltech ECU.  The ideal location is in the intake plenum, however it can be added to an intercooler pipe near to the throttle body.










O2 Sensor

Most RB variants have a single O2 sensor located on the down-pipe after the turbo.   Twin turbo models (RB26DETT) have 2x O2 sensors, one for each turbo down-pipe.

Older style O2 sensors are of a Titania type.  These actually vary resistance to the ECU but they can still be used.  They typically have an offset voltage output reading from around 0.4V to 1.4V, so a crossing voltage of around 0.7 to 0.8V will work better.


Newer style O2 sensors are of a Zirconia type and these are the same as all common 0-1V sensors used throughout the auto industry.  



These sensors only have a 1v sweep and by modern standards are not suitable for engine tuning.  It is strongly recommended to replace the sensor with a wideband O2 kit found here: https://www.haltech.com/product/ht-159976-wb1-single-channel-can-o2-wideband-controller-kit/.












Boost Control System

RB engines have a boost control solenoid.  The solenoid however is plumbed in such as way as to only offer a small amount of boost increase.  Instead of the valve acting as the distribution point, it is instead located on the section of the venting hose that comes off the T-piece, which restricts the amount of pressure that can be vented. The OEM vent hose also has a restrictor pill inside the hose and this can be located where the hose has a paint stripe.  As such the valve is only of a 2-port style and cannot be re-plumbed to give better control.  

When boost control is to be handled by the Haltech ECU all of the plumbing should be redone to suit the Haltech Boost Control Solenoid. The OEM wiring can be used to control the new solenoid. 












MAF Sensor

All of the twin cam RB's used a Mass Air Flow (MAF) sensor with the RB26DETT having 2x MAF Sensors.  This is often deleted when a Haltech ECU is added however it is possible to use them if this is preferred by the tuner.

 

This is the Color Code for the following diagram. 
Red: 12v Switched Power
Purple: Signal
Blue: Ground
Brown: Ground to Chassis















ATTESA 4WD System

ATTESA (Advanced Total Traction Engineering System for All-Terrain) is Nissan's control system that allows an All Wheel Drive vehicle to normally have drive to just the rear wheels, and as conditions require power can be directed to the front wheels.  The ATTESA system has it's own ECU to handle this, but does require a Throttle Position reading.  This is provided normally from the OEM ECU as a 0-5V signal with ~0.5V for 0% TPS and ~4.0V for 100% TPS.

All plug in ECUs and adapter harness kits from Haltech incorporate hardware that allows this signal output to occur, and this is mappable as a 0-100% duty signal.

For vehicles that are wired directly Haltech offers a TPS Output device to support the ATTESA system.  Part No. HT-038001














OEM ECU Information

In all R32/33/34's the OEM ECU is located in passenger side kick panel



R32 RB25DE / RB20DET ECU Pinout





R33 RB25DET ECU Pinout





R34 RB25DET NEO (GTT) ECU Pinout


                                                                  
                                 

                                        

                                   


R32/33/34 RB26DETT ECU Pinout
















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