Internal to External Wastegate

[JuiceGST]

Hello, I know this is an old and repetitive topic. I am still new to the DSM world and just wanted to get some clarification on this topic. I purchased an external wastegate with the O2 recirculating housing from STM. From what I have read, I have to remove the internal wastegate and flapper from the my Evo III Big 16G Turbo.

My question is, does the hole that the flapper was covering stay open or do I need to do something to that hole? That is the only part that is confusing me because I also read that if the external wastegate comes off the Manifold then the flapper must be welded shut.

Obviously my set up will be from the O2 housing so it doesn’t seem I need to weld it shut. Just wanted to get some clarification on what to do with the hole if anything after removing the internal wastegate and flapper.

Thank you.

 

[DSMPT]

does the hole that the flapper was covering stay open or do I need to do something to that hole?

You remove the actuator wastegate and hold the flapper open by a thin metal stay or a wire. That would work. No need to remove the flapper physically. This would allow you to go back with the actuator wastegate easily when you want. I used to do this for several year when I had an external wastegat on O2 housing and I had no issues. And now I have had the actuator wastegate back on the same housing. Just sharing my experience.

 

[99dsmer4g63]

Hiroshi explained it well.

However I will share my experience FWIW.

I removed the internal gate. Cut the arm it used to connect to. Then punched out the rest into the exhaust housing. I then welded the hole shut left from the arm. I then ported the original 28-32mm hole as large as I was comfortable with as to not weaken the housing.

On my original 20g I did exactly like explained as by Hiroshi. I however put a small tack weld on the flapper arm on the turbine housing instead of a thin piece of wire.

Hiroshi methods are much quicker and easier.

-Daniel

 

[JuiceGST]

@DSMPT thank you. I will try that. I didn’t feel like paying someone $500 just to install the external wastegate because it’s a bolt on part. I was just confused and skeptical about how to remove the internal wastegate and wether the hole stayed open or welded shut. Thank you again!

 

[JuiceGST]

@DSMPT @99dsmer4g63 what happens if you don’t port the hole bigger? I read that it can cause boost creep even with the external wastegate if the hole is not ported. Is that true?

 

[DSMPT]

what happens if you don’t port the hole bigger?

Maybe creeps, maybe nothing happens. You can't really know until you actually run. It would be depending on your setup.

I read that it can cause boost creep even with the external wastegate if the hole is not ported. Is that true?

This is because even with the external wastegate on O2 housing, the port size on the turbine housing is still the same. So if the reason why you want to go with the external wastegate on O2 housing is because of boost creep, then this may not solve the issue.

 

[JuiceGST]

This is because even with the external wastegate on O2 housing, the port size on the turbine housing is still the same. So if the reason why you want to go with the external wastegate on O2 housing is because of boost creep, then this may not solve the issue.

I see, the main reason I was going external was to hopefully eliminate boost creep. I’m running a big 16g Evo III turbo. It’s arriving this Friday, I’ll install it and see what happens with the boost creep. I’ll figure out a way to keep the flapper open.

I’m assuming I need to get my car re-tuned with the external wastegate and if so, they will be able to see if I am getting boost creep on the dyno, correct?

 

[DSMPT]

I see, the main reason I was going external was to hopefully eliminate boost creep. I’m running a big 16g Evo III turbo. It’s arriving this Friday, I’ll install it and see what happens with the boost creep. I’ll figure out a way to keep the flapper open.

I’m assuming I need to get my car re-tuned with the external wastegate and if so, they will be able to see if I am getting boost creep on the dyno, correct?

If you will have someone to tune or build the car, ask the person. You can probably run the same tuning for just swapping the wastegate but the best would be asking the tuner since I don't know your setup and how exactly you want. It would depend on the boost level and exhaust setup. Keep in mind that if you want to run low boost, let's say like 10 psi, you will have more chance to have the boost creep. This is because to control low boost, you would need more exhaust gas flow through the wastegate port than controlling higher boost.

 

[JuiceGST]

If you will have someone to tune or build the car, ask the person. You can probably run the same tuning for just swapping the wastegate but the best would be asking the tuner since I don't know your setup and how exactly you want. It would depend on the boost level and exhaust setup. Keep in mind that if you want to run low boost, let's say like 10 psi, you will have more chance to have the boost creep. This is because to control low boost, you would need more exhaust gas flow through the wastegate port than controlling higher boost.

Ok. I had a guy dyno tune my car but never gave me proof. He told me my car made around 350hp. The car runs better and faster but told me that my boost was set at 10-12psi because of boost creep and Once I hit 3rd and 4th my car would hit 20psi. Without having proof of anything, I took it to another person to inspect. He told me that there is no way my car is hitting 350hp because my boost controller was shut all the way down and it was only running off the internal wastegate. He also mentioned that the big 16g only makes around 350-380hp if done properly. Obviously I was upset because I paid for something that I didn’t receive. I asked the first guy for the dyno sheet and gave me the run around and ultimately gave me no proof.

Then I found out about the external wastegate to try and eliminate boost creep. So I decided to purchase it and wanna try to see if that helps.