The A45 AMG and the Case for a Turbo Upgrade

The Mercedes-AMG A45 is a benchmark in the hot hatch segment, largely thanks to its hand-built M133 2.0-liter turbocharged engine. From the factory, this four-cylinder produces staggering power for its displacement—up to 416 horsepower in the latest iterations. However, even this engineering marvel has its limits. The factory turbocharger is a compromise, designed to balance emissions, fuel economy, warranty, and performance across a broad range of operating conditions. For enthusiasts seeking more, a turbo upgrade is the single most effective modification.

This article examines one of the leading options, the MAPerformance Vspure Turbo, and compares it against other viable alternatives to help you decide which path delivers the best real-world performance gains for your A45.

Understanding Turbo Upgrades for the M133 Engine

The M133 engine benefits from a twin-scroll turbocharger from the factory, which provides excellent spool characteristics. However, the stock unit’s compressor wheel and turbine housing limit peak airflow and boost pressure, especially at higher RPMs. Upgrading the turbo allows the engine to inhale and exhale more freely, dramatically increasing horsepower and torque potential. This is not a simple bolt-on; it requires careful tuning and often supporting mods to realize full gains.

Factory Turbo Limitations

The stock turbo on the A45 is capable of sustaining around 30-32 psi of boost at its peak, but it runs out of breath in the upper rev range. This leads to a characteristic drop in power after 5500-6000 RPM. For those chasing bigger numbers (400+ whp on the M133 or 500+ whp on the M139), the factory unit simply cannot deliver the required airflow. Additionally, heat soak becomes a significant issue, reducing boost pressure and retarding timing as the intake air temperatures climb.

How an Upgraded Turbo Changes the Game

A larger or redesigned turbocharger addresses these shortcomings by providing a larger compressor wheel, a more efficient turbine housing, and sometimes a billet wheel for improved aerodynamics. The result is higher peak boost levels (often 35-40+ psi), sustained power to redline, and lower exhaust backpressure. However, this comes at a cost: potentially increased spool time (lag), greater heat output, and the necessity for robust engine management and cooling.

The MAPerformance Vspure Turbo: A Detailed Look

MAPerformance has developed the Vspure turbo specifically for the M133 and M139 platforms. It is designed as a direct replacement for the factory unit, using the same housing dimensions and mounting points, but with internal components engineered for much higher flow. The "Vspure" name refers to the use of a high-flow, billet compressor wheel and a ported turbine housing optimized for the engine’s specific exhaust characteristics.

Design and Engineering Features

  • Billet Compressor Wheel: Machined from a single piece of aluminum for precision balancing and superior aerodynamic efficiency. This reduces rotational inertia and improves spool compared to cast wheels.
  • Ported Turbine Housing: The factory housing is machined to remove restrictions and improve flow from the exhaust manifold. This reduces backpressure without sacrificing boost response.
  • Upgraded Bearing System: Uses a high-quality journal bearing (or optional ball bearing upgrade in some variants) to handle higher rotating speeds and oil temperatures.
  • CNC-Machined Compressor Cover: Precision-machined for optimal airflow into the compressor wheel.

Key Specifications and Performance Data

  • Power Gain: 100–130+ wheel horsepower over stock on a properly tuned M133.
  • Torque Gain: 80–100 lb-ft increase in the mid-range, with improved top-end torque.
  • Boost Levels: Capable of sustaining 35-38 psi on race fuel or ethanol blends.
  • Spool Characteristics: On a well-tuned car, full boost arrives by 3800-4000 RPM, only slightly later than stock, but with a much stronger surge.
  • Compatibility: Direct bolt-on for M133 (A45, CLA45, GLA45). Requires tuning (ECU remap) and often larger injectors and high-pressure fuel pump.

Real-World Results

Independent dyno results from platforms like MAPerformance and owner forums consistently show the Vspure delivering over 450 whp on pump gas (93 octane) and exceeding 500 whp on E85 with supporting mods. Quarter-mile times drop from low 12s to high 11s or below, with trap speeds increasing by 5-8 mph.

Comparing the Vspure to Other Turbo Options

The A45 community is not short of turbo upgrades. Three notable competitors are the Pure Turbo, the Garrett GTX2860R Gen II, and hybrid OEM solutions. Each has its own trade-offs.

Pure Turbo (Pure Turbos)

Pure Turbo is a well-known name in the European performance scene. They offer a drop-in upgrade for the M133 that uses a larger billet compressor wheel and a machine-ported housing. Like the MAPerformance unit, it is designed for high horsepower levels.

  • Peak Power: Similar to Vspure, capable of 450-500 whp with proper tuning.
  • Spool: Slightly earlier boost response than Vspure in some tests, but the margin is small (200-300 RPM).
  • Price: Comparable, typically within $100-200 of each other.
  • Reliability: Both are well-regarded; Pure has a slightly longer track record on this platform.
  • Availability: Often backordered; Vspure may have better stock.

Garrett GTX2860R Gen II

Garrett’s aftermarket turbo is a popular choice for custom setups, but it is not a direct bolt-on. It requires a custom oil and coolant line kit, a reclocked compressor housing, and often a different downpipe and intake piping. This is a more advanced installation suited for those building a dedicated high-horsepower engine.

  • Airflow: The GTX2860R Gen II flows slightly more than the Vspure, supporting up to 550 whp.
  • Spool: Slightly slower due to the larger turbine wheel; full boost around 4200-4500 RPM.
  • Cost: The turbo itself is comparable, but the custom fabrication and labor can make the total cost significantly higher.
  • Best For: Track-focused cars or those chasing 550+ whp who are willing to engineer a custom setup.

Hybrid OEM Solutions (e.g., Forced Performance, BNR)

These are factory turbos that have been rebuilt with larger internals. They are often cheaper but come with less robust quality control. Some hybrid options use a machined factory housing with a larger wheel, which can be hit or miss on reliability.

  • Power: Typically 380-430 whp, less than the Vspure.
  • Spool: Can be excellent, close to stock, due to the smaller wheel sizes.
  • Risk: Potential for imbalance, reduced lifespan, and inconsistent performance.
  • Best For: Budget-conscious owners who want a modest bump without a full turbo kit.

Supporting Modifications: The Complete Package

A turbo upgrade alone will not unlock its full potential. The engine, fuel system, and cooling must be prepared to handle the additional airflow and heat. Here are the essential supporting modifications.

Tuning and ECU Calibration

No turbo upgrade functions properly without a custom tune. Companies like Race Xtreme and Eurocharged offer ECU remaps specifically for the Vspure and similar turbos. The tune must adjust timing, fuel delivery, boost targets, and sensors to keep the engine safe. A poor tune can destroy the turbo or the engine within minutes. Always use a reputable tuner with M133 experience.

Fuel System Upgrades

The factory high-pressure fuel pump (HPFP) and injectors max out around 450-480 whp. To go beyond, you need a larger HPFP (e.g., from Dorch Engineering or updated OEM) and possibly larger injectors. Ethanol blends (E40 to E85) provide knock resistance and allow higher boost, but they require significant fuel system upgrades.

Intake and Exhaust

An upgraded turbo needs to breathe. A high-flow intake (like the Eventuri or MST) reduces restriction on the compressor side. On the exhaust side, a larger downpipe (3.0” or 3.5”) with a high-flow catalytic converter or catless setup is essential to reduce backpressure and spool time. A full turbo-back exhaust can further improve flow and sound.

Intercooler and Cooling

Heat is the enemy of boost. The stock intercooler is undersized for upgraded turbo levels. A bar-and-plate intercooler like the Wagner Tuning V2 or CSF improves heat rejection. Additionally, an upgraded radiator, oil cooler, and perhaps water-methanol injection can keep intake temperatures in check during extended hard driving.

Installation, Reliability, and Cost Considerations

Before committing, weigh the installation complexity and ongoing maintenance. The Vspure is a direct replacement, but the labor is still intensive due to the tight engine bay of the A45.

Installation

Most owners choose a professional shop. The job involves removing the factory turbo, transferring necessary heat shields, oil lines, and coolant lines, then re-installing with new gaskets and bolts. Expect 6-10 hours of labor. DIY is possible for those with mechanical experience, but access to the hidden lower bolts is challenging without a lift.

Reliability and Longevity

With a proper tune and quality oil, the Vspure turbo has proven to be durable. However, pushing 500+ whp places strain on the entire drivetrain: clutch (7-speed DCT), transmission, and engine bearings. It is wise to budget for additional drivetrain upgrades if you plan to track the car or run high boost frequently. Oil change intervals should be shortened (every 3,000-4,000 miles).

Cost Analysis

  • MAPerformance Vspure Turbo: $1,800–$2,100 depending on bearing option.
  • Tuning: $600–$1,200 for a custom remote or dyno tune.
  • Supporting mods (intercooler, intake, downpipe, fuel upgrades): $2,000–$4,000.
  • Installation labor: $800–$1,500.
  • Total estimated investment: $5,200–$8,800 for a reliable 450-500 whp setup.

This is significant, but it transforms the A45 into a car that can compete with exotics in straight-line performance while retaining daily drivability.

Conclusion

The MAPerformance Vspure Turbo stands out as a well-engineered, high-flow upgrade for the Mercedes A45 AMG. In head-to-head comparison, it offers power levels comparable to the Pure Turbo at a competitive price, with better availability and direct bolt-on convenience. While the Garrett GTX2860R Gen II can exceed its peak airflow, the complexity of a custom install makes it less practical for most owners. Hybrid options may suit a budget, but they lack the headroom and consistency of the Vspure.

Ultimately, choosing the right turbo depends on your horsepower goals, budget, and willingness to invest in supporting modifications. If 450-500 whp is your target, the MAPerformance Vspure provides an excellent balance of performance, reliability, and value. Pair it with a professional dyno tune and the necessary cooling and fuel upgrades, and you will unlock the true potential of the M133 platform—turning the A45 into a formidable machine that punches far above its weight class.