Ive got an s5 turbo over here that creeps now that I've got a full intake system. Rather than play around withthe stock internal w/g, I'd like to buy an aftermarket external w/g.

Tial sells one for about $230 bux. Anybody ever do this to a stock s5 turbo??

The reason why I dont want to buy a complete turbo kit is because this turbo already has an upgraded compressor. I also do not want to trim the turbine because the compressor will slow way down at higher rpms because I believe this compressor is heavier than stock.

Thanks!

 

Well, considering you're fixin' to do what no one I know of in the US has done, it's kinda tricky .

First off, I'm assuming you don't have the stock boost control hooked up. Might want to try porting the wastegate first, too - it's actually damn easy to do.

To put on an external wastegate, you'd have to fab up some serious stuff. You'll need a shop that can do some seriously good welding that can take the heat, expansion, and vibration too.

Dale

 

Actually my car is an 87 tII, Ive just got the newer style turbo (89).

Ya Im nuts but creep is why everyones engine blows up.

 

Do you have the S5 manifold as well?
If you do, just port the internal wastegate and you shouldn't have any problems even with an exhaust on the car too.

 

Go t04 and get the HKS manifold. Then add the external wastegate. That probably the easiest way. Seriously!

 

Matlock ir right!...but if you want a good advice you will have to PM (tim or tims) he has an TurboII race car and he had an external waste gate on a stock turbo.. I can tell you that it is alot of work..

 

If I change the size of my turbo then I'll be put into a different autox class. If I do an external w/g then I can probably get away with it.

 

there someone who has done this before. i think what you do is remove the stock waste gate, and maybe make a "back plate" with your flange... hmm now that i think about it that would be easy too

mike

 

Here's a couple of pics of an external wastegate on a stock turbo. Personally I think this looks like a pretty average execution of a good idea. Both the inlet and outlet pipes of the wastegate have horrible 90deg mitred bends, the worst flowing bends you can make. Maybe this was done for space reasons, but I still can't see it flowing very well. This could be improved by moving the wastegate further from the turbo and making the pipes from smoothly flowing bends, blending into the main exhaust pipe at an angle.
The other problem is that you still need to remove the original restriction: the stock wastegate port(s). You'd need to remove the stock flap entirely and enlarge the hole well beyond the extent of where the flap used to sit. The turbine exit and old wastegate port would also need to be completely seperated from each other, or boost will drop from gases bypassing the turbine and then leaking back into the main exhaust.
If anyone knows who di the work in the pic, I'd love to hear the results.

 

That installation does not look good, I would not recomend it!

/Dany

 

Thanks for that informative post...

I thought about it a bit more today and it would probably be easier (and better performing) to come straight off the stock manifold with the external wastegate, and just weld the stock wastegate flap closed. I've seen this done with other turbos. If you're on a budget and can do some or all of the work yourself, it'd be a much cheaper alternative to a full turbo replacement.