There are several steps that can be taken to get more horsepower from a 4-cylinder engine. There are many different ways to get better engine performance. Car manufacturers will change the variables to get better performance. However they also sacrifice on performance in several ways, and you can get this back by making your own alterations. There is more you can do than just add torque.
1. Compression Ratio
By increasing the compression ratio, it is possible to generate more horsepower. The more compression, the greater chances are that it will spontaneously burst into flames before the spark plug ignites it. Generally when the compression ratio increases, then a higher octane fuel is needed. Higher octane fuels will not combust too early. This is the reason why most high performance vehicles require high octane fuel.
2. Air Displacement
The greater the displacement or the volume of air from the top end of the piston to the bottom, then the more gas that can be burned each time the piston makes a revolution. In order to displace more air, the cylinders need to be bigger or you can add more cylinders. The limit to get the most aim out of cylinders tends to be 12.
3. More Air
By getting more air into each of the cylinders, it is possible to get even more horsepower from the engine. Normally superchargers and turbochargers can accomplish this. Superchargers offer the best performance, but most small vehicles tend to have a turbocharger. However turbochargers do not work well at low speeds because they use the exhaust. For the turbocharger to work, the exhaust pressure needs to build up.
4. Cold Air Intake
A cold air intake is a great way to increase horsepower. When air is compressed it will increase in temperature. However when air is hot, it will not expand much when it ignites. To ensure that the most expansion occurs on combustion, the air should be cold. So a cold air intake is key. Most superchargers tend to have an intercooler that will chill the air before it goes into the cylinder.
5. Air Resistance
The easier the air can move, then the more power that can be produced from the engine. This includes the air intake into the piston as well as the exhaust exiting the piston. Increasing the intake valves can dramatically reduce the air resistance. Also, a polished intake can reduce resistance. Having a large exhaust pipe or free flowing exhaust can reduce air resistance, which makes it difficult for the exhaust to leave the piston. A dual exhaust uses two exhaust pipes in order to improve the back resistance of the exhaust.
6. Fuel Injection
This is a way to monitor and meter the fuel that goes into each cylinder. By precise metering, it is possible to get better fuel economy and improve performance and power.
The lighter the vehicle, the more power that can be produced, as it takes less power to move the vehicle when it is lighter. In general, the lighter the pistons, the more horsepower. As less energy is expended to move the pistons when they change directions.