Why Turbocharging? Simple advice for beginners

Why Turbocharging? Simple advice for beginners

By Doug Erber:

In the United States, OEM’s (Original Equipment Manufacturers) are turning to turbocharging as a method of downsizing engine displacement and increasing fuel economy. At the other end of the spectrum, those in charge of developing high-performance and racing engines, are targeting it for substantial power gains.

The OEM’s regard GDI (Gasoline Direct Injection) as a key enabler for utilizing turbochargers to downsize the engine displacement. With modern direct injection coupled to variable cam timing, added power output generated by turbo boost is now exploited more fully than before without risk of detonation yet with significant benefits in fuel economy when running under light load.


In the Aftermarket, turbocharging is a relatively easy way to significantly increase the power density of an engine. In simplest terms, adding more air and more fuel to an engine will create more power.  Of course one must take care to assure engine and vehicle systems are adequately prepared to handle this additional power. Most systems will add an intercooler to reduce intake manifold temperatures and aftermarket ECU to control fueling and ignition. Depending on boost level, consideration for upgrades include, but not limited to, cylinder head gasket, head bolts clutch, pistons, connecting rods, crankshaft, transmission and differential. All components will be exposed to the rigors of additional power.


Compressor Stage




Through the compression process, density and air temperature is increased.  Feeding hot air to the engine that can reach temperatures of 300 degrees Fahrenheit, can lead to detonation and common practice is to run this hot charge of air through an intercooler prior to introducing it to the engine.


Turbine Stage:



Rotating Assembly:


03 Rotating Assy(6020)Lr

Figure 1 illustrates a piston ring which contains the oil flowing in the yellow areas. Its purpose is to prevent exhaust/boost pressure from gaining access to the center section. Figures 2 & 3 depict the oil lubrication areas that feed vital oil supply to the bronze radial bearings in which the shaft spins.


Smaller turbochargers can easily exceed 200,000rpm. Lubrication is critical and oil provides a thin boundary layer that allows the shaft to rotate within the radial bronze bearings. Oil also plays an important role in removing heat from the system.  Piston rings are used on either end of the shaft to contain the oil and prevent exhaust/boost pressure from entering the center section.  Due to the high exhaust temperatures in gasoline applications, water cooling is typically applied to reduce temperatures in the bearing housing and prevent oil coking during heat soak conditions.


179374_isoWastegate Assembly:




8374C_Beauty-shot_cutaway_JPEGCompressor Bypass (Blow-Off Valve):


CRV Operation Principles and Advantages

CRV Operation Principles and Advantages

When the driver lifts his foot off the throttle pedal, the intake throttle plate on the engine closes. At this point the turbocharger is still spinning and creating boost. Since the throttle valve is closed, the boost has nowhere to go except back into the compressor leading to a moment of instability known as surge.





Borg Warner

Asheville, NC

Borg Warner EFR

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