<P> External wastegates generally use a valve similar to the poppet valve found in the cylinder head . However they are controlled by pneumatics rather than a camshaft and open in the opposite direction . External wastegates can also use a butterfly valve, though that is far less common . </P> <Table> <Tr> <Td> An internally gated turbocharger . The internal gate is located to the right of the turbine wheel, but built into the turbine housing . Partially seen at the top is the wastegate . </Td> <Td> An external wastegate installed next to the turbocharger . </Td> <Td> A dual port Tial 44 mm (1.7 in) wastegate . The side port is the primary port . The top port is the secondary port and not necessary for proper operation . </Td> </Tr> </Table> <Tr> <Td> An internally gated turbocharger . The internal gate is located to the right of the turbine wheel, but built into the turbine housing . Partially seen at the top is the wastegate . </Td> <Td> An external wastegate installed next to the turbocharger . </Td> <Td> A dual port Tial 44 mm (1.7 in) wastegate . The side port is the primary port . The top port is the secondary port and not necessary for proper operation . </Td> </Tr> <P> An internal wastegate is a built - in bypass valve and passage within the turbocharger housing which allows excess exhaust pressure to bypass the turbine into the downstream exhaust . Control of the internal wastegate valve by a pressure signal from the intake manifold is identical to that of an external wastegate . Advantages include simpler and more compact installation, with no external wastegate piping . Additionally, all waste exhaust gases are automatically routed back into the catalytic converter and exhaust system . Many OEM turbochargers are of this type . Disadvantages in comparison to an external wastegate include a limited ability to bleed off exhaust pressure due to the relatively small diameter of the internal bypass valve, and less efficient performance under boost conditions . </P>

Where does the wastegate go on a turbo