This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages) This article may contain original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (April 2015) (Learn how and when to remove this message) This article needs more citations. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Redline" – news · newspapers · books · scholar · JSTOR (September 2008) (Learn how and when to remove this message) (Learn how and when to remove this message)

The redline is the maximum engine speed at which an internal combustion engine or traction motor and its components are designed to operate without causing damage to the components themselves or other parts of the engine.^[1] The redline of an engine depends on various factors such as stroke, mass of the components, displacement, composition of components, and balance of components.

Redlining is riding or driving an automotive vehicle above the redline. The actual term redline comes from the red bars that are displayed on tachometers in cars starting at the rpm that denotes the redline for the specific engine. Straying into this area usually does not mean instant engine failure, but may increase the chances of damaging the engine.