Do different skirt designs require different clearance?

Different cam and barrel profiles yield different clearance on the piston and are often chosen based on the conditions they will see. For example, an engine that has a large stroke, which causes the piston to come out of the bottom of the sleeve at BDC will generally get a straight or barely tapered barrel profile. Something that stays inside the sleeve or block at all times will have a more tapered barrel profile. A tapered barrel is where the bottom of the skirt is larger than the gauge point. The bottom of the skirt sees less temperature than under the oil ring, so we are able to run the bottom even larger than the gauge point. The profile is dictated by application, cooling system, block material, rod/stroke ratio, cylinder material and piston or forging design. We offer different finishes on the piston skirts, the smoother skirts for reducing friction and rougher skirts to hold more oil on the piston skirt and keep the cylinder lubricated. Our goal is to use the “roundest” cam we can without having issues in the corners of the piston skirt. We have approximately 250 different shapes we can choose from, some are application specific, some are forging specific, and we often make new shapes when a used piston is supplied for review. With the array profiles we have at our finger tips and our experienced staff, we are able to put our parts to the test and create the most stable and best sealed cylinders on the market.