wastegated twins question???

RJPotts · 05-11-2007, 05:05 PM

OK, I'm in the process of gathering parts for my twins. Currently my truck is as my sig says. I'm planning on running an S400 under my current turbo. I was wondering if it was possible to keep my internal wastegate and still have twins, or if there simply isn't enough room with the other turbo.
If not, how exactly does an external wastegate work, who sells them, or how hard is it to fab one?
My brain isn't letting this one compute.

Also anyone with a 98' auto that has done twins, is it necessary to relocate any of the coolant lines, or is there anything special that needs to be done to get everything to fit?
Thanks a lot in advance,
-R.J.

Rbratby · 05-11-2007, 06:13 PM

I have a friend that made his set of twins. He has a 96 auto. He didn't have to move anything. He didn't move his trans cooler under the exhaust manifold either. He's running an hx35 on top and a ht3b on the bottom. He uses his the stock hx35 wastegated housing.

RJPotts · 05-11-2007, 11:58 PM

So then, since the bottom turbo, be it an HT3B or S400, isn't wastegated, how does the external wastegate work? Or do most people just not run them?
Thanks,
R.J.

Cumnspwr · 05-12-2007, 12:05 AM

I thought the main reasons for an external wastegate were

1: less restrictive flow to the bottom turbo, and

2: with that amount of fuel the little internal wastegate wll not bypass enough not to overspool the smaller turbo.

Cumnspwr

Begle1 · 05-12-2007, 12:13 AM

They're also more eaisily adjustable. I think.

But mainly because it's possible to overwhelm the internal wastegates of the smaller turbochargers. I've seen all the "modification of internal wastegates", where people drill them out to make them flow more, but I can't tell you much more than that.

HOTMOPR · 05-12-2007, 01:46 AM

Check your PMs

HOTMOPR · 05-12-2007, 01:47 AM

Most current pict I have. Boost control is different now.

RJPotts · 05-12-2007, 09:57 AM

I think I get it. Well I decided to go with an ht3b instead of the S400. I think also I'm going to swap my 12cm housing for a 14cm.
I think I'd like to keep this as simple as possible, so I'll probably drill out the housing and port it a little bit also.
I appreciate the pics HOTMOPR that will definitely help me in figuring out how stuff should look. If anyone else has any other pics please PM them to me. I need all the help I can get.
Thanks,
-R.J.

raxley · 09-02-2007, 08:45 PM

Here's a thread from TDR that talks about the Relentless twin turbo set (which uses a stock upper turbo w/o external wastegate) which apparently gets good results. Couple of other people chime in about a design with an external wastegate. Long post, good info:
Artic Twins / Kendricks - TDR Roundtable
Think this link will work, if not I'll do something else.
Here's another: Twins w/ stock turbo - TDR Roundtable
Richard

Ground Shaker · 09-02-2007, 09:58 PM

Stock wastegates usually do over spool the turbo (even for a HX55/HTB3 setup) which is why alot of people go to an external wastegate. I'm building a HX40.HX60 setup and will be using the wastegate of the 40 for the system which will work only because it is much larger.