The RB20DET engine occupies a hallowed place in the Japanese performance car world. As the 2.0-liter turbocharged inline-six that powered the R32 Skyline GTS-t, the Laurel, Cefiro, and a host of other Nissan chassis, it offers an affordable entry into the RB family while still delivering the smooth power delivery and rev-happy character that makes these engines legendary. For drifters, budget street racers, and weekend track enthusiasts, the RB20DET presents a tantalizing compromise between cost and capability. However, the gap between a stock, reliable daily driver and a fire-breathing fully modified build is measured in thousands of dollars—and understanding where that money goes is critical before you pull the trigger on a swap or rebuild.

A Brief History of the RB20DET

Introduced in the mid-1980s, the RB20DET was Nissan’s first mass-produced turbocharged inline-six in the RB series. It featured a cast-iron block, an aluminum cylinder head with 24 valves (via dual overhead cams), and a small T3-flange turbocharger that delivered around 210–220 crank horsepower in stock form. The engine was renowned for its smoothness and ability to rev to 7,000 rpm without complaint. Over the years, it powered numerous Nissan platforms and became a favorite for engine swaps into older S-chassis cars (S13, S14, S15), Z31 300ZX, and even early Z cars. Despite being overshadowed by the larger RB25DET and RB26DETT, the RB20 remains relevant because of its lower cost, abundant availability, and surprising tuning potential when proper supporting modifications are applied.

Stock RB20DET Build: Baseline Costs and Realities

A “stock build” typically involves sourcing a used engine in good condition, performing routine maintenance, and addressing known weak points without chasing big power numbers. The goal here is reliability and daily drivability. Below is an expanded cost breakdown that goes beyond basic oil changes and parts.

Engine Acquisition and Condition

Used RB20DET long blocks from Japanese importers typically range from $1,500 to $2,500, depending on mileage, included accessories (alternator, starter, intake plenum, turbo), and whether it’s a front-clip or half-cut. Engines with higher miles or unknown histories may come cheaper but require immediate freshening. A compression test and leak-down test before purchase are non-negotiable—rebuilding a tired block later can double your initial investment.

Mandatory Baseline Maintenance

  • Timing belt, tensioner, and idler pulleys: $150–$300 (critical for interference engine; failure destroys valves)
  • Water pump and thermostat: $80–$150
  • Oil pump (high-volume or OEM): $120–$250
  • Gasket set (valve cover, intake, exhaust, head gasket if removed): $100–$300
  • Spark plugs and wires: $60–$120
  • All fluids (oil, coolant, transmission, diff): $100–$150
  • Vacuum lines and PCV system refresh: $20–$50

Budget $600–$1,200 for a thorough refresh that ensures the engine won’t grenade in the first thousand miles.

Stock Turbo and Exhaust

If the stock Garret T3 turbocharger is damaged or has excessive shaft play, replacement units can be had for $400–$600. A stock intercooler (or a direct-fit upgrade like a Frount mount intercooler from brands like Blitz or GReddy) runs $300–$600. The exhaust system—downpipe, mid-pipe, and cat-back—can range from $400 for a cat-back homemade system to $800 for a full turbo-back stainless system from a quality fabricator.

Supporting Mods for Reliability

Even a stock build benefits from a few upgrades: a metal head gasket (if rebuilding), ARP head studs ($200–$300) to prevent lift at higher boost, and a stronger fuel pump ($100–$150) to ensure consistent pressure. Adding a wideband oxygen sensor and a boost controller (manual, $50–$100) helps tune the stock ECU for safety margins.

Estimated Stock Build Total

Assuming you source a good used engine and perform all maintenance yourself, expect to spend $3,500–$5,500. If you pay a shop for labor (installation, timing belt, etc.), add another $1,000–$2,000, bringing the total closer to $4,500–$7,500.

Fully Modified RB20DET Build: The Path to Big Power

A fully modified build targets 350 to 500+ wheel horsepower and requires significant investment in every system. The goal is to make the engine withstand sustained high boost and high RPMs without breaking. Below is an exhaustive cost breakdown.

Engine and Bottom End

Almost every high-power RB20DET build starts with forged internals. The stock rods and pistons are weak points above 350 whp.

  • Forged pistons (CP, Wiseco, JE): $500–$800
  • Forged connecting rods (Manley, Eagle, Spool): $400–$700
  • Main and rod bearings (ACL King): $80–$150
  • Balanced and blueprinted rotating assembly (machine work): $500–$1,000
  • Oil pump (high-pressure/high-volume): $150–$300
  • Head studs (ARP): $200–$300
  • Metal head gasket (Cometic, Tomei): $100–$200
  • Timing chain conversion (instead of belt): $300–$500

Bottom-end parts and labor alone can run $2,500–$4,500.

Turbo and Induction

To make real power, the tiny stock turbo must be replaced. Options include Holset HX35, Garrett GT3076R, or Precision 5858.

  • High-performance turbo kit (manifold, wastegate, downpipe, intake): $1,500–$3,500
  • External wastegate (Tial, Turbosmart): $300–$500
  • Blow-off valve: $100–$200
  • Intercooler core and piping (custom or kit): $600–$1,200
  • Intake manifold (plenum upgrade, e.g., R33 or GReddy copy): $400–$800
  • Throttle body (larger than stock 60mm): $200–$400

Induction system total: $3,500–$6,600.

Fuel System

High boost requires more fuel. The stock injectors max out around 250 whp.

  • Upgraded fuel injectors (1000cc or larger for E85): $400–$800
  • Fuel pressure regulator (AEM, Aeromotive): $100–$200
  • High-flow fuel pump (Walbro 450 or dual pump setup): $150–$400
  • Fuel lines, fittings, and surge tank (if needed for track): $300–$600
  • Flex fuel sensor and controller (if running E85): $200–$400

Fuel system investment: $1,200–$2,400.

Engine Management and Tuning

A standalone ECU is mandatory for a fully modified build. The stock RB20 ECU cannot be properly tuned to control large injectors, boost, ignition timing, or additional sensors.

  • Standalone ECU (Haltech, Link, Motec, or AEM Infinity): $1,200–$2,500
  • Wiring harness (plug-and-play or custom): $300–$800
  • Professional tuning (dyno time): $500–$1,000
  • Wideband O2, boost, and knock sensors: $300–$500

Management and tuning: $2,500–$4,800.

Exhaust, Cooling, and Drivetrain

Power is nothing without proper cooling and the ability to transfer it to the ground.

  • Custom 3-inch or larger turbo-back exhaust: $800–$1,500
  • Aluminum radiator (Koyo, Mishimoto): $300–$500
  • Dual electric fans with shroud: $150–$300
  • Oil cooler setup (thermostat, cooler, lines): $300–$600
  • Upgraded clutch (Exedy or twin-plate): $400–$1,000
  • Lightweight flywheel: $200–$400
  • Transmission upgrades (RB25DET gearset or OS Giken): $1,000–$2,500
  • Driveshaft (one-piece aluminum): $300–$600
  • Differential (2-way or locker) and axle upgrades: $500–$1,200

Estimated drivetrain and cooling: $3,500–$7,500.

Labor and Miscellaneous

A fully modified build is labor-intensive. Expect many hours for fabrication, wiring, and assembly.

  • Engine assembly and installation labor: $1,500–$4,000
  • Custom intercooler piping and intake fabrication: $500–$1,000
  • Wiring harness modification or full rewire: $500–$1,500
  • Miscellaneous (gaskets, fluids, hardware, tools): $200–$500

Labor and incidentals: $2,500–$7,000.

Fully Modified Build Total Range

Adding all the categories above yields a realistic range of $14,000–$30,000 or more, depending on how much work you do yourself and how exotic the parts choices are. A shop-built 500 whp RB20DET can easily exceed $20,000 in parts and labor alone.

Hidden Costs Every Builder Should Expect

Beyond the big-ticket items, several smaller expenses frequently catch builders off guard:

  • Engine mounts and adapters (if swapping into a non-Nissan chassis): $100–$300
  • Wiring specialties engine swap harness (plug-and-play for popular swaps): $400–$700
  • Fluid and coolant lines (braided stainless hose and AN fittings): $100–$400
  • New sensors (crank angle, cam position, knock, coolant temp): $100–$300
  • Upgraded ignition system (coil-on-plug conversion or better coils): $200–$600
  • Interior modifications (gauges, harness bar, seat if power requires): $500–$2,000
  • Frequent fluid changes during break-in and tuning
  • Unforeseen machine work (cracked head, spun bearing – expect the unexpected)

Set aside a contingency fund of $1,000–$2,000 for surprises.

Cost Comparison Summary

  • Stock+ build (reliable daily driver): $3,500–$7,500
  • Stage 1 (bolt-ons, 280–320 whp): $7,000–$10,000
  • Stage 2 (forged internals, 350–450 whp): $12,000–$18,000
  • Fully built (450–600+ whp, track ready): $18,000–$30,000+

Note: these figures assume you start with a running engine and relatively clean chassis. If you need to purchase a donor car or a complete swap platform, add $2,000–$5,000.

Factors That Influence Final Cost Most

  • DIY vs. shop labor: Doing your own wrenching can save $3,000–$10,000, but requires tools, space, and expertise.
  • Part quality vs. budget parts: A cheap turbo or intercooler may fail quickly, costing more in the long run. Names like Garrett, Turbosmart, Haltech, and Cometic are trusted for a reason.
  • Local tuning availability: If you need a specialist in RB ECUs or a remote tune, costs rise.
  • E85 vs. pump gas: E85 requires larger injectors and fuel system upgrades, but allows higher power safely.
  • Chassis condition: Rusty or poorly maintained shells will eat time and money.

Should You Choose Stock or Fully Modified?

There is no universal right answer. A stock build is ideal for someone who wants to enjoy the RB20DET’s character without constant maintenance headaches or fear of breaking parts. It’s also a solid starting point for learning the engine’s behavior before investing in further upgrades. On the other hand, a fully modified build is for those who demand the best possible performance—whether for competitive drifting, time attack, or pure adrenaline. The key is to define your goals early and budget accordingly. Remember that the power you make is only as good as the rest of your car: brakes, suspension, tires, and chassis rigidity all demand attention and funds.

For deeper dives into RB tuning history and specific parts compatibility, check resources like Nissan RB Engine on Wikipedia and enthusiast forums such as DriftWorks or SAU Forums for real-world experiences and build logs.

Final Thoughts

Whether you keep the RB20DET stock or turn it into a high-horsepower monster, the cost of the build is ultimately a reflection of your ambitions and your patience. A well-planned build—with realistic parts choices and a contingency fund—will reward you with a reliable, thrilling engine that stands out from the crowd. Take the time to study the numbers above, compare them to your own budget, and decide which path aligns with the way you truly want to drive.