In automotive jargon, the term "torque specifications" or "specs" can mean three different things. It can refer to the engine and drive train's torque output, the torque specification for a bolt or fastener on the vehicle, or the torque spec for a specific type of bolt.
Commonly, the engine's power output is stated in horsepower. Torque values for engine and drivetrain output, however, are an important measure of the vehicle's ability to pull weight and so are often given on trucks and SUVs.
Engine torque is a measurement of the output power at peak rotations per minute (RPM). Different vehicles will have different peak RPM.
Component Torque Specification
The vehicle's owner's manual and most automotive repair manuals will give specific torque specifications for different fasteners on various components on the vehicle. The engine's cylinder heads, for example, will have a series of bolts that require specific torque be applied in a given sequence in order to fasten the head securely to the block and seal it in place to prevent leakage.
These torque specifications are applied to many components on vehicles and are engineering specs that keep everything in place and running smoothly on the automotive machine. Whenever a torque is given for a bolt or component fastener in the manual, it should always be followed carefully.
Fastener Torque Specs
Fasteners (nuts, bolts, screws, etc.) are made to specific tolerances with a lot of metallurgy going into how strong they are. Some bolts are made to bend while others are made to hold strong until they snap.
Given this, special attention should be paid to the grading of fasteners that have been removed and are to be replaced on your vehicle. Grade marks on the bolt's head and on some nuts and screws will list its SAE or metric grading and these fasteners should be replaced with exact matches in order to retain component integrity.