As of 2006, approximately half of all new car registrations in Europe were turbo diesel cars. The popularity of this type of car sprung out of the improvements it gives in fuel economy, noise reduction/elimination, vibration, and harshness.
Taking a closer look at the diesel engine you will find out that it has lesser speed range of about 1,000 to 5,000 rpm for private cars. This makes it ideal for turbo charging since the turbo will not exert much to change speed. Turbo lag is also reduced and efficiency is much more improved in a turbo diesel engine.
Since diesel engines need much compressed air to achieve ignition, there is no need to fit in dump valves, which could be an additional cost. Diesel cars do not have the throttle plates that close down when the car decelerates from a boost. The main function of the dump valve for the petrol-driven car is to serve as the bypass gadget for the extra pressure that has built up due to the closing of the throttle. This compressed air at very high temperature needs a way out else it will go back and eventually damage the engine.
Diesel cars have no use for the dump valve because their engines are built to use high-temperature compressed air. Performance is much better n a turbo diesel since there is hardly any lag in the next boost. With a gas-run car, the dump valve delays the next boost when gears are shifted.
In terms of fuel economy, turbo diesel cars are much more efficient. These cars can gain the much-needed power, plus more without waste of fuel. Fuel is burnt efficiently at an increased level to achieve optimum power. In diesel cars, the pressure that tends to increase the speed of the engine controls the turbocharger ? but this is dependent on the load.
Additional load to the diesel engine would result to greater resistance to the cylinders. Increased combustion and high temperature beget increased pressure and temperature on the exhaust gas. This revs up the car at a faster speed compared to a diesel car with less load ran on the same rpm.
Turbo diesel engines were used for light trucks in the 1990s in the United States. During that time, the diesel fuel had high sulphur content that caused a lot of problems with emissions. This was the reason why a lot of sedans, station wagons, and hatchbacks that have diesel engines did not sell as much.
In 2006, the ultra-low sulphur diesel came out in the market and manufacturers started to produce turbo diesels that run on this new fuel, with much attention on lowering emissions.
Turbo charging would also depend on the car to be modified. Take note that turbochargers increase the speed of the engine, which means there is increased temperature. The car to be fitted with a turbo diesel engine should be well equipped to withstand this heat.
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