What’s the difference between an internal or external wastegate?

A Wastegate serves as a turbine bypass valve, redirecting a portion of exhaust gas away from the turbine, which limits the power delivered to the compressor. This action controls turbo speed and compressor boost. Wastegates can be either “internal” or “external.”

External Wastegates are stand-alone valves independent of the turbocharger. The actuator in both types is calibrated by spring pressure to open the valve at a specific boost level, preventing further boost increase. Internal wastegates are integrated into the turbine housing and have a valve, crank arm, rod end, and a turbo-mounted pneumatic actuator.

Internally wastegated turbochargers are easily recognizable by a canister mounted on a bracket attached to the compressor housing. This canister houses a diaphragm and a spring set to the manufacturer’s preset boost pressure. When the pressure surpasses the spring force, the actuator extends the rod, opening the wastegate and diverting exhaust gas from the turbine.

External Wastegates, added to the exhaust plumbing, provide the advantage of reintroducing bypassed flow downstream of the turbine, enhancing turbine performance. In racing applications, the bypassed exhaust flow can be vented directly to the atmosphere.

Both internal and external wastegates share similar operational principles, although the bypass valve is self contained, rather than being a part of the turbocharger. Inside an external wastegate you will find similar components to internal wastegates, being a spring and diaphragm combination. An external wastegate has a bypass valve built in, instead of operating a rod when a desired boost pressure is reached.

At SHOUYUAN, we have been manufacturing top-quality turbochargers and turbo parts like wastegate assemblies, cartridges, turbine wheels, compressor wheels, and repair kits for over two decades. As a professional turbocharger manufacturer in China, our products are versatile and suitable for various vehicles. We are dedicated to providing our customers with high-quality products and outstanding service.