weird sound under boost.

[richardv6]

ok, i have a sound that i have not been able to put my finger on yet.maybe someocould help. i installed a 3 1/2 dp with 46mm wastegate{changed from 3in } and installed fast system and alky .now when over 18psi i get a crackling type noise, like its busting up. but i am not getting any knock or fast pulling timming out. my knock sensor works ok i installed a audible sensor and tested it.when this noise happens the car is pulling hard and runs good, i cannot seem to figure it out. no exhaust leaks found, running through exaust,got 2 1/2 hooker aero chambers muffs did have stock style turbos. thought the exhaust was choaked up so put free flowing muffs on but no change.never had this issue before installing these parts,i have ran as much as 25psi with no issues. i have good head bolts and cometic gaskets i cant see any obvious sighns of head lifting, so any ideas please give ,thanks

 

[1quick6]

My car made a crackling noise similar to that. Mine was caused by a broken tie down strap on the driver's side that allowed the engine to twist and let the downpipe quickly rattle against the frame. It wasn't loud, but it was a very quick tapping that only happened under a high load.

 

[TurboV]

do you have a tie down strap? Could have a bad motor or transmission mount.You did just install a larger downpipe, sounds like it has to do with the swap. Do you have a lift available you can use to inspect undercarrage? Thats what i would look at.

 

[richardv6]

weird

i checked motor mounts and strap is good.the dp is heat wraped and not touching frame or etc, the noise is no so much a rattle but a crackling detnation type sound , and is boost related.only here it over 18psi could alky being sprayed into motor cause this. think i am going to put racing gas and see if its still their.

 

[forcefed3.8's]

Leaking headgasket?

 

[WSLN 6]

Take a look at your coolant overflow, when I lifted a head mine would "snap" over a certain psi boost (which happened to be the rad cap pressure rating.....)

 

[QUIP'6']

head gasket. its blowing out between the head and block toward the header

 

[Ttype6]

head gasket. its blowing out between the head and block toward the header

Yes,turn the alky off and see if it goes away. Make a mixture of three parts 93 octain and one part zylene to insure against detonation.

 

[WeSS]

funny noise

Do you have a knock gauge, scantool, etc. ? So that you can read block learn and other parameters.

Try rolling into it from 3rd gear and roll into it and see if you hear the noise so that it is not a trans related shift noise. Make sure you are not detonating no matter if you are using meth or race gas. Find the problem without adding to it.

 

[TurboV]

If race gas makes it go away, it is a detenation type sound. I would stay out of it until this gets resolved. May want to do a compression test and possibly a leak down test if you may have blow by at the head. definetly check the coolant and make sure its clean and clear. Check the oil dipstick for discoloration also.(Milky?) NO W.O.T.

 

[QUIP'6']

no race gas is going to make it go away. the damage is done. the head is lifting and the exhaust is blowing out the side it isnt detonation it is exhaust sound.

 

[Phoneguy]

no race gas is going to make it go away. the damage is done. the head is lifting and the exhaust is blowing out the side it isnt detonation it is exhaust sound.

+1...
Been there


Bryan

 

[MichaelRoger]

Now when over 18psi i get a crackling type noise, like its busting up. but i am not getting any knock or fast pulling timming out. my knock sensor works ok i installed a audible sensor and tested it.when this noise happens the car is pulling hard and runs good, i cannot seem to figure it out. no exhaust leaks found, running through exaust,got 2 1/2 hooker aero chambers muffs did have stock style turbos. thought the exhaust was choaked up so put free flowing muffs on but no change.

Parking Sensor

 

[Ttype6]

Did you turn the alcohol off?

 

[4-71/Z-28]

i say youre lifting a head i think i just did the same thing last night. i have head studs and cometic gaskets and when i got to about the 1000' it sort of sounded like a machine gun, loud fast popping and now i have a slight very high pitched ticking wich i think is a headgasket becasue it only does it when theres load on the engine(way too high pitched to be a hurt piston or rod)