The Racing Head: Racing Cylinder Heads Explained


The cylinder head is a casting, either in iron or aluminum, which forms part of the combustion chamber. Performance of any internal combustion engine is dependent on its cylinder head because the compression ratio and efficiency of the engine is determined by the combustion engine’s shape. Cylinder heads cover the cylinders to build up engine compression.

Cylinder Heads

Iron heads, though cheaper, are heavy. Aluminum heads are about 50% lighter, but cost more than iron heads. In terms of porting, it is cheaper to port an aluminum head than an iron cylinder head. However, much care is needed when working on aluminum head. Due to the softness of the material, it is more prone to tread damage and some adjustment issues. Most aftermarket racing cylinder heads are made of aluminum due to weight advantage.

The amount of space or cubic capacity of a cylinder head’s combustion chamber is the most important determinant of the engine’s compression ratio with compression being the inexhaustible source of power. Measuring the cylinder head’s combustion chamber volume is crucial especially on V-type engines since they have more than one cylinder heads, to make sure that all cylinders produce same amount of energy.

 Cylinder Heads 2

When cylinders produce different amounts of energy due to difference in chamber volumes, a result of power loss is expected. Significant volume difference between combustion chambers causes imbalance on performance among the cylinders. One will be working harder than the other. Volume variations should be corrected to bring the value as close as possible to each other.

Stock cylinder heads are ported and massaged to improve performance. While tuning stock heads can actually increase an engine’s power, it still might not be able to perform as efficiently as aftermarket racing cylinder heads can.

Most race enthusiasts prefer buying an aftermarket race or performance cylinder head than having their stock heads ported because it can actually save them time and it is a much safer option, aside from the fact that race heads have more potential of power upgrade than stock heads.

Ported racing cylinder heads have larger intake valves and matching ports for higher airflow even at low engine revs. Demanding racers with no financial restrictions choose bare heads and have professional assemblers equip the heads according to their specifications. Racing heads are CNC (computer numerical control) machined for preciseness. Correct balance among port, air velocity and runner shape gives performance cylinder heads highest efficiency ratings in air- flow and chamber burning.

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