I dont understand, you say "larger turbo" then you say "stock sequential".

I would bet that it is your profec b. Mine sounds just like that too. There was a thread a couple of months back about someone who put some sound deadening material and it made a big improvement. It is the selenoid in the engine bay that is doing it. Check this out before you look at anything else.

Perhaps it's this?

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fixed-my-rattle-noise-here-what-169138/

larger of the two is what I meant. Since it was happening at higher loads, perhaps it was making the sound..

But I don't think that anymore

This was listed earlier in this thread.

Damien's description of when the rattle was happening is very different. I will check that though.

I think the biggest hint is that it requires boost to make the noise and it gets louder with higher boost.

I'm going to check the boost gauge lines. It could very well be the profec-b solenoid, so I'll check that too.

The build seems to be a standard 300whp set-up done by Gotham:
30k miles on gotham reman
power fc
stock fuel delivery
stock twins with ported WG
profec-b
hks-twin power
greddy ic
removed emissions
boost, water temp, oil temp, A/F & Knock, and egt gauge.

If you have this set-up and don't get any audible ticking under boost, then I'd like to know.

Thanks :)

Both turbo's are the same size, but since its coming in at higher boost, maybe the force of the increased cfm is causing something to rattle in your manifold.

Hehe, shows my noobness. I have been reading up more and looking at the sequential diagrams. What I meant was "Secondary" turbo, not larger.

Anyway, the verdict on the noise is that is the Profec-B Solenoid. It bugs me enough I may switch to a ball & spring MBC.

Ahh good ... I'm glad it's resolved. That was my first thought when I read your problem.

I also have this noise. I too have the Profec B. Just like you said, I hear it right when I start hauling a$$. I can slowly get into boost w.o tho noise but if I push the accelerator down and really get on the gas, right away i hear a BZZZZZZZZZZZZ. Mine is so loud that I can't really hear the spooling of the turbo (gt3574). I will upload a video soon.

FYI - apparently this only happens with the older Profec-B. The newer revision has a much smaller solenoid that is much quieter. Mounting location also can affect the noise level. I'm going to get a new EBC.

Hmm..I bought mine new almost a year ago. The interesting thing is I only heard this noise after my car was tuned.

Since we are talking about loud noises, how do all of these noises affect the knock sensor? I have stiff motor mounts and no restriction on the exhuast. Can these affect how much knock I will read?

Sorry to bring this one back up! Anyone got any videos of this noise?? I've not got a profec. but I've always had a slight noise like that from my boost gauge under boost... a kind of ticking.

Now that I've got an HKS downpipe fitted I can hear that noise outside of the car too... can only hear it with the windows down and especially when going through a built up area with the sound bouncing back to the car... it sounds quite sick to me :( Don't like it at all especially as it's a new sound!

Bump, anyone? It's not a loud sound, but it is noticeable. I could try and record it next time I go out but it probably wont be good quality enough to hear the noise... I'll give it a go if no one can help out with the info I've given!