Torque

the 21st century will be powered by specially tuned versions of the following overhead cam engines:
• QR25 4-cylinder engine
• VQ Series V6 engines
• VK45 V8 engine
• VK56 V8 engine

Torque

Torque is a measure of the twisting force generated by the engine’s crankshaft. The transmission and final drive (differential) are used to multiply the torque output of the
engine. The amount of torque an engine generates, calculated in “foot-pounds,” is an indication of how effectively it can generate its power. Different engines develop their peak torque at different rpm levels. Therefore it is important to recognize the level at which a given engine develops its peak torque.
• Engines that develop peak torque at low rpm are more responsive at lower rpm, but will “run out of steam” as rpm increase.
• Engines that develop peak torque at high rpm will be very responsive at high rpm, but will react slowly at low speeds.

Power-to-weight ratio

The power-to-weight ratio is a more useful measurement of engine power. The power-to-weight ratio is the ratio of horsepower to vehicle weight. If a vehicle’s engine has a high
horsepower rating, but a heavy weight, it may not perform as well as a vehicle that is lighter, even if it has less horsepower. A power-to-weight ratio is often expressed as a single number. For example, a power-to-weight ratio of 18.5 means one horsepower has to move 18.5 pounds of vehicle weight. A lower power-to-weight ratio may mean superior vehicle performance, regardless of the horsepower rating.

Horsepower

Horsepower is the customary unit for measuring the power of an engine. By definition, one horsepower is the power needed to lift 33,000 pounds a distance of one foot in one minute.
The horsepower rating of an engine gives an indication of how strong the engine is. However, other factors, such as the weight of the vehicle, affect how useful the horsepower will be. The more a vehicle weighs, the more horsepower is needed to move it.

ENGINE TERMINOLOGY

When discussing engine specifications and performance, the conversation almost always includes terms like “horsepower” and “torque.” “Power-to-weight ratio” is
another common measure of engine performance.
Finally, “fuel economy” is an important topic for almost every vehicle buyer.