How Much Horsepower Does A Turbo Add? Here’s What Experts Say

Previously, you could only find turbochargers in diesel cars and trucks. However, nowadays, most car manufacturers equip turbochargers under the hood.

It is almost certain that this device will continue to be used for many years to come because of the advantage of improved traction, helping you no longer be annoyed with the slow acceleration of the car.

However, how much horsepower does a turbo add?

A turbo can increase an engine's horsepower by 30 to 40 percent or about 70 to 150 HP. In the case of a supercharger with a direct connection to the engine, that can be from 50 to 100 percent.

The following article will analyze this topic in detail. Let's discover together now!

How Do Turbochargers Work?


How do turbochargers work?

In other words, a turbocharger is a specialized device that improves engine performance by using the laws of physics to influence airflow.

A typical turbocharger will include a turbine wheel and a compressor wheel. To put it simply, it's two propellers mounted on one shaft, each fan is located at one end of the shaft.

The exhaust gas of the engine is directed to a turbine wheel for the purpose of rotating the shaft and rotating the second fan by the opposite effect, called a compressor wheel. This compressor will be responsible for compressing air into the airflow intake compartment of the engine.

The benefit of compression is that more air is forced into the cylinder, more air is compressed into the cylinder, which means more fuel is put into the engine.

Because of using the exhaust air of the engine to compress, the compressed air has a very high temperature. There will be negative effects when put directly into the engine. To reduce this temperature, turbochargers often work with an intercooler to cool the air before it is injected into the engine.

This cooler is usually constructed as a simple radiator that not only cools the engine but also increases the air density before combustion.

How Much Horsepower Does a Turbo Add?

It is difficult to give an exact number when asking about the amount of horsepower that Turbo add brings. The process above is only a theory, and the turbocharger's efficiency is also related to other upgrades in your car.

For all engines, the turbocharger will increase power by about 30 - 40 percent.

If you have changed an injection system, the efficiency can be up to 100 percent or more. A turbocharger and an upgraded exhaust system will deliver 70-150 HP in horsepower.

In addition, you can also make other upgrades to the car and engine to achieve more decent numbers.

For example, Volkswagen has improved the TDI diesel engine, offering a wide range of options from 74 to 158 HP.

Advantages of Turbochargers

Here are some of the main advantages that turbochargers bring to your car:

  • Improved torque: The turbocharger improves torque, which makes a vehicle equipped with a turbocharger easier to drive uphill and more capable of pulling with more power.
  • More power: With the same size as a naturally aspirated engine, an engine with a turbocharger can deliver more power throughout the rev range.
  • Fuel economy: Thanks to the turbocharged engine, the fuel is completely burned, thereby reducing fuel consumption.
  • Better acceleration at the low RPM: cars with turbocharged engines when moving around the city will be a lot more interesting because the car has good acceleration at low RPM. Thanks to that, it gives a better driving feeling than a naturally aspirated engine.
  • Brings big tuning potential: A study shows that turbochargers can be modified to further improve their performance. It's not uncommon for a 2.0L turbocharged engine to be modified to achieve the same output and torque as a V8.

Disadvantages of Turbocharged Engines

  • Increased complexity: The turbocharger is a great invention. However, to be able to install additional turbochargers, the engine block itself needs to be built in such a way that the engine compression is safe to supercharge, along with additional piping. Also need to add oil and air cooling. The installation process also requires careful space and heat management.
  • Requires fine-tuning: Tuning a car with a turbocharged engine will be a lot more difficult. Turbines will operate more efficiently at high RPM if turbines already perform best at low RPM.
  • Latency: For a turbocharged engine larger than standard often causes lag. This requires the engine to increase rpm much higher. This makes the car difficult to steer smoothly when you max out the throttle. However, today manufacturers have overcome and selected the appropriate turbocharger to limit the lag to the lowest level.

What is Turbo Boost?


What is Turbo Boost?

Turbo boost indicates positive pressure coming from the turbocharger. Basically, turbo boost is an indicator that represents the difference between the pressure of the intake and the outside pressure.

The unit of measurement for turbo boost is bar or PSI. The higher the PSI value, the more significant the difference, which means more power.

However, the bigger Turbo Boost is not, the better. The index is too high beyond the turbocharger's capacity, and the engine will bring you some serious trouble. The leading cause comes from the controller not allowing the pump and injector to supply enough fuel.

As a result, you may face overheating, leading to engine detonation or component failure. In this case, you may need to make some other upgrades to get the most out of the Turbo.

What is Turbo Lag?

It is undeniable that the operating principle based on using exhaust gas as a catalyst of Turbochargers is highly effective in improving the engine's capacity. However, this extra air also inadvertently leads to the annoying phenomenon - Turbo Lag.

Turbo lag is the time between stepping on the gas and feeling the surge of peak torque coming from the turbocharger.

This lag comes from the time it takes the engine to generate enough exhaust pressure to turn the turbo, pump the intake air into the engine and add more torque. This time period is usually longest when the engine rpm is low, the vehicle is moving slowly or the vehicle's load is not large.

The question here is why not build a turbocharger that is absolutely optimized from idle to limited rpm? The answer is simple, like other engine parts, the turbocharger must reach a certain rpm to be able to operate most effectively.

A turbo that's small enough to power the engine at low revs will overload and possibly explode as soon as the driver fully hits the accelerator pedal. In contrast, if the turbocharger produces maximum power, it will have almost no effect until the car engine has reached the limited rpm.

Most turbochargers today have to find a way to balance these two extremes. You can handle this problem by 4 main methods:

  • Nitrogen oxide supplement

If you are looking for an effective and fast way to reduce turbocharger lag, look no further than nitrous oxide (N2O). A small amount of N2O is enough to make the pressure in the cylinder increase sharply and provide an almost instant source of energy to help spin the turbo, adding power to the engine.

N2O can help cut turbocharger lag time to just ¼. And when adding nitrous oxide, pay attention to the ratio between air and fuel, if this ratio is not compatible, the engine can be severely damaged.

  • Increase engine compression ratio

Increasing the engine compression ratio to compensate for heat and pressure helps to produce exhaust gas powerful enough to turn the turbo, start the turbocharger process, and produce more torque.

In the 1980s, turbochargers commonly used compression ratios in the range of 8:1. But when accelerating, the engine has a very low compression ratio and almost no power. So, as fuel quality and cooling are improved, the compression ratio can be increased to 15:1 to 25:1, greatly help to reduce turbo lag while still ensuring the engine does not overheat during operation.

  • Additional exhaust valve

The turbocharger can be adapted to operate with a smaller exhaust chamber and the addition of an exhaust valve provides additional high-pressure exhaust emissions ensuring efficient working, limiting turbo lag.

Usually there can be 3 to 4 different exhaust chambers. Multiple exhaust valves means the turbocharger will operate smoothly and seamlessly at high rpm. This is a fairly easy to implement solution that is highly effective in reducing turbo lag.

Besides adding new exhaust valves, large engine displacement (for a given power) combined with a multi-speed gearbox (usually a continuously variable automatic transmission) can keep turbo lag to a minimum.

  • Using the sequential turbocharger mechanism

Sequential turbocharger (bi-turbo) with large power and small lag

Sequential turbochargers or bi-turbo turbochargers consist of a large turbo and a small turbo, with a combination of two large and small intake air coolers. These two turbos can work independently to produce maximum engine performance when needed.

The mechanism of operation of sequential turbochargers is that the small turbocharger will rotate and provide power to the engine at low rpm range (average 2,000 - 4,000 rpm) while the large turbocharger will operate in the rpm range. larger rpm (over 4,000 rpm). These two turbochargers alternately supply power to the engine, ensuring seamless, smooth power and limited turbo lag.

In models using a single turbocharger, the driver only needs to add a smaller turbocharger to implement this sequential turbocharging mechanism.

Frequently Asked Questions (FAQs)

Here's the answer you've been looking for to frequently asked questions regarding turbochargers:

  • How much HP does twin-turbo add?

As mentioned, the efficiency of Turbo in general, and twin-turbo in particular, will depend on the engine's available power and how you install and optimize other parts of the car.

A twin-turbo engine should be able to improve 20 - 60% of horsepower, which equates to a 40 HP - 650 HP boost to your engine.

  • Can you turbocharge a V8?

You can add turbochargers to a V8. In particular, you can supercharge the Chevy V8 engine without affecting durability. Instead, the power is still guaranteed.

  • Is adding Turbo illegal?

Adding Turbo is entirely legal, as long as the engine, when using emissions, still meets the emission standards of each state in which you live.

For example, in California - where all standards on emissions and environmental pollution are stringent, there is no regulation banning Turbo.

You just need to make sure your exhaust system is working correctly; upgrades to engine performance are legal.

  • Can you Turbo a supercharged car?

The answer is yes. You can turbocharge a supercharged car.

Turbo and supercharger are not related nor affect each other's performance because they will drive by taking air from the crankshaft. Meanwhile, as mentioned, Turbo takes the perspective from turbine operation.


How much horsepower does a turbo add? Via this information, you probably have an understanding of the benefits and effects that this device brings.

Despite its effectiveness, when using it, you should also be aware that using too high an efficient turbocharger can bring some problems.

In this case, if you want to continue using the above turbocharger, you need to make changes to some other equipment of the engine.

If you have any related questions, do not hesitate to leave a comment in the section below so that we can promptly provide specific answers.

Don't forget to share this article with as many people as possible because it might help them. Thank you for taking the time to read the post!

1 thought on “How Much Horsepower Does A Turbo Add? Here’s What Experts Say”

  1. Hi’
    My 2005 320i Merc keeps going into sleep? mode particularly when pulling a heavy caravan. Mercedes has had one try to cure without success.
    I love the car any suggestions please!
    Peter Carter


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