At what point(psi) do you start seeing boost creep on an S4 with a stock wastegate?

 

depends.

what gear?
up hill?
outside temp?
hybrid turbo?
what exhaust?
cats?
T.I.D.?
crappy air filter or good one?
ect...
ect....
ect....................

 

i have a s4 TII with the following

stock turbo w/ stock wastegate
stock intake with cheap pureoilater (SP?) paper filter
RB 2.5 DP
gutted main cat and HKS 50mm catback

in 2nd gear going UP hill at WOT my boost went to 6PSI and stayed there till i shifted in 3rd went straight to 6PSI and stayed there till shift

BTW it was about 60F out side

 

Once you add an open intake with a 3" TID, you'll start seeing some boost creep. So I suggest you leave the stock intake on until you port the wastegate on that turbo.

 

Creep happened on my car with stock intake, straight 2.5" single exhaust. It's really mild (not a concern) with the same setup and a straight through 12" body, 2.5" diameter muffler in place of where the stock cat would go.

 

Creep is relatively mild to moderate depending on exhuast modifications. Like already mentioned; do NOT remove the stock intake until you are ready to go with an s5 turbo or weld on a larger puck onto your baby s4 wastegate.

 

I have been running a greddy intake, 2.5" downpipe, 3" main cat replacement pipe for about a year now. I have an aftermarket boost guage, and i dont seem to be getting any creep. 5th gear highway at WOT it will sit right at about 8.5 psi and not budge... what exactly cuases boost creep, and what are the damages?

 

Removing the stock TID is the big creep factor as far as the intake is concerned, not the filter itself.

Boost creep is exactly what is sounds like. Boost pressures slowly start to creep upwards as you stay WOT. The stock sized wastegate can no longer flow the needed amount of air through it to mantain the stock boost pressures. The only place left for the air to go is through the exhuast wheel. More air moving through the turbine in turn results in more air being sucked in on the intake side and higher boost pressures.

Wild boost creep has the potential to cause detonation and hence destroy your seals and send them on a suicide mission through the exhuast wheel of your turbo.

8.5 psi is fine.