Downpipe and Wastegate

[87BUICKGNTURBO]

Need some education here. Did a search but didn't find an explanation on the recommended 3" downpipe with wastegate. What benefits is (are) this (these) and what do they do? I want to become educated so I can make educated purchasing decisions. I see some 3" downpipes come with wastegate and some do not. And there is a downpipe with wastegate and test outlet???

Kevin

 

[SHADOWII]

The purpose of the larger d/p, i.e. the 3" or larger, is to reduce exhaust restrictions @ the turbo and allow for more air flow. The engine is an air pump, the more air you can push thru it, the more potential hp.
The waste gates are used to create or by-pass the turbine or hot side of the turbo. There are internal, like the stock style, which uses a puck to close off the by-pass port, to create boost. single or dual acting. There are external, which can be single or dual port, and can be attached to the d/p over the by-pass port or from header to w/g to d/p. Used w/a boost controller, depending on spring pressure used, can give control of a desired boost level. In some controllers, there are different stages of ramps that allow more precise boost control vs time to give repeatable performance. Such innovate msbc or the ams 500 or 1000's.
Hope this helps.

 

[87BUICKGNTURBO]

Great, thanks for the information. In your opinion, is the better way to go with external with a boost controller or internal like stock?

 

[psycho6cyl]

Guys are going 10s on internal gate (stock type) wastegate. It's cheaper going internal. Higher hp guys are running external gates w boost controllers. I have about $1300 tied up w down pipe external wastegate and boost controller. 3" down pipe from rjc or ta performance goes for about 550-600$. If you do Go bigger down pipe do use those vendors no matter how cheap other downpipe may seem to be. They won't have fit and finish as ta performance and rjc have and they're USA made.

 

[psycho6cyl]

I'd say depending on goals. But for most part 95% or more of these cars are running internal gate.

 

[87BUICKGNTURBO]

What about the test outlet? What is it used for?

 

[psycho6cyl]

You mean the test pipe? If so that's a catalytic converter delete. So it's just a straight pipe. There's also a y pipe you can place there and that's called a dump. Basically an exhaust cutout

 

[87BUICKGNTURBO]

You mean the test pipe? If so that's a catalytic converter delete. So it's just a straight pipe. There's also a y pipe you can place there and that's called a dump. Basically an exhaust cutout

Really appreciate the information. I'm learning a lot about my GN! Looks like I'll be getting a 3" straight downpipe with internal wastegate.

 

[SHADOWII]

Really appreciate the information. I'm learning a lot about my GN! Looks like I'll be getting a 3" straight downpipe with internal wastegate.

That's great, just take it one step at a time and you won't be disappointed.
I'm trying rjc's 5" d/p w/int. w/g, msbc controller, and dual port w/g(if I can find a sealed shaft unit) although I prefer the external w/g, but Jason didn't offer an ext, w/his. If this fails, I will mod the d/p for ext. w/g and sell the int. assembly.
The external offers better control in the higher hp levels, in my opinion, which is what I'm leaving to try this on a new combo.