Applications Nissan RB26DETT
Draft. Trigger offset has not been confirmed on a running Race Core install. Pins marked TBD are unknown — do not guess them. A wrong decoder or firing order can destroy the engine.
Nissan RB20 / RB25 / RB26
Skyline GTS-t, GT-R, Stagea. Factory optical CAS is 360 outer + 6 inner (RB26) or similar. Race Core does not decode 360°. Motorsport RB engines already wear a 24-1, 36-1 or Hall crank trigger — that is the path.
Recommended: Race Core F7. Six sequential injectors (RB26 is low-Z with a resistor pack — bypass the pack only after fitting high-Z injectors), six logic coils (R34 COP or coil conversion), N-VTC on RB25DET.
- Cylinders: 6
- Displacement: 1998 / 2498 / 2568 cc
- Firing order: 1-5-3-6-2-4
- Orientation: Cylinder 1 front (timing-belt / cam-angle sensor end on R32–R34).
Variants
| Variant | Years | Trigger | Notes |
|---|---|---|---|
| RB20DET | 1988–1996 | Optical CAS 360+n | 2.0 turbo. High-Z-ish with resistor on some. Cable throttle. |
| RB25DET | 1993–2001 | Optical CAS, N-VTC on later | 2.5 turbo, 8.5:1. NEO from ’98 with different turbo and N-VTC. |
| RB25DET NEO | 1998–2001 | CAS + N-VTC | 9.0:1, different intake. N-VTC intake cam. |
| RB26DETT R32/R33 | 1989–1998 | Optical CAS 360+6 | ITB, twin turbo, 6× throttle. Low-Z injectors + resistor pack. 440 cc. |
| RB26DETT R34 | 1999–2002 | Optical CAS 360+6 | Red cam covers, COP, 8.5:1, still ITB twins. |
Recommended pin assignment (Race Core F7)
| Pin | TunerStudio | Function |
|---|---|---|
| B10 | Digital 1 | Crank Hall after conversion (24-1 / 36-1) |
| B1 | Digital 2 | Cam Hall / CAS inner (not 360) |
| B5 / B13 | VR 1+ / VR 1− | Crank VR |
| A3 | Lowside 1 | Injector cylinder 1 |
| A15 | Lowside 2 | Injector cylinder 2 |
| A4 | Lowside 3 | Injector cylinder 3 |
| A16 | Lowside 4 | Injector cylinder 4 |
| A5 | Lowside 5 | Injector cylinder 5 |
| A6 | Lowside 6 | Injector cylinder 6 |
| A35 | Ign 1 | Cyl 1 logic coil |
| A34 | Ign 2 | Cyl 2 logic coil |
| A22 | Ign 3 | Cyl 3 logic coil |
| A33 | Ign 4 | Cyl 4 logic coil |
| A32 | Ign 5 | Cyl 5 logic coil |
| A31 | Ign 6 | Cyl 6 logic coil |
| C20 | Analog Temp 3 | CLT |
| C30 | Analog Temp 2 | IAT |
| C13 | Analog Volt 1 | MAP 0–5 V |
| C24 | Analog Volt 2 | TPS 1 |
| C34 | Knock 1 | Knock bank 1 |
| C35 | Knock 2 | Knock bank 2 |
| A20 | Lowside 10 | Fuel-pump relay coil |
| A21 | Lowside 12 | Main-relay coil |
| A12 | Lowside 15 | Radiator-fan relay coil |
| A2 | Highside 1 | RB25 N-VTC solenoid |
| A14 | Highside 4 | Boost solenoid (or twins: two outputs) |
| B18 | Battery Sense | Ignition-switched 12 V (5 A fuse) |
| B23 | +12 V MR | Main-relay 12 V into ECU |
| A17 A18 A24 B14 B19 B20 | Power GND | Engine block → battery − |
Trigger
Factory 360° optical CAS is not supported. The inner 6-slot (RB26) or equivalent is not a missing-tooth crank. Fit a crank trigger: common HKS/aftermarket 24-1 on the crank pulley, or a 36-1 Hall, plus a cam for sequential. TDC on an adjustable CAS is famously ‘about 109°’ — that number is for the OEM CAS, not for a 36-1.
Crank
| Recommended | 24-1 or 36-1 Hall/VR on Digital 1 or VR 1. |
| Factory CAS | Do not wire the 360 track. If you must keep the CAS body, a replacement disk (24-1 class) is the minimum. |
Cam
| Sync | One pulse per cam revolution on Digital 2. The inner CAS slots can work as cam if the 360 ring is gone and the decoder expects that pattern — still prefer a dedicated cam Hall. |
TunerStudio
| Setting | Value |
|---|---|
| Trigger / wheel type | 36-1 / 24-1 + cam. Not Nissan 360 CAS. |
| Use only rising edge | Hall: as logged. VR: typically yes on MAX992x |
| Invert primary | No — swap VR wires first |
| Firing order | 1-5-3-6-2-4 |
| TDC rumour | OEM CAS ~109° with the CAS body adjustable. Aftermarket crank: ignore 109, use a light. |
Offset: Light on cylinder 1. If you kept an adjustable CAS, lock the CAS, then set software offset — do not chase both at once.
- RB26 ITBs do not change the trigger. They change idle and MAP (often a MAP in a balance tube, or alpha-N plus MAP blend).
Injection
RB26 OEM 440 cc are low-Z with a resistor pack on the firewall. Race Core is saturated. Keep the resistor pack with OEM injectors, or fit high-Z 750–1,200 cc and delete the pack. Never put low-Z directly on a 4 A saturated driver and hope the current limit saves you — it will run, then cook.
| RB20/25 | Often high-Z 370–440 cc. Confirm resistance with a meter, not a forum. |
| RB26 | Low-Z + pack, or high-Z aftermarket. Sequential six. |
| ITB | One injector per throttle. Same six drivers. |
Ignition
R32/R33: igniter pack, logic into the pack. R34: COP. Convert everything else to logic COP on Ign 1–6.
| COP | Ign 1–6, dwell 2.5–3.0 ms on Nismo/R34 coils. |
| Dumb coils | Need an igniter. Do not ground a coil through Ign n. |
Idle
RB26 ITBs idle on throttle stop plus a small air bypass. There is no useful IAC on a stock GT-R. RB20/25 have an AAC solenoid — PWM a low-side.
First start
- Load the matching variant configuration in TunerStudio before the harness is live — injectors and coils stay disconnected until the decoder is confirmed.
- Fuel pump fuse out. Coils unplugged or spark outputs disabled. Crank. Open Diagnostics → composite / high-speed logger.
- Confirm crank teeth are even, the missing-tooth (or named pattern) is a single clean gap, and cam is one pulse per two crank revolutions for sequential four-stroke.
- RPM during cranking should sit in the 150–350 rpm band. 0 rpm or 12,000 rpm means the decoder is lost — polarity or wheel type, not offset.
- Lock timing to a fixed 10° (idle control off). Timing light on cylinder 1. Change trigger offset until the damper agrees with 10°.
- Recheck at ~3,000 rpm. If timing walks with RPM, it is VR polarity, a delayed Hall, or the wrong decoder — not offset.
- Enable spark. Confirm a healthy burn (timing light or plug colour) with fuel still disabled.
- Enable fuel. Prime, then crank. Catch the first idle on a rich-safe VE, then lean toward stoich at idle.
- Only then enable closed-loop idle, VVT, boost and traction. A base map is a starting point, not a dyno tune.
A base map is a starting point, not a dyno tune.