How much HP does a turbo add?

If you are considering adding a turbo to your car, we will help you find out how much horsepower a turbo can add to your engine’s performance with our easy Turbo calculator!

Do you want to get more power out of your engine? But, aren’t sure if turbos are worth spending your hard-earned money. We will explain how much horsepower to expect and some of the most commonly asked questions about turbos.

By Maurice Rodriguez
January 23, 2022

A brief history of forced induction

Ever since the invention of the combustion engine engineers and car enthusiasts have been obsessed with squeezing more horsepower out of their engines. The first supercharger was invented in 1878 by Scottish engineer Dugald Clark. Clark’s two-stroke engine was actually a one-cylinder motor with a secondary cylinder that force air into the combustion chamber. Gottlieb Daimler (of Mercedes Daimler) perfected the modern gear-driven supercharger as we know it today in 1885.

Turbochargers didn’t come about until 1905 by German engineer Alfred Buchi. Buchi was working on resolving an aeronautical issue when airplanes reach high altitudes the lack of air pressure and oxygen effectively starved conventional engines. In fact, at such high altitudes, the engine can lose half of its horsepower. To resolve this issue Buchi scavenged the exhaust gases of the engine to propel a small turbine compressor mounted the same shaft. This allowed them to increase horsepower from 1,750 hp to 2,500 hp. That’s a gain of almost 50% in power!

Supercharger Vs Turbo

You’ve probably have heard of superchargers and turbos but, which one is better? How are they different? They’ll both deliver more horsepower but they deliver the power differently and work differently. Let us explain.

A supercharger is typically a belt-driven air compressor that uses the engine’s power to spin the compressor to force more compressed air into the air intake manifold. This added compressed air makes more horsepower. But, because it uses the motor to spin the compressor it does draw some power from the engine but the gain in horsepower is still significant.

The advantage of the supercharger over a turbo is that the compressor is attached to the engine so the compressed air supercharges the air at much lower RPM’s which gives the engine more horsepower and torque at lower speeds. This is where superchargers are superior to turbos as they don’t experience turbo lag. Turbo lag is simply the time it takes the turbo spooler to start to force a significant amount of air into the intake. We will explain what turbo lag is in detail and how some manufacturers are finding solutions for this issue.

A turbo is technically a supercharger it just goes about forcing air differently than a supercharger. A turbo uses the engine’s exhaust gases to spin a small turbine that is attached to an intake turbine that draws in air, passes it through an intercooler, and forces this cooler, pressurized, denser air into the intake. This infusion of pressurized air is boosted and causes more air to be shoved into the engine creating more POWER.

How much HP does a turbo add?

The Formula: Turbo Output = Starting HP x ((PSI/14.7)+1)

The formula is very simple and I have put together an easy FindCarStuff Turbo Calculator so you can find out how much POWER you can squeeze out your next engine build with a turbo or supercharger.  Check it out below. It’s very simple, simply plug in your current HP and the amount of boost you plan on using, and voila! You have your horsepower estimate.

FINDCARSTUFF TURBO CALCULATOR

Many variables contribute to answering this tricky question. First, how much horsepower is your engine currently pushing out? How much boost do you plan on using? Are making any modifications to the ECU, the exhaust system? All these factors can affect the ultimate amount of horsepower you can generate.

But, after some research, we have found Richard Holdener, a Youtuber with a video that explains a rough formula for approximating how much horsepower you ‘should’ be making. His patent-pending Holdener Power/Boost formula works like this. First, start by dividing your boost PSI by 14.7 (atmospheric pressure) then multiplying by your starting horsepower and adding one.

This formula works on superchargers and turbos. Giving you a good estimate about whether you are making the amount of power you should be making or according to Richard, the guy bragging on the internet is just making up numbers to impress his audience.

He explains how the formula works. Most naturally aspirated engines work using 14.7 pounds of pressure. The amount of atmospheric pressure currently in the air naturally. If you double the atmospheric pressure by 14.7 pounds of boost you effectively double the horsepower of your engine. Simple.

What is Turbo Lag?

As we explained previously turbo lag is merely the time it takes from when you press the accelerator for exhaust gases to build enough pressure for the exhaust turbine to spin and create enough boost to start forcing air back into the intake.

Many car enthusiasts have heard lots of arguments against using turbos because of turbo lag and assume that this issue still plagues most turbos to this day. Turbos and the types of turbos have come a long way from the stories from when turbos used to come ‘on’ very suddenly and unsettle the car. Namely, Porsche 911 turbos had a nasty reputation of turbo boost coming on very quickly and causing the driver to lose control.

Nowadays, turbos come in many sizes to fit any application. Smaller turbos spin much up sooner and provide an added boost at lower RPM. Larger turbos take longer to spool up but can provide a much higher boost and more HP.

Variable twin-scroll turbos seem to be the answer as they have a split valve that allows exhaust gases to flow to different scrolls giving you the best of a small and larger turbo.

Are Turbos Bad For Your Engine?

Turbos are not necessarily bad for the engine but installing a turbo causes other issues that should be addressed if you want to ensure you don’t blow up your engine. With added boost pressure, comes large amounts of heat that are now being generated by the exhaust manifold. This heat must be managed through an intercooler, heat shielding for sensitive components, or adding hood vents.

Once you’ve added more power, a set of larger brakes are also a logical step to help you come to a stop safely.

How much HP does a supercharger add?

The formula for adding a supercharger is similar to the turbo formula but because most superchargers use the engine’s power there are always some parasitic losses when using a supercharger. So, a 5% parasitic loss should be applied to any calculations when a supercharger is added. But, the small loss is well worth the increase in torque and power.

Does a supercharger add more HP than a Turbo?

Generally, a supercharger is not able to produce the gains in horsepower that a turbo can produce. A supercharger can be adjusted to produce an increase in boost by swapping out the pulley a supercharger is using with a smaller pulley but a turbo has much more flexibility in how boost can be added. All you have to do is add more boost, no pulleys to swap out. But, there is only so much boost you can add before things start to break, melt, or blow up.

How much HP does a Whipple supercharger add?

A Whipple supercharger is a twin-screw supercharger that is light-weight, has high efficiency, is belt-driven, and creates power at very low RPM’s giving the engine an almost instant boost of power. A supercharger is no different than a turbo and follows the same formula depending on the amount of boost being applied minus a small loss in horsepower from parasitic loss. 

How much does it cost to turbo a car?

This is a really tough question to answer because adding a turbo involved modifying many more parts other than just ‘adding’ a turbo. With any modification to an engine, you must consider how the other components will be affected. With more air being added to the engine more fuel needs to be added as well. So, larger injectors, fuel pumps, fuel management at the ECU needs to be remapped as well.

But, strictly speaking about the cost of a turbo or two turbos for a V8 application (because you need two on either side of a V8 for both sides of the engine) the cost of a turbo is on average $1,381.24. As you can see not all cars have the same budget requirements to add a turbo. The older the car the cheaper adding more power to the engine. We are fans of the Miata and can see why a lot of enthusiasts on a limited budget choose the NA Miata to add more power. It’s cheap to buy, cheap to maintain, and very cheap to add more POWER!

How much is a turbo kit?

The average cost of a turbo kit is $4,392.64. Of course, it also depends on your car application, how much power you want to generate, and does not include labor. The more power you want to generate to higher the cost, complexity, and labor needed to set up and configure. The kits below are for DIY mechanics that want to learn how to work on their own engine. So include the engine tune files needed, extra parts like downpipes, and intercoolers. But, with any purchase check the fine print and understand that this is a very involved undertaking and could take months to complete.

Blown Turbo symptoms

Diagnosing turbo issues can be difficult to track down partly because a turbo system is complicated and involves the exhaust system, intake, intercooler, turbo, and engine management. If any one of those components has an issue it quickly cascades into a catastrophic engine failure. Below are some of the symptoms you may experience if your turbo is failing.

• Physical Damage to the turbo impellers
• Unusual turbo whistling or hissing noises
• Smoke from the tailpipe
• Oil smell
• Loss of oil
• Oil in the intake
• Turbo inlet shaft has a lot of play
• Power loss
• Acceleration is difficult or strained
• Engine fault codes

Conclusion

Adding a turbo to a car can be a great way to quickly add more power to your car’s engine. But with all car modifications they can be costly, time-consuming, and a real headache if you are not mechanically inclined. If the car you are modifying is your primary mode of transportation you may want to consider how long these types of modifications will take and how much they will cost. But, if you have the budget, time, and patience adding a turbo is a great way to take the performance of your car to the next level.

We are all things cars.

Maurice Rodriguez

Maurice is an avid car enthusiast, foodie, and loves hard rock. When he isn’t writing blogs he enjoys traveling and sight seeing.