Injector data for the 25 year import wave: RB26DETT specs for R32, R33, and R34 GT-R, the resistor box explained, plus RB25, SR20, CA18, KA24, and 300ZX twin turbo. Top feed versus side feed by chassis, impedance rules, and why a freshly imported GT-R should see a flow bench before it sees boost. Compiled by the injector cleaning department at Boost Lab, Inc.
Every RB26DETT from the R32 through the R34 GT-R runs 444 cc top feed injectors, yellow and black tops, and they are low impedance, which is the detail that governs everything else. The factory fits a resistor box to limit the current the ECU drivers see, which means the RB26 harness expects low impedance injectors: put high impedance units on it without rewiring and they will barely open. The stock 444s support roughly 444 horsepower at the engine on gasoline, and the community consensus upgrade path skips the middle sizes entirely and goes straight to 1000 cc class low impedance sets, or deletes the resistor box to open up high impedance options.
The rest of the JDM Nissan family splits by feed type. RB20 and CA18 run top feed; RB25, SR20 (S13 and S14), VG30DETT, and KA24 run side feed, with the S15 SR20DET stepping up to 480 cc side feeds. The Pulsar GTi-R shares its 440 cc top feed injector with the RB26. Side feed Nissans have the same story as side feed Toyotas: fine slots and filter baskets that varnish shut, discontinued part numbers, and cleaning as the only sensible service path. One quirk worth knowing: the 1990-94 300ZX twin turbo uses a side feed style unique to those years, while 1995-96 cars share the common RB25 and SR20 style.
Then there is the import math. Every one of these cars is at least 25 years old by the time it lands in the US legally, most sat in shipping and storage on old fuel, and the service history is a mystery written in Japanese. A baseline flow test and cleaning is the single best first service on a freshly imported car: it establishes what the injectors actually flow before anyone tunes against assumptions, and on an RB26 heading for boost, assumptions are expensive.
| Application | Chassis | Flow | Feed | Impedance / Notes |
|---|---|---|---|---|
| Skyline GT-R RB26DETT | R32 / R33 / R34, 1989-02 | 444 cc | Top feed | Low impedance, yellow/black, resistor box |
| Stagea 260RS RB26DETT | WGNC34 | 444 cc | Top feed | Same injector as GT-R |
| Pulsar GTi-R SR20DET | RNN14 | 440 cc | Top feed | Shares OEM injector family with RB26 |
| Skyline GTS-t RB20DET | R32 | 270 cc | Top feed | High impedance |
| Skyline GTS-t RB25DET | R33 / R34 | 370 cc | Side feed | High impedance |
| 300ZX Twin Turbo VG30DETT | Z32, 1990-96 | 370 cc | Side feed | 1990-94 unique style; 1995-96 common style |
| Silvia / 240SX SR20DET | S13 / S14 | 370 cc | Side feed | High impedance |
| Silvia SR20DET | S15 | 480 cc | Side feed | High impedance |
| 200SX CA18DET | S13 | 370 cc | Top feed | Low impedance |
| 240SX KA24DE | S13 / S14 | 270 cc | Side feed | High impedance |
| RB26 upgrades must respect the resistor box: with the box in place the harness expects low impedance injectors, and flow matched low impedance sets from 550 to 1200 cc exist for exactly this reason. Deleting the box opens the door to modern high impedance sets with ECU support. | ||||
GT-Rs and S-chassis cars straight off the boat, flow tested and cleaned as the first item on the build sheet. The report becomes page one of the car's new service history.
SR20, RB25, and Z32 side feeds with the same clogging pattern as their Toyota cousins: fine slots, old fuel, low flow. Cleaning with new filter baskets and seals typically brings them back to spec.
Stock 444s and aftermarket low impedance sets flow matched and documented before tuning, so six cylinders of RB26 start from known numbers instead of 30 year old assumptions.
All three run the same 444 cc top feed low impedance injectors, yellow and black tops, driven through a factory resistor box. They support roughly 444 horsepower at the engine on gasoline, which is why nearly every boosted build eventually replaces or supplements them.
The factory injectors are low impedance, and the resistor box limits current to protect the ECU drivers. With the box in place, the harness expects low impedance injectors, so upgrades must either stay low impedance or delete the box and rewire for high impedance units. Getting this wrong means injectors that overheat drivers or barely open.
Yes, before almost anything else. The car is 25 plus years old, sat through export and shipping on old fuel, and has no verifiable service history. A flow test and cleaning establishes a documented baseline, and on side feed engines it routinely recovers flow the car had quietly lost.
Mostly no; the OEM part numbers for SR20, RB25, and Z32 side feeds are discontinued or drying up, the same situation as Toyota side feeds. Professional cleaning with new filter baskets and o-rings, verified with a flow report, is the sustainable path for keeping original sets healthy.
Flow matched low impedance sets from 550 to 1200 cc exist specifically for the resistor box equipped RB26, and the community consensus skips small steps and goes to the 1000 cc class for a build with headroom. As an authorized Injector Dynamics and Fuel Injector Clinic dealer we can spec, supply, and flow verify a set of six for your combination.
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