All-Acura - Cylinder Head Port Basic

Well, if you are starting off with an Acura or Honda engine you are off to a good start. Honda/Acura's have excellent ports and strong engine blocks. Engine power is dependent on the amount of air that can flow through the engine. It is important to minimize intake and exhaust port restrictions in order to keep pumping loss at a minimum. Pumping loss is the extra work done by your engine to suck in the necessary air and blow out the necessary exhaust through smaller ports. By reducing pumping loss you also increase volumetric efficiency, the percentage of the engine's displacement that is filled with every stroke.

A nice Port & Polish job is the best way to decrease pumping loss and increase volumetric efficiency. This is achieved by carefully enlarging, and reshaping by hand, thus streamlining both ports. This is an extremely labor-intensive job for very skilled machinists, which you can imagine can be a little pricey. That is why it is not the most common of modifications. Now you might have an amateur try to do it for you, save a few bucks, but you might run into the problem of enlarging the port too much, which can actually rob you of hp, so be careful.