How much power is boost creep robbing?

[T9S1i]

ok, i have a 91 talon tsi awd, my profile says all the mods i have, but for my exhaust i have ; stock first bend, about a 10" piece of 2.5''piping to a 2.5 in clex section, from there i have 3" straight piping all the way back with no cat... i suffer from serious boost creep... i talked to RRE and they said they had never heard of creep on a stock turbo... but i doubt that... alright to get where im going with this... i have no boost controller hooked up.. i have my positive pressure from the turbo outlet pipe hooked up straight to my wastegate... theoretically this should hold 10lbs of boost strong... my car spools to 10 at about 3k rpm then holds till about 5000 and then "respools" creeps to about 20 psi in the next 1000 rpm... i then lean out and get spark plug blowout and all that good stuff, now today i put a 3" cat on and the creep delayed from 5000 rpm to about 6000... thats pretty close to where i usually shift at so the problem is pretty much fixed... im afraid however to turn up my boost to 18psi like i would like to because i dont have access to a logger so i cant change my fuel trims with my afc.... when i do turn the boost up to 18psi how much power increase should i see (in hp or time off of a 1/4)? also could the low boost be causing boost creep? like is it hard for the turbo to hold such low boost when the rpms are getting so high and there is such a non-restrictive exhaust...? will turning boost up to 18psi eliminate creep altogether?
Early next week my logger cable and software will come in for my palm pilot so ill be able to log and tune and tell you guys what happens... im just still somewhat confused about the whole creep thing.... i do know however that putting a 34 mm flapper on a 14b is pretty much unheard of so if 18psi doesnt fix it then im going to have to save up for an evo16G and get it flapped.....

thanks for any input or thoughts

Danny

 

[90blacktsiawd]

I had the same problem when i put my 2.5" turbo back on with the stock 14b. Didnt matter what the boost was set at around 5k it would rip up to 17 psi and hit fuel cut. I was goin to put the 34mm wastegate flapper in but i just ported out the wastegate opening in the turbo as much as i could with it still being able to seal properly. That fixed my problem.

 

[T9S1i]

Alright, i have an extra exhaust housing from my buddy's blown turbo.... i was going to try to get a bigger flapper on there but the only way to do it on a 14b is weld it on there so i guess ill port the heck out of the hole..
is there anyone that did this port, retaining the stock flapper door, and measured their porting with an inside caliper or sliding caliper and has a size that they ported it out to to make sure the flapper still closes or do you have to eyeball and test it?
no jokes here please... only real numbers if you have em

thanks

danny