Crazy boost creep.

[theevozero]

Quoting Wookalar:
Port that wastegate flapper hole and get a bigger flapper to cover the larger hole. Or go external gate.

Or it may be possible you have some build up on the exhaust manifold flange mating surface to head, and you need to lay it on a sanding belt or have it milled so the surface is true again. Of course if you had creep that bad due to a exhaust leak you would hear it.



Its hard to explain in text, but thats not all you do. You have to grind down the upper portion of the hole from the inside of the turbine housing, so that the exhaust hits the bottom portion of the hole and exits the flapper. It would be much easier to show.

A exhaust leak on the manifold would not cause creep, it would have the opposite effect.

 

[Barnes]

Quoting Spyder:
I checked the exhaust mani before I re-installed it. Put new exhaust studs in the head and helicoiled any studs that were loose. Used a multi layer metal gasket. New gasket for turbo to mani connection. new gasket for o2 to down pipe.



It's also entirely possible that you had a pre-turbo leak before. If you had a bad enough pre-turbo leak it's conceivable that you might not experience boost creep when you otherwise should.

It sounds like a combination of factors are at play here, so we may never know what caused. Either due to an exhaust leak, weak compression, bad cam or spark timing, or any number of things your old setup didn't creep when it should have.

As long as you check that the wastegate actually opens, It pretty much sounds like your car is doing what it *should* be doing, which is creeping with your current setup. (BTW, You can use an air compressor turned to 15psi to check that the wastegate opens like normal.)

I'd just look now towards a path forward for addressing creep. Some here have already listed such suggestions.

 

[Spyder]

After all this, I just remembered that when I took the turbo off the manifold while I was stripping the engine, the gasket was so blown out that one of the 4 holes for the bolts to pass through was completely gone. It was burned out completely into the center hole for the exhaust passage.

I have never experienced creep like this before and really didn't know how to address it. External Waste Gate? Port O2 housing? What is better?

 

[turbowop]

The best way to address it is more fuel and supporting mods to run the higher boost levels. /ubbthreads/images/graemlins/grin.gif

External gate is a little extreme on a 16g, IMO. I would start with porting the path to the wastegate hole on the turbine housing, which is practically free. Or port out the hole and do the 34mm flapper while you're at it.

 

[Wookalar]

Quoting theevozero:
Quoting Wookalar:
Port that wastegate flapper hole and get a bigger flapper to cover the larger hole. Or go external gate.

Or it may be possible you have some build up on the exhaust manifold flange mating surface to head, and you need to lay it on a sanding belt or have it milled so the surface is true again. Of course if you had creep that bad due to a exhaust leak you would hear it.



Its hard to explain in text, but thats not all you do. You have to grind down the upper portion of the hole from the inside of the turbine housing, so that the exhaust hits the bottom portion of the hole and exits the flapper. It would be much easier to show.



I understand what you are saying, I have seen the inside of the housing. Maybe op will post his progress if he decides to go that route.

 

[theevozero]

 

[Spyder]

How far do you go with it?

 

[theevozero]

Till you expose more of the lower portion of the wastegate hole. There is quite a bit of meat there to cut from I wouldn't worry too much. I pretty much outlined what you need to remove.