DownPipes??

[ToP cAt]

I am doing an engine swap, and both engines consist of turbochargers. I would like to know alittle more on what a down pipe does for the turbo. What exactly is a down pipe used for??? Help please??

[Sluttypatton]

The downpipe merely connects the exhaust outlet on the turbine housing to the rest of the exhaust system. Without a downpipe, your turbocharger would vent exhaust into the atmosphere. The exhaust manifold directs exhaust gasses into the turbine housing, the downipe reconnects the exhaust system and provides the pathway for exhaust to escape through the exhaust system.

[matt11583]

the biggest thing to know about downpipes is the bigger the pipe the faster the exhaust gases get out of the turbine and into the exhause so they can leave.

[Sluttypatton]

One should aim for as little restriction as possible in a turbocharged exhaust system, since the turbocharger partly relies on the pressure differential between the manifold and the downpipe in order to run. Therefor a greater pressure differential will increase the power to the turbine, and make for a generally more responsive turbocharger.

[SaabJohan]

Originally Posted by Sluttypatton

One should aim for as little restriction as possible in a turbocharged exhaust system, since the turbocharger partly relies on the pressure differential between the manifold and the downpipe in order to run. Therefor a greater pressure differential will increase the power to the turbine, and make for a generally more responsive turbocharger.

This is a very important point. The restriction before the turbocharger isn't that important. This has to to with the expansion ratio aka turbine pressure ratio.

The flow after the turbine has a swirl, it's the downpipes job to make this into a more normal flow. Preferbly there shouldn't be any disturbances here, that is, the flow from the wastegate should be separated from the flow from the turbine.

[Sluttypatton]

Many people with external wastegates run a separate mini exhaust for the wastegate, and reconnect it to the main exhaust just before the muffler so that it isn't horribly loud.

[ToP cAt]

Now that i know what a downpipe is for, wat exactly does the wastegasket do??