Lately I've noticed that My boost os dropping at high rpms.

Previously I had an unported S5 turbo/wastegate with RB 2.5 dp and silencer to 3inch CS catback.

No boost controller.

I would creep to 10psi easily in 4/5th and around 8psi in lower gears.

I ported the waste gate a month or two ago and put on a MBC. I set it for 7-8psi.

Lately I've noticed that it will go right up to 8psi but then rapidy drop to 5psi in the high rpms.

I didn't think that it would happen on my setup. I figure the exhaust flows enough that this shoudln't happen.

Now I do live in AZ where it's 90+ outside even at night. Could heat soak cause anything like this?

I do have a vac leak at the entrance to the turbo on the TID but it shouldn't affect boost right?

4/5th gears hold 8psi no problem.

thx

 

boink.

I just turned up the boost to 9-10psi.

It doesn't lose the boost as quickly but it still drops atleast 2psi in the 5.5k+ range.

Maybe a boost leak which only surfaces under higher pressures?It doesn't hesitate though so I doubt it.


This normal with a ported WG?
I did port a the side closest to the DP a bit more to make a better flow and it does leave 2-3mm's open even with the flapper completely shut. It wouldn't cause this though?

 

boink

 

now that i've read the whole thing over a second time, i'm not exactly sure what could be going on....