TURBOCHARGERS

Perfect Power Articles.

 

The idea of providing some form of forced induction system has been around since 1896 when Rudolf Diesel introduced his supercharger design. The use of exhaust gas energy to drive the compressor was introduced in 1901 when Buche patented his turbocharger. For a long time forced induction was limited to motor racing, aircraft engine designers and a few specialists’ applications. Gradually the use of forced induction, mainly via turbo charging and mainly on diesel engines increased until, suddenly in 1980's turbo vehicles appeared everywhere. Now "turbo" has become a generally used adjective, describing anything fast and powerful.

Turbo charging increases the density of air and internal combustion engine, allowing more fuel to be burnt, and increasing the power output of that engine. This in turn allows the use of smaller, lighter engines; with improved efficiency giving reduced specific fuel consumption.


TURBO CHARGED DIESEL ENGINES

The turbo charged diesel engine was introduced in 1957 and it's success is reflected in the fact that almost all heavy trucks use turbo charged diesel engines and this tread was continued into the small diesel for automotive application, particularly in Europe where their popularity has boomed due to low fuel consumption, durability and low emissions. Currently manufacturers are devoting a lot of their time on improving these engines still further. Recently we have seen the Golf Turbo diesel in Motor sport events with surprising success.

 

TURBO CHARGED PETROL ENGINES

The diesel success story was originally not repeated with petrol engines, mainly due to the fact that petrol engines:

 

  • Already have a high specific power output without forced induction.
  • Have a wild speed range causing turbo selection difficulties.
  • High exhaust gas temperatures require the use of exotic materials.
  • Require complicated and advanced engine management systems to control detonation, "turbo lag" and fuel economy.
  • Require comprehensive heat shielding to protect under bonnet components.
  • Require low compression ratios, and thus are very sluggish to start.

 

The turbo chargers gained acceptance with non-decompressed engines where the turbo boost is controlled by the ECU. In these cases the engine operates as a normal aspirated, non-decompressed engine until the turbo boost sets in gradually. The boost is adjusted by the ECU in accordance with the RPM, and when the airflow restrictions at high RPM reduce the efficiency, then the boost pressure is increased to bring it back. This provides an almost “flat” power curve. The XMS4 can provide such boost control!

 

Properly installed and setup, a turbo charged petrol engine can give many years of trouble free service, and although seemingly an expensive solution, turbo charging gives good value for money in terms of HP / Unit cost.

 

As emission controls become stickier there will be increased focus on forced induction engines as a means of meeting the new standards because of high specific power output reducing total emissions and the better combustion efficiency improving emissions.

 

The questions most people ask is: How does the bearing in a turbo work, and how long will it last? The turbo seal and bearing works like a piston (ring). Instead of going up and down, the piston turns at high speed, and the rings are the seal and the bearing. It is therefore not surprising that they last a long time, the same as the piston rings in your engine.