The Quest for 700 Horsepower in an Audi R8

The Audi R8, with its mid-engine layout and quattro all-wheel drive, is already a formidable supercar. But for enthusiasts who crave more, the path to 700 wheel horsepower runs through a carefully engineered twin-turbo system. Achieving this level of power reliably requires more than just bolting on turbos; it demands a holistic approach to engine, fuel, cooling, and drivetrain upgrades. This guide details the essential components and considerations for building a 700hp R8 twin-turbo kit that delivers both performance and durability.

Understanding Twin Turbo Systems for the R8

A twin-turbo setup uses two turbochargers, typically one per cylinder bank on a V10 or V8 engine. This arrangement offers several advantages over a single large turbo: faster spool time, reduced turbo lag, and more compact packaging. The R8's engine bay is tight, and twin turbos can be placed closer to the exhaust manifolds, improving throttle response. Systems like those from Underground Racing or VR Tuned are designed to fit without major body modifications, though some trimming of the rear bumper or under-tray may be required.

A 700hp target is relatively modest for the R8’s 5.2L V10 (or 4.2L V8) – it represents roughly a 50-60% increase over stock. This level of power is achievable with the factory engine internals if the tune is conservative and supporting systems are upgraded. However, pushing beyond 700hp often necessitates forged rods, pistons, and head studs to prevent failure under high cylinder pressure.

Turbocharger Selection: Matching Turbos to the Target

The heart of any twin-turbo kit is the turbochargers themselves. For a 700hp R8, the ideal turbo is one that flows enough air to reach the power goal while spooling quickly. The most common options fall into the 58-62mm compressor wheel range:

  • Garrett GTX3582R Gen II – An industry standard. Excellent response, capable of 700+ hp with the right supporting mods. Dual ball bearing core for reliability.
  • Precision Turbo 6266 – Slightly larger hot side, higher peak flow potential. Comes in journal or ball bearing variants. Known for strong mid-range torque.
  • BorgWarner EFR 7670 – Uses advanced metallurgy and an integrated wastegate port. Fast spool, high efficiency. Requires careful packaging due to its unique turbine housing.
  • Garrett G30-660 – Newer option, very fast spool, rated to 750hp. Ideal for a tight, responsive twin setup.

For a street-focused 700hp build, the GTX3582R or G30-660 are popular choices. If you plan to track the car heavily, the EFR 7670’s durability and heat management are advantages. All require a proper T4 or divided T4 twin-scroll manifold to maximize pulse separation and spool.

Supporting Components: More Than Just Turbos

A 700hp turbo kit is only as good as its supporting systems. Skimping on intercooling, fuel delivery, or exhaust flow will result in knock, detonation, or poor performance. Here is a component-by-component breakdown.

Intercooler and Charge Air System

Compressing air raises its temperature dramatically. Without an efficient intercooler, intake air temps soar, reducing oxygen density and inviting pre-ignition. For 700hp, you need a core with sufficient surface area and flow. Air-to-air intercoolers are common, but some builds use air-to-water systems for more consistent temps in stop-and-go traffic. Top options include:

  • CSF Racing intercooler – Bar-and-plate design, direct fit for the R8. Proven to support 800+ hp.
  • VR Tuned intercooler – Larger core, works with their own twin-turbo kit. Good for heavy use.
  • AWE Tuning intercooler – High-flow end tanks, excellent heat rejection. Often used with Vortech superchargers but adaptable.

Pipe diameter should be at least 2.5 inches to keep pressure drop low. Silicone couplers and T-bolt clamps are mandatory for boost retention.

Exhaust System

A restrictive exhaust strangles turbo performance. The factory R8 exhaust is relatively free-flowing but still a bottleneck at 700hp. A high-flow system reduces backpressure, allowing turbos to spool faster and maintain peak boost. Look for a system with mandrel-bent tubing, minimal muffler restriction, and heat management (ceramic coating or wrapping). Recommendations:

  • Armytrix Valvetronic – Remote-controlled wastegates for variable sound. Straight-through design.
  • Capristo exhaust – T304 stainless, unique step-design piping. Excellent power gains.
  • Audi Sport performance exhaust – Factory option, but may still be too restrictive. Consider aftermarket downpipes (catless or high-flow cats) to complement.

Don’t overlook the wastegate dump tubes. External wastegates (usually 38-45mm Tial or Turbosmart) should be routed to atmosphere or recirculated into the exhaust.

Fuel System Upgrades

At 700hp, the R8’s stock fuel system is at its limit. The high-pressure fuel pump and injectors cannot supply enough volume, leading to lean conditions under load. A complete upgrade includes:

  • Injectors: Larger port injectors (e.g., Injector Dynamics 1050X or 1300X) are essential. For the V10, you need six per bank.
  • High-pressure fuel pump (LPFP): The in-tank pump must be upgraded to a Walbro 450 LPH or similar. A boost-a-pump can also supplement voltage.
  • Fuel pressure regulator: A return-style system with an adjustable regulator (Fuel Lab, Aeromotive) maintains consistent pressure during high demand.
  • Fuel lines: At minimum, -6 AN feed and -6 AN return. For 700hp, -8 AN feed is safer.
  • Ethanol compatibility: If running E85, ensure all components (lines, seals, injectors) are ethanol-rated. E85 allows higher boost and more ignition timing.

A dedicated fuel system like the Audi R8 Twin Turbo Fuel Upgrade Kit from Injector Dynamics simplifies the install.

Tuning Software and Engine Management

Tuning is the glue that binds all hardware together. A 700hp R8 requires a custom calibration that respects engine limits and adapts to the specific turbo/IC/fuel combo. Reputable tuners include:

  • APR Stage 2 or beyond – APR offers off-the-shelf tunes for their supercharger kits, but for turbo builds you need a custom remote or dyno tune. Their software is flexible.
  • Unitronic Performance Software – Known for smooth drivability. Offers custom tuning via their flash loader.
  • ECUtek Custom Tuning – Very popular in the R8 community. Allows race-gas maps, launch control, flat-foot shifting, and boost-by-gear. Works with many professional dyno tuners.
  • Syvecs or MoTeC stand-alone ECU – For extreme builds, but expensive and requires expert wiring.

Ensure the tune includes knock detection, wideband O2 feedback, and fail-safe limits for boost, AFR, and IAT. Do not rely on a generic file – every build is different.

Engine and Drivetrain Preparation

700hp can be handled by the stock 5.2L V10 if the engine is healthy and the tune is conservative (low boost, high octane). However, long-term reliability improves with internal upgrades:

Forged Internals

  • Connecting rods: Stock rods may bend over 650-700 lb-ft of torque. Upgrade to Carrillo, Pauter, or R&R billet rods.
  • Pistons: CP-Carrillo or JE forged pistons – lower compression ratio (c.r. from 12.5:1 to 9.5-10.0:1) to safely run more boost on pump gas.
  • Head studs: ARP studs prevent head lift under high cylinder pressure.
  • Main studs/bolts: Optional but recommended for sustained high-rpm use.

Transmission and Clutch

The R8 comes with either a 6-speed manual (R tronic or gated manual) or the S-tronic dual-clutch automatic (DCT). For 700hp:

  • Manual (gated): Upgrade the clutch to a twin-disc (Sachs, Clutch Masters) rated for 800-900 hp. The stock clutch will slip immediately.
  • R tronic single-clutch: Many owners swap to a gated manual or upgrade the clutch pack. The R tronic is not ideal for high torque.
  • S-tronic DCT: The dual-clutch gearbox is robust. Stock clutches can handle 700hp with proper tuning (avoid harsh launches). Some tuners offer software upgrades for faster shifts and increased torque limits.

Don't forget the rear axle and differential. The R8's rear diff is strong, but regular fluid changes with high-torque diff fluid (Motul Gear 300) are recommended.

Cooling Systems

Turbocharging increases engine heat output significantly. Upgraded cooling is crucial:

  • Radiator: CSF or Mishimoto racing radiators with twin fans.
  • Oil cooler: Setrab or Mocal oil cooler with a thermostat. For a twin-turbo R8, a 34-row or larger is typical.
  • Intercooler water spray (if using air-to-air): A simple water mist kit can reduce IATs by 20-30°F on track.
  • Transmission cooler: For S-tronic, add an auxiliary cooler to prevent overheating during aggressive driving.

Installation and Cost Considerations

Installing a twin-turbo kit on an R8 is not a weekend project. It involves removing the engine, fabricating mounts, welding manifolds (if not a complete bolt-on kit), and routing all plumbing. Professional installation is strongly recommended – budget $5,000-$10,000 for labor alone. Complete turnkey installations from shops like Underground Racing or GMP Performance can cost $40,000-$80,000 all-in including parts.

For those piecing together their own kit, total component costs (turbos, manifolds, intercooler, fuel system, tuning) typically run $15,000-$25,000, plus engine work if needed. Here is a rough breakdown:

  • Twin turbo kit (manifolds, turbos, wastegates, downpipes): $8,000-$15,000 (e.g., VR Tuned kit)
  • Intercooler + piping: $1,500-$3,000
  • Fuel system (injectors, pump, lines, regulator): $3,000-$5,000
  • Exhaust: $2,000-$4,000
  • Engine internals: $5,000-$10,000 (if forged)
  • Clutch/DCT upgrades: $2,000-$5,000
  • Tuning: $1,000-$3,000

It's easy to see why many opt for a package deal from a specialized shop.

Final Thoughts: Balancing Power and Reliability

A 700hp Audi R8 twin-turbo build is a rewarding project that transforms an already fast car into a street-legal weapon. The key to success is not just choosing the right turbocharger, but a comprehensive system that includes proper fueling, cooling, engine prep, and professional tuning. Follow the recommendations in this guide, and you'll enjoy a reliable, exhilarating 700hp R8 that can dominate both canyon roads and drag strips. For more detailed build threads, visit forums like Audizine R8 or AudiWorld R8 to see real-world dyno sheets and reliability data.