KILLER-LS1

iTrader: (18)

Hey guys, so I just re-did my cold side, and all of a sudden I'm getting an odd bark sound every time i shift while at 10+psi. It doesn't sound like compressor surge... its not fluttering. Its just a one time "braaap" that sounds like a little dog bark. Its also accompanied by the traditional BOV pshhhhh sound. I tested the BOV and it is opening properly. Its the same BOV and it never did this before...

Here are the changes I made to the car all at once:

~New air filter almost double the size (creates more boost in first gear, also decreased spool time)
made short 6" long tube for air inlet.
~re-routed aluminum tubing. added aluminum o-ringed V-bands to replace some couplers
~ added threaded IAT
~Added meth nozzle (but Im not spraying anything right now)


has anyone every experienced something like this? My only guesses - Maybe air is squeaking out one of the v-bands making a funny sound. or maybe it has something to do with air being pushed into the methanol tube? I have no clue.

Otherwise the car runs great... Any ideas?

redhotev1

iTrader: (5)

Sounds like a shot of air screeching out from around a silicone coupler to me.

KILLER-LS1

iTrader: (18)

hmmm, thats possible, I'll have to double check the couplers. There's only 3 couplers.. 2 on each end of the intercooler and one into the throttle body.

it definitely sounds squeaky though. just never heard anything like it. All the end of the tubes are bead rolled btw

Sweet_SS

Do a boost leak test.

KILLER-LS1

iTrader: (18)

im not sure what I could cap it off with... It starts with a 3.5" aluminum V-band, and ends with a 3" tube. That end is easy, I can just get a cap, but how do i cap that v-band? i wouldn't be able to slide a rubber cap over that...

I'm think I'm leaning toward a leak in the cold side now. it does make the most sense.

Alpha

Try your old air filter.

killernoodle

Every time you shift? Sounds like the clutch.

If it happens when you let off then it is something in the bov.

KILLER-LS1

iTrader: (18)

no, every time i shift while at 10 or more psi of boost. its definitely not the clutch. Its definitely some sort of air sound

MaxxMitchell

iTrader: (15)

For a boost test I usually go to homedepot and get a rubber cap for the turbo inlet, drill a hole and have someone jam a air nozzle in while you listen, or spray soapy water for leaks. I usually do not remove the charge pipe from the throttle body (may help hold the bov closed) either and can maintain 8-12psi pretty easily with a compressor that flows ~4cfm and 20gallons or more.

On the dyno I had a car with a coupler that popped off and it sounded pretty similar but was constant noise under boost, maybe its there all the time in boost but you dont hear it until the shift?

killernoodle

What about when you're making 10psi and you let off and back on without shifting? (but modulate the throttle in the same way)