Possible boost leak? and boost calculation

[sirben711]

Hello all.

I installed an upgraded intercooler a few weeks ago and so far its working out pretty well I think. Makes a cool swirling noise between 5 inHG and 10 psi. Higher RPMs feel better. But it is a little hard to tell because it has been pretty cold outside since I installed it.

However, since the install sometimes when I start driving aggressively i will hear a ppprttt (squeak) noise for a fraction of a second. It almost sounds like an after market blow off valve (except I am still using the stock one) or almost like a tire chirp. So I am wondering 1. if I didn't clamp the hoses tight enough (because they were very difficult to tighten down based on their location and it occasionally leaks. 2. the intercooler is moving under load and rubbing up against something (because the mounting brackets had a little play in them) or finally 3. is just the noise of highly pressurized air hitting the bars and plate design.

When I hear this noise I don't see the boost gauge dip on the screen. And I don't feel loss of power. Would the boost gauge be able to show a brief loss in pressure like that? At peak, I seem to be making about 23psi under certain conditions with my FPTune.

What are the symptoms of a boost leak? How consistent do they tend to be?
What does a boost leak sound like, and would I still be making boost even with one?
Where is boost pressure measured? (and how accurate is it)

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[Vicr]

I saw you post on the other forum but I'll reply here. If you are making 23 lbs. of boost I doubt you have a boost leak. Perhaps there is an issue with the BOV. An intercooler is a dumb system, no moving parts just a heat exchanger. Make sure all your pipe to hose connections are good, clamps are tight etc. The only non-dumb part is the BOV so if the plumbing all checks out I'd start there.

 

[GJarrett]

You are describing a noise that might be similar to one that has me stumped lately when I have my PD Tune for 93 octane loaded. I have a built motor w/NX2 turbo dialed in to 25 lbs boost. During acceleration, or at the end right before the shift to the next gear, I get a chirp or quick double-chirp that sounds like a tire chirp but isn't. It doesn't do it with the 87 octane tune at much less power.

I don't know what it is but I don't think it has anything to do with the intercooler, I've had my intercooler for 100k miles and all connections are fine, never made this noise until the 93 octane tunes started getting dialed in with serious hp.

 

[Buldawg76]

Are you using the electric BPV valve, or a vacuum operated one and do you still recirc or blowoff the excess boost. If BPV is slow to react or just higher boost can make a chirp noise which is the turbo spool fluttering from the boost not releasing fast enough. Just a possibilty if running a blowiff system.

BD

 

[GJarrett]

BD, thanks for your reply, it has sent me on a research journey that leads me to believe I am experiencing compressor surge/turbo flutter. In case this is not the OP's problem I will start my own thread asking for fixes instead of hijacking this one.

Vicr may also be on the right track if the OP is also experiencing compressor surge but has a stock engine with just a tune; I would think that pushing from 20 lbs to 23 lbs boost might reveal a faulty BOV that is unable to vent the extra boost.

 

[Slopoke]

Check the torque of all of the clamps on the pressurized side of your pipes. Sounds like a small leak. When I had a duct leak, it sounded just like when you put a blade of grass between your fingers and blow.

 

[Buldawg76]

If using an electronic operated BPV/BOV your tuner can use datalogs to determine if it's a BPV/BOV issues and fix it with the tune.

BD

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