dump valve yes or no
02 December 2009, 08:29 PM
#32
Brother ran without any sort of dump valve when fitting his front mount to his Version 4 STi, The flutter does sound good, but when driving it on the motorway, when coming off boost the car felt like it was hitting a brick wall, it felt really jerky, and enough to annoy him after a day, In the end he fitted a aftermarket re-circ valve.
02 December 2009, 10:25 PM
#33
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The Impreza already HAS a dumpvalve, it's a recirculating type, so puts the dumped compressed air back into the intake. It's therefore a bit quieter than a VTA, (vent to atmosphere), one.
The MAF, (mass air flow meter), on the car meters the intake air passing it, before it's compressed, and the ecu adjusts fuelling accordingly. The standard recirc dumpvalve has no effect on this, since it just puts the SAME metered air back in to be recompressed.
The VTA d/v, however, allows a LOT of pre-metered air to escape, but the ecu STILL fuels for it, so producing a VERY rich mixture. The excess fuel in this mixture can cause the oil to be "washed" off the bores. That's borewash, and it produces premature wear in the bores, which can lead to engine failure.
A VTA d/v also produces pops and bangs in the exhaust and cat due to over-fuelling, this can burn exhaust valves, burn exhausts, destroy the cat, etc.
Think about it: if there was ANYTHING to be gained from fitting a VTA d/v, Subaru, or Prodrive, would do it. They don't. End of
The MAF, (mass air flow meter), on the car meters the intake air passing it, before it's compressed, and the ecu adjusts fuelling accordingly. The standard recirc dumpvalve has no effect on this, since it just puts the SAME metered air back in to be recompressed.
The VTA d/v, however, allows a LOT of pre-metered air to escape, but the ecu STILL fuels for it, so producing a VERY rich mixture. The excess fuel in this mixture can cause the oil to be "washed" off the bores. That's borewash, and it produces premature wear in the bores, which can lead to engine failure.
A VTA d/v also produces pops and bangs in the exhaust and cat due to over-fuelling, this can burn exhaust valves, burn exhausts, destroy the cat, etc.
Think about it: if there was ANYTHING to be gained from fitting a VTA d/v, Subaru, or Prodrive, would do it. They don't. End of
I have an hks dump valve on mine and am gonna be fitting a few bits and an apexi ecu shortly and gettin it remapped, would this prevent borewash?
03 December 2009, 11:43 PM
#39
There's not a lot you can do about the rich state between gear changes due to VTA BOV's just with a remap. If a customer tells me they have an aftermarket bov i ask them if they still have the oem air bypass valve. If yes then i ask them to fit it back on. If not then I just get on and map it.
On a newage with a snorkus delete mod you get all the turbo sucking and pssssst you could ever want (not overly loud but enough for some personal satisfaction) with the std recirc bypass valve fitted.
Compressor stall puts a big strain on the turbo bearing and vanes of the compressor and turbine wheels. Not worth it just for a bit of space ship sound.
On a newage with a snorkus delete mod you get all the turbo sucking and pssssst you could ever want (not overly loud but enough for some personal satisfaction) with the std recirc bypass valve fitted.
Compressor stall puts a big strain on the turbo bearing and vanes of the compressor and turbine wheels. Not worth it just for a bit of space ship sound.
04 December 2009, 02:12 PM
#40
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There's not a lot you can do about the rich state between gear changes due to VTA BOV's just with a remap. If a customer tells me they have an aftermarket bov i ask them if they still have the oem air bypass valve. If yes then i ask them to fit it back on. If not then I just get on and map it.
On a newage with a snorkus delete mod you get all the turbo sucking and pssssst you could ever want (not overly loud but enough for some personal satisfaction) with the std recirc bypass valve fitted.
Compressor stall puts a big strain on the turbo bearing and vanes of the compressor and turbine wheels. Not worth it just for a bit of space ship sound.
On a newage with a snorkus delete mod you get all the turbo sucking and pssssst you could ever want (not overly loud but enough for some personal satisfaction) with the std recirc bypass valve fitted.
Compressor stall puts a big strain on the turbo bearing and vanes of the compressor and turbine wheels. Not worth it just for a bit of space ship sound.
was gonna say the word stall allways sound bad in a setence
a plane stalls it crashes
a car stall it get get smacked up the *** by an inconciderate driver
and a market stall - sells counterfiet goods and the owners shout alot.
06 December 2009, 05:13 PM
#42
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brammer have you taken yours off yet? do you notice any difference in fuel/performance?.............i have a front mount intercooler on mine so would i need to invest in a recurculating dv or can i just run it with nothing on it safely?
06 December 2009, 06:29 PM
#43
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In addition, the more boost you run, the bigger the shock your turbo will get every time you lift, so the quicker the bearings wear and the more likely you are to suffer a broken compressor blade, which can ruin your day pretty quick if it ends up dumping little bits of aluminium swarf through the intercooler and into the engine.
It's all a question of degree though. You may be able to run like it for tens of thousands of miles, you may not. The question is ultimately as Scoobiewrx555 says - do you want to potentially compromise the reliability of your engine just to force it to make a noise? If the answer is yes, it's your car so do what you want with it.
07 December 2009, 07:22 AM
#45
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The Impreza already HAS a dumpvalve, it's a recirculating type, so puts the dumped compressed air back into the intake. It's therefore a bit quieter than a VTA, (vent to atmosphere), one.
The MAF, (mass air flow meter), on the car meters the intake air passing it, before it's compressed, and the ecu adjusts fuelling accordingly. The standard recirc dumpvalve has no effect on this, since it just puts the SAME metered air back in to be recompressed.
The VTA d/v, however, allows a LOT of pre-metered air to escape, but the ecu STILL fuels for it, so producing a VERY rich mixture. The excess fuel in this mixture can cause the oil to be "washed" off the bores. That's borewash, and it produces premature wear in the bores, which can lead to engine failure.
A VTA d/v also produces pops and bangs in the exhaust and cat due to over-fuelling, this can burn exhaust valves, burn exhausts, destroy the cat, etc.
Think about it: if there was ANYTHING to be gained from fitting a VTA d/v, Subaru, or Prodrive, would do it. They don't. End of
The MAF, (mass air flow meter), on the car meters the intake air passing it, before it's compressed, and the ecu adjusts fuelling accordingly. The standard recirc dumpvalve has no effect on this, since it just puts the SAME metered air back in to be recompressed.
The VTA d/v, however, allows a LOT of pre-metered air to escape, but the ecu STILL fuels for it, so producing a VERY rich mixture. The excess fuel in this mixture can cause the oil to be "washed" off the bores. That's borewash, and it produces premature wear in the bores, which can lead to engine failure.
A VTA d/v also produces pops and bangs in the exhaust and cat due to over-fuelling, this can burn exhaust valves, burn exhausts, destroy the cat, etc.
Think about it: if there was ANYTHING to be gained from fitting a VTA d/v, Subaru, or Prodrive, would do it. They don't. End of
However; I have one question. You used the term 'pre-metered air'.
Did you mean 'previously metered air'?
'Pre' is normally used as 'before', so if the air is dumped prior to/before metering then there would be no effect on fuelling.
Or am I wrong?
08 December 2009, 12:14 PM
#59
It comes from a few years back, when a picture of a Scooby half in and half out of a lake, did the rounds. It appeared the car had attempted to drive across ice and had broken the ice and sunk.
Loads of people kept "finding" it and posting it on here, saying, "have you seen this?"
So the term SIAL, Scooby In A Lake, was termed, and has come to mean anything that gets posted over and over again.
It's not nasty, or owt, just people on this site, who have been around a while, having a laugh at newb's expense.
08 December 2009, 12:15 PM
#60
It comes from a few years back, when a picture of a Scooby half in and half out of a lake, did the rounds. It appeared the car had attempted to drive across ice and had broken the ice and sunk.
Loads of people kept "finding" it and posting it on here, saying, "have you seen this?"
So the term SIAL, Scooby In A Lake, was termed, and has come to mean anything that gets posted over and over again.
It's not nasty, or owt, just people on this site, who have been around a while, having a laugh at newb's expense.