As title?, why are some 3 port (well 3 connector - I realise they all have 3 ports) and others only 2. Is there much advanged in piping the bleed air back into the air box?.

 

the 3 port ones (AMAL) are basically a on or off type and cant PWM reliably. the 2 port ones like the lektron (escos) valve can handle fast pulses of PWM to modulate teh amount of air fed to the wastegate, the resitcotrs in the T piece allow a smoothing effect of the pulses at the wastegate end.

 

Hi dave, I was thinking more of the simple brass ones but that is interesting stuff - so I assume the escos ECU changes the PWM duty cycle to the valve to regulate boost?

 

I didn't understand a word of that. Except "fast pulses" which sounded vaguely sexual.

Thank fock people like you are around or my RS would never start

 

most of it is through readin on here admitidly and playing with my car when its bwokenised

 

Any vehicle with an airflow meter requires the 3 port type so as not to introduce an unmetered air leak into the induction system.

 

Think what he means Stu is what is the 2 port for. Does it just restrict the airflow to slow it down? Never used one but seen them on some RST's.

 

I dont think he does mean that james, but i stand to be corrected.

 

Lol, OK I mean that then. Sorry was just curious.

 

FPMSL
Fair play mate your funny as fuck

 

2 port is commonly called a "Dawes device" and its a very simple pressure operated blow off valve

 

What I meant Stu was the kind like on RWs old bean tin. Looks like a brass 3 port, but only has an inlet and outlet? Are they a 3 with the middle outlet unscrewed so it looks like just has 2?

 

yes mate they are
They just DONT bleed back to the metering unit but they should do really..

 

Cheers Stu, always wondered

 

my piping is so long that it makes sod all difference.

U could have a valve inline with the wastegate/compressor that has two ports and a screw restrictor, with no actual bleed - but that would be pretty unstable i guess as u still have a constant pressure