Mercedes CLA Class C117 (2013-2019) CLA45 (2013-2015) Mercedes A/CL/GLA45 Turbo Blanket (M133 Engine 355/376 BHP) - FORGE MOTORSPORT FMTUBL9

FORGE Motorsport FMTUBL9 is a turbo blanket designed specifically for the Mercedes-AMG M133 2.0-litre turbocharged engine, used in early CLA45/A45/GLA45 applications.

What does the turbo blanket actually do?

Think of the turbocharger as a very hot energy converter sitting beside the intake and engine hardware.

The exhaust side of the turbo can reach extremely high temperatures. A turbo blanket wraps the turbine housing with a high-temperature insulating material, reducing the amount of radiant and convective heat escaping into the engine bay.

Basic thermal philosophy:

Exhaust gas → Turbine → Turbo housing → Engine bay

Without insulation:

🔥 Turbo housing radiates heat → intake piping / wiring / surrounding components absorb heat

With the blanket:

🔥 Turbo housing → thermal barrier → substantially less heat radiated outward

The objective isn’t simply “make the turbo hotter.” The objective is to keep heat concentrated where it is useful while reducing unwanted heat transfer to the surrounding engine bay.

Why it matters on the M133

The M133 is a particularly interesting application because Mercedes-AMG extracted substantial output from a relatively compact 2.0-litre four-cylinder.

Early CLA45/A45/GLA45 versions produced approximately 355–376 hp depending on model/year/market, meaning the turbocharger and exhaust system operate under significant thermal load.

A turbo blanket can potentially provide several benefits:

Area	Potential effect
Turbo housing	Reduced external heat radiation
Engine bay	Lower local heat exposure
Intake system	Less unwanted heat soak
Wiring/hoses	Reduced thermal exposure
Turbo response	Potentially improved thermal energy retention
Under-bonnet temperature	Potential reduction around turbo area
Track use	More useful than during gentle street driving

The interesting engineering point

The biggest misconception is:

Turbo blanket ≠ horsepower modification.

It doesn’t suddenly increase airflow or compressor efficiency.

Instead, it is a thermal-management modification.

For a high-output M133, that distinction matters.

A turbocharger works by extracting energy from exhaust gas. If thermal energy is unnecessarily dumped into the engine compartment, you’re creating a heat-management problem.

The blanket attempts to manage that thermal energy more intelligently.

Where it fits in a serious M133 build

For a mildly modified CLA45, I’d think about the thermal system as a chain:

Turbo blanket
↓
Downpipe / exhaust thermal management
↓
Intercooler
↓
Charge-air temperature
↓
ECU calibration
↓
Repeatable power

This is why thermal management becomes increasingly important as you move from stock → Stage 1 → Stage 2 → track/high-boost setup.

A powerful turbo system that repeatedly heat-soaks can become less consistent even if its peak dyno number looks impressive.

FORGE FMTUBL9 — the real purpose

The FMTUBL9 should therefore be viewed as a supporting performance component, rather than a direct power-adder.

Its philosophy is:

Control where the M133’s enormous exhaust-side heat goes.

For a CLA45/A45/GLA45 used aggressively, that can be more valuable than chasing another small bolt-on horsepower gain.

In engineering terms: the turbo blanket is not trying to make the turbo bigger. It’s trying to make the thermal environment around the turbo smarter.

Mercedes CLA Class C117 (2013-2019) CLA45 (2013-2015) Mercedes A/CL/GLA45 Turbo Blanket (M133 Engine 355/376 BHP) - FORGE MOTORSPORT FMTUBL9