In this section we ll take a look at some of the tricks used to overcome these challenges.

Optional Turbo Features

The Wastegate

Most automotive turbochargers have a wastegate which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too fast at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high it could be an indicator that the turbine is spinning too fast so the wastegate bypasses some of the exhaust around the turbine blades allowing the blades to slow down. Ball Bearings

Some turbochargers use ball bearings instead of fluid bearings to support the turbine shaft. But these are not your regular ball bearings -- they are super precise bearings made of advanced materials to handle the speeds and temperatures of the turbocharger. They allow the turbine shaft to spin with less friction than the fluid bearings used in most turbochargers. They also allow a slightly smaller lighter shaft to be used. This helps the turbocharger accelerate more quickly further reducing turbo lag.

Ceramic Turbine Blades

Ceramic turbine blades are lighter than the steel blades used in most turbochargers. Again this allows the turbine to spin up to speed faster which reduces turbo lag.

Sequential Turbochargers

Some engines use two turbochargers of different sizes. The smaller one spins up to speed very quickly reducing lag while the bigger one takes over at higher engine speeds to provide more boost.

Intercoolers

When air is compressed it heats up; and when air heats up it expands. So some of the pressure increase from a turbocharger is the result of heating the air before it goes into the engine. In order to increase the power of the engine the goal is to get more air molecules into the cylinder not necessarily more air pressure.

An intercooler or charge air cooler is an additional component that looks something like a radiator except air passes through the inside as well as the outside of the intercooler. The intake air passes through sealed passageways inside the cooler while cooler air from outside is blown across fins by the engine cooling fan.

The intercooler further increases the power of the engine by cooling the pressurized air coming out of the compressor before it goes into the engine. This means that if the turbocharger is operating at 7 PSI boost the intercooled system will put in 7 PSI of cooler air which is denser and contains more air molecules than warmer air.