GIVE YOUR HEAD A PORT JOB
An interview with Star Racing’s Derek Churchwell by 2Wheel Tuner Magazine
A better breathing engine is a key factor to more horsepower. The internal combustion engine is nothing more than an air pump, and the combination of parts comprising the pump are critical. The cylinder head of a four-stroke engine is made up of intake ports and intake valves, and exhaust ports and exhaust valves. This is how the air pump breathes. Camshafts actuate the valves, telling the head when to inhale and exhale. The fuel/air mixture enters through the intake ports and exits through the exhaust ports, so the shape of these ports greatly affect an engine's breathing characteristics.
Why should a motorcyclist invest money into porting their bike’s cylinder head? Mass produced stock motorcycles have cylinder heads with generic port shapes. The rough angles left behind by the casting process hinder the performance of the engine, leaving horsepower on the table.
If porting increases horsepower, does it reduce drivability? The right combination of porting and valve work will increase horsepower while maintaining drivability and reliability. The bike remains streetable, while overall performance of the motorcycle is increased.
What are the benefits of porting a cylinder head compared to turbo charging a motor or adding nitrous? Porting the cylinder head, if performed correctly, will have no adverse effects on the engine. The same cannot be said for turbo charging or nitrous, which puts strenuous loads on the engine, mainly on the lower rotating assembly. While all three will increase the horsepower of the engine, porting the cylinder head can be combined with both turbo charging or nitrous to further enhance their effect. The exhaust side of the cylinder head needs the most help when adding turbos or nitrous. This is because a lot of air is being forced in, but nothing is being done to help get the increased airflow out of the engine. Turbos also have a very distinct sound and are easily recognized. Nitrous, while concealable, is easily detected with a little investigation. With port work, only the bike owner knows if their head has been ported. These issues come up a lot at the local drag strip in deciding whom to race or not to race.
Stock ports are rough & the valve guides protrude into the airway .
. Finshed ports are smooth & valve guides are flush
Should port work be included when installing larger pistons or high lift camshafts? Yes, it is very important to have the cylinder head upgraded as well. Remember the air pump analogy. A one-size larger piston will usually be OK, but anything larger will actually start choking the engine. The engine runs, but it is screaming for air. The larger bore cannot be filled with the current head setup. The head will have to come off and have larger valves installed and port work done to get the engine back to maximum efficiency. This is why you should talk to a professional before starting a project of this nature.
What are the different stages of port work? At Star Racing we have four levels of port work beginning with the Street/Strip and continuing up to a Stage III. The Street/Strip port work will remove all blemishes left behind by the factory casting. A Stage I is basically the same as a Street/Strip but is usually accompanied by larger valves on the stock valve seats with additional port work to match. A Stage II typically involves replacing the stock seats in order to install even larger valves. The Stage III is an all out Pro Stock port job.
What should I expect to pay to get my cylinder head ported? Depending upon the type of head, prices start just under $700 and go up from there. All of our levels of port work include a competition valve job. We also will perform a thorough inspection of the head to check valves, springs and seals for wear.
Is there any advantage to having bigger valves if I port the cylinder head? Yes, to a certain degree, larger valves allow for additional port work, which increases airflow. Increased airflow equals more horsepower and a faster bike.
CYLINDER HEAD PORTING BY STAR RACING:
Cylinder head work at Star Racing is done on the latest equipment. We have the facilities to completely rebuild all motorcycle heads. We stock all high-performance cylinder head components including valve guides, valves, valve springs, retainers and more. There’s no waiting on parts like at some other shops. We provide state-of-the-art work with a short turn-around time so you won’t miss a day at the track. CNC ported heads are also available. We even offer custom CNC duplication. Have a port that you like? We can digitalize it for you and repeat as often as needed. Proprietary modeling will remain exclusive to your cylinder head.
Complete cylinder head enhancement: Services include:
Competition Valve Job: The most critical, high velocity flow around a valve is right at the valve seat. The competition valve job focuses on this area. The valve height is kept at a standard so you don’t lose compression ratio. A competition valve job alone can yield approximately a 3% gain in horsepower.
Porting: Porting is by far the biggest single gain for a normally aspirated motor. All port jobs come with a competition valve job. Up to 30 to 50 horsepower gains can be expected on some applications.
Valves and Valve Seats: To get more flow into a cylinder you can simply make the hole larger. This is accomplished by the installation of larger valves. We offer valves in a virtually limitless variety of sizes and materials. In addition to standard oversizes, we can have custom valves made.
Suzuki GS intake from Stock to Pro Port. Call Star Racing to get your cylinder head ported, any make, any model. 1-2 week turn around time. No down time. Specials on Hayabusa porting.
We can even port your car head. See the Acura head below.
Call 800-841-7827 to schedule your service work. Download work order form.
