Can someone please explain or throw up a link about compressor flutter - in normal driving I have no probs but when in a que of traffic, say slowly climbing a hill in 3rd gear - maybe 3000rpm and .2-.3bar of boost when I lift the throttle I get that Compressor flutter noise

Doesn't seem to do it under high boost/hi revs situation

Can anyone explain? as I thought flutter was bad

Cheers

What sort of dump valve do you have? My bailey dv26 does this all the time, but i think that's because it's pants.

It's definately a lot more pronounced now that i have a straight intake pipe though.

I have a good dump valve - a GFB (go fast bits) plumbback unit but I do thave the stright induction mod - maybe it is just that and the new turbo and is actually all fine

I think its because the vaccuum is so light at that throttle setting that it doesnt operate the dump valve, this is causing a slight pressure build up when the throttle closes and thats being pushed back through the compressor wheel causing the rally car sound fluttering.

I run this mother of all dump valves and it takes quite a lot of vaccuum to operate it so I get some major fluttering on mine !
Im thinking of running a lighter sprung dump valve in parallel with the big one so it will still dump at light throttle settings.

*cough* SSQV *cough*

yeah - that makes good sense - so to fix it a dual BOV like the SSQV jayell so subtly suggested - though at those low boost levels I doubt it is doing much damage

If you run a softer spring in a second dump valve, do you not run the chance of it leaking boost when boosting higher?

I've thought about going for an SSQV for a while now, but i really like the rally style noises. And if it breaks, it's a suitable excuse for some upgrades.

Not on a recirc dump valve Matt, if the boost is acting on side of the piston instead of the face of it then its not going to force the valve open under high boost.

i was runninga standard bosch recirc dump valve,started fluttering the other day everytime i lifted throttle.wasnt dumping properly,ended up swapping it for a forge dv0006 valve.Seems just like the dump valve because the new recirc is no problem.no flutter at all.
Oh yeh with induction kit to

Do you guys use the Greddy Type RS at all? Its a good BOV.

Regardless if its a small amount of boost or not. Over time even small amounts o compressor surge is bad.

Pistole,

I suppose they do them in various sizes and jimbo got the XXXL

v.

That's the mariani tuning beast, ex-JohnS?

Pistole, it looks more scary than it actually is It replaces the black intake pipe in front of the throttle

It takes some different plumbing in to get it to work but it seems to work ok now. It needs to be T'd into the servo pipe on the back of the inlet manifold as it uses an 8mm vaccuum pipe instead of the normal 3mm fiat jobbie. The outlet isalso much larger than standard so I had to fit a reducing 90' elbow on that too.

I'll take some pics if it ever stops raining ??

i want one of those dump valves...where could i get one from!!