Is it possible that I need a larger or uprated wastegate??? When I give my car full throttle it sounds like the turbo is fluttering. I've recently switched to simtek from a GEMS and this is a new sound. I'm running a TD05-20G on a forged build up to 1.6 bar. It sounds like its trying open the wastegate under load but surely this shouldn't be happening. Or is that how the simtek controls the boost, once it hits its peak will it open the wastegate and bleed off?? Any advice off here would be appreciated. Thanks

 

i'd give your mapper a shout and see what they say about it.

did it do the same when being mapped ?

 

i have simtec fitted as well, when i lift very gently at full throttle i get a flutter noise as well.

 

I get loads of flutter sounds since changing to a decat downpipe.
Wastegate openning to control boost pressure!

 

Thanks fellas. I wasn't there when it was mapped unfortunately but i'm booked in for rolling road power run 2moro so can investigate it further. Cheers

 

If Scoobys work same as Skylines then the flutter is the sound of your turbo blades stalling/spinning in the opposite direction and the sound is heard more if you have got an induction kit fitted.

Not very good for your turbo either so ive been told.

 

Ditto, and no concerns from my mapper either - it's holding boost fine

 

The compressor is not what's stalling it's the air itself. It's not great for the turbo, but a little isn't going to kill it. The 20g turbo is quite prone to it and silicone intake pipes make it worse. You ideally need to bring the boost in more gradually. As noted, closing the throttle slightly makes this worse, as you make it harder for the turbo to force air into the engine, sometimes you need to back off completely and then reapply the throttle to make things smoother while driving.

Paul

 

I think the word that is escaping people here is 'surge'......

 

its an awesome sound ,leave it as it is

 

It's not awesome when you're trying to accelerate at full throttle, it's a PITA!

 

Mine does it on full boost but i'm pretty sure its the waste gate controlling boost .there is no fluctuation on the boost gauge and pulls like a train.Mapper seemed happy may not be the same symptoms as yours though.

 

Oh great, I've recently bought a 20g and Samco v.3/4 turbo intake hose. But the turbo has polished and ported exhaust intake plus wastegate ports.

Will I still suffer the same problem (when I get it all fitted/mapped)?

 

I think you will at least have to be careful with spooling the turbo. Tubular headers certainly take the edge of it, and the right combination of dump valve can help. The normal size samco pipe isn't THAT bad compared to say a 3" straight steel pipe. Liz's old sti4 ran a 20g with samco inlet and it was fine provided you didn't try and make more than 1.6 bar by 3500rpm, but once upon a time I had a car that would let me have more than 1.2 bar until 4000RPM!

 

Does that mean I would have to temper the throttle and bring boost in gradually (kinda defeats the object ). If I were to tramp on the throttle will I eventually knacker the impeller over time? Would, perversely, the more restrictive OEM black plastic intake alleviate/get rid of the symptom?

I'm likely to make no more than 380bhp when done (WRX v.1 heads ). What sort of boost pressure would be needed with this setup? If low enough - e.g. below 1.6bar - will the fluttering not actually exist at that level?