Understanding the RB20DET Engine

The RB20DET is a 2.0‑liter inline‑six turbocharged engine produced by Nissan from 1985 to 2002. It belongs to the legendary RB engine family, which includes the RB25DET and RB26DETT found in the Skyline GT‑R. The RB20DET features an iron block and an aluminum cylinder head, making it both durable and affordable for swap projects. Its factory output was around 210‑215 horsepower and 195‑200 lb‑ft of torque, but its robust bottom end, strong rods, and well‑designed combustion chambers give it plenty of headroom for serious power.

Key design elements that make the RB20DET a great candidate for budget builds include:

  • Turbocharged layout – the stock T3 flange allows easy upgrades to larger turbos.
  • Strong crankshaft – a forged steel unit that can handle 350‑400 hp reliably.
  • Excellent aftermarket support – from standalone ECUs to bolt‑on turbos, parts are widely available.
  • Lightweight and compact – the inline‑six fits many engine bays without major firewall modifications.

With a budget of $3,500, enthusiasts can transform this humble engine into a 350‑horsepower, 300‑torque powerhouse. The key is smart part selection and careful assembly.

The $3,500 Budget: What It Covers

A common misconception is that a $3,500 engine swap covers only the motor. In reality, that budget includes everything needed to get the RB20DET running and making strong power. Here is a realistic cost breakdown based on current market prices and typical project experiences:

  • Complete RB20DET long block – $1,200 to $1,800 (including intake, exhaust manifolds, stock turbo, coil packs, and sensors).
  • Transmission – $600 to $900. A Nissan FS5W71C or a modified Z32 transmission often mates well.
  • Wiring harness and ECU – $500 to $700. A plug‑and‑play harness from a specialist or a DIY adaption of the stock loom plus a tuned Nistune or simple standalone ECU.
  • Engine mounts and adapters – $150 to $300. Aftermarket mounts for common chassis (S13, S14, R32, etc.).
  • Fluids, gaskets, and small parts – $200 to $400. Includes oil, coolant, seals, timing belt (replace while out), and an oil filter relocation kit if needed.
  • Upgraded intercooler kit – $150 to $300. A front‑mount intercooler and piping are essential for higher boost.
  • Used or rebuilt turbo upgrade – $200 to $400. A GT2871R or similar journal‑bearing turbo can be found on the used market.
  • Fuel system upgrades – $200 to $350. Larger injectors (550cc‑750cc) and a Walbro 255lph fuel pump.
  • Exhaust modifications – $0 to $200. You can reuse a modified downpipe or buy a cheap 3‑inch cat‑back.

Total: approximately $3,500 – and this leaves some wiggle room for unexpected repairs, such as a water pump or a thermostat. The engine itself is often the biggest variable; shopping for a low‑mileage JDM half‑cut is ideal because it includes the engine, transmission, wiring, ECU, and even some sensors all at once.

Building for 350 HP and 300 TQ – The Parts List

To hit 350 wheel horsepower and 300 lb‑ft of torque from a 2.0‑liter inline‑six, you need to replace the stock turbo, support more boost, and increase fueling. Here is a proven combination:

Turbocharger Upgrade

The stock T28 turbo from the RB20DET runs out of steam around 250‑280 hp. A GT2871R with a 0.64 A/R turbine housing is a popular choice. It spools quickly (full boost by 3500 RPM) and flows enough air for 350 hp on pump gas. A used unit can be found for $250‑$400. Pair it with a 3‑inch downpipe and a simple turbo blanket to keep heat in.

Intercooler and Induction

A front‑mount intercooler with 2.5‑inch piping and a good core (like an old eBay kit but with quality couplers) keeps charge air temperatures down. At 18‑20 psi, the intercooler is critical. Add a cold air intake (a 3‑inch pipe with a cone filter) and a recirculating or vent‑to‑atmosphere blow‑off valve.

Fuel System

  • Injectors: 550cc or 650cc high‑impedance injectors (e.g., Denso or Bosch) are sufficient. Expect to pay $150‑$200 used.
  • Fuel pump: Walbro 255lph is a must. $90 new.
  • Fuel pressure regulator: Aftermarket adjustable unit (Aeromotive or equivalent) if using bigger injectors and a tuned ECU.

Engine Management

Factory ECU can be chipped or a Nistune board can be installed for about $300‑$400, but a MegaSquirt or Haltech plug‑and‑play unit gives you full control. For this budget, a used AEM EMS or Link ECU can be found for $500. However, many budget builds use a tuned Nistune board with a base map from a reliable tuner.

Exhaust

A free‑flowing 3‑inch exhaust system from the turbo back is essential. You can often repurpose a stock RB25 exhaust with minimal modification. Expect $100‑$200 for a used cat‑back.

Additional Reliability Upgrades

  • Timing belt and water pump – always replace during the build. $60‑$100.
  • New spark plugs – NGK BKR7EIX or similar one heat range colder. $20.
  • Oil catch can – helps reduce detonation from oil vapor. $30‑$50.

Installation Walkthrough

Dropping a RB20DET into a Nissan S‑chassis (240SX), a Laurel, or a Cefiro is a well‑documented process. Here are the major steps and common pitfalls.

Engine Preparation

  • Clean the engine thoroughly and replace all gaskets (valve cover, intake manifold, exhaust manifold, front cover).
  • Install the upgraded turbo and intake piping while the engine is out – it’s easier than laying under the car.
  • Swap the oil pan if needed (some JDM engines have a rear‑sump pan that may interfere with crossmembers).

Mounting and Drivetrain

  • Aftermarket engine mounts (e.g., from McKinney Motorsports or ISR Performance) bolt directly to the chassis. Expect to drill a couple of holes for some kits.
  • Use the Z32 transmission upgrade for stronger gears; it requires a short bellhousing adapter or a modified RB25 transmission. For the budget build, the stock RB20 transmission is adequate if you avoid hard launches.
  • Shorten the driveshaft or have a custom one made ($100‑$150).

Wiring and ECU

  • If you have the original RB20DET engine harness, it is mostly plug‑and‑play for R32 and R33 chassis, but for S‑chassis you need to repin the body side connectors. Many builders buy a pre‑made adapter harness ($200‑$400).
  • Label every connector as you remove the old engine to avoid confusion.
  • For the ECU, either use a Nistune board with a base map or purchase a plug‑and‑play standalone like a Haltech 550 that includes a base calibration for 350 hp.

Common Pitfalls

  • Oil lines – Ensure the turbo oil supply and drain are not kinked. A -4AN feed and -10AN return line with a proper drain flange in the oil pan is recommended.
  • Coolant lines – The RB20DET uses a throttle body coolant hose that can leak; replace with silicone hoses.
  • Sensors – The crank angle sensor (CAS) is fragile; handle with care and check the connectors.
  • Clearance – The power steering pump and AC compressor may interfere with the intercooler piping. Plan your routing beforehand.

Tuning the RB20DET for Reliable Power

350 horsepower is achievable on pump gas (93 octane) with a conservative tune. The bottom end can handle 400‑450 hp, so 350 is a safe zone. Here is the tuning approach:

Base Map Loading

Start with a known base map for your ECU/engine combo. Many tuners share files for a GT2871R, 550cc injectors, and a 3‑inch exhaust. Load it and verify timing and fuel trim.

Boost Control

Use a manual boost controller or a simple electronic boost controller (e.g., Hallman Pro). Set boost to 15‑16 psi for the first few dyno pulls, then increase to 18‑19 psi. The GT2871R will hit 20 psi efficiently, but factory pistons are cast – keep peak boost under 20 psi for longevity.

Dyno Tuning

  • Aim for an air‑fuel ratio of 12.0‑12.5:1 under full boost (rich enough to cool the combustion, but not so rich that it washes the cylinders).
  • Keep ignition timing around 12‑15 degrees at peak torque, then taper to 18‑20 degrees at redline (7000 RPM).
  • Watch for knock – use a knock sensor and listen for ping. If detected, pull timing and add fuel.

Ignition and Cooling

  • Upgrade spark plugs and gap them to 0.028‑0.032 inches.
  • Consider a larger radiator (Koyo or Mishimoto) to keep coolant temps safe during long pulls. A $150 replacement is cheap insurance.
  • Use a high‑pressure radiator cap (1.3‑1.5 bar).

Real‑World Performance and Owner Experiences

After completing the swap and a proper dyno tune, owners report the following:

  • 0‑60 mph: 4.8‑5.2 seconds with sticky tires (varies by chassis weight).
  • Quarter‑mile: 12.5‑12.9 seconds at 110‑115 mph.
  • Drivability: The engine pulls hard from 3500 RPM to 7000 RPM, making it fun for street and light track use.
  • Reliability: With proper cooling and a conservative tune, the engine lasts for years of daily driving and occasional abuse. Many forum members report 30,000+ miles without issues.

One builder on Zilvia shared: “I did the swap with a used $1,200 engine, a $300 GT2871R, and a $400 Nistune. Total was $3,600 with all the bits. It made 346 whp and 297 lb‑ft on a Dynojet after tuning. The car is an absolute riot – reliable, torquey, and way cheaper than an LS swap.”

Is the RB20DET Swap Right for You?

Pros

  • Low initial cost compared to turbo LS engines or modern 4‑cylinders.
  • Excellent aftermarket support and community knowledge.
  • Engine is lightweight and fits many RWD platforms.
  • 350 hp / 300 lb‑ft is a very usable street power level.

Cons

  • Wiring can be daunting for beginners (but pre‑made harnesses help).
  • Parts for the RB20 are getting slightly harder to find as the engine ages.
  • The 2.0‑liter displacement means you need higher boost to make big torque; spool is slower than a 2.5‑liter RB25.
  • Stock bottom end is not forged – you need to monitor knock closely.

Alternatives

If you have a larger budget ($5,000+), the RB25DET swap yields 350 hp with less boost and easier spool. Another option is a turbo K‑series, which can make similar power but with a lighter package. However, for the price point, the RB20DET remains a cost‑effective path to big fun.

Conclusion

The RB20DET swap proves that you don’t need a six‑figure budget to hit 350 horsepower and 300 lb‑ft of torque. With $3,500, careful shopping, and a willingness to turn wrenches, you can build a reliable, quick car that stands out at meets and autocross events. The key is choosing the right turbo, supporting fuel upgrades, and investing in a solid tune. Whether you’re swapping into a 240SX, a Skyline, or an older Z‑car, the RB20DET delivers real‑world results that punch far above its weight class.

For further reading, check out the RB engine Wikipedia page, browse parts at Auto Icarnage for used turbo deals, or consult the Nistune tuning guide for ECU options.