stock turbo + MBC = boost taper theory

[jrohner]

Increased exhaust backpressure is where the boost taper comes in mostly, but air seeping by the MBC does attribute to it as well. My 16G could only hold 22 psi, I gained a few psi by using a Holset WGA. If your wastegate spring is too light, you can also end up with the wastegate fluttering at certain RPMs; you'll see your boost gauge bounce around a lot.

[Archertsi]

Originally Posted by jrohner

Increased exhaust backpressure is where the boost taper comes in mostly,

If your wastegate spring is too light, you can also end up with the wastegate fluttering at certain RPMs; you'll see your boost gauge bounce around a lot.

Can you explain the back pressure theory a little more? Im not sure I understand what you mean, even if back pressure wasnt letting the turbo push air into the engine, the turbo can still make pressure in the intake plenum.

Also, is the flutter from the back pressure pushing the flapper open? Then boost drops and so does back pressure so the flapper closes again?