Nissan 370Z Forum - View Single Post

cooltoy · 10-27-2014, 02:40 PM

WIKEPIDIA has a pretty good explanation.

Quote:

When a car with a manual transmission is in motion with the clutch engaged, there is a mechanical connection between the engine and wheels which keep them in sync with each other. When shifting however, depressing the clutch is required. This breaks the mechanical connection between the engine and wheels, and the engine speed is no longer linked to that of the wheels. When upshifting, this is usually not a problem, as the tendency of the engine to reduce speed itself without gas will slow it to loosely match the lower speed of the higher gear. However, when downshifting, the engine needs to speed up to come to speed with the wheels. If the accelerator is not "blipped" (or briefly and quickly pressed to speed up the disengaged engine), the engine will have to take power from the wheels and momentum of the car to come to speed, which is often accompanied by a sudden deceleration of the vehicle due to the power suddenly going to the engine, often described as a "lurch" or "jolt". This sudden external acceleration of the engine through the transmission also causes increased wear on the mechanics of the car. Therefore, a staple of advanced or professional manual-transmission driving is the "rev match", or "throttle blip", in which the driver quickly brings the engine up to speed with the wheels by use of the throttle. As downshifting is often necessary when accelerating out of a curve or other slow-down, advanced techniques such as the "heel-toe method" are often required, in which the toe of the right foot presses on the brake pedal, while the heel of the same foot blips the throttle.

Nissan's SynchroRev Match system makes such throttle blipping and advanced techniques by the driver unnecessary, and accomplishes engine rev-matching automatically.