DUMP VALVES, BLOW-OFF VALVES - OFFICIAL THREAD
24 July 2013, 12:35 PM
#1
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Thread Starter
DUMP VALVES, BLOW-OFF VALVES - OFFICIAL THREAD
Mods can you PLEASE make this a sticky.
Many new owners of Subarus appear to have a somewhat misguided belief that the first port of call for a standard car when tuning should be to uprate the standard-fit recirculating valve on their car for significant performance gain, or at least a desirable gain in performance dynamic.
I am hoping that this thread can stimulate discussion that can answer most common questions and anyone can ask whatever they want so that this can provide as many answers as possible, without risk of feeling castigated for doing so.
Ultimately it is not wrong to fit one as most of us need something where a valve should sit, but there may be issues associated with running them that need to be understood.
I intend for this post to act as a resource for people coming onto our forums seeking advice on the issue, and allow them to read the below to make their own mind up on them. We therefore want
* technical information
(car, modifications, intended use, type of dump valve fitted)
* examples/experiences;
(data if possible, type of valve e.g. VTA or recirc, other options e.g. Syvecs and no valve, mafless setup with VTA)
* subjectivity er.... personal points of view
(It felt better, it felt worse, I felt no difference, it sounds awesome, it sounds lame)
I do not intend for this post to descend into a belligerent flaming war between misguided newbies, experienced Scoobynetters and many of us inbetween. It is for us to put our opinions up, discuss the possible or proven gains and advantages and then let people make their own mind up.
Before I summarise the points so far I will enlighten the layman on the types of setup possible.
Firstly there is a recirculating type valve. Built up pressure is recirculated into the system. The Subaru engine is fitted with one of these as standard.
There is also a vent to atmosphere part, or VTA. Built up pressure is released into the air and out of the system. These are quite controversial devices!
There are hybrid valves which try to do both.
Some people advocate the use of a system that does away with them completely. This is used on high performance Subaru engines in Motorsport e.g. WRC. Some cars may use recirculating valves in competition but the days where this is common practice at the highest level is over.
As this thread has progressed we have learned the following, assuming your car is manufacturer standard, largely standard or running under 25psi
Dump valves are a controversial subject. Some people love them and some people really hate them.
Upgrading or changing them leads to NO DISCERNIBLE performance gain at best, but can lead to a performance deficit.
The OEM recirculating valve is perfectly adequate for the task it was designed for.
However the OEM valve is a mass-produced part and there may be an occasional issue with this item failing. Failure of the OEM valve would appear to be rare but typically involves leaking or the spring failure.
Some aftermarket recirculating valves are of high quality and preferable to the OEM valve for this reason alone. We have had recommendation from an engine builder on this forum that the Forge Recirculating BOV set to the correct spring strength is a high quality unit, and I have experience of running GFB recirculating BOVs without issue.
For high end builds running higher pressures the owner and engine builder may choose a recirculating valve with stronger springs provided they wish to keep a dump valve in the system. This is not for performance gain.
If you replace the OEM recirculating part with an aftermarket part it may need remapping and will almost certainly need to if it is VTA. However if the recirculating valve performs the same function as the one it is replacing then there is not really much chance of the need for a remap.
No one has argued in favour of the use of VTA or hybrid valves. It is believed that running these parts can cause issues with mass air flow (MAF) among others, and that as a consequence of this may lead to serious issues associated with over-fuelling.
VTA can be used with a remap, preferably as part of a MAF-less setup but there is no associated performance gain from doing this. It would appear to just make some noise.
If you insist on a dump valve it is best to go for a recirculating type from a well-respected manufacturer.
Ensure that your uprated dump valve has the correct settings to deal with the application it is intended for.
Though some performance cars (Subarus) used in competition may run a dump valve either OEM or aftermarket, the serious machinery actually makes do without one and runs a MAF-less setup. This creates the modern rally car noise where it chatters.
Some of us think that loud dump valves are antisocial and not really part of the image we wish to convey.
Some of us think that they sound cool and make the car sound faster.
A few still maintain that running one of these devices is vastly preferable to the standard option and is associated with performance gain.
If anyone's got any more questions fire away
From experience I have the following to add:
I currently run a GFB TMS Respons BOV on my Cosworth STi. It is set to fully recirculate and is intended for use as a high quality replacement for the stock valve and piece of engine bay bling.
I previously ran a GFB adjustable BOV on my '05 STi PPP and had no issues in terms of running when set to fully RC. However it would nearly stall in neutral when set to full VTA and ran dog rough most of the way toward RC. I did not like the noise and therefore ran it as quiet as possible without the trumpet.
I test drove an RB320 that had been fitted with a VTA system by a well known major supplier of these parts. The car did not feel right inbetween shifts and I requested the dealer to fit a normal part and took it out again. The issue was no longer present after the swap.
Many new owners of Subarus appear to have a somewhat misguided belief that the first port of call for a standard car when tuning should be to uprate the standard-fit recirculating valve on their car for significant performance gain, or at least a desirable gain in performance dynamic.
I am hoping that this thread can stimulate discussion that can answer most common questions and anyone can ask whatever they want so that this can provide as many answers as possible, without risk of feeling castigated for doing so.
Ultimately it is not wrong to fit one as most of us need something where a valve should sit, but there may be issues associated with running them that need to be understood.
I intend for this post to act as a resource for people coming onto our forums seeking advice on the issue, and allow them to read the below to make their own mind up on them. We therefore want
* technical information
(car, modifications, intended use, type of dump valve fitted)
* examples/experiences;
(data if possible, type of valve e.g. VTA or recirc, other options e.g. Syvecs and no valve, mafless setup with VTA)
* subjectivity er.... personal points of view
(It felt better, it felt worse, I felt no difference, it sounds awesome, it sounds lame)
I do not intend for this post to descend into a belligerent flaming war between misguided newbies, experienced Scoobynetters and many of us inbetween. It is for us to put our opinions up, discuss the possible or proven gains and advantages and then let people make their own mind up.
Before I summarise the points so far I will enlighten the layman on the types of setup possible.
Firstly there is a recirculating type valve. Built up pressure is recirculated into the system. The Subaru engine is fitted with one of these as standard.
There is also a vent to atmosphere part, or VTA. Built up pressure is released into the air and out of the system. These are quite controversial devices!
There are hybrid valves which try to do both.
Some people advocate the use of a system that does away with them completely. This is used on high performance Subaru engines in Motorsport e.g. WRC. Some cars may use recirculating valves in competition but the days where this is common practice at the highest level is over.
As this thread has progressed we have learned the following, assuming your car is manufacturer standard, largely standard or running under 25psi
Dump valves are a controversial subject. Some people love them and some people really hate them.
Upgrading or changing them leads to NO DISCERNIBLE performance gain at best, but can lead to a performance deficit.
The OEM recirculating valve is perfectly adequate for the task it was designed for.
However the OEM valve is a mass-produced part and there may be an occasional issue with this item failing. Failure of the OEM valve would appear to be rare but typically involves leaking or the spring failure.
Some aftermarket recirculating valves are of high quality and preferable to the OEM valve for this reason alone. We have had recommendation from an engine builder on this forum that the Forge Recirculating BOV set to the correct spring strength is a high quality unit, and I have experience of running GFB recirculating BOVs without issue.
For high end builds running higher pressures the owner and engine builder may choose a recirculating valve with stronger springs provided they wish to keep a dump valve in the system. This is not for performance gain.
If you replace the OEM recirculating part with an aftermarket part it may need remapping and will almost certainly need to if it is VTA. However if the recirculating valve performs the same function as the one it is replacing then there is not really much chance of the need for a remap.
No one has argued in favour of the use of VTA or hybrid valves. It is believed that running these parts can cause issues with mass air flow (MAF) among others, and that as a consequence of this may lead to serious issues associated with over-fuelling.
VTA can be used with a remap, preferably as part of a MAF-less setup but there is no associated performance gain from doing this. It would appear to just make some noise.
If you insist on a dump valve it is best to go for a recirculating type from a well-respected manufacturer.
Ensure that your uprated dump valve has the correct settings to deal with the application it is intended for.
Though some performance cars (Subarus) used in competition may run a dump valve either OEM or aftermarket, the serious machinery actually makes do without one and runs a MAF-less setup. This creates the modern rally car noise where it chatters.
Some of us think that loud dump valves are antisocial and not really part of the image we wish to convey.
Some of us think that they sound cool and make the car sound faster.
A few still maintain that running one of these devices is vastly preferable to the standard option and is associated with performance gain.
If anyone's got any more questions fire away
From experience I have the following to add:
I currently run a GFB TMS Respons BOV on my Cosworth STi. It is set to fully recirculate and is intended for use as a high quality replacement for the stock valve and piece of engine bay bling.
I previously ran a GFB adjustable BOV on my '05 STi PPP and had no issues in terms of running when set to fully RC. However it would nearly stall in neutral when set to full VTA and ran dog rough most of the way toward RC. I did not like the noise and therefore ran it as quiet as possible without the trumpet.
I test drove an RB320 that had been fitted with a VTA system by a well known major supplier of these parts. The car did not feel right inbetween shifts and I requested the dealer to fit a normal part and took it out again. The issue was no longer present after the swap.
Last edited by thenewgalaxy; 08 August 2013 at 04:10 PM. Reason: [5th Edit] Editing with information as the knowledge progresses
24 July 2013, 12:44 PM
#3
Scooby Regular
while i agree there's not alot, if any performance gain, they dont always cause problems. So you can't just blanket say oem recirc is best.
Running without isn't all its cracked up to be, to get any gains you have to very very agressive with gear changes, not to mention it puts a hell of alot of pressure on the turbo and other components, thats why most are rebuild after every event.
Alot of what you have said looks like your opinion to me, unless you've got data to back it up?
Running without isn't all its cracked up to be, to get any gains you have to very very agressive with gear changes, not to mention it puts a hell of alot of pressure on the turbo and other components, thats why most are rebuild after every event.
Alot of what you have said looks like your opinion to me, unless you've got data to back it up?
24 July 2013, 12:47 PM
#4
while i agree there's not alot, if any performance gain, they dont always cause problems. So you can't just blanket say oem recirc is best.
Running without isn't all its cracked up to be, to get any gains you have to very very agressive with gear changes, not to mention it puts a hell of alot of pressure on the turbo and other components, thats why most are rebuild after every event.
Alot of what you have said looks like your opinion to me, unless you've got data to back it up?
Running without isn't all its cracked up to be, to get any gains you have to very very agressive with gear changes, not to mention it puts a hell of alot of pressure on the turbo and other components, thats why most are rebuild after every event.
Alot of what you have said looks like your opinion to me, unless you've got data to back it up?
Dont get me wrong i think a sticky is the way forward....
24 July 2013, 12:51 PM
#5
Scooby Regular
It's another long debated subject simply becuase there is no hard and fast rule for it. a sticky thread will just be one long argument so not worth the hassel
Some cars do run fnny when they switch to vta
some cars run fine when they switch to vta
Some people like the sound
some people dont like the sound
people tend to get very anti something they dont like, most of the threds about them 1/2 the posts are 'sounds crap, don't'
24 July 2013, 01:00 PM
#6
Sticky this from "Enginemappers tuning guide". Least this way it takes into account the trouble they can cause.
Dump Valves and Blow off valves
These are fitted purely to redirect the turbo pressure which builds up in the intake system, post turbo, pre-throttle plate when the throttle is closed quickly, i.e when you lift off. In all of the production based vehicles with MAF sensors reading ECU load it is highly likely that any dump valve will be of the recirculating type.
Meaning the air pressure built post turbo, pre-throttle will be dumped back into the turbo inlet side, post MAF. This is a key point to note regarding what dump valve you choose and why.
On a MAF system, all the air that enters the engine will travel through the MAF to be measured for the engine management to work out how much fuel is needed for the combustion process. When you lift off and the pressurised air back up against the back of the throttle plate, the dump valve, (on a standard recirculating system), will dump it back into the intake system, so the same total volume of air that the MAF has measured remains within the system and will still be consumed by the engine.
Fitting an externally venting dump valve, or a vent to atmosphere, (VTA), valve will cause a number of problems when you lift off and general engine running, as that dumped air has been measured by the MAF, but is then not used by the engine, although it expects it.
The other main issue regarding externally venting dump-valves and MAF sensors, is that the dumpvalve will always open under vacuum, i.e when not is boost, (positive pressure).
This means that on idle and cruise, an external venting dump valve will always be letting in extra air post MAF, (essentially an air leak). This means that initially it will run leaner than it should until the ECU learns some corrections, (standard ECUs only). This problem is not applicable when running a mafless ECU, like a Simtek, Syvecs, Link etc.
My advice; on a standard ECU stick with a recirculating dump valve for drive-ability and general integrity of the engine management control systems.
As said before, if you are running mafless, then running an external dump valve won’t matter or not.
Dump Valves and Blow off valves
These are fitted purely to redirect the turbo pressure which builds up in the intake system, post turbo, pre-throttle plate when the throttle is closed quickly, i.e when you lift off. In all of the production based vehicles with MAF sensors reading ECU load it is highly likely that any dump valve will be of the recirculating type.
Meaning the air pressure built post turbo, pre-throttle will be dumped back into the turbo inlet side, post MAF. This is a key point to note regarding what dump valve you choose and why.
On a MAF system, all the air that enters the engine will travel through the MAF to be measured for the engine management to work out how much fuel is needed for the combustion process. When you lift off and the pressurised air back up against the back of the throttle plate, the dump valve, (on a standard recirculating system), will dump it back into the intake system, so the same total volume of air that the MAF has measured remains within the system and will still be consumed by the engine.
Fitting an externally venting dump valve, or a vent to atmosphere, (VTA), valve will cause a number of problems when you lift off and general engine running, as that dumped air has been measured by the MAF, but is then not used by the engine, although it expects it.
The other main issue regarding externally venting dump-valves and MAF sensors, is that the dumpvalve will always open under vacuum, i.e when not is boost, (positive pressure).
This means that on idle and cruise, an external venting dump valve will always be letting in extra air post MAF, (essentially an air leak). This means that initially it will run leaner than it should until the ECU learns some corrections, (standard ECUs only). This problem is not applicable when running a mafless ECU, like a Simtek, Syvecs, Link etc.
My advice; on a standard ECU stick with a recirculating dump valve for drive-ability and general integrity of the engine management control systems.
As said before, if you are running mafless, then running an external dump valve won’t matter or not.
24 July 2013, 01:04 PM
#7
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Not categorically you can't, as there will always be exceptions to that rule...but generally you can; if they were the best option Subaru would have fitted them as OE or at the very least offered them as an option.
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24 July 2013, 01:05 PM
#8
Scooby Regular
There's certain things in that guide that i dont agree with. The other thing is were not talking on boost when the air volume is high, its when the turbo drops down and stops producing so much boost, so the actualy volume of air isn't huge.
24 July 2013, 01:07 PM
#10
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You can't say that just because a manufacturer doesn't supply it it must be bad.
24 July 2013, 01:09 PM
#11
Scooby Regular
hmmmm, lol
If its the doc im thinking of im pretty sure my old car produced more power than that doc says is possible on the injectors I had
24 July 2013, 01:11 PM
#13
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I knew you would ask me that question without thinking it through...think about the cost of the examples you cite above, especially compared to a VTA BOV. Still want to ask that question?
24 July 2013, 01:17 PM
#15
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"Upgrading or changing them leads to NO DISCERNIBLE performance gain at best, but is more likely to cause a performance DEFECIT. The best you can hope for is a "psssshhht" noise inbetween gear changes.
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
Many aftermarket dump valves do not recirculate and instead vent built up pressure to the air, e.g. Vent to Atmosphere or VTA. It is argued that releasing this pressure is easier on the turbo but many of us feel that this can cause issues with over-fuelling and the MAF. From experience, running a dump valve on VTA causes quite an apparent lag inbetween gear changes (as the boost has to build again).
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
If you insist on a dump valve it is best to go for a recirculating type from a well-respected manufacturer and opt for a recirculating option.
Though some performance cars (Subarus) used in competition may run a dump valve either OEM or aftermarket, the serious machinery actually makes do without one and runs a MAF-less setup. This creates the modern rally car noise where it chatters."
24 July 2013, 01:27 PM
#16
Scooby Regular
which part Shaun?
"Upgrading or changing them leads to NO DISCERNIBLE performance gain at best, but is more likely to cause a performance DEFECIT. The best you can hope for is a "psssshhht" noise inbetween gear changes.
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
Many aftermarket dump valves do not recirculate and instead vent built up pressure to the air, e.g. Vent to Atmosphere or VTA. It is argued that releasing this pressure is easier on the turbo but many of us feel that this can cause issues with over-fuelling and the MAF. From experience, running a dump valve on VTA causes quite an apparent lag inbetween gear changes (as the boost has to build again).
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
If you insist on a dump valve it is best to go for a recirculating type from a well-respected manufacturer and opt for a recirculating option.
Though some performance cars (Subarus) used in competition may run a dump valve either OEM or aftermarket, the serious machinery actually makes do without one and runs a MAF-less setup. This creates the modern rally car noise where it chatters."
"Upgrading or changing them leads to NO DISCERNIBLE performance gain at best, but is more likely to cause a performance DEFECIT. The best you can hope for is a "psssshhht" noise inbetween gear changes.
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
Many aftermarket dump valves do not recirculate and instead vent built up pressure to the air, e.g. Vent to Atmosphere or VTA. It is argued that releasing this pressure is easier on the turbo but many of us feel that this can cause issues with over-fuelling and the MAF. From experience, running a dump valve on VTA causes quite an apparent lag inbetween gear changes (as the boost has to build again).
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
If you insist on a dump valve it is best to go for a recirculating type from a well-respected manufacturer and opt for a recirculating option.
Though some performance cars (Subarus) used in competition may run a dump valve either OEM or aftermarket, the serious machinery actually makes do without one and runs a MAF-less setup. This creates the modern rally car noise where it chatters."
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
24 July 2013, 01:31 PM
#17
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Upgrading or changing them leads to NO DISCERNIBLE performance gain at best, but is more likely to cause a performance DEFECIT. The best you can hope for is a "psssshhht" noise inbetween gear changes.
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
Last edited by trails; 24 July 2013 at 01:33 PM.
24 July 2013, 01:52 PM
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Upgrading or changing them leads to NO DISCERNIBLE performance gain at best, but is more likely to cause a performance DEFECIT. The best you can hope for is a "psssshhht" noise inbetween gear changes.
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
Loud dump valves are antisocial and not part of the image most of us as enthusiasts wish to be associated with.
The OEM recirculating valve is best. It is what your car engine is mapped to deal with and what the engine is designed to be used with.
If you replace the OEM one with an aftermarket part it will most likely need remapping especially if it is VTA.
Never seen a proven measured improvement to perfomance post VTA BOV fitting...a link would make for interesting reading.
Give you the second point, not my cup of tea but that is personal opinion
The OE recirc is the most appropriate option for the standard engine, particularly when you consider the OE ECU uses a MAF not a MAP sensor.
Not sure why you would want a remap after just installing a BOV though.
24 July 2013, 02:28 PM
#21
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Thread Starter
Without trying to influence the discussion and from a point of view only as an anecdotal opinion based on experience, I ran a GFB adjustable valve on my 05 Blob PPP. I removed the trumpet as it sounded ridiculous but didn't notice any performance gains or problems with it on full recirc (which the manufacturer claims was the same as OEM) yet it ran like a dog between gear changes on anything inbetween that and full VTA (as well as making a massive hiss even when changing up at 3500 rpm as I was generally driving normally).
I have also driven an RB320 with a forge VTA fitted, I thought there was something wrong with the car. I asked the dealer to fit the OEM one as I was actually going to buy the car (but didn't) and it ran fine.
I have not felt the need to add one to my current car.
For the record, I quite like a small hiss to remind me that I have an aggressive car but I have one from my air intake system that only comes when I'm pressing.
And yes people get very anti things they don't like. This is the Internet.
Someone has mentioned figures, I can provide none. Surely if there was a benefit to running these devices there would be many branded about by manufacturers. I would be grateful if anyone could point us in the right direction.
Last edited by thenewgalaxy; 24 July 2013 at 02:29 PM. Reason: Autocorrect nightmare, thinking of turning it off.
24 July 2013, 02:33 PM
#22
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Shaun your tone is somewhat troll-esque. For the benefit of this thread can you provide a reasoned and balanced explanation of why you disagree with the Enginetuner and my summary of a quite ridiculous number of threads on this subject?
Someone has mentioned figures, I can provide none. Surely if there was a benefit to running these devices there would be many branded about by manufacturers. I would be grateful if anyone could point us in the right direction.
Someone has mentioned figures, I can provide none. Surely if there was a benefit to running these devices there would be many branded about by manufacturers. I would be grateful if anyone could point us in the right direction.
24 July 2013, 03:02 PM
#23
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I have grown out of chav valves in my old old age and except for the blob, all the other cars run recirc.
My question is, for those recommending using OE, have any of you researched that PSI the OE valve is rated to hold? All well and good saying "stick with OE recirc" but if you have upped the boost past a certain point, will the OE valve hold it on max boost????
My question is, for those recommending using OE, have any of you researched that PSI the OE valve is rated to hold? All well and good saying "stick with OE recirc" but if you have upped the boost past a certain point, will the OE valve hold it on max boost????
24 July 2013, 03:17 PM
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I have grown out of chav valves in my old old age and except for the blob, all the other cars run recirc.
My question is, for those recommending using OE, have any of you researched that PSI the OE valve is rated to hold? All well and good saying "stick with OE recirc" but if you have upped the boost past a certain point, will the OE valve hold it on max boost????
My question is, for those recommending using OE, have any of you researched that PSI the OE valve is rated to hold? All well and good saying "stick with OE recirc" but if you have upped the boost past a certain point, will the OE valve hold it on max boost????
OE circa 25psi iirc...and that is more than adequate for the majority of applications as close to 1.6bar.
24 July 2013, 03:24 PM
#26
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Thread Starter
If these things were even slightly beneficial I would have thought a very eager and mod happy bunch would be going mad for these things.
We all put uprated oil caps and branded bits on our cars that do nothing yet there is a wave of general apathy towards the fitment of uprated dump valves.
I would have thought someone with a nice car that is clearly a seriously tuned piece of kit would be able to put across a valid point of view rather than a troll that would be better placed on his "muppet forum". Pleas Shaun, enlighten us.
Excellent point.
So basically we are wondering here on a tuned car if the OEM valve is capable of dealing with the pressures involved and that there may be a limit to what it is capable of?
However how can we be sure that an aftermarket recirc valve is capable of any better? Is this something that is used to market them?
If there is any validity to this point it is worth wondering at what point someone should consider these engine bling and at what point a sensible mod.
For the record I cannot recall the high power Type 20, Type 25 or Cosworth ever being fitted with uprated dump valves but these run pretty standard boost compared to OEM.
We all put uprated oil caps and branded bits on our cars that do nothing yet there is a wave of general apathy towards the fitment of uprated dump valves.
I would have thought someone with a nice car that is clearly a seriously tuned piece of kit would be able to put across a valid point of view rather than a troll that would be better placed on his "muppet forum". Pleas Shaun, enlighten us.
So basically we are wondering here on a tuned car if the OEM valve is capable of dealing with the pressures involved and that there may be a limit to what it is capable of?
However how can we be sure that an aftermarket recirc valve is capable of any better? Is this something that is used to market them?
If there is any validity to this point it is worth wondering at what point someone should consider these engine bling and at what point a sensible mod.
For the record I cannot recall the high power Type 20, Type 25 or Cosworth ever being fitted with uprated dump valves but these run pretty standard boost compared to OEM.
24 July 2013, 03:34 PM
#30
Scooby Regular
Thread Starter