Garrett turbochargers are renowned for their precision engineering and innovation, serving a wide range of performance and industrial applications. Each turbo model comes with a specific letter designation (the ones after the numbers e.g. GTB2260VK) that provides insight into its features and capabilities. Here, we decode these designations to help enthusiasts and professionals alike understand what each letter means and how it relates to turbocharger functionality.

Garrett do not publicly list these designations so the information below has been source from multiple forums and websites:

A - VAT (Variable A/R Turbine)

The "A" designation stands for Variable A/R Turbine, which allows for adjustments in the turbine's aspect ratio. This feature optimizes performance across different engine speeds, enhancing efficiency and responsiveness.

B - Boreless

"Boreless" turbos lack a traditional bore in the turbine, which reduces weight and potentially improves the flow dynamics within the turbocharger.

C - Ceramic

Ceramic turbochargers, designated by "C", use ceramic components for better heat resistance and reduced inertia, leading to faster spool times and durability under high temperatures.

D - Dual Passage Bypass

This feature allows for a bypass of exhaust flow through dual passages, optimizing the turbo response and managing exhaust pressure effectively.

E - Elbow, Integrated (Monoblock Turbine Housing)

An integrated elbow in the turbine housing, as indicated by "E", means the turbocharger is designed with fewer components, reducing potential leak points and improving flow dynamics.

F - Face Seal, Carbon

The "F" designation indicates the use of a carbon face seal, which provides superior sealing properties under high-temperature conditions, crucial for maintaining turbo integrity.

G - Compressor Recirculation Valve

This valve helps in managing the compressor flow to prevent surge, enhancing the operational stability of the turbocharger.

H - Separate Exhaust Elbow

Turbos with a separate exhaust elbow ("H") are designed for versatile installations, allowing for better adaptation to different engine layouts.

I - Integral Manifold, Elbow and Turbine Housing

"I" denotes a turbocharger where the manifold, elbow, and turbine housing are integrated into a single unit, reducing complexity and improving exhaust flow efficiency.

J - Die Cast Compressor Housing

Die-cast compressor housings are robust and precision-engineered for optimal performance and durability, marked by "J".

K - Electric Actuator

Turbochargers with an electric actuator ("K") offer precise control over the turbo's variable geometry or wastegate, improving boost response and control.

L - Water Cooled Center Housing

The presence of a water-cooled center housing ("L") significantly enhances the thermal stability of the turbocharger, extending its life by preventing overheating.

M - Manifold and Turbine Housing Integrated

Like "I", the "M" designation refers to a design where the manifold and turbine housing are integrated, streamlining the turbocharger assembly and enhancing performance.

N - Ported Shroud Compressor

A ported shroud compressor helps to increase the surge margin of the turbo, allowing for broader operational ranges and improved engine performance.

O - Opposite Rotation

Turbochargers designed for opposite rotation ("O") are used in twin-turbo setups, providing balanced engine loading and improved packaging.

P - Side Vane Variable Geometry Turbine

This sophisticated design allows for dynamic adjustment of the turbine vanes, optimizing turbo response and efficiency across varying engine loads.

Q - Wrapped Turbine Housing

Turbochargers with a wrapped turbine housing ("Q") feature additional thermal insulation, improving heat retention and performance efficiency.

R - Rolling Element (Ball) Bearings

Rolling element bearings reduce friction and wear within the turbo, enhancing rotational speed and turbo response.

S - Single Passage Bypass or Special Application

This designation can either refer to a simple bypass setup or a special application tailored for specific performance requirements.

T - Titanium Aluminide Turbine Wheel

Titanium aluminide is used in turbine wheels for its exceptional strength-to-weight ratio, significantly enhancing the turbo's ability to handle high exhaust temperatures.

U - Pedestal - Mounted Center Housing

A pedestal-mounted center housing provides a robust mounting solution that can help with the thermal expansion and alignment of the turbocharger.

V - Multi Vane Variable Geometry (VNT)

Variable Nozzle Turbine (VNT) technology allows for precise control of exhaust flow through the turbine, improving efficiency and control.

Z - Journal Bearings

Standard journal bearings are designated by "Z", known for their durability and cost-effectiveness in various applications.

Unfortunately, the designations "W" and "X" are unknown, but they may represent upcoming technologies or specialized configurations not yet widely discussed.

Understanding these designations can significantly enhance your knowledge and choice when dealing with Garrett turbos, whether you're selecting a new turbocharger or optimizing an existing setup for better performance.