Turbochargers & Superchargers

How much extra air should your engine be forced to take in, and with which technology? In this category we bring together turbochargers, superchargers and the parts that control and feed them: wastegates, actuators, blow-off valves, oil and water lines, and spare parts. It is for you if you want to build a new turbo project, upgrade an existing one or maintain it.

Turbo or supercharger: what is the difference?

A turbocharger is driven by the exhaust gas and can deliver high boost pressure relative to engine size, but boost typically only builds once there is sufficient gas flow. A supercharger is driven by the engine via a belt or gears and usually gives a more direct response from low revs. On the other hand, it takes some engine power to drive. Which solution suits you depends on the engine, the space in the engine bay and how you use the car.

How to choose a turbocharger

Size alone does not determine performance. Look at several factors together:

• Your power target and the rev range in which boost should be available
• The dimensions of the compressor and turbine wheels and the A/R ratio of the housings, which affect response and flow
• Flange and connections, which must match your exhaust manifold and your piping
• Oil and water connections, and whether the engine can supply the turbo correctly

In this category you will find brands such as Garrett, BorgWarner and Forced Performance. More air usually also requires more fuel and better cooling, so think of the whole system as part of the project.

Boost control: wastegates and blow-off valves

A wastegate routes exhaust gas around the turbine and thereby limits boost pressure. It can be internal in the turbine housing or an external unit on the manifold. An external solution requires space and piping back to the exhaust. Spring pressure and valve size must match the desired boost pressure and the gas volume. A blow-off valve relieves pressure in the intake when the throttle closes, so the air is not forced back against the compressor wheel. On some cars with a mass air flow sensor, a valve that vents to atmosphere can cause an uneven idle. In that case a recirculating valve may be necessary. From Turbosmart, for example, there are replacement solenoids for Kompact valves, and TiALSport is also represented in the category.

Installation and maintenance

A turbo depends on clean oil with the correct pressure and flow. So use suitable oil and water lines, change oil and filter according to schedule, and remove debris from a previously failed turbo before fitting a new one. Let the engine idle for a moment after hard driving so the temperature can drop. Changes to boost pressure typically require adjustment of the engine management. Whether the modification is legal and can be approved for inspection depends on the product and the car. Check this for the specific part number.

Frequently asked questions

What is the difference between an internal and an external wastegate?

An internal wastegate is built into the turbine housing and controlled by an actuator. An external wastegate sits separately on the manifold and can provide more precise control at high boost, but requires space and extra piping.

Why does a turbocharger typically fail?

Damage can be caused by inadequate lubrication, contaminated oil, foreign objects in the intake or excessive exhaust temperatures. Find the cause and clean the oil and air systems before you fit a new turbo, so the damage does not happen again.

Does the engine management need to be changed if I switch to a different turbo?

It depends on the turbo and the car. If boost pressure or airflow changes, fuel and ignition typically need to be adjusted. Without adjustment, the engine can run too lean and be damaged.

Can I drive on the road with a blow-off valve that vents to atmosphere?

It depends on the product and the car, and on whether noise and emissions still meet the requirements. Check the approval for the specific part number before you fit the valve to a car that has to pass inspection.