Originally Posted by
Doug_MPS6
Ranton, Hi, if you were really "giving it stick" in 6th at only 3000 rpm, and I'm assuming by that you mean that you were flat to the floor, it's highly likely that it was not your BOV fluttering and leaking but your wastegate dumping off excess boost, as you had a high load at relatively low rpm.
There are distinct differences in the sounds made by each, and if you were on throttle, the BOV should not have activated anyway, for the reasons I defined before, as its piston is under neutral pressure.
6th is a very tall gear with a big step up from 5th and is best treated as a cruise gear, with serious pull needs best being left to 5th.
Any issues I have with boost relief or slowness of the BOV to dump all that FMIC (and related plumbing)-contained boosted air as fast as I would like on throttle lift-off come in 6th at relatively low turbine spindle speeds.
I can't recall when I floored it in 6th, if ever, but even at ~30-50% throttle opening and ~3,000-4,000rpm, the amount of air dumped on sudden and total throttle closure easily exceeds that handled by bypass and vents huge amounts immediately and noisily to atmosphere, almost enough to sweep the streets clear of leaves!.
(We read here a while back of some member wondering why his engine would rattle badly and blow smoke when flat to the floor in 6th at 1500-2000rpm!! That was his poor engine about to have conniptions due to relatively high boost levels at high engine loads. We don't know what octane rating fuel was being used, though that appears to be academic at this combination of rpm and TPS).
Hope this helps. Cheers.