How to increase horsepower?
This is a guide on just that…ways to increase hp!
I think you will agree with me when I say:
Horsepower is addictive. Once you’ve had a taste for it it…you want more!
Lucky for you, we’ve created a list of 10 ways you can increase horsepower and get the performance you need!
From the very beginning of the automotive age, engineers and mechanics have looked for ways to increase horsepower in their cars. For example, one of the first cars ever produced for consumers was called the Velo. It’s the third car ever built by Karl Benz. It originally came with a 1.5 horsepower engine in 1894.
By the time the Benz motor company finished production in 1901, the output doubled to three horsepower. The trend has continued since then, with 700+ horsepower cars a relatively common sight on public roads.
A common adage among car tuners and customizers is, “if it’s not modified, it’s not yours.” Many enthusiasts anticipate the first few things they’ll buy for their cars as soon as they buy them. Whether it’s an exhaust system for better flow and sound, a higher-performance program for the engine computer, or simply a cold air intake, more power is always welcome.
Horsepower vs. Torque
“Horsepower sells cars but torque wins races.”
Carroll Shelby famously coined this maxim, and it shows up frequently on car blogs, message boards, and social media pages. The former chicken farmer, race car driver, and automotive legend from Texas had a point, even if it wasn’t completely accurate.
Horsepower is a function of torque and engine speed, and Shelby meant that it was important to have an engine that produced torque throughout the RPM range. That’s why his high-torque 4.7- and 7.0-liter V8s were able to beat the high-revving 4.0-liter Ferraris despite having similar horsepower figures.
Without going too deep into the details on the relation, here’s a rundown of torque, horsepower, and how they fit together. Defined most simply, torque is twisting force. It’s measured in pound-feet In the US,. What exactly is a pound-foot? Picture a wheel with a diameter of one foot. If you apply one pound of force to turn that wheel, then the twisting force is one pound-foot.
Horsepower is a measure of how much work an engine can do. It’s a function of both torque and engine speed, and is represented by the following equation:
On a dynamometer graph, torque and horsepower meet just above 5,000 RPM:
Simply looking at an engine’s horsepower and torque figures can show a lot about the engine. An engine with 300 horsepower and 200 pound-feet of torque is probably a high-revving, small-displacement powerplant. This engine would be matched well to a smaller, sporty car.
If you have an engine with that same 300 horsepower but 410 pound-feet of torque, it’s likely a bigger displacement engine that doesn’t rev high. Something like this would be better matched to a work truck or a large American luxury car.
Tuners, racers, and internet “experts” debate the merits of torque and horsepower but the fact is that each application needs its own balance of the two. Above all, a car’s engine is basically a big air pump, and the more air that can flow through it, the more power it can make. There are many ways to boost performance, and this article will explore how to increase horsepower with ten popular methods.
“A car’s engine is basically a big air pump, and the more air that can flow through it, the more power it can make.”
Ways to Increase HP – 10 Methods
10. Cold-air intake
The cold-air intake is one of the simplest and least expensive ways to increase horsepower. Often, these are sold as kits from various tuning companies and can be as simple as a large-diameter tube from the air filter to the throttle body, or a specially-tuned high-flow intake that places the inlet at the optimal point for airflow.
The reason it’s called a cold-air intake is that most of these place the air inlet in the coldest place possible.
Middle-school science easily answers that question for us. Air is a gas. The colder a gas gets, the denser it is.
Air is a solution of mostly nitrogen, oxygen, and water vapour, with other gases mixed in. Colder air has more nitrogen, oxygen, and other gases in the same amount of space. More oxygen in the intake means more intense combustion of fuel and more power.
Often, a performance cold-air intake engineered for your car can increase the horsepower noticeably: 5 to 10% depending on the car and conditions. a cold-air intake engineered specifically for your car usually starts around $250 and can go up from there.
- Horsepower increase: 5-10%
- Price: $250+
9. Larger-diameter throttle body
The second engine modification that many people do is to swap out the throttle body for a unit with a larger inner diameter.
A larger inner diameter means that more air can flow through the throttle body, allowing fuel to burn more intensely and produce more power.
Most modern cars use a mass-airflow or manifold air pressure sensor to determine the amount of fuel to inject, when to inject it, and when to send electricity to the spark plug. Consequently, a larger throttle body often doesn’t need any additional tuning to show a power increase because the sensors in the intake will simply adjust the fuel and ignition timing to allow the engine to produce the best power based on conditions.
Once the engine is modified further, a larger-diameter throttle body will be necessary to meet the greater airflow needs.
A large diameter throttle body can show a horsepower increase up to 5% depending on the vehicle and the engine. A performance throttle body can cost as little as $200, and that’s not much to pay for an extra 10 hp.
- Horsepower increase: up to 5%
- Price: $200+
8. Exhaust part 1: Headers and manifolds
With the intake taken care of, the next place to go is the exhaust.
It’s no use to have an engine that can pull in lots of air if it can’t push it out the other end.
The terms headers and manifolds are often used interchangeably but there’s an important distinction:
- A manifold is simply a chamber that has multiple openings. The intake manifold takes atmospheric air and branches it off into the cylinders. The exhaust manifold takes exhaust from each of the cylinders and combines it into one or two pipes to be released back into the air.
- A header is a specific type of exhaust manifold that is made of steel tubing designed specifically for high flow.
Many exhaust manifolds even today are cast from iron or steel and are designed to deliver adequate factory performance. Headers have the advantage of being lighter and allowing as much exhaust to be pushed out of the cylinders as possible with each revolution of the engine.
Depending on the car, upgrading exhaust to a header or headers can increase horsepower by 5-10% without any additional modifications. A header can cost anywhere from $200 for an inline-four to $1500 for a big V8.
- Horsepower increase: 5-10%
- Price: $200-1500
7. Exhaust part 2: High-flow catalytic converter
After flowing through the manifolds or headers, the exhaust now needs to flow through the catalytic converter.
The catalytic converter is an important part of the emissions system, converting unburnt fuel to less volatile and dangerous compounds.
It’s required in most states to be able to register the car, and a high-flow catalytic converter can often help the car produce better power than a straight pipe.
It helps keep the car legal and can lead to a power bump of 1-3% depending on the car, catalytic converter, and other factors. A single high-flow cat can cost around $150-300, and a pair of dual exhausts can run around $300-600
- Horsepower increase: 1-3%
- Price Single: $150-300
- Price duel: $300-600
6. Exhaust part 3: High-flow cat-back exhaust
At the end of the exhaust system, behind the catalytic converter(s) are the mufflers, resonators, and exhaust pipes.
Just like the cold-air intake, increased-diameter throttle body, and headers, a high-flow cat-back exhaust helps the engine breathe better.
As discussed before, an engine that breathes better produces more power.
The cat-back exhaust will allow more air to flow through the pipes, and the car will make more power. In addition to increasing the horsepower of the car, a high-flow cat-back exhaust can make the car sound better, too.
With a cat-back, expect about a 5-10% increase in horsepower. You’ll spend about $500-2000 or more depending on the car.
- Horsepower increase: 5-10%
- Price Single: $150-300
- Price duel: $300-600
5. Performance chips and programmers
All cars sold in North America after 1996 are equipped with a system called OBD-II.
This is to allow better diagnosis of emissions issues and more accurate reading of engine conditions.
Error codes were standardized across the market, and all OBD-II cars have a standard port that allows any code reader to read the conditions that caused a check engine light. As an added advantage, this made engine tuning significantly easier for many.
On the market now are many different electronic power adders. They all work the same basic way – by adjusting and changing the engine tuning to increase power.
Many are plug-and-play and allow for quick adjustments with preset ECU programs. Some of these devices allow adjustments directly from a smartphone, tablet, or laptop.
All of these programmers allow the user to adjust fuel delivery, ignition timing, and sometimes valve timing. On cars with forced induction, many programmers allow the user to increase turbo or supercharger boost in order to make more power. The cost varies, and performance gains vary depending on the car.
Chips and programmers can net a 5-20% increase in horsepower and can cost from $120-1000. If you are looking for cheap ways to increase horsepower, check these out as they are one of the easiest ways to increase hp.
- Horsepower increase: 5-20%
- Price: $120-1000
4. Forced induction
This is the big one.
There are two types of forced induction used in cars:
Supercharging and turbocharging.
Both work by compressing the air that goes into the engine, allowing better burning of fuel and creating more power.
A supercharger – also often called a blower – is an air pump. These are typically powered with a drive belt from the engine, although sometimes they are electric or even gear-driven.
There are several different types of superchargers, based on how they compress air. They all do the same thing, though – pump more air into the engine to increase horsepower.
A. Supercharger 1: Centrifugal
A centrifugal supercharger is a belt-driven turbine wheel that compresses air like a fan.
These are popular because they can be bolted directly onto the front of the engine and require minimal supporting modification.
Typically, a centrifugal supercharger doesn’t require a new intake manifold, but just a cold-air intake, drive belt and performance chip or ECU programming.
They make power like a turbocharger, allowing for high boost at high RPMs.
Another advantage to the centrifugal supercharger is that it can easily have an intercooler added, allowing for colder air to be forced into the engine. Centrifugal supercharger kits can be had for $1500-3000 and increase horsepower by 30-70%.
- Horsepower increase: 30-70%
- Price: $1500-3000
B. Supercharger 2: The roots blower
The roots supercharger is the most commonly used blower in factory applications.
They’re typically reliable, and can be found on cars as exciting as a Buick Park Avenue.
It compresses air using a pair of interlocking, lobed rotors that push air into the engine. These are excellent for making low-end power and they produce boost quickly.
They do, however, produce significant amounts of heat and lose efficiency at higher RPMs. A quality roots blower will cost between $2,500-$5,000 and typically adds about 50-90% more horsepower.
- Horsepower increase: 50-90%
- Price: $2500-5000
C. Supercharger 3: The Lysholm/Twin-Screw
The twin-screw supercharger looks similar to the roots blower on the outside, but uses two screws to push air from one end of the unit to the other.
These have very close tolerances inside the unit, and don’t really create heat other than the heat that comes from compressing the air.
These are often significantly more expensive than a roots or centrifugal blower due to their design and construction. A twin-screw blower is typically the most expensive type, with kits that cost between $5,000-12,000.
- Horsepower increase: 50-90%
- Price: $5000-12000
D. The turbocharger
A turbocharger is simply a supercharger that’s driven by exhaust gases that spin a turbine. Jeremy Clarkson, provides this valuable insight:
Adding a turbocharger to an engine that doesn’t already have one can be daunting, but many companies make kits that allow anyone to easily turbocharge their Honda K-series, or GM LS-V8.
It’s also common to put a bigger turbocharger on a car that already has one.
A bigger turbo means more boost and more power, especially at higher RPMs.
Adding or upgrading a turbocharger can cost between $1000-10,000 but the power increases are staggering. Expect at least a 40% increase in horsepower by adding a turbocharger. Adding a bigger turbocharger to a car that already has one can increase horsepower by up to 75% or more, depending on how much you want to spend.
- Horsepower increase: 40-75% or more…
- Price: $1000-10000
Almost all turbocharged and some supercharged cars also come with an intercooler to reduce heat and allow denser compressed air into the cylinders. It typically looks like a radiator and is often placed right behind an air vent in order to allow maximum cold air to flow over the fins.
The disadvantage to all of these methods of forced induction, however, is an increase in engine stress. Higher cylinder pressures and added heat can cause engines to wear out prematurely, and even cause significant engine damage. On the other hand, power gains are often immense.
Having driven a 2018 Mustang GT with a ROUSH supercharger, I can say it makes a world of difference. The current generation of Mustang GT was already fast. With 670 hp and the acceleration was violent and exhilarating.
3. Water injection
Water injection is a common addition to highly-tuned turbocharged cars, but some high-compression, high-revving naturally aspirated cars use this to increase horsepower as well.
Most systems in tuned cars use a mixture of methanol and distilled water and it’s typically injected into the intake manifold. Methanol is an alcohol and burns alongside the other fuel in the engine.
In a water injection system, the fluid is injected into the intake manifold as a mist. The droplets absorb heat and turn to vapor, and this cools the intake air by up to 100°F.
Colder air is denser, and there’s more air in the cylinders. This means there’s a bigger explosion under combustion, and the pistons are pushed down in the cylinder with more force.
These systems allow you to crank up the boost without the worry of detonation or air starvation, which can destroy an engine. For example, in the BMW M4 GTS, the water injection system adds 75hp over the standard M-car. Because of the increase in power and better reliability, the $500-1000 you’ll spend will likely be worth it.
- Horsepower increase: 5-20%
- Price: $500-1000
2. Performance camshaft and other internal engine modifications
All of the above methods to increase horsepower can be done without disassembling the engine. Many of them can be done with the engine still in the car. Adding a performance camshaft requires more labor, but the payoff in terms of power can be immense.
The camshaft or camshafts in an engine control the valves – how far they open and how long they stay open. A performance camshaft can increase horsepower by allowing valves to open farther and stay open longer. This allows for better airflow into and out of the engine.
Performance camshafts are often sold as ready-to-install units, especially for common engines like the GM LS V8 or the Honda K-series 4-cylinder.
In an overhead-cam, front-wheel-drive sport-compact car like a Volkswagen GTI or Civic Si, the camshafts can be changed without removing the engine.
On a pushrod V8 like the LS series or the Chrysler Hemi, the engine must be taken out of the car.
For this reason, it’s common to add other modifications while changing the camshaft. Most engine builders will also add high-performance parts to the rest of the valve train.
Adding a performance camshaft can increase horsepower by over 30%. The parts are often not very expensive – between $300-$700 for an overhead valve engine and $500-1000 for overhead cam engines.
- Horsepower increase: Over 30%
- Price: $300-700
1. Nitrous Oxide
Nitrous oxide, N2O, is a volatile compound that doesn’t like to stick together as a gas. When it is evaporated from liquid to gas form, it quickly decomposes into nitrogen and oxygen.
This reaction typically displaces any air in the intake manifold.
Air is made up of about 70% nitrogen, 20% oxygen and 10% other gases. By injecting nitrous oxide into the intake manifold, that changes to 67% nitrogen and 33% oxygen. Because of the liquid evaporating, it also cools down the intake charge. This makes it denser and causes the engine to produce more horsepower.
Nitrous oxide kits generally come either dry or wet and tend to be easy to install.
- A dry system injects just the N2O without adding fuel.
- A wet system injects fuel with the nitrous oxide. The intake is also wet with fuel.
There are also foggers and multi-stage injection systems for drag racing cars.
There are some risks to adding nitrous oxide.
Increased pressure can lead to strain on gaskets, valves, and pistons. Backfires can happen even in modern, fuel injected cars.
I’ve witnessed this before.
A friend added a kit by NOS to his 350Z and took it to the local drag strip for a test-and-tune night. He missed a shift and we heard a bang. The backfire cracked the upper intake manifold and singed his air filter.
Before adding nitrous oxide to your car, check local laws. In many places, it’s illegal to add a nitrous oxide system to a street car. On the flipside, nitrous oxide can increase horsepower by double or more for only about $600.
- Horsepower increase: 50% or more…
- Price: $500+
Increasing horsepower in a car can make it more enjoyable to drive, win races, or just give you something to brag about.
Sometimes, though, the haters will come out.
If your car is under warranty, the manufacturer will often refuse to fix damages caused by your modifications.
In some states, a car can’t be registered or insured when it’s got significant modifications.
If you decide to increase the horsepower of your car with one of these methods, you may be taking a risk of your car not being legal to drive on the street.
So, what to make of all of this?
Increasing the horsepower of your car can be a fun project and make driving more enjoyable, allow you to tow or haul bigger loads, or go racing.
While these methods are the most common, they’re not the only ways. All of them have risks and benefits, but often the benefits outweigh the risks.
So build your faster, more powerful car. Make your truck the beast you know it can be.
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