powertrain
How Much Power Does the Garrett Gtx2871r Turbo Provide on an Audi Tt 2.0t?
Table of Contents
Garrett GTX2871R Turbo on the Audi TT 2.0T: Power Potential and Build Guide
The Audi TT 2.0T (8J chassis with the EA113 engine) is a capable platform, but the factory K03 turbo leaves enthusiasts wanting more. The Garrett GTX2871R has become a benchmark upgrade for this engine, offering a balance of quick spool and substantial top-end power. This guide covers the real-world power output you can expect, the supporting modifications required, and the tuning strategies needed to safely unlock the turbo’s potential.
Garrett GTX2871R: Specifications and Design
The GTX2871R is part of Garrett’s GTX series, which uses a billet compressor wheel and advanced aerodynamics. Compared to the older GT2871R, the GTX version offers improved efficiency and a broader power band.
Key Specs
- Compressor inducer diameter: 71mm
- Turbine exducer diameter: 60mm
- A/R sizes: 0.60 (compressor housing), 0.64 (turbine housing – common for T3 flange)
- Maximum boost pressure: up to 30 psi
- Power rating: 300–400 horsepower (crank, depending on application)
The 71mm compressor flows enough air to support around 400+ crank horsepower, while the 60mm turbine is sized to spool well on a 2.0L engine. This turbo is often chosen because it offers a significant upgrade over the stock K03/K04 without the lag of larger turbos like the GTX3071R.
For official specifications and compressor maps, visit Garrett Motion’s GTX Series page.
Power Output on the Audi TT 2.0T
When correctly installed and tuned on a stock internal engine, the GTX2871R typically produces between 300 and 350 wheel horsepower. On a higher compression engine or with aggressive tuning on E85, outputs of 400+ wheel horsepower are achievable with forged internals.
Expected Dyno Results (SAE corrected)
- Stock Audi TT 2.0T (200–210 whp) – baseline
- GTX2871R with minimal supporting mods (pump gas, 18–20 psi) – 300–320 whp, 330–350 lb-ft torque
- GTX2871R with full bolt-ons and 93 octane (22–24 psi) – 350–380 whp, 350–390 lb-ft torque
- GTX2871R with E85, upgraded fuel system, and built head (28–30 psi) – 400–430 whp, 420–450 lb-ft torque
These numbers are wheel horsepower on a Mustang or Dynojet; crank figures are roughly 15–20% higher. Most street builds target the 330–360 whp range for reliability and drivability.
Factors That Influence Power Output
Engine Tuning
The ECU calibration is the single most important factor. A generic “off-the-shelf” tune may yield 300 whp, while a custom dyno tune dialing in boost, timing, and fuel trims can unlock 30–50 additional horsepower. Fuel quality determines knock margins; higher octane allows more aggressive timing and boost.
Fuel Selection
- 91 octane (US): limited to 18–20 psi, lower timing, ~300–320 whp
- 93 octane: allows 22–24 psi, moderate timing, ~350 whp
- E85 (ethanol): excellent knock resistance, can run 28–30 psi with higher timing, supporting fuel system required
- Meth injection: can bridge the gap between pump gas and E85, but adds complexity
Supporting Modifications
Without adequate supporting mods, the turbo will be choked. The table below shows which modifications are considered necessary vs. optional for different power levels.
| Component | 300–350 whp | 350–400+ whp |
|---|---|---|
| Intercooler | Required (stock is inadequate) | Required (larger core) |
| Downpipe + Exhaust | Required (3” downpipe, 3” cat-back) | Required (full 3” system) |
| Intake | Required (cold-air, high-flow) | Required (larger MAF housing often needed) |
| Fuel Injectors | Required (550–630cc low impedance) | Required (1000cc or larger) |
| High Pressure Fuel Pump | Optional (recommended with E85) | Required (upgraded HPFP or auxiliary injection) |
| Engine Internals | Stock (with conservative tune) | Required (forged rods, pistons for 400+ whp) |
Engine Condition and Compression
A tired engine with worn rings or low compression will produce less power and be more prone to knock. Performing a compression test before installation is wise. The factory compression ratio of 9.7:1 is safe for 400 whp with proper fuel and tuning.
Detailed Supporting Modifications
Intercooler Upgrade
The stock side-mount intercooler cannot handle the heat load from the GTX2871R. At 350 whp, intake temperatures can soar over 140°F, robbing power and increasing knock risk. A front-mount intercooler (FMIC) like the unit from EuroSport Acceleration or a DIY treadstone core is highly recommended. Look for a core with at least 3” inlet/outlet and bar-and-plate construction.
Exhaust System
A restrictive exhaust creates backpressure that limits spool and top-end power. A 3” downpipe (preferably with a high-flow catalytic converter or test pipe) mated to a 3” cat-back is standard. Some tuners recommend a downpipe with a divorced wastegate path for better flow.
Intake and Inlet Pipe
The factory airbox is too restrictive. A cold-air intake with a large dry-flow filter (e.g., K&N, AEM) will help. The turbo inlet pipe should be upgraded from the stock rubber piece to a smooth 2.5”–3” silicone or aluminum pipe to reduce turbulence.
Fuel System Upgrades
The factory EA113 fuel system (radial pump, 4 bar FPR, 380cc injectors) will max out around 300 whp on pump gas. To go higher, you need one of the following:
- Injectors: 550cc or 630cc (Bosch EV14 style) for pump gas up to 380 whp. Above that, 1000cc injectors are required especially for E85.
- High Pressure Fuel Pump (HPFP): The factory cam-driven pump can fail under high load. Upgrades from companies like Autotech or Integrated Engineering offer higher flow and pressure limits.
- Low Pressure Fuel Pump: At 400+ whp, the in-tank pump may need to be upgraded to a unit like the Walbro 450.
Engine Internals
For sustained 400+ whp, forged connecting rods are mandatory. The factory rods are the weak point and will bend under high cylinder pressures. Forged pistons are also recommended if you plan to push 450+ whp or run high boost on E85. Stock pistons can survive 400 whp with a conservative tune, but rods are the first failure point.
Installation Considerations
Turbo Mounting and Manifold Fitment
The GTX2871R with a T3 turbine housing requires an aftermarket turbo manifold. For the EA113 engine, popular options include the full-race manifold or the Trackslag top-mount header. These are designed for the transverse layout of the Audi TT and VW Golf R/GEN platform. Expect to modify or relocate the coolant overflow tank and possibly the air conditioning lines.
Oil and Coolant Lines
The turbo uses a water-cooled center cartridge. You will need to run oil feed (braided line with restrictor if using factory oil pressure) and oil return (–10AN or larger) lines. Coolant lines can be spliced into the existing heater core lines using 5/8” hose or a kit from Chase Bays.
V-Band Compressor Discharge
Garrett uses a 2.5” V-band outlet on the compressor housing. You will need a silicone coupler and a T-bolt clamp to connect to your intercooler piping. Some builders prefer to weld a V-band flange into a custom aluminum charge pipe.
Tuning: Custom vs. Off-the-Shelf
While some companies offer “base calibrations” for the GTX2871R, a custom dyno tune is far superior. The turbo responds differently on every car due to exhaust backpressure, intercooler efficiency, and fuel quality. A professional tuner can dial in boost curves, ignition timing, and lambda targets to maximize power while keeping knock and EGTs safe.
For the EA113 engine, popular tuning platforms include Maestro, Syvecs, or standalone ECUs like Haltech and MaxxECU. Flash tuning via tools like COBB or Unitronic is less common for this engine but still available. Expect to spend 8–12 hours on the dyno for a full optimization.
Comparison to Other Turbo Options
- GTX2860R: Smaller, spools slightly faster, but runs out of breath above 350 whp. Good for street use with stock cam.
- GTX3071R: Larger, capable of 500+ whp, but significant spool lag. Requires built engine and upgraded valvetrain.
- K04 Hybrid (e.g., CTS K04): Direct bolt-on, 300 whp max, but low cost. Not comparable in top-end.
- BV43 Hybrid: Similar to GTX2860R, but uses factory manifold, 330 whp limit.
The GTX2871R hits the sweet spot for a daily-driven Audi TT that still wants to surprise on track days.
Real-World Performance
With 350 whp and the right suspension (H&R coils, rear sway bar), the Audi TT can run quarter-mile times in the 12.0–12.5 second range at 110–115 mph. 0–60 mph drops to the 3.8–4.2 second range with a good launch. The turbo’s spool characteristics mean full boost arrives by 3500–3800 RPM, which keeps throttle response lively.
One common upgrade to improve traction is an upgraded clutch (Southbend or Sachs stage 2–3) and a limited-slip differential. The stock Haldex gen4 with software tuning can handle 350–400 whp, but wheel hop can be an issue.
Conclusion
The Garrett GTX2871R turbo provides a transformative power increase for the Audi TT 2.0T. With proper supporting modifications and a professional tune, you can expect 300–400 whp depending on fuel and engine internals. The key is not to cut corners—cheap intercoolers, injectors, or a half-assed tune can lead to blown engines. Invest in a quality FMIC, a 3” exhaust, and a custom dyno session, and you’ll have a fast, reliable TT that can hang with much more expensive machinery.
For further reading on GTX series turbo sizing, check Garrett’s official page. For community dyno results, the Audizine forums have extensive build threads.