How do I remove my dump valve ?
05 January 2001, 12:13 AM
#1
Scooby Regular
Thread Starter
Join Date: Jan 2000
Posts: 809
Likes: 0
Received 0 Likes
on
0 Posts
This should probably be in the 'modifications for vain buggers' section but hey 
After watching the recent rallying and hearing all those chirping noises the rally cars make between gear changes etc, I thought I would like that sound myself
So the question is, where is my dump valve ? can I remove it ? will it cause any damage to my engine ? Has anyone else tried it yet ?
Gary
After watching the recent rallying and hearing all those chirping noises the rally cars make between gear changes etc, I thought I would like that sound myself
So the question is, where is my dump valve ? can I remove it ? will it cause any damage to my engine ? Has anyone else tried it yet ?
Gary
05 January 2001, 12:58 AM
#2
Scooby Regular
Join Date: Aug 2000
Posts: 616
Likes: 0
Received 0 Likes
on
0 Posts
just remove the hose from the dump valve to the air box, then plug the whole in the side of the air box, this will then release the air to atmosphere giving you that woooshing sound you desire, it cant hurt the engine as its only "waste" air
05 January 2001, 01:34 PM
#3
Scooby Regular
Join Date: Dec 2000
Location: Gosport, near Portsmouth
Posts: 641
Likes: 0
Received 0 Likes
on
0 Posts
Gary,
The chirping noise isn't from the dump valve, It's from the actuator. Dump valve makes the wooshing sound (like airbrakes on a bus!) when you change gear. I found I could hear nice chirping sounds from the actuator after I had a Blitz induction kit fitted.
Karlos
The chirping noise isn't from the dump valve, It's from the actuator. Dump valve makes the wooshing sound (like airbrakes on a bus!) when you change gear. I found I could hear nice chirping sounds from the actuator after I had a Blitz induction kit fitted.
Karlos
06 January 2001, 01:15 AM
#4
Scooby Regular
Join Date: Sep 2000
Location: Notts, UK
Posts: 4,935
Likes: 0
Received 0 Likes
on
0 Posts
Gary,
The noise you hear on WRC cars is wastegate chatter. As they have no dump valve the wastegate opens to control boost when the driver lifts off.
You may get some of this sound by removing the dump valve but no where near the WRC cars which are using 35psi boost at 4000rpm compared to your 12 psi(ish) at 6000rpm. They also have antilag.
You will also put severe strain on your turbo as the dump valve's main function is to protect the turbo when you lift off.
Some of the RS boys run large boost with no BOV, have a listen to Dingy's MK2 Escort, but they run hybrid turbo's with 360 degree thrust bearings. I wouldn't try it on a standard Impreza.
Richbay,
Removing the standard dumpvalve hose from the airbox is not a good idea. The air that is returned when the dumpvalve "dumps" is measured by the airflow meter. Removing the hose confuses the ECU and you will experience fueling problems. When fitting an atmo type dumpvalve you need to make sure its designed for fitting on cars with this arrangement.
Lee
[This message has been edited by logiclee (edited 06 January 2001).]
The noise you hear on WRC cars is wastegate chatter. As they have no dump valve the wastegate opens to control boost when the driver lifts off.
You may get some of this sound by removing the dump valve but no where near the WRC cars which are using 35psi boost at 4000rpm compared to your 12 psi(ish) at 6000rpm. They also have antilag.
You will also put severe strain on your turbo as the dump valve's main function is to protect the turbo when you lift off.
Some of the RS boys run large boost with no BOV, have a listen to Dingy's MK2 Escort, but they run hybrid turbo's with 360 degree thrust bearings. I wouldn't try it on a standard Impreza.
Richbay,
Removing the standard dumpvalve hose from the airbox is not a good idea. The air that is returned when the dumpvalve "dumps" is measured by the airflow meter. Removing the hose confuses the ECU and you will experience fueling problems. When fitting an atmo type dumpvalve you need to make sure its designed for fitting on cars with this arrangement.
Lee
[This message has been edited by logiclee (edited 06 January 2001).]
06 January 2001, 06:28 PM
#5
Scooby Regular
Thread Starter
Join Date: Jan 2000
Posts: 809
Likes: 0
Received 0 Likes
on
0 Posts
Richbay
I don't want the 'Max Power' sound of a dump to atmosphere type dump valve, definitely not my style.
Karlos
The wastegate makes more of a chattering noise (well I can't hear it on my Impreza but it did on my last car). The actuator opens the wastegate when a pre-determined boost level has been reached, ie when your accelerating hard - not when you lift off.
I think the wastegate is on the other side of the turbo (ie exhaust gases not inlet air)
The noise I'm thinking of is a chirp - like a bird chirping.
LogicLee
I thought the noise was the air escaping back the wrong way through the turbo's impeller (as you've lifted of the pressure goes negative so the air has nowhere to go except back through the turbo the wrong way).
Yes there is more stress on the turbine blades as the turbo is being 'braked' (slowed down) by the air now going the wrong way.
I hadn't thought about the 360 deg thrust bearing (or even roller bearing) thing, as I thought the real stress would be on the impeller blades. I didn't think it would be a big deal as some turbo cars don't have a dump valve at all at in manufacturers spec (My old RS Turbo for example).
Hmmm still tempted - although it could be a pretty expensive mistake I know.
Gary
[This message has been edited by Gary Foster (edited 06 January 2001).]
I don't want the 'Max Power' sound of a dump to atmosphere type dump valve, definitely not my style.
Karlos
The wastegate makes more of a chattering noise (well I can't hear it on my Impreza but it did on my last car). The actuator opens the wastegate when a pre-determined boost level has been reached, ie when your accelerating hard - not when you lift off.
I think the wastegate is on the other side of the turbo (ie exhaust gases not inlet air)
The noise I'm thinking of is a chirp - like a bird chirping.
LogicLee
I thought the noise was the air escaping back the wrong way through the turbo's impeller (as you've lifted of the pressure goes negative so the air has nowhere to go except back through the turbo the wrong way).
Yes there is more stress on the turbine blades as the turbo is being 'braked' (slowed down) by the air now going the wrong way.
I hadn't thought about the 360 deg thrust bearing (or even roller bearing) thing, as I thought the real stress would be on the impeller blades. I didn't think it would be a big deal as some turbo cars don't have a dump valve at all at in manufacturers spec (My old RS Turbo for example).
Hmmm still tempted - although it could be a pretty expensive mistake I know.
Gary
[This message has been edited by Gary Foster (edited 06 January 2001).]
07 January 2001, 12:52 PM
#7
Scooby Regular
Join Date: Sep 2000
Location: Notts, UK
Posts: 4,935
Likes: 0
Received 0 Likes
on
0 Posts
Gary,
I still believe the WRC noise is wastegate chatter, even though they have lifted off the antilag keeps the turbo pressurized so there is no reverse flow just the actuator and wastegate controlling the boost. Don't forget with antilag full boost is maintained with the throttle fully closed.
Craig H had a horror story of shattered impellers due to BOV removal and you are right in saying the impellers would take the brunt of the abuse. John Felstead posted a full explanation of the whole thing but I can't find it. Be great when the search is back.
Lee
I still believe the WRC noise is wastegate chatter, even though they have lifted off the antilag keeps the turbo pressurized so there is no reverse flow just the actuator and wastegate controlling the boost. Don't forget with antilag full boost is maintained with the throttle fully closed.
Craig H had a horror story of shattered impellers due to BOV removal and you are right in saying the impellers would take the brunt of the abuse. John Felstead posted a full explanation of the whole thing but I can't find it. Be great when the search is back.
Lee
Trending Topics
07 January 2001, 03:33 PM
#8
Scooby Regular
Thread Starter
Join Date: Jan 2000
Posts: 809
Likes: 0
Received 0 Likes
on
0 Posts
Who need search when you've got EvilBevel around eh ? cheers for that, I sort of understand now
LogicLee
It appears you are correct, hell I'm always spouting of bull**** anyway everyone should be used to this by now
Ps I don't think ALS has anything to do with the noise, funnily enought it was an Mpeg of Mr Felsteads car on a track where I first noticed the noise (he hasn't got ALS). I only mentioned WRC as more people have heard it with them.
Ps I am now armed with the knowledge, just waiting for my Warranty to expire and I'll get the spanners out.
LogicLee
It appears you are correct, hell I'm always spouting of bull**** anyway everyone should be used to this by now
Ps I don't think ALS has anything to do with the noise, funnily enought it was an Mpeg of Mr Felsteads car on a track where I first noticed the noise (he hasn't got ALS). I only mentioned WRC as more people have heard it with them.
Ps I am now armed with the knowledge, just waiting for my Warranty to expire and I'll get the spanners out.
08 January 2001, 01:29 PM
#10
Scooby Regular
Join Date: Aug 2000
Posts: 616
Likes: 0
Received 0 Likes
on
0 Posts
logiclee, i have contacted bailey motorsport, who make a dump valve for the impreza, they state that fitting a dump valve, i.e returning the air to atmosphere rather than the airbox will have no effect on the ecu at all, so i can only assume removing the hose from the airbox and plugging the airbox, will have the same effect. but i would be interested to know if anyone has had any problems when using a after market dump valve
cheers
Rich
cheers
Rich
08 January 2001, 02:50 PM
#11
Scooby Regular
Join Date: Sep 2000
Location: Notts, UK
Posts: 4,935
Likes: 0
Received 0 Likes
on
0 Posts
Richbay,
Where is the search when you need it?
The atmo dump valves for the scoob are set so that at a certain pressure they stop/start dumping, normal atmo valves dump everything. You can buy atmo valves for use before or after airflow meter. If a standard type atmo valve is fitted (ie same as removing hose from airbox) then fueling problems will occur.
I don't know all the techy stuff but its been well discussed on this board.
Cheers
Lee
Where is the search when you need it?
The atmo dump valves for the scoob are set so that at a certain pressure they stop/start dumping, normal atmo valves dump everything. You can buy atmo valves for use before or after airflow meter. If a standard type atmo valve is fitted (ie same as removing hose from airbox) then fueling problems will occur.
I don't know all the techy stuff but its been well discussed on this board.
Cheers
Lee
08 January 2001, 03:51 PM
#12
Scooby Senior
Join Date: Oct 2000
Location: Zurich, Switzerland
Posts: 3,105
Likes: 0
Received 0 Likes
on
0 Posts
Maybe you'll get flames from the back though?!
Not really a good thing (imho) - if your ecu meters air and your dump valve then doesn't recirculate it, ecu fuels for original amount.
Richard
Not really a good thing (imho) - if your ecu meters air and your dump valve then doesn't recirculate it, ecu fuels for original amount.
Richard
08 January 2001, 05:57 PM
#13
Scooby Regular
Join Date: Oct 1999
Posts: 3,491
Likes: 0
Received 0 Likes
on
0 Posts
Dowser, that is correct. But when I presented this to the guy that works on our cars, he said :"OK, but since you are off throttle anyway when the dump valve activates, there seems to be no harm".
I do know from some people that you indeed could get a bit of "afterburn" effect with the vent to atmo though.
I do know from some people that you indeed could get a bit of "afterburn" effect with the vent to atmo though.
09 January 2001, 07:17 AM
#14
Scooby Senior
Join Date: Oct 2000
Location: Zurich, Switzerland
Posts: 3,105
Likes: 0
Received 0 Likes
on
0 Posts
Evil - know what you mean, but doesn't it depend where the unburnt fuel ignites? Wouldn't want it happening any where near my turbo impeller blades, thanks
Mute point for me anyway - the average Swiss would report you to the police (or fire service!) as soon as they saw a flame......it's bad enough with just a Prodrive backbox on full chat overtaking maneouvres!
ScoobyMike would probably take the risk
Richard
Mute point for me anyway - the average Swiss would report you to the police (or fire service!) as soon as they saw a flame......it's bad enough with just a Prodrive backbox on full chat overtaking maneouvres!
ScoobyMike would probably take the risk
Richard
Thread
Thread Starter
Forum
Replies
Last Post
shorty87
Full Cars Breaking For Spares
19
22 December 2015 11:59 AM
