Introduction

The Nissan RB26DETT is one of the most celebrated engines in automotive history, powering legends like the R32, R33, and R34 Skyline GT-R. While the stock engine is a capable performer, delivering around 280 horsepower, the aftermarket world has pushed it far beyond its factory limits. Reaching 700+ horsepower requires a systematic overhaul of nearly every system. This article compares the stock RB26DETT to a 700+ HP build, detailing exactly which changes are necessary and why. Whether you are planning a build or simply curious about the engineering hurdles, this guide will walk you through the critical modifications step by step.

The RB26DETT: A Legendary Platform

Stock Specifications and Output

The factory RB26DETT is a 2.6-liter inline-six with a cast-iron block, an aluminum 24-valve DOHC cylinder head, and twin Garrett T25 or T28 turbochargers. It features Nissan’s NVCS (variable cam timing) on the intake side and a sophisticated multi-fuel injection system. At the crank, Nissan rated it at 276 horsepower (280 PS) under the Japanese “gentleman’s agreement,” but real-world dynamometer results often show 280 to 300 wheel horsepower in stock trim. Torque peaks around 271 lb-ft, and the engine revs to 7,000 rpm. The stock fuel system includes 370 cc/min injectors and a single in-tank pump; the intercooler is a compact air-to-air unit. While robust for its era, every one of these components becomes a bottleneck at 700+ horsepower.

Why 700+ HP Is a Threshold

700 wheel horsepower represents roughly 800 crank horsepower with drivetrain losses. At this level, the engine must handle boost pressures of 25-35 psi, airflows approaching 80 lb/min, and combustion pressures that can crack pistons or bend rods in the stock configuration. The stock block is strong—it can survive 700 hp with proper prep—but virtually everything bolted to it must be replaced or heavily upgraded. The drivetrain (gearbox, clutch, axles) also becomes a weak link. This article will focus on the engine and its immediate supporting systems, but we will also touch on the downstream components that must be addressed.

Critical Engine Modifications for 700+ HP

Turbocharger Upgrade: Choosing the Right Twins or Single

The stock twin turbos are too small to sustain the airflow for 700 hp. They choke above about 400-450 hp. Two main paths exist: larger twin turbos or a single turbo conversion. Larger twins (such as Garrett GT2860RS or GT2871R, or BorgWarner EFR 6758) can support 600-650 hp while retaining quick spool. For 700+ hp, many builders opt for a single large turbo like a Garrett GTX3582R, a Precision 6266, or a BorgWarner S366. A single turbo simplifies the exhaust system, improves engine bay access, and often provides higher peak power. The trade-off is increased lag, though modern ball-bearing centers and anti-surge housings minimize this. Whichever path you choose, you will need custom exhaust manifolds (or a twin-scroll design for the single), a proper wastegate (44-50 mm), and a blow-off valve. External wastegates are essential for precise boost control at high power levels.

A good turbo upgrade alone can add 200-300 hp, but only if the fuel system and tuning are ready. A recommended starting point for 700+ hp is a GT3582R (Gen II) with a 1.06 A/R housing, which can flow about 75-80 lb/min—enough for 800 crank horsepower. Pair it with a 50 mm Turbosmart wastegate and a 3-inch downpipe. Garrett Motion’s website provides detailed performance maps to help match the turbo to your power goals.

Fuel System: From Injectors to Pump and Lines

Stock 370 cc injectors flow roughly enough for 400 hp (gasoline). At 700+ hp, you need injectors that flow at least 1,000 cc/min (1000 cc = ~100 lb/hr), many builders use 1300-1600 cc injectors for safety and future headroom. The fuel pump must be upgraded to a high-flow unit like a Walbro 525, AEM 400, or a dual-pump setup for E85 or high boost. A surge tank with a secondary lift pump is often used to prevent starvation during hard cornering or high-G maneuvers. The stock fuel lines (8 mm ID) are marginal; running a -8 AN feed line and a -6 AN return is strongly recommended. A fuel pressure regulator (FPR) rated for high flow and a return-style system allow the tuner to maintain stable pressure. If you plan to run ethanol blends, all components (including hoses) must be ethanol-safe. Radium Engineering offers comprehensive direct-fit fuel system kits for the R32-R34 chassis.

Engine Internals: Pistons, Rods, and Block Prep

The stock cast pistons and cracked-cap connecting rods are fragile above 500-550 hp. For 700+ hp, forged pistons (e.g., CP-Carrillo, JE, Wiseco) are mandatory. Choose a compression ratio that works with your fuel: 8.5:1 to 9.0:1 for pump gas, or higher (9.5:1) if running E85 with excellent intercooling. The stock rods can be replaced with forged I-beam rods (Manley, Eagle, Carrillo) that are rated for 800+ hp. The crankshaft is a forged unit from the factory and can generally handle 700-800 hp, but for peace of mind, many builders knife-edge it and balance the entire rotating assembly. The block’s main bearing journals should be align-honed, and the cylinders may need to be bored for oversized pistons if there is wear. ARP main studs and head studs replace the factory bolts to prevent head lift under high boost. For extreme power (800+ hp), builders o-ring the block or use a copper head gasket to ensure a perfect seal.

Head Upgrades: Cams, Valves, and Porting

The stock cylinder head flows well for a 2.6L engine, but it can be improved significantly. Larger camshafts (264° to 280° duration, 10.5-12 mm lift) allow the engine to breathe at high rpm. Aggressive cams require upgraded valve springs (e.g., Brian Crower or Supertech) and titanium retainers to prevent valve float. While the stock valves are adequate for 700 hp, many builders install stainless steel or Inconel exhaust valves (especially if running very high exhaust temps) and do a three-angle valve job. Porting the intake and exhaust ports for flow balance can add 30-50 hp. The NVCS (variable cam timing) can be retained, but it requires careful tuning and may complicate the engine management. Simpler is to delete it with a solid cam gear setup. A good head package combined with proper turbo choice can push power well past 800 hp while keeping the engine reliable.

Supporting Systems

Cooling: Radiator, Intercooler, and Oil Coolers

A 700+ hp RB26 generates enormous heat. The stock 2-row radiator is insufficient; a high-performance aluminum radiator (Koyo, PWR, or Mishimoto) with a large core and dual electric fans is essential. A thermostat with a lower opening temperature (160°F) helps keep coolant temperatures in check. The intercooler must also be upgraded: a front-mount unit with at least a 4-inch core and 3-inch inlet/outlet is common. For track use, consider an air-to-water intercooler setup. Oil temperatures can quickly exceed safe limits; a thermostatic oil cooler (Setrab or Mocal) with a 19-row or larger core is highly recommended. Running a high-quality synthetic oil (0W-40 or 5W-40) with an oil cooler ensures the bearing and turbo survive sustained high load. Lastly, a coolant reroute kit (available from shop outfits like “Coolant Reroute” for RBs) improves flow to the rear cylinders, which tend to run hotter.

ECU and Tuning: Standalone vs Piggyback

The stock ECU cannot handle larger injectors, MAP sensors, or high boost without signal clamping tricks. For 700+ hp, a standalone engine management system is practically mandatory. Popular choices include the Haltech Elite 2500, Link G4+ Fury, Motec M130, or a plug-in option like the AEM Infinity 708. Standalone ECUs allow full control over ignition timing, fuel maps, boost control, and auxiliary features like launch control and flat-shift. They also support flex-fuel sensors, which enable tuning for E85 and gasoline on the fly. Tuning must be done by an experienced RB specialist on a dynamometer. A well-tuned car at 700 hp can be street-friendly and reliable; a poorly tuned one will scatter pistons in a few pulls. Link Engine Management provides excellent support for the RB platform with pre-made base maps.

Exhaust System: Downpipes to Exhaust

The stock exhaust on a GT-R is heavily restrictive. For 700+ hp, you need a 3-inch or larger exhaust system from the turbo outlets back. The downpipes are especially critical: they should merge into a single or twin 3-inch pipes with a high-flow catalytic converter (if required) or a straight-through test pipe. A free-flowing muffler keeps backpressure low, which helps spool and top-end power. Many builders use a titanium or stainless-steel system to save weight. The turbo-to-manifold gaskets should be upgraded to multi-layer steel (MLS) versions to prevent exhaust leaks under high boost. A large wastegate dump tube (venting to atmosphere) further reduces backpressure and improves boost control.

Drivetrain and Chassis Considerations

Transmission Upgrades

The stock R32/R33/R34 five- or six-speed transmission (Getrag for R34 six-speed) can handle about 500-600 hp in good condition. At 700+ hp, the input shaft and synchros are likely to fail. Stronger options include dog engagement gear sets (like those from PPG or Albins), a swap to a Holinger sequential, or a conversion to a Tremec T-56 Magnum. Many budget-conscious racers use a brand-new stock gearset with cryo-treating and shot-peening, but 700+ hp will eventually break them. A heavy-duty bell housing is also common to reduce flex under load.

Clutch and Flywheel

A multi-plate clutch is necessary to transmit 700+ hp without slipping. Twin-plate clutches (like OS Giken R2C, Exedy Hyper Twin, or Competition Clutch) are popular; for street use, a single carbon/carbon disc can work with smooth engagement. The flywheel should be billet steel or aluminum (forged) that is SFI-approved for safety. Avoid lightweight flywheels that are too thin—they can disintegrate at high rpm. The clutch master cylinder may need upgrading to a larger bore (17/16 inch) to handle the heavier pedal pressure.

Driveshaft, Axles, and Differential

The stock one-piece driveshaft on the R33/R34 can be replaced with a lightweight carbon fiber or aluminum unit (rated for 1000 hp). Under 700+ hp, the stock half-shafts (axles) often twist, especially with sticky tires. Upgraded axles from companies like DSS (Driveshaft Shop) or GReddy are rated for 1000+ hp. The differential—whether the stock mechanical LSD or the electronic ATTESA-ETS controller—must be properly set up. The ATTESA unit can be tuned via the ECU to manage torque distribution, but the clutch packs inside the rear diff may need a rebuild with higher-friction discs to prevent one-wheel peels under high power.

Suspension and Brakes

700+ hp is useless if you can’t stop or turn. For the R32/R33/R34, coilover suspension with spring rates around 10-14 kg/mm front and 8-12 kg/mm rear is recommended for a street/track mix. Adjustable sway bars and solid subframe bushings reduce flex and improve traction. Brakes should be upgraded to six-piston calipers with 355 mm or larger rotors (Brembo, AP Racing, or StopTech). Running brake ducts and high-temperature fluid (RBF600) is essential for track use. A larger master cylinder or pedal ratio adjustment helps firm up the pedal. Good tires (e.g., 265/35R18 front, 305/30R18 rear) are necessary to put down the power.

Budgeting and Planning

A 700+ hp RB26DETT build is not cheap. Including the engine, turbo, fuel, cooling, and drivetrain modifications, expect to spend between $20,000 and $40,000 in parts alone. Labor for machine work (block honing, head porting, assembly) adds another $5,000-10,000. Tuning costs are around $1,000-2,000. It is wise to prioritize reliability—do not cut corners on the fuel system, head studs, or clutch. Plan the build in stages, starting with turbo, fuel, and tuning, then internals and drivetrain as the budget allows. If you are modifying a street car, consider retaining the stock twin-turbo configuration for better drivability up to 600 hp; then swap to a single for 700+. Nissan’s Heritage Parts program can still supply genuine RB components, but many are discontinued, so aftermarket sourcing is essential.

Conclusion

Comparing a stock RB26DETT to a 700+ horsepower build reveals that the engine block itself is a solid foundation, but nearly every ancillary system must be upgraded. The turbochargers, fuel system, internals, cooling, ECU, and drivetrain all require careful selection and installation. A well-executed 700+ hp RB26 is not only possible but also a joy to drive—if you respect the power and maintain the car diligently. With proper planning, the legendary inline-six can continue to dominate drag strips, circuits, and the hearts of enthusiasts for decades to come. Whether you choose single or twin turbos, aggressive cams or mild, the key is quality components and professional tuning. Good luck with your build.