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External Gate In Exhaust Housing

Brodie.Maher

By Brodie.Maher,
in Engines & Forced Induction

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Brodie.Maher Apprentice

Brodie.Maher

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Hi guys,

There doesn't seem to be a great deal of information how best to mount an external gate off the exhaust housing.

I recently finished building a steam pipe manifold for my SR and deliberately didn't include an external gate as it makes the most sense to me to evenly bleed the exhaust gases from the highest pressure point, which would be the exhaust housing, plus i wanted to be a little different.

It doesn't seem to be all that common to mount the external gate off the housing, i am curious to how far i around on the housing i should weld it onto and also which way to face the pipe. A lot of the housing's i have seen face the pipe in the same direction to gas flow of the housing, but shouldnt the gate be mounted at a 90 so that it isnt the easiest path for the gases to travel?

Thanks

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Brodie.Maher Apprentice

Brodie.Maher

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the most optimal angle to not impede 'flow' i've attached a snipet from turbosmarts installation guide.

How have you managed to mount the gate like that on a standard low mount?

I have got a mate who is going to weld onto the cast housing but he only wants to weld on a 90" off the housing to ensure its strong and to allow the tig to get into there, which is going to make it hard to not impede the flow some what.

The other issue is my manifold is top mount, ideally to limit impeding flow i could come somewhere off where the housing starts to curl around after the straight to the flange, but i might be limited by space.

Mine is mounted off the exhaust housing. It probably could be better angled but I didnt really have the room. All good, seems to work fine:

20131024_173749_zps01749055.jpg

So you have ran this and have no problems? Because it seems to go in an opposite direction to the flow?

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

The logic is simple. When the wastegate is shut all of the exhaust will go through the turbo. When the wastgate opens if the path is not direct much (or too much) of the exhaust will continue to flow through the turbo leading to overboosting.

Here's how mine goes:

post-49463-0-52442300-1418017474_thumb.jpg

scotty nm35 Grand Master

scotty nm35

Posted
Posted

The optimal mounting is to improve gas flow, which increases top end power. Simply venting the pressure at a 90 may hold boost well enough, but the gains won't be as great in my experience.

This setup I do works very well, but I spend a lot of time die grinding the inside to get a smooth path into the gate. External gate housings are obviously preferred.

post-63525-0-05491300-1418045082_thumb.jpg

Brodie.Maher Apprentice

Brodie.Maher

Posted
  • Author
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Thanks for all of the pictures and ideas guys,

It seems since it is a pressure system the angle doesn't greatly affect the ability to hold or vent boost, but isn't giving the best performance, but realistically my biggest issue is going to be space.

Obviously the shorter the runner to the waste gate the better, but should that be a priority over angle?

sucram Rising Star

sucram

Posted
Posted

If you were running a GT30 internal, then switched to an external with optimal flow, power difference atw will be less then 10hp

The internals are at 90 deg, which isn't great but will really only overboost on big engines with a small (relative) turbo/housing, the Xr6t is an example.

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scotty nm35 Grand Master

scotty nm35

Posted
Posted

Well the TD06 10cm was good for around 50kw more. Smaller housings will react better to external gates as opposed to the 1.06 Garrett internal, and such a simple way to get the results of a good top mount.

I thought making 430kw from the stock rb25 manifold was proof enough... Don't mistake boost control with the gate's ability to flow.

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