Borg Warner Turbo- Exhaust Gas Turbocharging
Design and function of Borg Warner Turbocharger
Borg Warner Turbocharger compressors are generally centrifugal compressors consisting of three essential components: compressor wheel, diffuser, and housing. With the rotational speed of the wheel, air is drawn in axially, accelerated to high velocity and then expelled in a radial direction.
The diffuser slows down the high-velocity air, largely without losses, so that both pressure and temperature rise. The diffuser is formed by the compressor back plate and a part of the volute housing, which in its turn collects the air and slows it down further before it reaches the compressor exit.
Advantages of Exhaust Gas Turbocharging
Compared with a naturally aspirated engine of identical power output, the fuel consumption of a Borg Warner turbocharger engine is lower, as some of the normally wasted exhaust energy contributes to the engine’s efficiency. Due to the lower volumetric displacement of the turbo engine, frictional and thermal losses are less.
- The power-to-weight ratio, i.e. kilowatt (power output)/kilograms (engine weight), of the exhaust gas turbocharged engine is much better than that of the naturally aspirated engine.
- The turbocharger engine’s installation space requirement is smaller than that of a naturally aspirated engine with the same power output.
- A turbocharged engine’s torque characteristic can be improved. Due to the so-called “maxi dyne characteristic” (a very high torque increase at low engine speeds), close to full power output is maintained well below rated engine speed. Therefore, climbing a hill requires fewer gear changes and speed loss is lower.
- The high-altitude performance of a turbocharged engine is significantly better. Because of the lower air pressure at high altitudes, the power loss of a naturally aspirated engine is considerable. In contrast, the performance of the turbine improves at altitude as a result of the greater pressure difference between the virtually constant pressure upstream of the turbine and the lower ambient pressure at outlet. The lower air density at the compressor inlet is largely equalized. Hence, the engine has barely any power loss.
- Because of reduced overall size, the sound-radiating outer surface of a turbocharger engine is smaller, it is therefore less noisy than a naturally aspirated engine with identical output. The turbocharger itself acts as an additional silencer.
What is good for a Borg Warner turbocharger?
The Borg Warner turbocharger is designed such that it will usually last as long as the engine. It does not require any special maintenance; and inspection is limited to a few periodic checks. To ensure that the turbocharger’s lifetime corresponds to that of the engine, the following engine manufacturer’s service instructions must be strictly observed:
- Oil change intervals
- Oil filter system maintenance
- Oil pressure control
- Air filter system maintenance
What is bad for a Borg Warner turbocharger?
90 % of all turbocharger failures are due to the following causes:
- Penetration of foreign bodies into the turbine or the compressor
- Dirt in the oil
- Inadequate oil supply (oil pressure/filter system)
- High exhaust gas temperatures (ignition system/injection system)
These failures can be avoided by regular maintenance. When maintaining the air filter system, for example, care should be taken that no tramp material gets into the turbocharger.
If the engine does not operate properly, one should not assume that the turbocharger is the cause of failure. It often happens that fully functioning turbochargers are replaced even though the failure does not lie here, but with the engine.
Only after all these points have been checked should one check the turbocharger for faults. Since the turbocharger components are manufactured on high-precision machines to close tolerances and the wheels rotate up to 300,000 rpm, turbochargers should be inspected by qualified specialists only.