Hissing noise before spool up

[Lewis]

Hi there fellow forum people.

I have an FG XR250 turbo ute with a growler intake, a three inch exhaust from the turbo back and a turbo smart BOV that has a blanking plug to stop the shhhhhh noise on lifting off the throttle.

The car is very quick and I am trying to make the car more refined, sort of a stealth car and one of the main issues I have is part throttle noise from inside the cabin.

For example when you are briskly accelerating, just squeezing the throttle and the rev range from 1500 to 2000 starts to sweep by I get a very hissy, rushing , leaking air noise.

On hard acceleration all sounds as it should with a high pitched compressor sound from the turbo when it's spinning hard but it's the low range lazy turbo boost that sounds totally wrong.

Is this a normal sound from the car or should I be looking for leaks in the pressurised side of the intake?

Could the noise be caused by the open style of the growler air filter?

Any feedback would be welcomed, I used to have a Subaru WRX and it did not sound like this at all, more of a very efficient and tight sounding turbine whine with no hissing noise.

Maybe it's an issue with the design of the  whole intake system and I need to replace it with an after market system.

cheers

lewis

[k31th]

Any reasonable opening in the air intake will cause the symptoms you speak of. Stock airbox with stock boost will be the quietest combination. 

[4321]

I had the same problem with my fg, (gtx3576)  very noisy with herrod air filter I took it of & put a fg xr8 air filter on - much quieter!  Mate put it on his stock XR6T , nowhere as noisy as mine. IT sounds like you've got a pressure side air leak, first place I'd look is a split joiner on t/body or pressurize intake &find leak.

[Guest]

mine does the exact same through the pod filter prior to boost. as it sucks air prior to making positive pressure it sounds like a massive air leak/hissing. on idle if you have the bonnet open can distinctly hear it sucking through the pod. that's with the airbox lid off and 6" pod though

 

As keif said best way to quit down it standard airbox etc but will lack power if that's what your chasing. Have seen cars making 350-360wkw all standard intake and cross over etc

[Lennox]

Check all the hose clamps on your intake especially around the turbo inlet. I had noises like this and found there was a couple of loose clamps. Was an ugly "whoosh" kind of sound

[skidxr6t]

If you don't know much, take it to a good mechanic and ask them to tighten up all the turbo bolts on exhaust side under heatshield and check all the pipework to throttle body. 

[Lewis]

Thanks for all the advice.

I will get on to checking all the inlet connections to make sure they are tight.

lewis