What Does A Turbo Do In A Car

So, you're curious about turbos, eh? Good on ya! Understanding forced induction is crucial, whether you're aiming to boost your car's performance, diagnose a sputtering engine, or just impress your buddies with your mechanical knowledge. This article will give you a solid grasp of what a turbocharger does, how it works, and what to look out for. We'll delve into the core components and cover essential troubleshooting tips. Consider this your practical guide to mastering the inner workings of turbochargers.

Purpose: Why Understanding Turbos Matters

Why bother learning about turbos? Well, for starters, they're becoming increasingly common on everything from economy cars to high-performance beasts. Knowing how a turbo system functions is invaluable for diagnosing performance issues, performing routine maintenance, and even considering performance modifications. If you're a DIY mechanic, understanding the turbo is a game-changer when diagnosing a lack of power, unusual noises, or oil leaks. Plus, when contemplating performance upgrades, knowing your way around a turbo is vital to selecting the right components and tuning your engine properly. We have a handy diagram for you to download at the end of this article, illustrating all the components we'll discuss.

Key Specs and Main Parts

Let's break down the key players in the turbocharger system:

Compressor Wheel: This is the heart of the compressor side. It's a fan-like impeller that draws in ambient air and compresses it. The trim and A/R (Area/Radius) ratio of the compressor housing influence the compressor wheel's flow characteristics.
Turbine Wheel: Located in the exhaust side, the turbine wheel is spun by the exhaust gases exiting the engine. It's directly connected to the compressor wheel via a shaft. The size and design influence how quickly the turbo spools up (response).
Turbine Housing: This houses the turbine wheel and directs exhaust gases onto it. The A/R ratio is a critical specification, influencing the turbo's spool-up characteristics and peak power output. A smaller A/R will spool faster but can choke flow at higher RPMs, while a larger A/R will spool slower but allow for greater peak power.
Compressor Housing: This houses the compressor wheel. It's designed to efficiently compress the incoming air.
Shaft: This connects the turbine and compressor wheels. It spins at incredibly high speeds, often exceeding 100,000 RPM.
Bearings: These support the shaft, allowing it to spin freely. They can be journal bearings (oil-lubricated) or ball bearings (providing reduced friction and quicker spool-up).
Wastegate: A valve that allows excess exhaust gas to bypass the turbine wheel, preventing overboost. It can be internal (integrated into the turbine housing) or external (a separate unit).
Blow-Off Valve (BOV) / Diverter Valve: Releases excess pressure in the intake system when the throttle closes, preventing compressor surge. A BOV vents to the atmosphere, while a diverter valve recirculates the air back into the intake.
Intercooler: Cools the compressed air from the turbo before it enters the engine. Cooler air is denser and allows for more efficient combustion.

Symbols Explained (Diagram Legend)

When you download the turbocharger diagram, you'll see various symbols. Here's a quick breakdown:

Solid Lines: Typically represent the flow of air or fluids (oil, coolant).
Dotted Lines: Often indicate vacuum lines or control signals (e.g., wastegate control).
Arrows: Show the direction of flow.
Color Coding: Varies, but common conventions include:
- Blue: Represents intake air.
- Red: Represents exhaust gas.
- Yellow/Brown: Represents oil flow.
- Green: Represents coolant flow (if applicable, some turbos are water-cooled).
Icons: Represent specific components like:
- Fan Blade: Represents the compressor or turbine wheel.
- Pressure Gauge: Indicates a pressure sensor.
- Valve Symbol: Represents a valve, such as the wastegate or BOV.

How It Works: A Step-by-Step Guide

The magic of a turbo lies in harnessing otherwise wasted exhaust energy. Here's the process:

Exhaust Gases Drive the Turbine: As the engine runs, exhaust gases are expelled from the cylinders. These gases are directed into the turbine housing, impinging upon the turbine wheel's blades.
Turbine Wheel Spins: The force of the exhaust gases causes the turbine wheel to rotate at high speed.
Compressor Wheel Spins (Connected via Shaft): Because the turbine wheel is connected to the compressor wheel via a common shaft, the compressor wheel also spins.
Compressor Wheel Compresses Air: As the compressor wheel spins, it draws in ambient air through the air filter and compressor inlet. The spinning wheel compresses this air, increasing its density and pressure.
Compressed Air Cools (Intercooler): The compressed air is heated during the compression process. It then passes through an intercooler to reduce its temperature. Cooler, denser air contains more oxygen, which leads to more efficient combustion.
Air Enters Engine: The cooled, compressed air then enters the engine's intake manifold, ready to be mixed with fuel and burned in the cylinders.
Wastegate Controls Boost: To prevent excessive boost pressure, the wastegate opens to bypass exhaust gases around the turbine wheel, limiting the speed of the turbo.
Blow-Off Valve Prevents Surge: When the throttle is closed suddenly (e.g., when shifting gears), the air pressure in the intake manifold builds up rapidly. The blow-off valve or diverter valve releases this pressure, preventing "compressor surge" – a damaging phenomenon caused by the compressed air reversing direction and stalling the compressor wheel.

Real-World Use: Basic Troubleshooting Tips

Here are a few common turbo-related issues and how to troubleshoot them:

Lack of Power:
- Check for Boost Leaks: Inspect all hoses and connections in the intake system for leaks. Even a small leak can significantly reduce boost pressure. Use soapy water to spray on connections and look for bubbles when the engine is running (exercise extreme caution!).
- Wastegate Issues: A stuck-open wastegate will prevent the turbo from building boost. A faulty wastegate actuator can also cause problems.
- Faulty Sensors: MAP (Manifold Absolute Pressure) or MAF (Mass Airflow) sensors can provide incorrect readings, leading to poor engine performance.
Excessive Smoke:
- Blue Smoke: Indicates oil burning, potentially due to worn turbo seals.
- Black Smoke: Indicates excessive fuel, potentially due to overfueling or a faulty boost controller.
Whining or Screeching Noises:
- Could indicate a failing turbo bearing. This is a serious issue that requires immediate attention.
- Could also be caused by a leak in the exhaust manifold or turbo gasket.

Important: Always use a boost gauge to monitor boost pressure. This will help you detect overboost or underboost conditions early on.

Safety: Risky Components

Working with turbochargers involves inherent risks. Here are some key safety considerations:

Extreme Heat: Turbochargers operate at incredibly high temperatures. Allow the engine to cool completely before working on the turbocharger or surrounding components. Never touch the turbo immediately after the engine has been running.
High Pressures: The intake system is pressurized under boost. Be cautious when disconnecting hoses or fittings.
Sharp Edges: Turbocharger components can have sharp edges. Wear gloves to protect your hands.
Moving Parts: Avoid working on the turbo while the engine is running.
Oil Leaks: Oil leaks can be a fire hazard. Address any oil leaks promptly.

Turbochargers are complex pieces of machinery, but with a basic understanding of their components and operation, you can diagnose and troubleshoot common problems. Remember safety first when working on your car. We have prepared a comprehensive diagram for you to reference. This will provide a visual aid as you work on your car or learn more about turbos. Download the diagram by clicking here.