dump valves - ill probably get slaughtered for asking this!!
09 February 2005, 06:00 PM
#1
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dump valves - ill probably get slaughtered for asking this!!
hi
i know its probably been asked a million times..and i have read alot of the posts but i still cant figure out which dump valve to get...i own a 2000 wrx...the classic shape...
help please!!
thanks
i know its probably been asked a million times..and i have read alot of the posts but i still cant figure out which dump valve to get...i own a 2000 wrx...the classic shape...
help please!!
thanks
09 February 2005, 06:35 PM
#2
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HI, I have recently taken my turbo xs one off as its just too loud for me, went back to standard recirculating one.
If you want really loud then this claims to be the loudest in the world.
Forge is a claimed to be a fairly decent one with the right spring in place.
Many pepole on here are against the idea od these but if its what you want then its your car mate...go for it.
P.S. Turbo xs BOV and MY99-00 fitting kit, second hand for only £150
If you want really loud then this claims to be the loudest in the world.
Forge is a claimed to be a fairly decent one with the right spring in place.
Many pepole on here are against the idea od these but if its what you want then its your car mate...go for it.
P.S. Turbo xs BOV and MY99-00 fitting kit, second hand for only £150
09 February 2005, 08:58 PM
#6
Re-circ only, unless you like to mess up the ECU measured air flow by letting loads of it go back to atmosphere when ever the dump valvce fancie stoo!
Forge are fine, even for uprated motors.
Forge are fine, even for uprated motors.
09 February 2005, 10:05 PM
#7
Originally Posted by vulnax999
Re-circ only, unless you like to mess up the ECU measured air flow by letting loads of it go back to atmosphere when ever the dump valvce fancie stoo!
Forge are fine, even for uprated motors.
Forge are fine, even for uprated motors.
This has all been done before and like I said its down to personal preference. I've had both OE and HKS SSQV and I much perfer the HKS. Have had to re-fit the OE temporarily and the gear changes now feel sloppy.
As far as the dv venting to air whenever it fancies to
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09 February 2005, 10:18 PM
#8
Well, whenever the engine vacuum reaches the level the piston / diaphragm / spring is set for, the dump valve dumps the excess/pressurised air ( which the MAF has already measured and the ECU is now calculating the fuel for, etc. ) - this is brought about by the driver lifting off .. the WWHHhhOOoooSSsshhhh you hear is all that nice measured / metered air being let out, that the ECU expects to be recirculated into the air inlet and reused ... with the right amount of fuel etc.
Personal preference is right though, your choice!
Personal preference is right though, your choice!
09 February 2005, 10:27 PM
#10
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Yep, been there done that and Bob and I always disagree 
There are no performance benefits unless you run without a MAF and have big flow / pressure through the turbo. To be fair to Bob's point, people don't fit them for performace reasons on SNet
MB
There are no performance benefits unless you run without a MAF and have big flow / pressure through the turbo. To be fair to Bob's point, people don't fit them for performace reasons on SNet
MB
09 February 2005, 10:33 PM
#11
agreed that most do not fit for performance gains
but there is all this scaremongering going on.
I would say if you want to fit a vta then go for it....its not going to cause your engine harm etc etc. On the plus side you'll get plenty of pops and flames (with de-cat).
Personally am finding gearchanges sloppy on the OE STi item after using a HKS for 2 years+. Personal preferences.
but there is all this scaremongering going on.
I would say if you want to fit a vta then go for it....its not going to cause your engine harm etc etc. On the plus side you'll get plenty of pops and flames (with de-cat).
Personally am finding gearchanges sloppy on the OE STi item after using a HKS for 2 years+. Personal preferences.
09 February 2005, 10:37 PM
#12
Originally Posted by BOB'5
We all know that but it doesnt explain the above statement.
Bob
Bob
Maybe my choice of the word "Decides" was inappropriate, lets choose to say "when the user's set level is reached " instead?
09 February 2005, 10:43 PM
#13
Originally Posted by vulnax999
As I stated above, when ever the VTA dump valve 'decides' ( as in is set to blow off ) then it dumps metered air out to atmosphere and so the ECU has "no" real idea of the exact amount of air it is supposed to use to burn the fuel, it puts in the fuel it thinks for the measurement and the combustion charge is heavily rich ( great for low fuel economy, fouled plugs, smokey exhaust, pops and bangs on overrun, lower exhaust gas temperatures, catalyst damage, bore washing and hence more piston & bore wear, possible oil dilution as fuel passes rings into oil, etc. )
Originally Posted by vulnax999
Maybe my choice of the word "Decides" was inappropriate, lets choose to say "when the user's set level is reached " instead?
Bob
09 February 2005, 10:50 PM
#14
The user set d/v level, ok...
Of course the OEM dump valve works like this, ( but is not adjustable, holds boost well, but anyway it's not about the OEM vs after market dump valves, it's about recirculating dump valves as opposed to vent to atmosphere dump valves ) but the metered air is recirculated back into the inlet tract a few inches along, so the measured air is still seen by the ECU, so the fuelling is still correct.
Pops and bangs from the exhaust indicate a major fuelling issue! Do you need the no. for API Engines or Scoobyclinic?
I'm out of here.
Of course the OEM dump valve works like this, ( but is not adjustable, holds boost well, but anyway it's not about the OEM vs after market dump valves, it's about recirculating dump valves as opposed to vent to atmosphere dump valves ) but the metered air is recirculated back into the inlet tract a few inches along, so the measured air is still seen by the ECU, so the fuelling is still correct.
Pops and bangs from the exhaust indicate a major fuelling issue! Do you need the no. for API Engines or Scoobyclinic?
I'm out of here.
09 February 2005, 10:59 PM
#15
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Originally Posted by BOB'5
Thats a matter of opinion and personal preference.
Bob
Bob
I was also advised by a very reputable mapper to bin the VTA before having it mapped.
10 February 2005, 02:04 PM
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I have just received my dump Valve which i ordered. After reading this i don't thik im gonna fit it!!!
I've only had my MY98 for about a month so its all pretty new to me. Think i will have to have a good read on here before i go spending my pennies again.
I've only had my MY98 for about a month so its all pretty new to me. Think i will have to have a good read on here before i go spending my pennies again.
10 February 2005, 02:52 PM
#22
Originally Posted by FTscooby
I have just received my dump Valve which i ordered. After reading this i don't thik im gonna fit it!!!
I've only had my MY98 for about a month so its all pretty new to me. Think i will have to have a good read on here before i go spending my pennies again.
I've only had my MY98 for about a month so its all pretty new to me. Think i will have to have a good read on here before i go spending my pennies again.
10 February 2005, 03:07 PM
#23
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put the dump valve on u will only know if u want one or not after u have heard it as for all the **** about bore wash..maf sensor....that they ecu is reading wrong do u know how long the ecu takes to re-correct the air,fuel mixture next they will be on about putting smaller turbos on coz big ons make the engine work harder 
how many times has u heard of someone blowing an engine coz of a dv has been fitted....answer.....never......half of u people are (not for people with normal answers)
how many times has u heard of someone blowing an engine coz of a dv has been fitted....answer.....never......half of u people are (not for people with normal answers)
10 February 2005, 03:44 PM
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John, the extra fuelling when the DV opens it quite significant, and agreed bore wash is unlikely over the medium term - your MPG will be affected quite a bit. I have to own up and say many years ago when I was 23 I tried one for a few weeks. The 3 main draw backs were as below:
One of the most reputed tuners on here will not sell you one, says a lot to me.
MPG dropped significantly (correctly fitted)
Jerky on lift off (correct shim / spring rate)
Sounded like a Nova driving chav
MB
I tried one for a few weeks. The 3 main draw backs were as below:One of the most reputed tuners on here will not sell you one, says a lot to me.
MPG dropped significantly (correctly fitted)
Jerky on lift off (correct shim / spring rate)
Sounded like a Nova driving chav
MB
10 February 2005, 04:02 PM
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ha ha...the 3 main draw backs to ur answers are....
1...,u drive an impreza...whats mpg got to do with it buy a diseal
2....mine has never jerked lifting off and did 3bhp more with it on on the rr
3.... if u hear one of these on a nova chances are it a cav turbo in the chavs nova and unless ur running a big brake impreza u are not going to get away from this?????....so what was ur point....
10 February 2005, 04:06 PM
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Originally Posted by Dark Blue Mark
John, the extra fuelling when the DV opens it quite significant
MB
MB
i'd have thought the fuel would have been cut to idle levels at this point
also with the recirc valve it cannot pressurize the intake (maf to turbo) very much so the air thats been through the turbo must go back out over the maf and this will have oil in it(small ammounts) which cant be good for the maf surely
what sort of air volumes are we talking about anyway?
richie
10 February 2005, 04:32 PM
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Woaaah cowboy 
Its taken me a while to work out what language both your posts are written in, but I think its some form of gibberish.
1) When you have an STi, driving daily and barely pushing 22 mpg - its an issue.
2) There's no way a dump valve will increase BHP - unless your old one was leaking. You haven't got a clue if you believe it will give more power than a fully working recirc. It *may* improve spool time by allowing better spin.
3) My horsepower is plenty big enough thankyou
If you're going to post, learn to spell
MB
Its taken me a while to work out what language both your posts are written in, but I think its some form of gibberish.
1) When you have an STi, driving daily and barely pushing 22 mpg - its an issue.
2) There's no way a dump valve will increase BHP - unless your old one was leaking. You haven't got a clue if you believe it will give more power than a fully working recirc. It *may* improve spool time by allowing better spin.
3) My horsepower is plenty big enough thankyou
If you're going to post, learn to spell
MB
Last edited by Dark Blue Mark; 10 February 2005 at 09:44 PM.
