Internal & External Wastegates

[shaeff]

origionally posted by KirkMKIV:

Here is some info that can help most of you as to knowing what differences are between an Internal or an External wastegate. An internal wastegate is built in as part of the turbocharger's turbine housing. It consists of an flapper door that allows exhaust gas to bypass the the turbine blade, thus regulating the amount of boost created. An external wastegate is a separate unit from the turbocharger, located on the exhaust header/manifold between the engine and the turbo. Regulating boost is done in a similar bypassing method, but is done before the exhaust gas reaches the turbochargers turbine housing. The size of an internal wastegate is proportionate to the size of the turbo, where as an external wastegate, because it's located outside of the turbo, can be made much larger. An internal wastegate becomes too small when the volume of exhaust gasses coming from the motor exceeds the efficiency of that size wastegate. That's when an external wastegate can be utilized, to vent the extra exhaust gasses to stabilize boost pressure

 

[boost fiend]

so if a external w.g. *might* be better, can you convert internal to external. or is that just odd thinking. this is my first turbo can and i do know a bit bout no turbo cars. just looking for more efficency.

 

[americanjebus]

you can run an external wastegate on an turbo with an internal wastegate but it would only be worth it, or needed if the external wastegate was set at the psi where the internal wastegate losses its efficiency that way only the maximum desired exhaust gas will reach the turbine housing wastegate.

you would only need this when you start getting boost creep and the internal wastegate is simply overwhelmed by the sheer volume of exhaust gas.

 

[IJ.]

With my GT30R and it's .63 ar turbine housing I ran a big arse ext gate but on the GT3540R and it's 1.06 I can get away with the internal gate as there's less chance of over speeding the Turbo or out flowing the gate due to the big loose housing.