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Air circulator valve/Air Bypass Valve options?

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Old 11 February 2009 | 10:55 AM
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Default Air circulator valve/Air Bypass Valve options?

Hi

I've got the standard air by-pass/air circulator valve on my bugeye but it's started to make a whoosing noise when I lift the accelerator.

Looking to get it replaced and the part is £160 from subaru. Are there any third part valves that will be silent? (or are they all?)

Cheers
Richard.
Old 11 February 2009 | 11:08 AM
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Probably find the actual dv is starting to leak... or more commonly, the rubber recirc hose that it's attached to, has a split in it/becoming disconnected.

My 1993 WRX's recirc pipe (moulded to the turbo intake hose) had a massive split in it and I gradually heard it venting to air louder and louder lol, as the split got worse.

Last edited by joz8968; 11 February 2009 at 11:10 AM.
Old 11 February 2009 | 11:55 AM
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Originally Posted by joz8968
Probably find the actual dv is starting to leak... or more commonly, the rubber recirc hose that it's attached to, has a split in it/becoming disconnected.

My 1993 WRX's recirc pipe (moulded to the turbo intake hose) had a massive split in it and I gradually heard it venting to air louder and louder lol, as the split got worse.
Thanks for that - I'll have a look

I thought that you had either a DV or a air by-pass valve?
Old 11 February 2009 | 01:05 PM
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Originally Posted by Scotsman
...I thought that you had either a DV or a air by-pass valve?
All Imprezas have with recirculating dump valves as OEM fitment - none are vent-to-air jobs.

Between MY93-98 they are black plastic items.

From MY99>on, they were metal (like yours), and bolted directly to a cast flange on intercooler.

Last edited by joz8968; 11 February 2009 at 01:06 PM.
Old 11 February 2009 | 01:39 PM
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Originally Posted by joz8968
All Imprezas have with recirculating dump valves as OEM fitment - none are vent-to-air jobs.

Between MY93-98 they are black plastic items.

From MY99>on, they were metal (like yours), and bolted directly to a cast flange on intercooler.
Thanks again

Sorry to be a numpty - so is the recirculating dump valve, air circulation valve (what my local subaru dealer called the air by-pass valve) and air by-pass valve different names for the same thing?

Cheers
Richard.

Last edited by Scotsman; 11 February 2009 at 01:45 PM.
Old 11 February 2009 | 01:59 PM
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'Air-bypass' is probably called that as the the valve causes the closed throttle boost to sidestep going back through the turbo (as it's designed to), which would otherwise suddenly stall the compressor and put great strain on the reciprocating parts. To this end, ALL dump valves, or blow-off valves - whether 'recirculating', or 'vent-to-air' - can be considered 'air-bypass' valves.

The difference between recirc's and vta's is that the recirc's have an extra outlet port on, so that the redirected boost can be channelled back into the turbo intake to help keep the compressor spinning harder between gearchanges, for even less lag upon reapplying the throttle.

The vta's just have an open vent on the side that's exposed to the air - hence the familair loud # PFSSST # type noise that you hear when a car with one fitted is accelerating up through the gears...

Last edited by joz8968; 11 February 2009 at 02:05 PM.
Old 11 February 2009 | 02:42 PM
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Superb - with you now!!

Very disappointed then that my local independant specalist garage didn't realise that the standard UK runs a recirc and not a vta - as they thought the new 'psssst' noise my car was making was normal.....

Away out now to check the rubber recirc hose.

In your debt
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