How To Increase Horsepower On A Carbureted Engine?

Everyone wants to drive a powerful car. Having some more horsepower at your disposal can immensely improve your driving experience, especially when you want to overtake slower drivers on the road. Read on to find ideas on how to increase horsepower on a carbureted engine.

improving the horsepower of a carburetted engine may not give you a super car, but you will feel the diference all right

Ever since man invented the wheel, people have been trying to improve the performance of their set of wheels. At first, the quest was for better horses to pull your chariot. Now it is greater horsepower from your engine to drive your car. You may not get the horsepower of a racing car. However, with these simple modifications, you can improve your engine’s horsepower output.

How Does A Carbureted Engine Work?

carburated engine

In a carbureted engine, the fuel enters the engine chambers through a carburettor. It is a mechanical component that supplies a mixture of fuel and air to the engine. In this manner, the engine receives well-mixed fuel and air, leading to more powerful combustion.

carburetetor internal working

The carburettor lets the airflow suck in the fuel on its way to the engine compartments. It is technically an old mechanism compared to modern fuel injectors. However, it still has its advantages.

  • Simple and low cost. Consequently, the maintenance and repair of a carburettor are cheaper.
    carburettor
  • The user can tune it as per his wishes.
  • Better response to revving, making it suitable for off-road vehicles.
  • You can overlook some amount of fuel contamination in a carbureted engine without the risk of damage.

Ways To Increase Horsepower On A Carbureted Engine

The engine is pumping in some air, taking a little fuel and igniting the mixture. Due to combustion, the rapidly expanding gases push down on the piston with a lot of force. There are a few ways to make this combustion more powerful to increase the horsepower of the engine.

1. Advancing the Ignition Timing

With a distributor type ignition, you can advance the base ignition timing by, say, 5 degrees and get an immediate rise in the power. Your engine will feel a little more responsive and preppy. The spark plugs will fire a small amount of time before the piston reaches the top dead centre. Thus, the fuel-air mixture will have an extra moment to combust. As a result, when the piston is at TDC, there will be more force on it.

You will need a wrench of the appropriate size, a timing gun and Allen keys. The only cost will be time and effort.

Now, what do you do if you don’t have a timing light? This kind of equipment is somewhat costly. Don’t worry. We have an article on modifying ignition timing without a timing light. Feel free to check that out.

 High-Performance Electronics

If you have a modern fuel-injected engine instead, a Powertrain Control Module regulates the fuel flow rate. You can use a chip or an electronic tuning box to update the programmed ignition advance curve in the PCM. The kit, usually just a software package, will also instruct the fuel injector to increase the fuel supply by a tiny amount to forestall the knocking and pinging.

powertrain control module to be reprogrammed for increasing the horsepower of a carbureted engine
Powertrain Control Module

An assortment of electronic chips and kits are available for reprogramming the powertrain control the way you want it.

Drawbacks

When you advance the ignition timing, you can encounter knocking and pinging phenomena due to the increased combustion pressure. To prevent engine damage, you will have to use a higher-octane fuel. It is slightly more costly than regular fuel.

2. Increasing the Air Intake

The more air your engine can take in, the harder it can work. A cost-effective alteration is to replace the 2-barrel intake manifold and carburettor with a 4-barrel set. Thus, you can let in more air to the engine.

4 barrel carburettor to increase horsepower on a carbureted engine

If you want it to be as low cost as possible, you can find a used factory 4-barrel intake manifold made of cast iron for sale on eBay. However, the carburettor should be brand new to increase horsepower on a carbureted engine. The cost of a new set (carburettor and intake) is around USD 800.

Appropriately sized wrenches are a must. As detailed in the video, you will also need a flat head screwdriver, along with the new parts and some adapters.

Don’t be influenced by appealing advertisements for fuel injection kits. The total cost of retrofitting the fuel injection system on a carbureted engine can easily be three times that of the 4-barrel intake and carburettor set. If you later plan to install a supercharger, remember to buy a carburettor designed for blow-through operation.

3. Adding Cold Air Intakes

A car engine runs better in cooler air because it can intake denser, more oxygen-rich air. Temperatures in the engine compartment can reach 200 degrees Fahrenheit. Consequently, it highly thins out the air near the engine block.

cold air intake for improving the engine horsepower

A Cold Air Intake solves the problem by ducting in the air from near the grill at the front. Colder, denser air yields more oxygen. Consequently, your engine can produce more power.

You will need appropriately sized wrenches, a drill driver (for faster work), a flathead screwdriver, a wire cutter and the new parts.

Once you have it installed, remember to check for any leaks in the intake. The cost of a cold air intake is between USD 300 to 600.

4. Nitrous Oxide Systems

We have already seen that having more oxygen in the engine chambers will increase the power of the carburetted engine. Nitrous Oxide is a super oxygen producer. While not technically a fuel, it releases a tremendous amount of oxygen molecules in the heat of combustion.

nitrous oxide system to increase the engine power

With all the oxygen in the engine chamber, we can add some more gasoline and suddenly have a lot more power in our hands. A bigger fuel injector and a high volume fuel pump may also be required to capitalize on the extra oxygen. Be advised that a nitrous oxide system is slightly costlier than the other mods listed here, falling in the range of USD 600 to 1300.

To install the Nitrous Oxide System, you will require appropriately sized wrenches, a drill driver, a few drill bits, a hole saw, and the nitrous oxide installation kit. Watch the first part of the video below for instructions.

Upon installing a NOS, it is advantageous to change your spark plugs to ones that are one step colder.

5. A Larger Throttle Body

If you have a late model car, you will have to get a larger throttle body to let more air into the engine. The greater bore size of the new throttle body will increment the air intake of your car’s engine, thus, aiding the engine’s power.

large bore throttle body to increase the horsepower of engine

It will not be as noticeable an increase in horsepower as changing to a 4-barrel carburettor on a carburetted engine. However, it will be something. Again, you will need to tweak the programming of your PCM so that it increases the fuel intake a little.

6. Short Tube Headers for the Exhaust Manifold

You have already improved the air intake of your engine. Now, you need to let it breathe out better as well. That is where the Tube Headers for the exhaust manifold comes in. The stock exhaust manifolds from the factory are restrictive. It is because they don’t need to be otherwise for most people, who drive their cars in economic and sensible ways.

short tube headers for exhaust manifold

Replacing the factory exhaust manifold with some bolt-in short tube headers will give your engine another increment in horsepower. Being roughly the same size as the stock part, they can be installed without modifying the existing exhaust system and work well with the stock catalytic converters.

To install a compatible short tube header set, you will need an impact wrench or torque wrench of the appropriate size.

They will make your car louder, which is a plus for your purpose. They will also look cool under your hood – a great way to one-up your competitive neighbour.

7. Long Tube Headers – Even Better

A nice set of long tube headers can give your engine a lot more of a performance boost than the shorty headers. However, they are more expensive and also need a matching exhaust system. Stainless Steel is the norm in the manufacture of long tube headers to get the best looks.

long tube headers for increased engine horsepower

Installing them is also more of an effort because it requires a lot of disassembly. Hence you will need a wide assortment of tools and some mechanical knowledge. It is best if done at a well-equipped shop.

8. Improving The Camshaft Profile

A set of inexpensive high-lift rocker arms will give you an instant increase in the horsepower of your carbureted engine.

high lift rocker arms for greater horse power in a carbureted engine

Unfortunately, you will probably not find such rocker arms for late model modern cars since they would cause interference between your valves and pistons.

9. Installing A Supercharger or Turbo Set-up

The best way to add more horsepower to your engine is a supercharger. That is because what it does is force more air into the engine to facilitate better combustion. As you have already seen, more air means more power. A supercharger installs between the cold air intake and the carburettor.

If you intend to use a supercharger, make sure that your carburettor can handle blow-through operations.

A supercharger is, by far, the costliest component in this list of modifications, coming between the range of USD 1800 to 4200. To install one, follow the steps in the video.

The Intimidating Rumbling Idle

In most cases, you will not have a chance to show off your higher performance car engine. It is because, usually, you will be driving in creeping city traffic, filled parking lots and going to your kids’ soccer practice.

The longer-duration cam profiles increase the power of your engine at higher rotational speeds (rpm). However, to get the loping mean-sounding idle, you need to use the cam profiles with the most overlap. Overlap means the period where both intake and exhaust valves are open.

overlapping cam profile for rumbling idle

Drawbacks of Overlapping Cam Profiles

A longer overlap means that some unspent fuel will sweep out into the exhaust. Thus, it will lead to a higher amount of emissions. It is not something recommended for late model cars that require emission control certificates.

Conclusion

Regarding the horsepower of your engine, there is a saying:

If a little is good, then too much is just right.

With the simple ideas detailed above, you will have understood how to increase horsepower on a carbureted engine. Most of these modifications can be made right at home. You will have to make sure that you buy the correct parts to ensure compatibility with your car. Consult a mechanic if you need help.

Thus, you are now ready to show off your modified performance car to your friends.

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