The RB20DET is a turbocharged 2.0‑liter inline‑six that originally delivered around 210–215 horsepower in the Nissan Skyline R32 and R33 GTS‑t models. While that was respectable in the early 1990s, modern enthusiasts expect far more. With the right combination of modifications, the RB20DET can reliably reach 350 horsepower at the wheels—a gain of roughly 135–140 hp over stock. This article expands on the original top‑10 list, providing detailed technical explanations, part recommendations, and practical tuning advice to help you build a strong, streetable 350‑hp Skyline.

1. Upgrade the Turbocharger

The stock RB20DET turbo (a T3‑flanged Garret or MHI unit) is small and hits a wall around 230–250 hp. To reach 350 hp, you need a turbo that flows more air without excessive lag. A popular choice is the Garrett GT2871R with a 52‑trim compressor and 0.64 A/R turbine housing. It spools quickly, supports up to 400 hp, and retains good low‑end torque. Other options include the HKS GT2540 or Greddy T518Z. When upgrading, pair the turbo with a proper wastegate (tial 38 mm is common) and a boost controller (covered later).

For 350 hp, target about 14–17 psi of boost on pump gas. Nengun Performance offers a range of RB20DET turbo kits. Remember that a larger turbo often requires a tune and supporting mods—do not just bolt it on and crank the boost.

2. Install a High‑Performance Intercooler

Cooler intake air is denser, containing more oxygen per volume. The RB20DET’s side‑mount intercooler (SMIC) quickly heat‑soaks under sustained boost. Upgrade to a front‑mount intercooler (FMIC) with a core size of around 600 x 300 x 76 mm. A quality FMIC from brands like Hybrid, CSF, or HKS can lower intake temps by 30–50°F, reducing the risk of knock and allowing more aggressive tuning.

Ensure to use aluminum piping with a 2.5‑inch (63 mm) diameter and high‑efficiency couplers. BOV (blow‑off valve) choice matters too—a proper HKS SSQV or Tial Q keeps the charge side stable. A well‑cooled charge directly contributes to the 350‑hp goal by letting you run higher ignition advance.

3. Upgrade the Exhaust System

The stock RB20DET exhaust is restrictive, with narrow tubing and a catalytic converter that creates back pressure. To liberate power, replace the entire exhaust from the turbo outlet back. Start with a dump pipe or downpipe (3‑inch diameter), then a front pipe, and a cat‑back system with a straight‑through muffler. 3‑inch (76 mm) is the ideal diameter for 350 hp; anything larger may lag a bit.

Many owners choose stainless steel systems from Buddy Club, HKS, or Fujitsubo. Expect a 10–15 hp gain from the exhaust alone, plus improved turbo spool. For street use, keep one high‑flow catalytic converter if emissions are a concern. A well‑sorted exhaust system reduces exhaust gas temperatures (EGT) as well, prolonging engine life.

4. Install a Performance ECU Tune

Without a tune, no combination of parts will reach 350 hp safely. The stock ECU uses a closed‑loop fuel map that cannot handle bigger injectors, higher boost, or altered airflow. You have two paths: a remap of the stock ECU using software like Nistune (popular for RB engines), or a standalone ECU like Link G4+, Haltech Platinum Pro, or MoTec M150.

Nistune is cost‑effective and retains factory features, but standalone gives complete control over ignition, fuel, boost, and auxiliaries. For 350 hp, focus on tuning the air‑fuel ratio to 11.5:1 on boost, ignition timing around 12–16° BTDC at peak torque, and adding fuel via injector scaling. Always dyno‑tune after major mods. A good tuner will also set up knock control and limit boost to safe levels. Driftworks carries Nistune boards and standalone ECUs.

5. Upgrade Fuel Injectors

Stock RB20DET injectors (often 370 cc or 380 cc) max out around 250–270 hp on pump gas. To feed 350 hp, you need injectors in the 550–750 cc range. Nismo 555 cc drop‑in injectors are a direct upgrade and are easy to tune. For more headroom, DeatschWerks 700 cc or Injector Dynamics ID725 work well. A high‑impedance injector set simplifies wiring; low‑impedance injectors may require a resistor box.

When installing, replace the fuel filter and inspect the injector seals. After the injectors are in, a retune is mandatory to avoid lean conditions. Many tuners prefer to scale the injector latency and flow rate in the ECU to keep the map smooth. Upgraded injectors also allow you to run more boost later if you push toward 400 hp.

6. Install a High‑Performance Fuel Pump

Higher flow injectors are useless if the fuel pump cannot deliver the volume required at higher rail pressures. The stock RB20DET pump supports maybe 250‑280 hp. For 350 hp, a Walbro 255 lph (or AEM 320 lph) in‑tank pump is the standard choice. It is a direct fit and provides consistent pressure up to 400 hp.

Wire the pump with a relay and larger gauge wiring to avoid voltage drop. Consider a fuel pressure regulator (like an Aeromotive or Vortec) if you run base pressure above 43 psi. The pump upgrade alone won’t add power, but it ensures the rest of the fuel system operates safely. Import Image Racing stocks Walbro and AEM pumps for the Skyline.

7. Upgrade the Intake System

To make 350 hp, the engine must breathe freely. The stock airbox and intake pipe are restrictive. Replace them with a high‑flow intake kit that includes a pod filter (e.g., HKS Super Mega Flow or K&N) and a larger diameter intake pipe (3‑inch recommended). This reduces restriction and allows the turbo to pull air more efficiently.

If you still use the stock airflow meter (MAF), be careful: a large pipe can desensitize the MAF signal. Many tuners relocate the MAF further from the turbo, or switch to a Z32 MAF to handle higher airflow. Alternatively, go speed‑density (MAP‑based) with a standalone ECU, which eliminates the MAF entirely. This mod contributes 5–10 hp on its own and improves throttle response.

8. Strengthen the Engine Internals

The stock RB20DET block is fairly robust, but the pistons (hyper‑eutectic) and rods (cast) become a reliability risk above 300 hp, especially if detonation occurs. For a 350‑hp target, you are at the edge of stock internals—many owners do fine with a good tune and the mods listed above. However, if you plan to track the car or run aggressive boost, upgrade to forged components.

Consider forged pistons (e.g., CP‑Carillo, JE Pistons) with a slightly lower compression ratio (8.5:1) to tolerate more boost, paired with forged connecting rods (Eagle, Manley, or K1). ARP head studs are highly recommended to prevent head lift. While this is a major expense, it provides headroom for future upgrades beyond 350 hp. Balanced rotating assembly also reduces vibration at high RPM.

9. Install a Boost Controller

Dialing in boost precisely is key to hitting 350 hp while keeping the engine safe. An electronic boost controller (e.g., Greddy Profec B Spec 2 or HKS EVC‑S) allows you to set two boost levels, adjust gain, and monitor pressure. A manual boost controller is cheaper but less consistent.

For the RB20DET, start with a baseline of 12 psi, then increase in 1‑psi increments on the dyno while watching knock sensors. Electronic controllers also offer overboost protection and can be mapped with RPM. For 350 hp, you will likely settle around 14–16 psi on a GT2871R. Remember that boost controller alone does not add power—it realizes the potential of the turbo and tune.

10. Optimize Cooling Systems

With 50% more power than stock, the RB20DET generates significantly more heat. The factory cooling system struggles to keep coolant and oil temps within limits during hard driving. Upgrade to a thick‑core aluminum radiator (e.g., Koyo, Mishimoto, or Z32 radiator with an RB conversion). Add a high‑flow thermostat and electric fans with a shroud for better airflow at low speed.

Oil temperature is just as critical. Install an oil cooler (13‑row or 19‑row, with a thermostatic sandwich plate) to keep oil below 220°F. A power steering cooler is also advisable if you track the car. Overheating can cause detonation and head gasket failure, so do not skip cooling mods even if they don't directly add horsepower—they allow you to use the power reliably. RHDJapan offers quality cooling parts for Nissan Skylines.

Putting It All Together: Tuning and Final Notes

Reaching 350 hp on the RB20DET is a well‑documented path, but the order of mods matters. Start with supporting mods (fuel system, exhaust, intake) and a tune, then add the turbo and intercooler. After installing the turbo, dyno tune again to finalize the boost and timing maps. A typical 350‑hp RB20DET will have a torque peak around 3,500–4,000 RPM and hold power to 6,500 RPM. The motor will feel strong and responsive on the street.

Always use good quality fuel (91 octane or higher, preferably 93 or 98) and monitor knock. Consider a wideband air‑fuel ratio gauge and a boost gauge as essential dash items. If you follow this guide, your Skyline will not only hit 350 hp but also be reliable enough for daily driving and weekend track days.

Conclusion

These ten modifications form a comprehensive build guide for the RB20DET engine. From the turbo upgrade to the cooling system, each part works in concert to produce 350 horsepower safely. With careful planning, quality parts, and a professional tune, your Nissan Skyline will achieve impressive power gains while retaining the character that makes the RB20DET a classic turbo engine. Respect the engine’s limits, invest in proper tuning, and you will enjoy a strong, reliable 350‑hp Skyline for years to come.