External Wastegates on a Q4

[jimnielsen]

I am using a T3/T4 turbo - nothing at all special..But with the cams I am using, the gas flow at high RPM makes the small internal wastegate of the turbo not able to control the boost properly. In effect I can still make too much boost with the wastegate wide open, such that boost will continue to rise to approx 2 bar.

To control this I am using a dual port BOV that bleeds some air on the inlet side of the pressure system (and I am controlling this function with an electronic controller..).

What I really need is an external wastegate..

I am currently using the stainless steel tubular manifold that many people use..

Do we have any pictures of how to modify this manifold to make it use an external gate?

Or any other ideas on the best way / location etc. for an external wastegate on a Q4?


jim..

[SteveNZ]

You could free up the turbine a little to stop it boost creeping. Machine out the turbine housing millimetre or two. This effectively lets some exhaust bypass the turbine. Also backcutting the turbine wheel will make it less efficient so it will flow more exhaust for the energy it can extract. Depending on how much it is boost creeping this may or may not be adequate.

I would fit your wastegate to the turbine housing. Have it pointing straight down and the exhaust can exit direct to the downpipe. Did I send you the photos of how my mate did it?

The cheapest and easiest solution is fitting it to the manifold collector; I would think it would fit there somewhere. It can be skewered in at any angle really.

[mpampis_]

I had this problem too. At high rpm I lose boost because the wastes open the port of the wastegate. I put pictures here. http://forum.berlinasportivo.com/showthread.php?t=2115

[Steve Webb]

The cheapest and easiest solution is fitting it to the manifold collector; I would think it would fit there somewhere. It can be skewered in at any angle really.

Ideally if you are fitting an external wastegate, the exhaust gases should be able to flow into the wastegate in a similar path to that when they flow into the turbo. However with the limited space around the turbo in the Q4, the best you are going to be able to do is the 90degree takeoff similar to how mpampis has done.

[mpampis_]

There is one more solution but you have to move about 60mm the turbo and the downpipe too. There is an adaptor beside the tubular manifold and the turbine with T3 flange and you can put the external wastegate there it is like that
http://i157.photobucket.com/albums/t79/mpamphnos/5e23e85d.jpg

[jimnielsen]

Great - mpampis, I didn't really notice the pics of the way that you have cutout the tubular manifold and welded a new pipe onto it... I think I will do that as well. Can you put the pics up again at a higher resolution? Any any pictures that you have that show how the exact routing of your pipe for the external wastegate?

Stevenz - yes, I have the pics, thank you for them...

[mpampis_]

This is finished. I haven't any other photos but it is very easy to do that
http://i157.photobucket.com/albums/t79/mpamphnos/9b1e7aec.jpg

[mpampis_]

As you see the route of the scream pipe of the external wastegate. I had no space and it is turning to the otherside on the left. I will try to take photos tomorrow as it fitted

[Xti]

I use to have an (XS Power) external WG adapted to OEM manifold of my spare engine. I'd like to have it on with the T3/T4 sometime, never had the chance yet to see how it works.

There are some pictures (page 1) in the thread (http://forum.berlinasportivo.com/showthread.php?t=1933&highlight=external+wg) if might help you in some way, Jim...

Cheers,
Cristian.

[mpampis_]

This is xs-power external wastegate and turbo too

[Steve Webb]

I use to have an (XS Power) external WG adapted to OEM manifold of my spare engine. I'd like to have it on with the T3/T4 sometime, never had the chance yet to see how it works.

There are some pictures (page 1) in the thread (http://forum.berlinasportivo.com/showthread.php?t=1933&highlight=external+wg) if might help you in some way, Jim...

Cheers,
Cristian.

:hijacked:

Just a quick question, but how did you find welding the cast iron manifold? Did you have any issues?

[Xti]

It wasn't welded but "screwed in" (if I'm correct).

[mpampis_]

Steve look how I pierced my tubular manifold and I stuck a steel angle for the wastegate

[Steve Webb]

It wasn't welded but "screwed in" (if I'm correct).

Ahh, that explains things. I only asked as I've got a cracked cast manifold that I need to get welded.

[Steve Webb]

Steve look how I pierced my tubular manifold and I stuck a steel angle for the wastegate

Cheers but it was the welding part I was interested in. Welding cast iron is a little tricky, and certainly more difficult than normal steel.

[jimnielsen]

I have a manifold that you can have for the cost of postage, Steve ...

[Steve Webb]

I have a manifold that you can have for the cost of postage, Steve ...

Cheers Jim, but the cracked manifold is from the 75 Turbo not the Q4, I'm just going to get it repaired until I splash out on either a tubular one, or one from a 75 Turbo Evo. (Split plane one)