King Motorsports Philosophy and Methodology

At King we’ve been porting, reworking, flow bench testing and dyno testing Honda cylinder heads for over 25 years. From the first King Motorsports SCCA championship-winning Civic 1200 and championship-winning GT3 CRX’s, to the Class-winning all-motor B series drag car and the supercharged K20 project track car, to our K20/K24 all-motor street monsters - we have unsurpassed proven experience.
Properly reworking a head is not a "one size fits all” scenario. Simply removing material from a port so it looks smooth is not the correct way to port a head. Measuring port CFM, velocity, turbulence, along with taking wave dynamics into consideration is the only way that the correctly determine contour and. Port and Chamber Balancing are imperative.

All of this requires an in-house flow bench, dummy heads to port and shape with test configurations, as well as hours and hours of development and testing on the flow bench itself. The development must then be followed up with dyno testing to give proven results. At King we have all of that and 25+years of experience. We back up all of our work with flow bench results as well as numbers from our dyno.

We offer three Porting and Valve Job options as starting points: OEM, Street Performance and Ultra Build. But similar to our engine builds, we first find out everything you’re looking for and what your budget is. We then apply a port/chamber design specific to your application. In addition, we have a comprehensive offering of individual services.
Theory and Important Terms

Let’s start out with a basic fact - the internal combustion engine is basically an air pump. This makes the amount of available air to be compressed in the cylinders directly proportional to the amount of power it will produce. In this regard, conventional engine building places the most importance on static compression ratio. Not only does this narrow focus not produce the desired results, too much compression interferes with air flow.
Below is a list of terms, their definitions and why they’re important.
The process of modifying the intake and exhaust ports to improve the quality and quantity of the gas flow. As manufactured, OEM heads are usually suboptimal due to design and manufacturing constraints. Porting the head is required to bring the engine to the highest level of efficiency. The porting process is one of the most important things responsible for the high power output of modern engines. We tend to think of air as light and nearly non-existent - however, an engine running at high speed experiences a totally different substance. In that context, air can be thought of as thick and heavy. Pumping it is a major problem for engines running at speed and head porting helps to alleviate this.
Used primarily for testing the intake and exhaust ports of cylinder heads, it is also used to test the flow capabilities of any component such as air filters, carburetors, manifolds or any other part that is required to flow gas. It is one of the primary tools of high performance engine builders and porting cylinder heads is hit or miss without it. A flow bench consists of an air pump/vacuum, a metering element, pressure and temperature measuring instruments such as manometers, and various controls. The test piece is attached in series with the pump and measuring element, and air is pumped through the whole system. All the air passing through the metering element also passes through the test piece. Modifying areas of a port that do not need improvement can lead to less flow and lower velocities in a port. That is why high-end, quality engine builders use a flow bench in not only determining the final result of their work, but as a valuable tool during the porting process to determine the areas of a port that need improvement, and what areas should be left untouched.
When the valve opens, the air in the runner and port decompresses into the low-pressure region (the cylinder and combustion chamber). The air on the upstream side of the port is completely isolated and unaffected by what happens on the downstream side of it until the valve opens, allowing the compressed air at the valve to flow in, sending a wave back up the port. The air at the runner entrance does not move until that wave reaches all the way to the end. Up to that point all that happens is the higher pressure gas filling the volume of the runner/port decompresses or expands into the low-pressure region advancing up the runner. Once the low pressure wave reaches the open end of the runner it reverses direction, and the inrushing air forces a high pressure wave down the runner. Conversely the closing of the valve does not immediately stop flow at the runner entrance, which continues completely unaffected until the signal that the valve has closed reaches it. The closing valve causes a buildup of pressure which will travel up the runner as a positive wave. The runner entrance continues to flow at full speed, forcing the pressure to rise until the signal reaches the entrance. At the closing of the intake valve, pressure rises far above atmospheric. It is this phenomenon that enables the so-called "ram tuning" to occur and it is what is being "tuned" by tuned intake and exhaust systems. The speed that the signal can travel is the speed of sound in the gas inside the runner. This is why port/runner volumes are so important; the volumes of successive parts of the port/runner control the flow during all transient periods. That is, any time a change occurs in the cylinder - whether positive or negative - such as when the piston reaches maximum speed. At first glance this wave travel might seem to be blindingly fast, but calculations show the opposite is true. In an intake runner at room temperature the sonic speed is about 1,100 feet per second (340 m/s) and will traverse a 12-inch (300 mm) port/runner in 0.9 milliseconds. The engine using this system, running at 8500 rpm, takes a very considerable 46 crank degrees before any signal from the cylinder can reach the runner end. 46 degrees during which nothing but the volume of the port/runner supplies the demands of the cylinder. Why not eliminate the delay with short ports? At the end of the cycle when that big long runner now continues to flow at full speed disregarding the rising pressure in the cylinder and providing pressure to the cylinder when it is needed most. The runner length also controls the timing of the returning waves and cannot be altered (except with OEM variable runner intakes, like the Acura Integra GSR). A shorter runner would flow earlier but also would die earlier while returning the positive waves much too quickly and those waves would be weaker. The key is to find the optimum balance of all the factors for the engine requirements. When the valve closes, it causes a pile up of gas giving rise to a strong positive wave which must travel up the runner. The wave activity in the port/runner does not stop but continues to reverberate for some time. When the valve next opens, the remaining waves influence the next cycle. The goal of tuning is to arrange the runners and valve timing so that there is a high-pressure wave in the port during the opening of the intake valve to get flow going quickly and then to have a second high pressure wave arrive just before valve closing in order to fill the cylinder as much as possible. The first wave will be what is left in the runner from the previous cycle while the second will primarily be one created during the current cycle by the suction wave changing sign at the runner entrance and arriving back at the valve in time for valve closing.
The common assumption is that porting a head entails enlarging the ports to the maximum possible size and applying a mirror finish. This is simply wrong. Ports may be enlarged to their maximum size where the actual size of the ports has become a restriction, but sometimes the size of the port is reduced to increase power. A mirror finish of the port does not provide any real increase in flow. In fact, within intake systems, the surface is deliberately textured to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. Exhaust ports may be smooth finished because of the dry gas flow and in the interest of minimizing exhaust by-product build-up, but again, a mirror finish offers no advantage. The reason that polished ports are not advantageous from a flow standpoint is that at the interface between the metal wall and the air, the air speed is ZERO. This is due to the wetting action of the air. The first layer of molecules adheres to the wall and does not move significantly. The rest of the flow field is then allowed to shear past, which develops a velocity profile across the port.

A very important, but usually overlooked process, either to save time or out of ignorance. It’s a time-consuming process of CC’ing (volumetrically measuring) the chambers to make certain they all have the same volume, therefore producing the same compression ratio. If any chamber varies, it has to be matched to the highest measuring chamber. After removing enough material to do this, the chambers must all be flowed to ensure uniform flow rates. This process is repeated until all the chambers flow the same and have equal volume.
Like Chamber Balancing, this is a critical but often overlooked process. Developing a design and modifying four ports with that design is only the first step. Each port must then be CC’d and flowed, ensuring all ports measure and flow the same. Not doing so will cause an uneven power distribution across the cylinders resulting in a rough-running engine and loss of overall power.
A multi angle valve job is the cutting or grinding of 2 or more angles on the seat and valve. The purpose of a multi angle valve job is to improve airflow. Depending on the application, up to 5 angles are cut, or in some very specific circumstances, an actual radius is cut into the seat. Our flowbench testing has proven time after time that the correct angles and angle widths is what is important. More CFM gains have been made through this procedure than applying additional angles or radiuses.
A proper balance between Port Flow and Port Velocity is a difficult, but important step when modifying a cylinder head. Valve size, intake runner length and cam lift - as well as what the primary use of the engine will be (street, track, strip) must all be considered to arrive at the optimal velocity. CC’ing the chambers, measuring and calculating cross sections, flowing for CFM and substantial calculations are all required.
Material is removed from the back side of the valve head, allowing air to flow around it faster and with less turbulence. In addition this also lightens the valve.
Multi-Angle Radius is when 3 or more angles are cut into the valve seat, giving a vectored "radius". Seats can also be cut with a radiusing cutter, more commonly found on domestic engines.
The process of hand-seating each individual valve into its respective seat. This involves applying a fine abrasive compound to the seat and valve head, they gently oscillating the valve, "seating" the valve for a perfect fit. The valve to seat seal is vacuum tested.
Refers to how shallow or deep into the valve seat the valve sits when closed. It is critical that the entire engine build be considered when making this decision. Flow requirements, operating temp and amount of porting are just a few factors in calculating this.
Removing a small amount of material off of the gasket surface of the cylinder head. A small amount just for "clean up" will not affect compression - but removing a substantial amount allows for changing compression, and in addition may alter cam timing.
Porting FAQs

If I’m building a motor, do I need to have porting done?
Any Honda motor will produce more power with headwork. Any bolt-ons for intake or exhaust will be substantially enhanced.
What is the biggest benefit of porting?
Your engine will be able to breath better, allowing it to move more air. More air = more power.
What type of engine build benefits the most from porting?
While any Honda powerplant will benefit, the bigger the build, the more gain.
I race in SCCA, can I still get headwork done?
Your class determines what modifications can be done to your engine. We have modified hundreds of SCCA/Road Race cylinder heads. If you’re head must be left at OEM specs, we’ll get you the most power within those limits.
What’s the most common misconception/mistake people make in regards to porting?
That more is better. Often incorrect and can, in fact, be detrimental. A flowbench is a MUST HAVE when doing headwork.
How much return for the cost in real WHP?
10-20 WHP depending on the build.
Does increased flow relate directly to WHP?
Yes, especially if head was constricting adequate flow.
Does King still have different "stages" for valve jobs/headwork?
Yes, we offer three levels or packages, but these are almost always modified for each particular build.
When discussing a build or headwork, what are the questions you ask the customer?
Here’s the big three we start out with: What are your build goals, what cams are being used and what are your budget considerations.