knightkarr

At what psi does the stock wastegate open up. I'm planning on porting my wastegate in the near future for upcoming mods. Anyone know?
Thanks

Wanked_FC

iTrader: (1)

According to the S4 factory service manual it is 6.56 psi.
Or for me, I prefer metric, so just under .5 bar (.46 bar to be precise)

NZConvertible

That's max boost. That wastegate will actually start to open at 3-4psi. Not that this really matters for wastegate porting.

knightkarr

Does this mean that on a ported wastegate i won't be able to achieve psi higher than 3 or 4 psi without a boost controller? Thanks for the help

poor_red_neck

Now I'm still trying to understand this whole boost thing... new to it

From what I understand, when you lower restrictions in the exaust (remove cats, straight shot mufflers, free flowing TID and filter) the wastegate is too small to let the exaust gases out. The outcome of this is boost creep. Adding a boost controller does nothing, as the wastegate is open as far as it can go. When you port the wastegate.. you are allowing more exaust gases to escape... then with the boost controller you can actually control it.

Am I correct on this?

NZConvertible

No, I said that's when the flap starts to open. It will continue to open until it reaches a point where boost stops rising. Thats max boost.

This is called wastegate creep (not boost creep, that's different), and all wastegates do it. It slows the rate of boost increase. EBC's eliminate this by holding the flap closed until just before max boost, resulting in quicker boosting and stronger mid-range.

knightkarr

oh, cool. That makes more sense now.