Close-ratio transmission

However, because CVTs do not have specific (fixed) gear ratios unless programmed as such, it would not be considered a close-ratioed transmission.

High-performance engines often are tuned for maximum power in an even more narrow range of operating speeds.

A close-ratio type of transmission is designed to allow an engine to remain in this relatively narrow range of operating speeds and generally are offered in sports cars, in which the driver can be expected to enjoy shifting often to keep the engine in its power band.

The 1967 Porsche 911 S was equipped with a 2.0 L flat-six engine which produced 160 hp (120 kW) at 6600/min and 179 N⋅m (132 lbf⋅ft) of torque at 5200/min.

However, the Nürburgring specification has a "taller" (numerically lower) 5th gear ratio than the Hill Climb gearbox, allowing for higher top speeds necessary for this faster racing circuit.

In the 1960s, cars equipped with manual transmissions typically had four forward speeds and a top gear offering a 1:1 ratio.

Following the oil crises of the 1970s, final drive ratios went to 3:1 or lower to improve fuel economy and to accommodate this, vehicle manufacturers began adding more forward speeds into the gearbox, typically pairing an overdrive fifth with an even lower first gear, resulting in what would have been considered a very wide ratio transmission.

As an example, consider three manual transmissions fitted to Honda cars, each with an overall change in ratios (

To meet requirements to maximize fuel economy, manufacturers began offering 5- and, in the 1990s, 6- speed manual transmissions.

By reducing the spacing between ratios allowed by having more gears, a vehicle's engine speed can be kept in a narrow band.

With a 5-speed transmission, the power range must be relatively wide, which requires compromising the engine's efficiency.

The recent introduction of continuously variable transmissions (CVTs) attempts to push this strategy to its logical conclusion.