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   HRD Racing Heads
   7791 Aqua Circle, Unit 4
   Dalton Gardens, ID 83815

   Al Dicksen
   Phone (208) 762-9600
   Fax (208) 762-1597

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In the past, and to a large extent even today, head porting has been not much more than making large shiny holes out of smaller ones, with the resulting head actually performing no better than stock. The blame for this is laid on the presumed fact that these "ported" heads need other related equipment to make them work. This is NOT true. A properly "flowed" head will perform better regardless of the nature of the other components used. Of course, it is a fact that the proper coordination of engine parts will produce the maximum power.
An engine, being no more than a highly refined air pump, makes the amount of available air to be compressed in the cylinders directly proportional to the amount of energy (h.p.) it will produce. Very often too much emphasis is placed on static compression ratio, and if the means to gain this higher compression interferes with air flow, then nothing has been gained. For example: a very high dome piston can cause an actual loss in operating pressure, since during the valve overlap it can disrupt smooth air flow, which in turn will limit the total amount of air available to be compressed in the cylinder. Maximum flow must be the prime consideration over any other factor because our "air pump" must have its #1 commodity - air.
There is a definite intake to exhaust ratio in terms of air flow that must be attained in order to produce maximum efficiency. This is one of the things the amateur head porter often overlooks or isn't even aware of. When an intake system is improved, the exhaust system must be brought into the proper ratio or balance to achieve maximum horsepower.
In most cases American engines have sufficient port area and simply increasing the size of the port is not the answer. The real secret is in modifying those areas that will allow the air to more efficiently move around obstacles in the air flow path. Such things as the turns or bends in the port, the valve guide bosses, and most importantly the valve, can affect air flow much more than the actual size or smoothness of the port.
It is the shape and not the shine at critical areas that counts. Air flow and dyno tests have proved without a doubt that a super smooth finish will not gain horsepower. In fact, in some areas a certain amount of texture or roughness os needed to insure fuel suspension in the air stream. Port shape is the prime consideration in air flow improvement.
Valve seat angles and valve shapes are very critical. The straightest and best-contoured port will not work well, unless the seat valve area and the valve itself are specifically designed to work with that same port.
The naked eye cannot tell how a port system will flow, especially a strange one. Even the familiar, most popular ones must have every single port flowed and retouched to get consistency. Ports looking exactly the same can vary from 10% to 12% and even more.
The cam shaft and cylinder heads work very closely together, so closely in fact, that they are a function of each other. After a head has been reworked to its maximum flow efficiency, a proper cam can then be selected to match the head and the intended use of engine.

Here at HRD, we have proved these facts to be valid and true, and are interested in producing cylinder heads of high functional quality. This is to say that we are trying to give our customers heads that will produce horsepower. To do this, and still keep the cost at a reasonable level, we concentrate on those modifications that actually produce results and not on such things as satin smooth finishes, super large ports and eye blinding shininess. These things look good and require a lot of time to achieve, but do not have anything to do with performance and horsepower. Since time is money, we feel that it can be better spent in areas other than the "spit and polish." As an example, we flow test and balance every port in all out competition heads … something that some of the most respected head companies cannot say.

In conclusion, and keeping the above facts and statement in mind, you are not going to keep up with your competitors unless you use a head service such as ours.

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