Turbo seeing pressure?
 

Alright, I searched for this but couldn't find any answers. I just changed my T3 for a new T3/T4 hybrid for obvious reasons. But now when I let off the gas and the BOV opens, I hear a strange noise...kind of like if your ABS was to kick in, that kind of rapid but brief noise. So I'm guessing the turbo is seeing pressure when I let off? I have an aftermarket BOV next to the throttle body. I had an extra one laying around, so yesterday I decided to put that one next to the turbo (yes, 2 BOVs). It didnt help that much...maybe a little, but not much. Would a BOV set up work better before the intercooler, since it's closer to the turbo? Should I put both there? Just curious about all this, I wouldn't want to damage the new turbo. Is this sound I'm hearing the turbo getting back pressure? Thanks.

Re:Turbo seeing pressure?
 

Turbo seeing pressure eh? You're venting to the atmosphere right? And you can hear the BOV? If you can hear it, I doubt there is any problems as far as your turbo seeing pressure, especially if you put two BOV's in there. Are you sure it isn't something else?

Re:Turbo seeing pressure?
 

I'm not sure what else it could be. This happened 2 months ago when I first got the new BOV and new intercooler. The BOV wouldnt open enough (spring was too strong), so that same sound was made. I took out the spring and cut it, and it worked fine. Now I install the new turbo, and it's making the same sound. I even opened the BOV all the way (it's an adjustable one). There's definitely more air flow going there due to the new turbo. At first I was thinking maybe one of the housings is crooked and a blade is grinding. But wouldn't it always make that sound when spooling then? It's only when I let off the gas as far as I can tell.

Also, at first the blades wouldnt spin at idle. Now that the other BOV is next to the turbo, it spins and creates a lot of air out of it. So you're right, it shouldn't be seeing any air at all. I'm quite confused over this.

Re:Turbo seeing pressure?
 

Anybody have any ideas of what the problem could be?

Re:Turbo seeing pressure?
 

Sounds like compressor surge to me.. like a small amount? Take the blow off valve off completely and go drive it, and see if the noise is the same, (but alot louder of the version your hearing) Dont worry its not going to hurt anything. Compressor surge only starts to hurt turbos when running large amounts of cfm. A t3/t4 running like 15-18psi might hurt it a bit.

Just try to figure out what causes the noise, what your doing? Is it when you throttle it, and let off? Also it is normal for a reman turbo not to spin at idle when you first get it, bearings are stiff and takes a bit to get them lubed, a few heating cycles should free it up fine.

What type of cams do you have? I had a similar problem with my built ZC, the blow off valve would not open all the way, or it would be to early. When you have big camshafts (fixed profile not vtec) the engine will not draw as much vacuum. So its hard for the blow off valve to open. I had to get a different spring for my Tial Blow off valve, that opened at 18-19in.

Jeff

Re:Turbo seeing pressure?
 

This is in an Accord F22B1 VTEC. Everything internal is stock, I'm only running 5 psi. Yeah, I guess it would be surge though. It seems to happen when I let off the gas. The big ass aftermarket BOV is near the throttle, and has a spring that's already cut nearly in half, otherwise it wouldnt open enough. I have the smaller BOV near the turbo. I can hear the smaller one more than the louder one, so more pressure is near the turbo, right? I'm thinking I should switch places. Put the big one near the turbo, might let out more air.

If I took off the BOVs, wouldnt there be no pressure at all, since there'd be holes in the charge pipes? I'm pretty sure it's surge, like you're saying.