i have a vf35 and when i comes on boost the induction noise is fine till about 9psi then it sounds like its fluttering till about 17psi then goes ok again to peak 22psi?????? it is spooling ok and is also holding fine just noise is strange my previous pe1820 was also set to 22psi but did not make this noise anyone else had or got this or even know what it could be???

 

Surge i.e. mismatch between how much the compressor can push through the throttle body and how much it can pull through the inlet pipe. That's my understanding at least. I've had it with a VF35 and a TD05 16G to a lesser extent, mostly cured by using a standard DV and freeing up the exhaust with a back box swap.

 

is it worse on part throttle than full throttle?

if you have a electronic boost controller try altering so boost doesn't come in so early.

 

the d/v is a standard unit from a nissan 200sx which works excellent with my fmic and the exhaust is a hks super dragger full turbo back as for boost control
it uses a 3 port i think i may have a very tiny leak on the downpipe gasket not sure if this may affect it??? would say part throttleis worst as is fine at full boost!!

 

yeah, you need to lower boost early on in the rpm as the turbo is producing too much air than the motor can suck in. causing the compressor surge, which over time can damage the turbo (depending how severe the surge is).