2 port vs 3 port bleed valves - why 2 sorts?
28-09-2004, 08:01 PM
#1
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2 port vs 3 port bleed valves - why 2 sorts?
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?.
28-09-2004, 08:04 PM
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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.
28-09-2004, 08:06 PM
#3
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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?
- so I assume the escos ECU changes the PWM duty cycle to the valve to regulate boost?
28-09-2004, 08:08 PM
#4
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Originally Posted by Dave Henshall
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 the amount of air fed to the wastegate, the resitcotrs in the T piece allow a smoothing effect of the pulses at the wastegate end.
Thank fock people like you are around or my RS would never start
28-09-2004, 08:37 PM
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Originally Posted by Stu @ M Developments
Any vehicle with an airflow meter requires the 3 port type so as not to introduce an unmetered air leak into the induction system.
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28-09-2004, 08:43 PM
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Originally Posted by Stu @ M Developments
I dont think he does mean that james, but i stand to be corrected.
28-09-2004, 08:47 PM
#10
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Originally Posted by paddy1977
Originally Posted by Dave Henshall
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 the amount of air fed to the wastegate, the resitcotrs in the T piece allow a smoothing effect of the pulses at the wastegate end.
Thank fock people like you are around or my RS would never start
Fair play mate your funny as fuck
28-09-2004, 09:05 PM
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Originally Posted by Stu @ M Developments
2 port is commonly called a "Dawes device" and its a very simple pressure operated blow off valve
28-09-2004, 09:08 PM
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Originally Posted by Stu @ M Developments
yes mate they are
They just DONT bleed back to the metering unit but they should do really..
They just DONT bleed back to the metering unit but they should do really..
28-09-2004, 09:22 PM
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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
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
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