How Your Silverado Breathes & Increasing Intake Efficiency

When you start poking around the idea of working on an intake manifold, you must have a good understanding of the parts involved before you begin. All of the parts in the system are responsible for drawing in air for the engine to make power.

Despite having a simple job, a considerable amount of parts go into achieving this goal. Below are most of the major parts of the factory intake system on a Silverado and the parts you can make major gains with by modifying or swapping them out. 

• Air Filter
• Throttle Body
• Intake Manifold
• Cylinder Head 
• Intake Valves
• Camshaft

When you set out to start modifying or swapping parts, you want to know their specific role in the process. Just by understanding what each part does, you can start to draw conclusions on what modifications can help provide the gains you are looking for. To really understand the role of the parts below, you will first want to understand the four-stroke engine cycle. 

This process starts with the piston moving down in the combustion chamber. This creates a vacuum that draws air and fuel in. Afterward, the piston will move back to the top of the chamber compressing the fuel. At the top of the stroke, the fuel is ignited sending the piston back down, and then it travels back to the top of the chamber the exhaust is pushed out. Following is an explanation of each part of the intake system.

The piston traveling down in the chamber starts the intake process, but the camshaft is what makes it possible. The timing of an engine controls the camshaft by turning it in time with the crankshaft. As the appropriate piston in the engine travels down during the intake stroke, the cam works to open the valves in the cylinder head to allow air to flow in. The grind of the camshaft dictates how far the valves will open and how long they will stay open.

The intake valve is pushed open by the lobes of the camshaft. The valve doesn’t solely rely on the cam to provide the fuel and air mixture. The diameter and angle grinds of the valve will affect how much fuel and air enters the chamber and how efficiently. 

The cylinder head plays many roles in the engine’s combustion cycle, but for this topic we will focus only on the intake process. The cylinder head has runners that lead back to the intake manifold. As the valve opens, these runners are responsible for helping the air flow into the chamber. 

The intake manifold will sit in between the cylinder heads and is essentially the reservoir for air and fuel before it’s delivered to each cylinder. As each cylinder draws in air, it will have to follow a path through the runners in the intake manifold to flow into the appropriate cylinders. 

The throttle body is essentially a butterfly valve that opens and closes to allow more or less air to be drawn into the intake manifold. The throttle pedal controls this, and the further you push the pedal down, the more the valve will open and the more air will be drawn in. 

The air filter is on the front line of duty in the intake process. This unit’s role is to allow air to flow freely into the intake system while simultaneously working to keep debris out of the engine. 

The intake system can start to deteriorate over time which will hinder the process. Unfortunately, you can’t prevent mechanical parts from wearing or electrical parts from failing, but you can work to keep them clean throughout their lifespan. 

The mass airflow sensor is located in the intake system just before the throttle body. Though the filter is working to keep dirt out, fine particles will manage to get through. Overtime, these particles can build up on the mass airflow sensor and throw off the readings. Every so often it’s a good idea to pull the sensor out and give it a cleaning with the appropriate chemicals. There are dedicated solutions for cleaning the mass air flow sensor that can be purchased off the shelf from any auto parts store. 

Carbon deposits will build up on valves, the throttle body and many other parts of the engine and will hinder the ability of air to flow and fuel to burn. Stripping the engine down and scrubbing the carbon off is a viable process. It’s very time consuming but relatively expensive. Luckily, engine treatment chemicals can be added to the fuel system to help break these deposits up and keep things flowing smoothly. 

High-performance parts are all over the market when it comes to GM engines. You can blindly purchase mods and hope for the best, but understanding the upgrades thoroughly will help you pick out the right ones to achieve the level of gains in performance you’re looking for. 

A cold air intake is by far the easiest modification you can make to your Silverado’s intake system. By allowing colder air to flow into the chamber, you are providing the engine with more oxygen. The dense nature of cold air means it can contain more of the element and oxygen is essential for a good clean burn. This will head minimal gains in power and fuel economy but it is well within range of an hour’s worth of work. 

While a cold-air intake raises the quality of air that is drawn in, an aftermarket throttle body will allow more to flow in. A throttle body can be built to have a larger valve opening and this will help provide much more air in the system. This means that you have to open the valveless to achieve the same amount of airflow that the standard throttle body can provide. This all equates to a greatly improved throttle response. 

An aftermarket intake manifold can come in a variety of configurations. Runners on the intake and the plenum will be manipulated in a number of ways to affect the airflow with different principles in mind. Depending on the configuration chosen, the air flow will work to increase horsepower as well as affect the power-band of the engine’s output. 

The cam is responsible for opening the valves. The grind of the cam dictates how long the valve will be open and how far it will open. An aftermarket cam can come with a variety of grinds to help keep that valve open longer and further to increase power or shorter to improve fuel economy.  

The valve is a part that can be modified or replaced. By putting a proper angle grind on a valve, you can increase air flow. Additionally, a larger valve can be swapped in to allow more air to enter the chamber. This will require cylinder-head modifications though. 

Aftermarket cylinder heads will come with a variety of improvement to increase power output. To improve airflow, larger runners with a better angle will be used. Larger valves are generally used as well. You can take your factory cylinder head to a machine shop to make your own improvements. As stated, larger valves can be installed with appropriate machine work. Porting and polishing can also be done to improve airflow. 

Boosting an engine sort of throws a curve ball in everything we’ve discussed so far. Rather than waiting for the piston to provide the vacuum needed for air to be drawn in, boosting an engine adds an air compressor to the engine to force air into open cylinders. 

Boost can be done in two ways – either with a supercharger or a turbocharger. It does change the dynamics of the role of each part in the intake system but the idea of modifying each part will still have beneficial results in terms of improving the process.