Redline refers to 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. The redline of an engine depends on various factors such as stroke, mass of the components, displacement, composition of components, and balance of components. The word is also used as a verb, meaning to ride or drive 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. Operating an engine in this area is known as redlining. Straying into this area usually does not mean instant engine failure, but may increase the chances of damaging the engine. Variation of redline The acceleration, or rate of change in piston velocity, is the limiting factor. The piston acceleration is directly proportional to the magnitude of the G-forces experienced by the piston-connecting rod assembly. As long as the G-forces acting on the piston-connecting rod assembly multiplied by their own mass is less than the compressive and tensile strengths of the materials they are constructed from and as long as it does not exceed the bearing load limits, the engine can safely rev without succumbing to physical or structural failure. Redlines vary anywhere from a few hundred revolutions per minute (rpm) (in very large engines such as those in trains and generators) to more than 10,000 rpm (in smaller, usually high-performance engines such as motorcycles, some sports cars, and pistonless rotary engines). Diesel engines normally have lower redlines than comparably sized gasoline engines, largely because of fuel-atomization limitations; even a small diesel engine, such as a Yanmar 2GM20 found on a sailboat, has a redline of 3400 RPM continuous, with a maximum 1-hour rating of 3600 RPM. Gasoline automobile engines typically will have a redline at around 5500 to 7000 rpm. The Gordon Murray Automotive T.50 has the highest redline of a piston-engine road car rated at 12,100 rpm. The Renesis in the Mazda RX-8 has the highest redline of a production wankel rotary-engine road car rated at 9000 rpm. In contrast, some older OHV (pushrod) engines had redlines as low as 4800 rpm, mostly due to the engines being designed and built for low-end power and economy during the late 1960s all the