Cylinder Head Porting & Polishing
The term "Cylinder Head Porting" is used to describe the process of modifying cylinder heads by removing material to reshape the passage ways in the cylinder head that are called "ports". Specifically, the passage ways that flow air and fuel into the engine through the cylinder head are called "intake ports" and the passage ways that flow exhaust air out are called "exhaust ports" and the process to modify the intake and exhaust ports in the cylinder head to develop more power is referred to as "porting". Porting and polishing cylinder heads is the best way to deliver efficient engine performance and the most important way to achieve the maximum power potential of a high performance racing engine.
Porting is a procedure of cutting and grinding that removes material to reshape the ports in order to improve engine airflow and the process of polishing the ports helps to flow more air do to the smoother surface finish that lowers the flow restrictions in the port by reducing friction.
Porting modification are the most complicated engine modifications to perform and the most important alterations to the engine for generating power with typical performance gains from porting the heads on an 8 cylinder engine ranging from 30 horsepower for mild porting modifications to over 100 horsepower improvements in power from sophisticated custom porting modifications.
Technically, a cylinder head porting modification to the intake port that increases 1 CFM (Cubic Feet per Minute) airflow through one intake port can develop 0.255 horsepower per cylinder which is over 2 horsepower for all 8 cylinders in a V8 engine. Porting modifications to the intake port of a cylinder head can increase flow by 20 CFM from mild porting modifications to over 80 CFM for extensive porting modifications that incorporate the use of larger valves and high tech valve jobs. No other engine modifications can generate more power or develop better performance than cylinder head porting modifications which is why it is important to have the best cylinder head porting services to develop the best engine performance.
Originally, all porting modifications were performed through hand porting by using a grinding tool to remove material from the ports, which is a very labor intensive process that limits the production volume of providing porting modifications to cylinder heads. The need to increase the production volume of providing ported cylinder heads along with the requirement to provide equal porting modifications for each port eventually resulted in automated porting being conducted by machines that perform CNC porting. CNC porting refers to Computer Numerical Control porting which requires a computer program that instructs a machine to cut material from a cylinder head based on a port configuration that has been developed by a person who ported a cylinder head by hand using a hand grinder tool. This means that the CNC machine is programmed to port a head based on a porting modification that was developed by someone who previously developed a porting modification to a cylinder head by hand porting.
Although it is generally believed that a CNC ported cylinder head is a finished product that has been ported to perfection the reality of CNC porting is that there can be significant improvements made to CNC ported heads to flow more air and produce more power. It is important to understand that CNC porting is a copy of a port that was developed through hand porting and that this one CNC porting configuration is not best suited to all engine applications. Engine size that is different in cubic inch displacement requires different port sizes and shapes and engines that have power adders such as nitrous oxide require different port modifications and forced inducted engines that are supercharged require different port configurations and turbo charged engines also require completely different port and chamber configurations. As the term implies, an engine that is "forced inducted" which refers to supercharging and turbo charging has more intake airflow that is forced into the engine which requires more exhaust flow to discharge the larger volume of exhaust gases that are generated through forced induction. This is where it is important to understand that a CNC ported head that is typically designed to work on a naturally aspirated head is not best suited to work on a forced inducted head . Custom hand porting modifications through flow bench testing can develop more power and better performance for specific engine applications that provide more efficient engine airflow.
Performance Power of Cylinder Heads
The cylinder head is the most important engine component for producing power in a high performance engine and the most expensive engine component to purchase and modify in order to improve engine performance.
All cylinder heads can be modified to deliver more power and the most important reality of fact to understand about high performance engines is that the best engine performance is delivered by the best cylinder head performance and the performance of any engine, even engines with CNC ported heads, can be improved by technologically advanced cylinder head modifications that are only available by qualified cylinder head specialists who have successful experience in providing the right cylinder head modification services for the intended engine application. It is important to understand that not all cylinder head services are the same and not all cylinder head porting services deliver great results, In fact, improper porting modifications and the wrong valve job can reduce power output while high tech porting modifications and high tech valve jobs can deliver incredible performance.
Since the cylinder head is extremely important for engine performance and the most expensive engine component to purchase and upgrade, a comprehensive understanding of cylinder heads can assist in making good choices about the type of cylinder head to use for a specific engine application and the performance modification upgrades that are best suited for the type pf performance required from the engine.
The performance value of cylinder heads is evident with a thorough understanding of how a high performance engine functions. Since an internal combustion engine produces power by combusting air and fuel, the volume of air and fuel consumed along with the combustion efficiency of the cylinder head directly determines the amount of power produced.
The cylinder head is located on top of the engine block and directly above the cylinders in the block, which is why this engine component is referred to as the "cylinder head".
The cylinder head performs three basic functions that affect power production and engine acceleration. The intake ports flow air and fuel into the cylinder, the combustion chamber directs the combustion process within the cylinder and the exhaust port allows the exhaust to exit the cylinder.
When the intake and exhaust valves are closed, the cylinder head becomes the main restriction for airflow in the engine. Since the intake and exhaust valves in the cylinder head create the biggest restriction for airflow when closed, modifications are necessary to improve the movement of air, fuel and exhaust through the cylinders and ports when the valves are open.
Power Production Science
The more air and fuel that flows in and out of each cylinder, and the faster and more efficiently the air & fuel mixture burns, the greater the potential for engine power production.
The most important objective for increasing power output is making modifications that improve combustion. Since the combustion process determines power production, creating a more volatile rate of combustion by increasing air/fuel mixture volume produces additional power. The efficiency of the combustion process by way of a faster burn also helps to promote better combustion efficiency. The fast burn rate creates combustion pressure on the top of the piston, at a greater rate of speed, which results in an increase in power production and a faster rate of engine acceleration.
Improving airflow can be achieved by reducing restrictions in the intake and exhaust passages that enter and exit the cylinders and the best way to ibcrease airflow is by porting and polishing the heads and intake manifold.
Intake and Exhaust Valves
The intake and exhaust valves open and close to allow airflow to enter and exit the engine. The size and shape of intake and exhaust valves have a significant impact on airflow and power production. In addition, the valve seat angles in the valve job and valve angles on the valves also have a very important affect on airflow and engine performance.
Technically, air and fuel cannot flow straight from the intake port directly into the cylinder, and the exhaust gases cannot flow straight out from the cylinder directly into the exhaust port. Fundamentally, air, fuel and exhaust must move around the valve to get in and out of the cylinder. The effective and efficient movement of air around the valves is what promotes better airflow and improves power and performance.
Port Shape vs. Port Volume
The shape of the intake and exhaust ports is more important than size. It is the shape of the intake and exhaust ports and the shape of the combustion chamber that helps to flow air, fuel and exhaust around the valves.
It is often believed that just making intake and exhaust port passages larger is the method to use for increasing airflow. This is simplistic thinking, as bigger is not always better. In this case, the correct shape is more important than size. Making an intake or exhaust port bigger, just to increase the size of the flow path does not always contribute to moving more air around the valves and into, or out of, the cylinder. Increasing port volume by removing material can actually decrease airflow and efficiency when material is removed from the wrong area, thereby creating an inefficient flow path. A properly sized port, with the right shape to promote efficient airflow around the valve, is best.
The relationship of port shape and increasing airflow around the valve, dictates that the more valve area used to flow air, the better the results of cylinder filling. This means that a port shape must be configured to flow more air around the entire diameter of the valve. This is why shaping a port to flow in a specific direction is more important than simply removing material to increase port size. A larger port configuration does not necessarily help to direct airflow around the valve, but a port designed to move air around the entire radius of the valve can flow more air and thereby increase power and performance.
Air speed is another item that requires consideration. The bigger the port, or more specifically, the wider the port, the slower the air moves. To illustrate this principle, consider what happens when you open a window or door. When either is opened by one or two inches wide, a noisy draft usually occurs. However, when they are fully opened, the noise generally disappears. The noise of the draft, generated by the narrower opening, is the sound of air flow rushing through, or more appropriately, the airspeed. The louder the noise, the faster the air is moving, and conversely, the quieter the sound, the slower the air speed. A narrower open area creates a faster movement of air, and thereby increases air speed.
Cylinder heads with proportionally larger intake and exhaust port sizes can reduce air speed, resulting in a lower volume of air entering the cylinder before the valve closes. It is the opening and closing process of the valves that requires faster, high velocity airspeed to complete the cylinder filling process before the valves close.
The key to obtaining superior performance is to have the best port volume with the best airspeed, and the best camshaft valve timing events for a specific engine combination.
Proper Cylinder Head Modifications
Understanding why airflow passage modifications require proper shape for increasing flow and improving efficiency is the first step to recognizing the complications associated with cylinder head modifications. Modifying cylinder heads is a highly complex process that requires extensive knowledge, specialized skills, and successful experience.
Improper Cylinder Head Modifications
The wrong cylinder head porting modifications or valve job can reduce airflow, cause turbulence, lower air speed, reduce mixture velocity and thereby decrease the performance of an engine. These are some of the reasons why engines with improper cylinder head modifications do not perform to their potential.
Cylinder Flow Rates
Another important area is determining how much flow is required to properly balance the flow relationship between intake ports and exhaust ports for a specific application. The basic formula for intake to exhaust flow, for a naturally aspirated engine is generally understood to be in the 65% to 75% range. However, when an intake manifold is installed, the airflow to the head can drop from 2% to 30% depending on the efficiency of the intake manifold, and when an exhaust header is installed, the exhaust flow can increase. In addition, the intake and exhaust duration of a camshaft can help to increase airflow and help to provide the proper intake to exhaust flow balance. Producing too much exhaust flow for a specific engine application can hurt performance by reducing engine power output. Balancing the right rate of exhaust port flow with the intake airflow is important for cycling air in and exhaust out of an internal combustion engine.
Cylinder Head Power Production
To fully understand the performance capabilities of cylinder heads, a thorough understanding of the science is essential.
The fundamentals of airflow dictate that the power of an engine is directly determined by the amount of air that is consumed in the engine until combustion occurs.
Air flow is what determines fuel flow, as the volume of air is matched by the volume of fuel for the required air/fuel ratio. Fuel is also suspended and transported to the cylinder by air flow.
Power production depends on the quality of air and fuel flow, as dry air does not flow the same as wet air. Since fuel is denser and heavier than air, fuel flow through the intake port and combustion chamber takes a different direction than air flow alone. Cylinder head porting modifications and valve jobs that improve the quality of wet flow and increase air/fuel mixture velocity are what enhance power production and deliver incredible engine performance.
Engine Power Developement
The ability to significantly improve engine airflow with custom cylinder head porting modifications and custom intake manifold porting modifications is most important for developing superior engine performance.
In order to achieve maximum engine power and performance it is necessary to develop the cylinder heads and intake manifold to work as a complete system by matching the flow capability of the intake manifold to the cylinder head in order to minimize any floss loss through the manifold.
It is also important to develop the right amount of exhaust flow to discharge the intake flow that enters an engine in order to have the right balance of intake to exhaust flow for maximum power production, which is entirely dependant on the engine application. Typically a 70% intake to exhaust flow ratio is required in a naturally aspirated engine while nitrous oxide injected engines, supercharged engines and turbo charged engines require more exhaust flow to produce more efficient engine power and having insufficient exhaust flow can limit the power potential of engines equipped with these power adders. As the term implies, an engine that is "forced inducted" which refers to supercharging and turbo charging has more intake airflow that is forced into the engine which requires more exhaust flow to discharge the larger volume of exhaust gases that are generated through forced induction. Since most aftermarket heads and CNC ported heads are usually developed for naturally aspirated engines, standard CNC ported heads have insufficient exhaust flow to discharge the large volume of intake airflow that is generated by forced inducted engines and also for nitrous oxide injected engines that also require more exhaust flow. Our custom designed and developed forced induction exhaust port profiles and super competition valve jobs can generate efficient performance improvements with increased flow rates for these applications.
The custom cylinder head porting modifications services that we provide to improve CNC ported head intake and exhaust flow rates can generate 100+ horsepower with our custom camshaft profiles and intake manifold porting modifications. More technologically advanced cylinder head porting modifications with larger diameter valves and high tech valve jobs can produce over 200+ horsepower in a naturally aspirated engine which is what we can do with our custom engine design and development services. Forced inducted racing engines that use standard CNC ported heads can be further developed to generate over 400 horsepower more with our custom cylinder head modifications and custom designed forced induction camshaft profiles that we can design, develop and custom modify to deliver improved performance.
Once the cylinder head and intake manifold are modified and flow tested on our flow bench the flow data can be used to develop a custom camshaft profile that we computer design with our high tech engine development software. This process ensures that our cylinder head port profiles that are also computer designed with our engine development software are matched to work as a complete system with our custom camshaft profiles. The techniques we use to develop custom modified engine components that incorporate our computer designed and developed cylinder head port profiles and intake manifold port modifications along with our custom designed camshaft specifications deliver superior engine performance. Our computer designed and flow bench tested and tuned custom cylinder head modifications, custom intake manifold porting modifications and custom designed camshaft profiles based on flow bench test data can deliver superior engine performance that sets race records and establishes the highest standard of engine performance. This is why we specialize in designing and developing state-of-the-art cylinder heads, efficient high flow intake manifolds and custom designed high tech camshaft profiles to deliver technologically advanced engine performance.
At the Speed Store we know that the best custom designed and developed cylinder head porting and polishing modifications deliver the best engine performance.