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View Full Version : Dump valve - yes or no?



Danny Boy
27-02-2006, 12:37 PM
Hi all,
I have just come back from a track day at Snetterton and have decided that I need a dump valve for my '97' Leggie VR-4.
I then done a quick search on here for some guidance as to what to go for.... and it seems there is a very mixed response as to whether it is a good idea to stray away from the factory fit.
I'll be totally honest and say that I want it for the whooosh more than for any performance increase, and didnt want to spend too much on it is poss. Your comments would be most appreciated!
Also, I have read that you get the whoosh from the autos when you lift off the throttle..does this work the same when in tiptronic mode, or only if you lift off during gear changes?

Cheers in advance,

Danny

WildCards
27-02-2006, 12:42 PM
See here (http://www.clubvr4.com/forum/showthread.php?t=14359) all the whoosh you could ever need by the sounds of it.

BraindG
27-02-2006, 12:44 PM
Theres always been a debate, the big boys (rocket ron AN-Racing etc) say to use a recycler.. something to do with keeping pressure constant.

But, for the "power" loss factor, its minimal, and the sound is just great :)

Danny Boy
27-02-2006, 01:08 PM
Cheers guys, but dont think I want to go that loud....I want to keep it within the realms of decency!!! lol A relatively quiet (& cheap) dump valve will be fine, but dont want the problems when idling and running 'too rich' that i have read about.

pezza
27-02-2006, 01:43 PM
The hybrid valves are probably the best to go for (or adjustable VTA/recirc). but they are not always cheap, unless you can find one on ebay?

Over the past few months I have switched from stock recirc to evo FQ stock recirc to adjustable ... The best times I achieved, were with the evo recirc valve (which is slightly stronger sprung than the stock VR4 one). My car would reek of fuel when using Fully VTA (with recirc pipe blocked) which I assumed meant rich mixture.

The recirculated air keeps front turbo spinning (which helps pickup in between gear changes reducing lag) and keeps ECU happy reducing idling and mixture issues.

Hope this helps

Danny Boy
27-02-2006, 02:43 PM
Would this work?

http://cgi.ebay.co.uk/Universal-Greddy-Style-Dump-Valve-Blow-Off-valve_W0QQitemZ8040439670QQcategoryZ72205QQrdZ1QQc mdZViewItem

pezza
27-02-2006, 03:40 PM
Would this work?

http://cgi.ebay.co.uk/Universal-Greddy-Style-Dump-Valve-Blow-Off-valve_W0QQitemZ8040439670QQcategoryZ72205QQrdZ1QQc mdZViewItem


It would work but require some adapters to fit the pressure feed 35mm pipe..


The flange connector is the wrong kind of fitment...one as seen here (http://www.clubvr4.com/forum/showpost.php?p=72183&postcount=24) or here (http://www.clubvr4.com/forum/attachment.php?attachmentid=3597&d=1105482551) shows the type of attachment required..

Both of these are hybrid valves..

The first one is a non adjustable hybrid... It sounds good.. ask Jakester on here.. It was bought from ebay for under 50 I believe..

Danny Boy
27-02-2006, 04:08 PM
Sounds good, cheers Pezza....much appreciated

WireD
28-02-2006, 12:28 PM
if you want to go for the expencive stuff, go for this:

Blitz Supersound BOV:

either as a full on open BOV:

http://www.mercurymotorsport.com.au/products/blitz/supersound.jpg

or abit more subtle sound with the filter on it:

http://www.southcoastperformance.com/images/BLITZ%20BOV.jpg

I have this on my 323 F (Astina), and the sound is awesome!


the debate on using recycle/BOV is a well debated topic all round the world.

The difference is minimal.

recycle= keeps the pressure higher than a BOV.

BOV = lets the turbo spinn freely, giving you AWESOME sound, when u go on the throttle again, the turbo allready have a good spin on it, minimalizing lag.

bottomline, minimal difference, the choise is up to you :)

personally, i want the "WWHHHOOOOOsssshhhhhh" :evilgrin:

jakester
01-03-2006, 05:45 PM
It was nice to meet you on Sunday Danny, sorry I didn't get to chat to you more, had I thought about it, I would have taken you out for a few laps.

Danny Boy
03-03-2006, 09:54 PM
No probs Jakester, looked as though you were having fun!!!

Smokinmasta2
12-03-2006, 12:53 PM
It would work but require some adapters to fit the pressure feed 35mm pipe..


The flange connector is the wrong kind of fitment...one as seen here (http://www.clubvr4.com/forum/showpost.php?p=72183&postcount=24) or here (http://www.clubvr4.com/forum/attachment.php?attachmentid=3597&d=1105482551) shows the type of attachment required..

Both of these are hybrid valves..

The first one is a non adjustable hybrid... It sounds good.. ask Jakester on here.. It was bought from ebay for under 50 I believe..


Yes i bought the DV for that car - and only cost £35 (think it was £50 BIN though?) as Jake and Pezza will testify it's quite noisy! (Pez - Japfest 05 ;) )

Wodjno
12-03-2006, 01:17 PM
Money no object this is the 1 for me.. Had it fitted for couple of years now, with No adverse affects.. :happy:

http://www.gfb.com.au/index.php?parentid=products&option=products&sub_option=bovs&sub_sub_option=stealth_fx

As Quiet or as Loud as you like :2thumbsup And all in a Few Seconds..

Smokinmasta2
12-03-2006, 02:54 PM
:2thumbsup its the one i wanted........................however, having looked into the the performance gains or lack of on a std ish car, i found out that fitting one that will do the job well enough; will certainly do!!
Alloy body, brass piston etc etc!!
My advice is to pay what YOU think; just be mindful that spending 200 quid on an HKS one is giving u no more gains than one for 50 quid - other than possibly some longevity?? But most will service fairly easily anyway.............

Danny Boy
14-03-2006, 02:01 PM
Smokin.....did you fit your own DV?

I dont want to spend alot on it, as I am afraid i'll get p**sed off with it after a while, but am really unsure as to what will fit the VR-4, and how I would go about fitting it.

Is it a big job? Where did you get yours done?

WildCards
14-03-2006, 02:03 PM
I has to take my standard one off the other week to repair (with Kierans help) it's very easy, undo Jubilee clips, unbolt and whip it off. As long as the new one goes on in the reverse order you'll be fine.

Wodjno
14-03-2006, 02:07 PM
?

I dont want to spend alot on it, as I am afraid i'll get p**sed off with it after a while

Apart from the Price it sounds like the GFB Stealth is the 1 for you.. :thinking: I do exactly like you say, and get p****d off with it after a while.. But then i close it off just by turning the valve.. Then it's a recirc again.. Couple of weeks or a month down the line if i fancy a bit of noise i just turn the valve and Whooooooooooosh !
Just obviously it ain't cheap /help

pezza
14-03-2006, 02:11 PM
TIs a great bit of kit, there's even an in car electrically controllable version for silly money..


..............if i fancy a bit of noise i just turn the valve and Whooooooooooosh !


Excepts its more of a Pssst on mine that lasts for a fraction of a second /Hissy

Smokinmasta2
14-03-2006, 03:16 PM
Smokin.....did you fit your own DV?

I dont want to spend alot on it, as I am afraid i'll get p**sed off with it after a while, but am really unsure as to what will fit the VR-4, and how I would go about fitting it.

Is it a big job? Where did you get yours done?

Yes m8 - as said piece of wee wee to fit - if you get one, pop around mine and i'll fit it for ya (1/2 half drive to mine) - but give me notice first m8 - Sundays are usually best.

I have adjusted mine this morning (added another couple of washers to the spring!!) it now does not PSCHHHHHHHH quite so readily!!

Danny Boy
14-03-2006, 03:50 PM
Thanks Smokin....will probably do that as long as you dont mind.

Can you post a link to the DV you got for £35....at least i'll know that it fits the VR-4, and not too much of a prob to fit!

Cheers mate - will be in touch..... :2thumbsup

Smokinmasta2
14-03-2006, 11:28 PM
Danny - ive asked the guy if he can get any more of the same type (he's not showing any on current auctions at least ). Will let you know when he replies OK m8?
This is the one i got:
http://img.photobucket.com/albums/v732/Smokinmasta/DSCN1075a.jpg
http://img.photobucket.com/albums/v732/Smokinmasta/DSCN1066.jpg


John

pezza
15-03-2006, 12:48 AM
This is the one i got:
....


*covers ears and runs away* :anxious:

Kenneth
15-03-2006, 01:13 AM
I was recently looking around the net, cant remember what for exactly...

Anyway, I came across an article about dump valves which I thought made a lot of sense.

The gist went like this:
The reason dump valves are used is to drop the pressure in the pipework as fast as possible so that the turbo doesn't feel any deceleration forces from the air pressure stacking on the compressor blades. this not only impacts performance but also stresses the turbo and shortens its life expectancy.

While the benefits of Recirc vs VTA are a moot point, the objective is not; Dump as much pressure as fast as possible.

To do this, you need to have a fair sized opening for the air to escape AND you need it to open easily and quickly when you release the throttle.

because of this, your DV [should] be open at idle and use boost pressure to keep it closed when boosting.

This is interesting, as it poses a couple of issues. One is that if you use VTA you will be taking in air at idle, so you [need] an air filter on your DV outlet.
That is fairly minor in comparison to the fact that if you use VTA along these lines, you just wont be able to use it on an un-modified VR-4 due to the use of a MAF sensor.


Take this info as you will, but I found it worth while thinking about.

Smokinmasta2
15-03-2006, 01:45 AM
Danny - u have PM, ive had a reply back from the guy. Will leave it to you to speak to him now - u have his reply and email on the PM.

Smokin...............

Smokinmasta2
15-03-2006, 01:47 AM
I was recently looking around the net, cant remember what for exactly...

Anyway, I came across an article about dump valves which I thought made a lot of sense.

The gist went like this:
The reason dump valves are used is to drop the pressure in the pipework as fast as possible so that the turbo doesn't feel any deceleration forces from the air pressure stacking on the compressor blades. this not only impacts performance but also stresses the turbo and shortens its life expectancy.

While the benefits of Recirc vs VTA are a moot point, the objective is not; Dump as much pressure as fast as possible.

To do this, you need to have a fair sized opening for the air to escape AND you need it to open easily and quickly when you release the throttle.

because of this, your DV [should] be open at idle and use boost pressure to keep it closed when boosting.

This is interesting, as it poses a couple of issues. One is that if you use VTA you will be taking in air at idle, so you [need] an air filter on your DV outlet.
That is fairly minor in comparison to the fact that if you use VTA along these lines, you just wont be able to use it on an un-modified VR-4 due to the use of a MAF sensor.


Take this info as you will, but I found it worth while thinking about.

It dumps baby - fecking loud too !!

Kenneth
15-03-2006, 02:18 AM
It dumps baby - fecking loud too !!

I am sure it does, but that was not the point of my post. :P

This however, is: how much deceleration force is your turbo subject to in the process of dumping?

My DV is rather loud too, but I can still tell that there is compresor surge happening.

The info was provided as food for thought, not as a challenge to how good or how bad your DV is, or any DV for that matter. There may be those who find it useful, and those that dont care... it doesn't matter, except that the info was actually given rather than withheld.

/addition: how I know I get compressor surge
if you take note of the boost gauge when letting off the gas, you can work out how much manifold pressure you need to dump. if you sit around tho the minimum needed, you will hear it if it is there.
There is some playing to do too, because if you are accelerating sharply you will dump anyway because the turbo is accelerating still as you let off the gas

I could loosen the DV spring to avoid this, but the chance of it being open when I go into vacuum and drawing in crap from the atmosphere (especially with the DV so close to the road!) is just too high.

Dream Weaver
15-03-2006, 01:51 PM
When I frst got my Evo 6, it had a HKS SSQ on it which was novel and fun for about five minutes. Too noisy for me and it atracted the wrong kind of attention - kids with caps on backwards, police etc.

So now I have a Tial dumpvalve which is quiet in normal use but if you boot the car it is a bit noisier but nowhere near as noisy as the HKS.