Introduction: The R34 GT-R as a 700 HP Canvas

The Nissan Skyline R34 GT-R occupies a hallowed place in automotive history. Its RB26DETT engine, ATTESA E-TS all-wheel-drive system, and aggressive styling have made it a tuner staple and a collector’s dream. While the stock engine is robust from the factory, reaching a reliable 700 horsepower requires a methodical approach. This build target sits in a sweet spot: it is far beyond stock output yet remains largely streetable when the correct components are chosen. Achieving this level of power without sacrificing durability demands careful selection of turbochargers, internal engine components, and a comprehensive set of supporting modifications. The following guide outlines a proven path to a 700 HP R34 GT-R that can handle spirited driving, track days, and the occasional street cruise.

Selecting the Right Turbochargers

The RB26’s twin-turbo layout offers unique opportunities and challenges. At 700 HP, you must move beyond the stock turbochargers, which are small and prone to becoming a bottleneck. The goal is to choose a pair of turbos that can deliver the airflow for 700 HP while maintaining reasonable spool characteristics. Typically, this means sizing each turbo to flow roughly 350-400 HP worth of air. Below are the most commonly recommended options for this power level.

Garrett GTX3076R

This is a frequent choice among experienced R34 builders. The Garrett GTX3076R features an advanced turbine wheel design and a billet compressor wheel that provide excellent mid-range response without sacrificing top-end pull. At moderate boost pressure (around 1.5–1.8 bar), a pair of GTX3076Rs can easily support 700 HP while keeping the powerband usable for daily driving. The ceramic ball-bearing cartridge reduces lag and allows for quick transient response. For those who want a familiar, well-documented setup, the GTX3076R is hard to beat.

HKS GT-RS

HKS has been a longstanding partner in the R34 community, and their GT-RS turbochargers are purpose-built for the RB26. The GT-RS uses a smaller housing than some competitors, which helps with early spool, yet the compressor trim is optimized to deliver strong top-end flow. Many 700 HP builds run GT-RS turbos with cams and head work to realize their full potential. Their reliability is proven across hundreds of builds worldwide. HKS provides complete bolt-on upgrade kits that simplify installation.

Blitz K5-700R

Blitz offers the K5-700R series specifically targeted at the R34 GT-R. These turbos are engineered to hit the 700 HP mark without pushing the boost unreasonably high. The turbine wheel is made from high-temp Inconel material, which improves durability under sustained high load. The K5 line is known for delivering power with a smooth, linear delivery, making them a favorite for street-driven cars that also see track time.

Precision Turbo 6266

While the Precision 6266 might be more commonly known in single-turbo applications, some builders run a pair in a twin setup. These turbos have a larger compressor wheel (66 mm inducer), so they will spool slightly later than the GTX3076R or GT-RS, but they have headroom to exceed 700 HP safely. Precision uses a billet compressor wheel that is extremely efficient; even at 700 HP, you are not pushing the turbo near its limits, which improves longevity.

When selecting turbos, also consider the housing A/R. For twin-turbo RB26s, A/R values of 0.60 to 0.70 on the compressor and 0.70 to 0.85 on the turbine are common. A lower A/R can help spool but may restrict top-end power; a higher A/R does the opposite. Your tuner can help match the appropriate housings to your specific cam and displacement choices. For further reading on turbo selection, visit Garrett Motion for technical papers on compressor maps, or the HKS website for their product line.

Building a Robust Short Block

The RB26’s factory iron block is surprisingly stout; many builders retain the original block for 700 HP builds after suitable preparation. However, the rotating assembly must be upgraded to handle the increased cylinder pressure and sustained high RPM. Here are the essential internal upgrades.

Forged Pistons

Stock cast pistons are the first weak link at this power level. Forged pistons from manufacturers like CP-Carrillo, JE Pistons, or Ross Racing Pistons are mandatory. Choose a 4032 or 2618 aluminum alloy depending on your intended use; 2618 is better for high-boost, high-heat applications, though it has slightly more thermal expansion. Pistons should be designed with a strong ring pack and adequate skirt clearance. Compression ratio can be set between 8.5:1 and 9.0:1; lower ratios allow more boost but may require more timing to spool. Always have the piston-to-wall and ring end gaps set by an experienced engine builder.

Forged Connecting Rods

The stock RB26 rods are capable of around 500–550 HP before bending becomes a risk. For 700 HP, you need aftermarket forged rods. Eagle Specialty Products offers budget-friendly 4340 forged rods that have been used in countless builds. For a higher budget, Manley Performance and Carrillo make H-beam rods with improved fatigue life. The rod length should remain stock (130.2 mm center-to-center) unless you are building a stroker. Use ARP 2000 or L19 rod bolts for clamping force. Shot-peening and magnafluxing the rods before installation adds an extra layer of safety.

Crankshaft Options

The RB26 crankshaft is a forged unit from the factory and is surprisingly durable. Many 700 HP builds reuse the stock crank after it has been thoroughly inspected, balanced, and micropolished. If you are building for higher power levels or want extra robustness, aftermarket cranks from Tomei or HKS are available, but they are not strictly necessary at 700 HP. What is critical is the main bearing choice: use a high-quality bearing like ACL Race Series or Clevite, and ensure the oil clearance is set according to the manufacturer’s specs. A girdle brace (often referred to as an “oil pan baffle” or “windage tray”) helps maintain oil pressure and crank stability at high RPM.

Short Block Assembly and Balancing

Once the pistons, rods, and crank are chosen, have the assembly balanced as a set. Most machine shops can spin-balance the rotating assembly to within 1 gram. Use an ARP main stud kit to improve main cap stability. Do not neglect the thrust bearing clearance; on RB26 engines, this can be tight. A properly assembled short block will handle 700 HP with ease and provide a calm foundation for the cylinder head.

Upgrading the Cylinder Head and Valvetrain

The RB26’s cylinder head is a work of art, but the valvetrain is not designed for the high spring pressures needed at 700 HP and elevated RPM. The factory valve springs can float above 7500 RPM, leading to piston-to-valve contact. Upgrades here are non-negotiable.

Valves and Seats

Stock valves can be used if the engine is limited to moderate boost, but most builders upgrade to Ferrea or Supertech valves in inconel or stainless steel. Inconel exhaust valves are particularly beneficial because they resist heat better at high exhaust gas temperatures. Larger valves (1 mm oversized) can be fitted if the porting work is done, but this is not required for 700 HP. The valve seats should be cut to match the new valve angles; a multi-angle valve job improves flow without needing extensive porting.

Valve Springs and Retainers

Upgrade to dual valve springs with titanium retainers. The GT-R community widely uses Brian Crower and Kelford spring kits. The spring seat pressure should be around 80–90 lbs, and open pressure around 200–220 lbs. This prevents valve float up to 8500 RPM. Do not forget to check installed height and use shims as necessary.

Cams and Timing

Camshafts are a major contributor to the power curve. For 700 HP, a 264-degree intake and 264-degree exhaust grind with 10–11 mm lift is a popular choice. It provides good mid-range torque and allows the turbochargers to spool effectively. More aggressive 272-degree cams shift the powerband higher and can extract the full potential of the turbos, but they may sacrifice some responsiveness. HKS and Kelford offer drop-in cam sets for the RB26. Adjustable cam sprockets (HKS or JUN) give the tuner control over cam timing, which can optimize the torque curve. Have the head assembled by a specialist who understands the RB26’s valvetrain geometry.

Supporting Modifications: Fuel, Induction, Exhaust, and Cooling

Fuel System

An engine producing 700 HP requires substantial fuel flow. The factory fuel system is inadequate. You need a high-flow fuel pump capable of supporting at least 1000 HP if the engine runs on E85 (which consumes roughly 30% more fuel). A dual pump setup (e.g., two Walbro 525 or Aeromotive 340 pumps) is common, with one pump triggered at idle and the second at boost threshold. Install a dedicated fuel surge tank and a swirl pot to prevent starvation under hard cornering. Upgrade the injectors to a minimum of 1300 cc/min; many tuners prefer 1500 cc injectors with E85 compatibility. Use a billet fuel rail, a fuel pressure regulator (e.g., Aeromotive or Fuelab), and -8 AN feed lines from the tank to the rail. Return line should be -6 AN. Tune the fuel pressure to 43.5 psi base and adjust boost pressure ratio accordingly.

Intake and Intercooling

A larger intercooler is critical to keep intake air temperatures low. The stock side-mount intercoolers are insufficient; they become heat-soaked quickly. Upgrade to a front-mount intercooler (FMIC) with a core size of at least 650 mm width, 300 mm height, and 75 mm thickness. Look for a bar-and-plate design with cast end tanks. Reputable brands include Hybrid Racing, Plazmaman, and Turbosmart. The piping should be 2.5” or 3” diameter with smooth mandrel bends to reduce turbulence. On the intake side, consider an aftermarket intake manifold such as the Plazmaman, GReddy or Kelford plenum. These manifolds improve distribution and runner length tuning compared to the stock unit, which is a compromise for emissions. Use a large throttle body (80 mm to 90 mm) to match.

Exhaust System

At 700 HP, you need a free-flowing exhaust. Start with upgraded downpipes that eliminate the restrictive factory pre-cats. A 3-inch downpipe per turbo is the standard, merging into a 4-inch or 3.5-inch front pipe. The main exhaust should be at least 3.5 inches in diameter to minimize back pressure. Use mandrel-bent stainless steel tubing and a high-flow catalytic converter if required for emissions. The exhaust finish often includes a titanium or stainless steel muffler. Brands like HKS, GReddy, Kakimoto, and A’PEXi offer complete systems for the R34. Be aware that noise regulations may limit your muffler choices; a resonated system can help keep the sound civil.

Cooling System

Increased power generates more heat, especially on a track. Upgrade the radiator to a dual-core or triple-core aluminum unit with a high-flow thermostat. A Koyo, PWR, or Mishimoto radiator is common. Install a high-performance electric fan setup with a shroud to pull air at idle. Oil cooling is equally critical: use a thermostat-controlled oil cooler with a core size of at least 10×10 inches. Many builders mount the oil cooler in the front bumper area. Consider an air-to-water intercooler if you plan on extended high-load runs, but an air-to-air setup works for most street and track applications. Use a coolant expansion tank with a proper overflow line.

For more details on fuel system design, Aeromotive provides technical guides. For intercooler core data, visit Plazmaman.

Engine Management and Tuning

A standalone ECU is a prerequisite for 700 HP. The stock Nissan ECU cannot be reliably re-tuned to this extent. Options include Haltech Elite 2500, Link G4+, Motec M1, and AEM Infinity. All offer full control over fuel, ignition, boost, variable cam timing (if VCT is retained), and additional features like anti-lag, flat-foot shifting, and traction control. The ECU wiring is a significant task—many shops offer plug-and-play harnesses for the R34, which greatly simplifies installation. The tuner will map the fuel table and ignition table on a dyno, paying special attention to knock detection. Use a knock sensor module (e.g., Haltech K-8 or Link knock block) to listen to engine noise. The RB26 is sensitive to detonation, so a conservative tune with a proper safety margin is wise.

Boost control is typically handled by a solenoid valve controlled by the ECU. Set boost levels gradually; a 700 HP engine might run peak boost of 1.6–1.8 bar (23–26 psi) on pump gas, or higher on E85. Always verify fuel pressure and injector duty cycle during tuning.

Driveline Upgrades

The R34 GT-R’s drivetrain is sturdy, but 700 HP will find weak points. Start with the clutch: a single- or twin-plate clutch from Exedy, OS Giken, or Competition Clutch can handle the torque. A sprung hub disc is more streetable than a rigid disc. The Getrag six-speed transmission is capable, but it may not last indefinitely under hard use. Consider a gear set upgrade from PPG Gearset or G-Rev for peace of mind. The transfer case should be inspected and possibly fitted with an upgraded oil pump or a billet output shaft. The front and rear differentials are robust, but upgrading the limited-slip diff clutches or switching to a torque-biasing diff can improve handling. Drive shafts and axles should be upgraded to billet units from vendors like DSS (Drive Shaft Shop) to eliminate the risk of snapping half-shafts during hard launches.

Chassis, Suspension, and Braking

With 700 HP, you need a suspension that can put the power down and a brake system that can stop the car from high speeds. Upgraded coilovers from Ohlins, KW, or HKS allow precise damping control. Adjustable sway bars and solid bushings reduce chassis flex. For braking, big brake kits with 6-piston calipers at the front and 4-pistons at the rear are recommended. Brembo, AP Racing, and Endless all offer bolt-on kits for the R34. Use slotted or drilled rotors and high-performance pads (e.g., Pagid RS29 or Ferodo DS2500). Don’t forget to upgrade the brake master cylinder and install braided stainless steel lines. Tires are the final link; a 700 HP R34 needs at least 265 mm front and 295 mm rear tires on 18-inch wheels. Semi-slick tires like Michelin Pilot Sport Cup 2 or Yokohama Advan A052 provide the grip needed to accelerate and brake effectively.

Cost Considerations and Build Planning

Building a 700 HP R34 GT-R is not an inexpensive undertaking. A rough budget breakdown might look like this:

  • Turbocharger kit (twin): $3,000–$5,000
  • Forged pistons and rods: $2,500–$4,000
  • Crankshaft (if replaced): $1,500–$3,500
  • Cylinder head work (valves, springs, cams, assembly): $3,000–$6,000
  • ECU and tuning: $3,000–$5,500
  • Fuel system (pump, injectors, lines, surge tank): $2,000–$4,000
  • Intercooler and piping: $1,500–$2,500
  • Exhaust system: $1,500–$3,000
  • Cooling upgrades: $1,500–$2,500
  • Clutch and flywheel: $1,500–$3,000
  • Suspension and brakes: $5,000–$10,000
  • Labor and miscellaneous: $5,000–$10,000

This totals roughly $30,000–$55,000 on top of the purchase price of a clean R34. Costs can vary widely based on region, shop rates, and parts selection. It is wise to build a detailed parts list and have a trusted shop perform the assembly and tuning. Many owners choose to buy a well-sorted example rather than build from scratch; either route requires patience and careful sourcing.

Conclusion

Reaching 700 horsepower in an R34 GT-R is an achievable goal that rewards meticulous planning. The engine requires forged internals, a robust valvetrain, and properly sized turbochargers. The supporting systems—fuel, induction, exhaust, cooling, and engine management—must be upgraded in concert to ensure reliability. The drivetrain and chassis need attention to handle the increased power safely. Because every R34 is unique, consulting with experienced builders and tuners is essential to tailor the build to your driving style and intended use. When done correctly, a 700 HP R34 GT-R remains a thrilling, daily-drivable machine that can dominate at the track and on the street.