Aug 16, 2022
Forest city, NC
E92 335i FBO+e85
Has anyone tried running the n54 WITHOUT diverter valves or blowoff valves? Like how some JDM cars or Honda civics will hold their excess boost in to make the turbos flutter instead of a pshhh like a bov? I was wondering if the n54 stock twins or any twins for that matter would make the stustustustu sounds, yes I know it’s not good for turbos because it’s basically making them spin in reverse if I’m not mistaking. But I’m ONLY ASKING this out of curiosity to see who’s tried or if anyone has and if so what sounds it really makes or if it makes any sound at all???


May 22, 2019
Perth, Western Australia
2008 E92 335i 6MT
I have a VRSF BOV chargepipe that has an aftermarket TiAL BOV flange blockoff fitted. The stock twins flutter under certain throttle inputs and rpm's and it certainly sounds different to a BOV or DV setup, but more or less sounds like a loud BOV when the throttle closes under high or full boost conditions. Running a single with this setup would definitely sound more like what you're describing.

It isn't the sort of flutter you would hear on a big turbo barra or JZ motor though, as you usually have room to fit a long metal turbo inlet pipe and big filter on the end of it. I think that helps a lot with making flutter noises more pronounced, whereas highmount N54 setups usually run the filter on the compressor housing.

I don't want to get into the topic of whether it is bad for your turbo/s, as that always devolves into a shit debate with very little numbers or actual science behind it. At the end of the day we should use our cars the way we want to, and factor any real or perceived risk accordingly.

Hope this helps.