wastegates and emap

[88turboii]

this is probably a stupid question, but i have been reading up on emap (pre-turbo exhaust pressure) lately and got to thinking.. on an internal wg setup, what stops this from opening your wastegate before target boost is reached? i figured this is not a problem on external wg, because usually they open against the flow of exhaust, and/or they have dual ports so boost pressure works to keep the valve closed before target boost is reached

im running a 60-1/p-trim S5 hybrid with the stock 6psi wg actuator. but im running 15 psi, so the emap at that level has to be like 15psi minimum, right? why doesnt it push open the 6 psi wg door and let all the exhaust out?

[TitaniumTT]

Honestly, at 15 psi MAP it's probably closer to 30psi EMAP.

It's a function of a few things, the surface area on the actuator that's getting your 15 psi (pounds/SQUARE inch) is probably about twice that of your wastegate.

The flow of exhaust out of the wastegate is not going to be enough to divert ALL the gases away from the turbine wheel.

[RETed]

Wastegate spring


-Ted

[88turboii]

well i ordered a dual port wg actuator, im thinking with a dual port, the wg will be held shut by boost pressure as well as spring pressure