External Gate In Exhaust Housing

[Brodie.Maher]

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

[KiwiRS4T]

No should be mounted so that gate is easiest path to travel. Off the turbo housing is best.

[89CAL]

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:

[zebra]

I'm liking that manifold!

6-Boost?

[Badgaz]

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

[Brodie.Maher]

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:

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

[Badgaz]

Scotty here on the forums might be best to answer this... I had a really good fabricator to it for me.

[Badgaz]

I'll take a better picture when I get home so you can see the join

[Badgaz]

This is another forum members setup that I copied.

[89CAL]

Opposite direction to flow is back towards the cylinder head. I know my setup could be better but it is what it is and I havent had any boost issues

[Dose Pipe Sutututu]

Installed view

[KiwiRS4T]

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:

[Badgaz]

There you go

[Griffin]

This is mine. No issues with boost control.

[scotty nm35]

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.

[Brodie.Maher]

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?

[scotty nm35]

No, angle is more important. Google how a spray gun works and you will get some idea of why the angle is important.

[discopotato03]

I like Scotty's idea of the bend so that the vent paths area is large at the housing casting . I was always told that big is what flow paths have to be if the angles are compromised by packaging etc .

A .

[sucram]

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.

[scotty nm35]

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.