911 turbo 2(965) strange spitting noise when boosting
 

hi
i am new to this site have owned numerous porsches 3.0.sc,3.2 carrera, 930 turbo etc....my new purchase is a midnight blue 1992 911 turbo 2....before i start investigating the issue i have just now i thought i would give all you fellow car buffs a chance to help me..
when i push the throttle pedal down on my car and the turbo begins to spool up on boost whilst driving there is like what i can only describe as a spitting noise coming from round the exhaust/wastegate area(quite a metallic spitting like noise),,,the car seems to be pulling strong and seems to show 0.7 bar boost but has this quite loud noise from when driving alongside the car which can also be heard easily from inside..has anybody got any ideas???

also the car a couple of times when rev'ed very quickly at a standstill i have heard like an unburt fuel popping noise??
the car has been fitted with a k&n powerflow filter which seems to do away with the last section of the original air box!!..is this good for the car as it doesn't seem like it could get much cold air in its current position
hope yous can help in anyway!!
thanks

Hmm...spitting? Hard to imagine what kind of sound you want to explain but it might be ruptured pressure hose that is opening and closing.

Either that or turbo is surging. You are sure it's not pinging? It sounds like BB's roling in a barrel or like hail hitting a tin roof. Pinging is a very expensive sound.

waste gate venting to the atmosphere?????? thats what it sounds like

Wastegate sound is more like a flutter, and it's not metallic. The metallic business worries me...

Could it be a broken head stud allowing movement/blowby on cylinder #1 or #2? Compression & leakdown test might help. How is the oil consumption?

hi
again,,,,its quiet hard to explain the noise..if you were to clench your front teeth and try and tut tut very quickly and sharply it is like this
(remember make sure no-one else is around when you try this as they might think your going mad,,lol)

Sounds like Detonation to me... Like Goran said,very expensive.
You might have picked up a tank of bad fuel. Run the highest octane you can.