Wastegates and Boost Creep

[ImolaFem]

Two nights ago I finally swapped out my Extreme 2.5 inch high flo
cat to a 2.5 inch test pipe. My exhaust now consists of:

unported 2G exhaust manifold -> big 16G turbo -> unported o2 housing ->
Buschur 2.5 downpipe -> 2.5 test pipe -> Thermal R&D 3 inch cat-back (necked
down to 2.5 inch at cat)

Now I have boost creep from H-E-double hockey sticks! I know a non-ported
o2 housing isn't helping this, but since I am about to install a Big28 in
place of my big16G, I'd like to know what you guys recommend from an autox
perspective for the wastegate. Should I have the Big28 internal wastegate
ported and have a 35mm flapper door welded on? Should I go external 35 mm
wastegate? Is there another option? Will everything be fine with o2
housing porting (This I doubt)?

Regards,
Mandy

[DSMxTSi]

Boost creep is more common with as cold as it has been the past few days. The test pipe, obviously, did not help this. I imagine that once the weather starts to warm up, you shouldn't have as much trouble with boost creep. Porting the o2 housing will definately help, but I'd just wait till you swap out the 16G for the Big28. The Big28 may not be as suseptible to boost creep as the 16Gs are. I had a 95 AWD Talon with full 3" exhaust, including test pipe, but with a T25 and it NEVER ever boost creeped. I would opt for the larger internal wastegate flapper, it should eliminate boost creep along with a ported o2 housing and will definately be much more cost effective.

Cody

[hoffman]

cheap idea.

thermal wrap the 02 housing and down pipe. i believe boost creep is associated with gas not being able to flow out of the way fast enough. so just thermal wrap the 02 housing and DP. this should help with the exhaust getting cold and heavy.

[Van]

Boost creep is the inability of a wastegate passage to effectively redirect the exhaust flow from the turbine wheel.

The exhaust has a much "straighter" path thru the turbine wheel. To go thru the wastegate port it almost has to make a 90 degree turn before the turbine wheel. This means that the wastegate passage has to be big enough and free flowing enough that it creates an area with less pressure (or more of a pressure delta than it has thru the turbine wheel into the dp,) so that it will draw the exhaust gas away from the turbine wheel.

An upgraded wg flapper door and really porting the hell out of and smoothing out the WG side of the O2 housing will help out a bunch.

But you already talked to Robert didn't ya...;)

[hoffman]

i've also seen this done- grind out about half the wall that seperates the exhaust side and the wastegate side of the 02 housing.

why, read the post above this.