Search terms: s5 wastegate port, port wastegate, boost creep, boost spike, overboost

Alright so I've been getting boost spikes... 14psi with no boost controller sometimes. The previous owner had done a little bit of work to the wastegate but not enough apparently, so I took it to a local shop that mostly does GM stuff, but one of the senior guys there took on the project.

FC3SPro also has a writeup here:

http://www.fc3spro.com/TECH/HOWTO/KWG/kwg.html

I sent the writeup to the guy at the shop for him to get an idea of what to do.

I didn't do any of this. A shop did, so I unfortunately can't provide much more information than the commentatary of the guy who did it.

the original thread with this stuff on a local message board, so I will just post word-for-word his pics and commentary:


Ok now I am quoting the guy who did the work:

"It's done. After almost a day and a half, we seem to be flowing much better.

This is what it looked like with a little porting done earlier on in it's life. Note the ports are small and there is virtually no sealing area on the inside of port #2 (at the right).....in one place, there was no sealing area [due to prior porting mistakes]:





The port on the left (port #1) rode along the outside casting wall. Because of this coupled with the little area for sealing, I could only port to the right to keep from sacrificing any structural integrity of the turbo housing. Port #2 was best to work to the left simply because of sealing area. In all, they were joined like seimese twins and forced to share. Note the loss of sealing area—especially around port #2.

 

With the sealing area pretty much gone bye-bye, I built (by welding) it back up and ground down to accomplish plenty of sealing area. To ensure flatness and a good positive seal, I painted the new sealing surface so I could recognize and see the high and low spots. I then took a flat grinding stone and hand cut the surface using the disappearance of color/paint as a reference (this took quite a while).

 

The factory “door” at this point was worthless. It was far too small for the new larger ports. Attempting to attach anything to it as a new door was futile since the wastegate arm would have to be relocated and the entire flap/door would open less………restricting flow. I removed the factory door and fabricated a new one. This new door was fitted and then heat treated/hardened prior to installation/welding to keep it from distorting under the heat of operation.






The limitations to the port sizing were of the case and the focus was given to the thick areas of it. What the pics don’t show is the inside the port work where flow and velocity was improved greatly (little tricks learned from porting heads). Although they may not look like it, the new wastegate ports will act as if twice the size of the originals."


-- That's the end of his commentary. I haven't gotten the car running yet. I put the turbo on but I need to retap the threads on a bolt on my oil return line, so it won't be up and running until next weekend probably. This wastegate should hopefully cure my boost creep and will hopefully be durable under the heat of a turbo rotary.

 

Out of curiosity, what did you use for welding rod? Nickle? How did it weld?

 

^ unfortunately I can't answer that. I don't even know how to weld, and that's partly why I took it to a shop.

 

oh yeah and for quick comparison this is the pic of a stock s5 wastegate from FC3SPro:

 

nice.. supposedly my wastegate is ported also, but i stil have creep problems in higher gears

 

I know it might be a dumb question, but how do you remove the turbine. Do you have to take the turbo apart to port the wastegate?

 

Not to be a nagger, but is it even needed? Seems like the S5 turbo would be out of effeciancy by the time you outflowed the stock ports, let alone those things. Alot of S4 guys have no problem with a single 30-35mm port, looks like you have the equivelant of 2x40mm ports. Ok Im done being negative. Looks pretty good though, welds are a bit rough looking, but whos gonna see it. I wouldnt imagine it would cause any failure.

 

This is what i have to do... Good pictures. However i think porting the whole thing out to look like an oval will be the best flow, reall no point of having the middle seperator in there anymore.

 

So have you gotten the turbo back in..... any boost creep?? How does it work??


Also you never mentioned the full diameter of both wastegate holes.. i would like to know as i an in the process of doing this.

Thanks,


Ben