Turbo Engine Explained: Should You Buy Or Avoid One?

"Turbocharger Animation by Tyroola" by PatriciaWrites, used under CC BY 4.0 / Modified from original

In this article, we explain what a turbo engine is, how a turbocharger works, why carmakers are switching to turbo engines, and the benefits and drawbacks you should know before buying a turbo petrol or turbo diesel car.

What Is A Turbo Engine?

Any internal combustion engine, regardless of if it runs on petrol, diesel or CNG fuel, which uses a turbocharger is called a turbo engine. Unlike a normal engine, a turbo engine uses forced induction to push more air into the engine. 

An engine needs fuel, air and heat to create combustion. A turbocharger mainly improves the air part of this process. It increases the amount of air entering the engine, which allows the engine to burn more fuel when required and produce more power.

Before turbochargers, car manufacturers achieved this larger volume of air by increasing the size of the engine - larger the cylinders, more air and fuel could be added for better performance. But there is a limit to the amount of air an engine can pull naturally, a way to ‘push’ more air in was needed.

"Bentley_4½_Litre_1929" by DeFacto, used under CC BY-SA 4.0 / Modified from original

The earliest method of forcing air into cars was with ‘blowers’, the modern version of which is called a supercharger. These are usually linked to the engine via a belt, so while they respond to accelerator inputs quickly, they put more strain on the engine. Superchargers usually offer quicker response than turbochargers because they are driven directly by the engine. However, since they take power from the engine to run, they are generally less efficient.

Also Read: Different Types of Car Engines Explained

How are turbochargers different? Here’s a simple explanation:

How Does A Turbocharger Work?

Simply put, a turbocharger is an air pump with 2 main wheels inside it. One wheel sits on the exhaust side and spins using the force of the exhaust gases. The other wheel sits on the intake side and pushes more fresh air into the engine. When the engine exhaust air reaches a certain speed, it has enough flow to turn the turbocharger fan, which makes the other side of the turbocharger pull more fresh air and compress it into the engine. 

So, the turbocharger system uses exhaust air from the engine, which would otherwise have been wasted, to push in more fresh air into the engine. This higher density air helps the engine make more power from the same amount of fuel, increasing performance as well as mileage.

Turbo Engine Vs Normal Engine: What Is The Difference?

Let’s compare a normal engine and a turbo engine of different cars at the same price and same body style. In this case the Maruti Suzuki Brezza VXi normal petrol manual and the Hyundai Venue HX 2 turbo petrol manual:

As can be seen clearly from the table above, despite being 32 percent smaller in displacement, with one fewer cylinder and powering a car that is heavier, the Hyundai Venue turbo petrol develops more power and torque while returning 5 percent better mileage than the Maruti Suzuki Brezza normal petrol. 

Why Are Indian Car Brands Switching To Turbo Engines?

While turbocharged diesel engines in cars are not a new phenomenon, the adoption of small turbo petrol engines has grown in recent years - especially in smaller cars and SUVs. For manufacturers, the biggest draw for offering small turbocharged engines in small cars is the better ARAI-certified mileage and lower emissions these engines produce.

Turbocharging helps carmakers use smaller engines without giving up too much performance. Smaller engines can help reduce fuel consumption and emissions in official test conditions, especially when they are driven gently. We have already explained how turbo engines use less fuel for the same amount of performance, but as can be seen in the table above - they can develop even more performance while using less fuel. This combination of higher mileage and higher performance helps car makers market turbo engine cars to even more customers, even if there is a slight price difference between cars with normal engines and turbo engines. On paper, it looks like a win-win for both carmakers and car buyers.

Benefits Of A Turbo Engine Car

For a car buyer, the biggest advantage offered by turbo engine cars is the performance they offer for the price. A small turbo engine in a small car can deliver more performance than a normal engine that is much bigger for not a lot more money, as can be seen in the Brezza normal petrol vs Venue turbo petrol example given above. If you look closely at the torque figures, you will notice the Venue’s 1.0L engine develops more torque much lower in the engine rev range and for longer too. This means easier acceleration from a stop, easier overtakes on highways and better performance with a full load of passengers and luggage. 

Drawbacks Of A Turbo Engine Car

Turbo engine cars are not perfect, though. The basic design of a turbocharger means it needs the engine exhaust air to reach a minimum speed before it can push fresh air into the engine - which means there is always a lag between you pressing the accelerator and the turbocharger actually delivering that rush or performance. In budget cars, manufacturers cannot always use expensive lag-reducing technology. So, drivers may feel turbo lag more clearly in such cars. This is especially noticeable with a full load or while driving uphill.

With power comes responsibility. And if you get addicted to the higher power/torque of a turbo engine, the fun and fast driving style will lead to much lower mileage. In V3Cars-tested mileage runs, we also found that small turbo engine cars give better mileage on the highway than in the city.

Normal engines have less moving parts than turbo engines. With the added complexity comes the chance of more things to take care of, higher maintenance costs and higher repair/replacement costs. Turbo engines are also more sensitive to bad fuel than normal engines, which requires the driver to be more careful of where they choose to fill up fuel.

Turbo Petrol Vs Turbo Diesel Engine

Turbo diesel engines have been on sale in India for much longer than turbo petrol engines. This is because diesel engines can use extra air more effectively to improve torque, pulling power and efficiency. The Sipani Rover Montego was among the earliest turbo diesel cars sold in India, though more buyers may remember the original Tata Sierra Turbo. The trend of downsized turbo petrol engines became more common after BS6 emission norms came into effect. However, Ford introduced one of the earliest small turbo petrol engines in India with the 1.0L EcoBoost in the EcoSport in 2013.

Turbo diesels offer more torque low down in the engine rev range, while turbo petrol engines usually have a wider performance range - with the turbo boosting torque lower down the engine rev range and the petrol engines can still develop strong power at higher RPM. On the flip side, turbo diesel engines do not lose as much mileage as turbo petrol engines do if driven fast. For example, we have compared the turbo petrol and turbo diesel engines of the Tata Nexon, both when paired to manual transmissions.

Turbo Engine Mileage In Real World Driving

Turbo engine cars often show good mileage in official tests because ARAI tests them inside a highly controlled laboratory with extremely gentle acceleration. Because the acceleration is so mild, the exhaust gases never build up enough boost. Off-boost, a 1.0L 3-cylinder turbo engine behaves exactly like a tiny, low-friction, 1.0L normal engine. 

They can also deliver good mileage in real-world driving if driven gently. However, fuel efficiency can drop quickly if the driver uses the turbo boost often. This is why a turbo petrol car may return good mileage on the highway at steady speeds but lower mileage in heavy city traffic or during aggressive driving. 

V3Cars’ real-world mileage tests show that turbo petrol cars can be very sensitive to driving conditions. In our highway tests, some turbo petrol cars delivered slightly better mileage than their ARAI-certified figure, while others returned up to 23.28 percent lower mileage. In city conditions, however, none of the turbo petrol cars we tested matched their claimed mileage. The best result was 22.45 percent lower than the claimed figure, while the biggest gap was 60.11 percent lower.

For example, the Volkswagen Virtus 1.0L turbo petrol automatic has a claimed mileage of 18.70kmpl. In our tests, it returned 8.50kmpl in the city and 13.65kmpl on the highway. That makes its city mileage 54.55 percent lower than claimed, while its highway mileage was 22.79 percent lower.

Should You Buy A Turbo Engine Car?

Buy a turbo engine car if:

• You drive often on highways
• You want stronger acceleration
• You travel with full load frequently
• You enjoy driving
• You are okay with higher maintenance, repair and replacement costs for parts related to the turbo and engine

Avoid or think twice before buying a turbo engine car if:

• Your usage is mostly slow city traffic
• You want the lowest maintenance cost
• You want predictable mileage
• You are buying mainly for relaxed commuting

 List of Turbo Engine Cars in India by Segment

The following table lists some of the turbo engine cars in each segment:

Also Read: What is a TSI Engine?

FAQs

What Is The Benefit Of A Turbo Engine?

The main benefit of a turbo engine is that it can produce more power and torque from a smaller engine. This helps carmakers offer stronger performance and higher claimed mileage without using a larger engine. For buyers, this usually means better acceleration, easier overtakes and better performance with a full load of passengers and luggage.

Is A Turbo Engine Better Than A Normal Engine?

A turbo engine is better if you want stronger performance, especially on highways or with a full load. A normal engine can be better for relaxed city driving, predictable mileage and lower long-term maintenance costs. So, the better choice depends on your usage.

Does A Turbo Engine Give Better Mileage?

In the real world, a turbo engine can deliver good mileage if driven gently, especially at steady speeds. However, mileage can drop quickly if you use the extra performance often. This is why turbo petrol cars may deliver better mileage on highways than in heavy city traffic.

What Is Turbo Lag?

Turbo lag is the short delay between pressing the accelerator and the turbocharger delivering extra power. This happens because the turbocharger needs enough exhaust gas flow to spin fast and push more air into the engine. Modern turbo engines have reduced turbo lag, but some delay can still be felt in budget cars.

Does A Turbo Engine Need More Maintenance?

A turbo engine has more parts than a normal engine and works under higher heat and pressure. So, timely servicing, good engine oil and good-quality fuel are important for long-term reliability. If maintained properly, a turbo engine will be reliable.

Before you finalise your next car, these V3Cars tools can help you make a more informed decision: 

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