{"id":1245,"date":"2018-02-12T00:00:52","date_gmt":"2018-02-12T04:00:52","guid":{"rendered":"http:\/\/maxtorqueperformance.com\/?p=1245"},"modified":"2018-02-12T00:12:32","modified_gmt":"2018-02-12T04:12:32","slug":"piston-to-wall-clearance-myths-mysteries-and-misconceptions-explained","status":"publish","type":"post","link":"https:\/\/maxtorqueperformance.com\/staging\/index.php\/2018\/02\/12\/piston-to-wall-clearance-myths-mysteries-and-misconceptions-explained\/","title":{"rendered":"Piston-To-Wall Clearance: Myths, Mysteries, and Misconceptions Explained"},"content":{"rendered":"
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by John Baechtel<\/a><\/p>\n<\/div>\n<\/div>\n

Piston-to-wall clearance is a crucial measurement for any engine, and different applications can require wildly different specs. We explain the science of why.\u00a0<\/span><\/p>\n

Among\u00a0the shiny objects that emerge from a new box of high-performance pistons, you are also presented with a spec sheet detailing the piston\u2019s critical dimensions and, among other things, the all-important piston-to-cylinder wall clearance. It\u2019s the core specification that engine builders always target to ensure trouble-free operation of the engines they build.<\/span><\/p>\n

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Piston-to-wall clearance is set near the bottom of the skirt on the thrust side as shown here. Between the clearance point and the ring pack, no part of the piston comes close to contacting the cylinder wall.<\/strong><\/figcaption><\/figure>\n<\/div>\n

It is universally understood that proper clearance is essential to successful operation, and that too much or too little can easily lead to fatal engine damage. Some small clearance is essential to provide room for the lubricating medium, but most clearance is built in to accommodate component expansion rates as an engine come up to operating temperature.<\/p>\n

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Your new set of Wiseco pistons will give you top performance if you follow the instructions that come in every box. The recommended piston-to-wall clearance ensures proper fit and trouble-free operation.<\/strong><\/figcaption><\/figure>\n<\/div>\n

\u00a0Most end users regard the recommended piston-to-wall clearance as an all-inclusive indicator of the piston\u2019s optimum fitment in the cylinder bore for safe operation. <\/span><\/p>\n

In the overall sense they are correct, and careful attention to the recommended fit will almost always ward off the dreaded evils of excessive friction, piston slap, ring damage, and attending failures.<\/span><\/p>\n

The recommended measurement point on the piston is the largest diameter point on the piston, thus it must be fitted with the proper manufacturer\u2019s clearance. Think of it as the safety point manufacturers provide to prevent improper fitment and subsequent engine damage. But there is more to it. \u00a0When the engine is running at operating temperature, every point on the piston skirt and the ring land area has a specified clearance designed to ensure proper function of the piston and associated ring pack.<\/p>\n

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The piston skirt is the point of contact on the thrust sides of the piston. Clearance is measured here at the manufacturer\u2019s recommended point, which varies between pistons. It is the piston\u2019s largest diameter and the point of critical clearance.\u00a0<\/strong><\/figcaption><\/figure>\n<\/div>\n

\u00a0In determining the optimum piston-to-wall clearance, designers consider the entire physical and thermal operating environment of the piston by evaluating the following factors and how they inter-relate for each piston design.<\/span><\/p>\n