I am your change gears, you use me!


there Was a time in which the engines gave it all to high speed, when the atmospheric were the most common, both in petrol as well as diesel. With the arrival of the compressors and turbochargers, the rules of the game changed, leaving to the hand of the driver strength to a lower number of revolutions.

on the other hand, the automatic changes went from being a luxury to a reality even in cars very modest budget. In the simplest case, we talk about clutches piloted and gearboxes manual robot. No matter what technology we talk about it, it was intended to replace the driver in this task.

little by Little, the machines are being implemented mainly in cars of higher performance, and the reasons are various. Great torrents of power are more controllable as well, and can greatly facilitate your management to inexperienced drivers, even if they are inexperienced with decades of card above.


torque Curve of a gasoline engine, turbocharged

But let’s get back to cars a little bit more earthly, with powers normalitas, say, 200 HP down. We have to understand the concepts of torque and power to make best use of the change. If you look at the graph, corresponds to the engine 1.2 TCe from Renault, with 130 HP of power.

The line light gray represents the power, the dark pair. Where are those 130 HP? AT 5,500 RPM. However, the maximum torque of the engine, and 190 Nm, is located between 2,100 and 3.750 RPM, more or less. As a good turbo engine, has more power at low rpm a maximum torque.

Power = torque * speed

There are people who believe, erroneously, that the turbo run more than the gasoline atmospheric. If you step on the accelerator to one of each, in fourth to 80 km/h, the diesel will arrive prior to 120 km/h -simulation of overtaking – on the basis of equal power and number of speeds. What has gone wrong? The gasoline should have done the maneuver in the third. There the thing would change.


torque Curve of a diesel engine biturbo

diesels deliver more torque at low revolutions, but fail quickly and find it difficult to gain laps. In the engine dCi 160 CV does not deserve to stretch beyond 4,000 RPM, need to climb up. To the gas air, it happens otherwise, it seems that they are not pushing, until they reach high speeds -close to the cut of injection – and the performance improves substantially. Hence, it is important to know how to use the gear.

The turbochargers we are malacostumbrando, make us more lazy, because they do not need to change gear so often. We were able to verify this with the new Kia cee’d, comparing the engines 1.4 CVVT and the 1.0 T-GDi, both with 100 HP; the maximum torque and maximum power by using the shift lever more often to get the best result, the T-GDi is the swift better for the turbo.

If we are to achieve faster acceleration, we must have the maximum of power. If on the contrary we want the motor to have the lowest consumption (or support an effort such as a ramp or tow), we must move within the limits of the maximum torque. Discarding the aerodynamic resistance, is the point at which each gram of fuel is best used.

Engines Kia cee’d gasoline 1.4 CVVT 100 HP 1.0 T-GDi 100 HP
Transmission Manual 6 vel. Manual 6 vel.
Horsepower (HP) 100 100
maximum Torque (Nm) 134 171
Maximum Speed (km/h) 183 185
Acceleration 0 to 100 km/h (sec) 12,7 12,8
Recovery 80 to 120 (sec) 16,9 14,3
Consumption (l/100 km) 6,0 4,7
CO2 Emissions (g/km) 138 109

Let’s look at this table. Although the turbocharged engine has more torque (171 Nm compared to 134 Nm), the advantage in acceleration pure is very discreet, as well as in top-end speed. Another thing is to talk about recoveries, in this case measures in fifth, where the turbo is snack to the atmosphere. If the 1.4 CVVT makes the manoeuvre in third, the result would be the opposite. And in actual consumption, the difference is not so large, it is more, comes out in favor of the maximum torque.

For drivers who do not like to change gear often, the machines are a excellent option. There are some cases of boxes that are best taken advantage of using the semiautomatic mode, but in general we can speak of a better use of the engine with respect to a driver’s lazy. A look at the instruction manual to see the technical data of the engine can help us to improve our driving.

Although the speed limits are what they are, is not regulated the derivative of it with respect to time (acceleration). overtaking and additions must be made in the minimum possible time, for safety, and the engine will thank you, always, and when it is not freshly booted. Your shift lever you are asking, you can use it as is because.