psi tapers too much!!

[kingGSX]

i just recently intalled a new mbc ...i have it set to 16 psi...but when i floor it, it will hold 16 psi for a second, and then it will taper to about 11 psi...is it normal for the turbo to taper so much??...please help...

 

[1fast97gsx]

mods? Maybe you have a small boost leak?

 

[kingGSX]

mods? Maybe you have a small boost leak?

i have a turbosmart mbc, a turbo xs blow off valve which should hold up to 25 psi, and a blitz stainless steel adapter style intake....thats it under the hood...

 

[BoostInsideTSi]

sounds to me like you have two things effecting your psi
1. stock turbo is small in size, at high rpms, your boost will drop off. most people with the stock turbo will shift at an earlier rpm because the powerband only goes up to about 5.5k-6k rpms.
2. you are experiencing boost spike, where when you get on it, the boost will shoot up, then drop off a bit, before decending to the 12psi. try lowering your MBC a bit, you will not see much of a power difference if any at all, and you will be saving your engine/turbo.

 

[kingGSX]

sounds to me like you have two things effecting your psi
1. stock turbo is small in size, at high rpms, your boost will drop off. most people with the stock turbo will shift at an earlier rpm because the powerband only goes up to about 5.5k-6k rpms.
2. you are experiencing boost spike, where when you get on it, the boost will shoot up, then drop off a bit, before decending to the 12psi. try lowering your MBC a bit, you will not see much of a power difference if any at all, and you will be saving your engine/turbo.

thanks...i'll try adjusting the boost, but do u think that something wrong with my wastegate?..

 

[BoostInsideTSi]

not quite sure with the wastegate. When I had my t25 It dropped down like yours.. so I imagine this is somewhat a normal problem, however, 16-11psi is a BIG drop. so it might be worth looking into.