chrisp

I think you may find that vibrations cause maf failures as well, on the my99-> thin wire mafs. Some of the induction kits have been known to do this.

[Edited by chrisp - 7/6/2003 12:20:39 PM]

janaid

In the context of a Subaru wrx my opinion is you do not need to change the re-circulating dump valve Subaru has already fitted.

In a car which does not have a re-circ dump valve one is required for 2 reasons

1. When you lift of the throttle the inlet butterfly closes, meaning the compressed air from the turbo charger is trapped and this causes the compressor wheel of the turbo to stall.

What this means is that there is more turbo lag as the turbo has to spool up again

2. In the instance above the turbo bearings come under a lot of stress and over a period of time can wear causing turbo to seize.

The standard Subaru dump valve does both the above, as an atmospheric dump valve would.(one that makes the loud noise)
But unlike an atmospheric dump valve it does not waste this compressed air by venting it out, insted it is reuses and dumped air by putting it back into the induction pipe.

If you want the sound of a dump valve, and still want to use the original Subaru set up.
Do the following ,as I am going to do

Fit an MRT inlet plenum pipe and a Blitz metal sus induction kit

1. The mrt inlet plenum pipe gives an increase in induction noise (so the Subaru dump valve can be heard better)
It also increases low end torque and significantly improves high RPM throttle response

2. The blitz dry sus metal induction kit, in my opinion is the best one on the market for the following reasons

1. Its free flow metal mesh design allows a unique induction ROAR to be heard as well as the Subaru dump valve.

2. Many filters on the market have oil on them or need oil,
This oil can go on the MAF sensor and burn. The result of this is the car will run very badly and if you’re running higher boost your going to be in trouble a few miles down the road.

Check out http://www.jap-innovations.co.uk/ for the
MRT inlet plenum pipe £50
Blitz sus induction kit £180

janaid

i meant to say the dump valve prevents the first two problems

wideboyuk

I've heard comments on here before about a VTA screwing up the air/fuel mixing - don't ask me how though!

Bob Rawle

A VTA does affect fueling and can cause cars to jerk, jolt etc, the factory items have very weak springs in them, replacement with an aftermarket recirc offers benefits if exhaust/induction/ecu upgrades are being done specifically in terms of response. They do not increase power though.

bob

image doctor

So basically cars that go Phhhsssst are gay?

ID - Concise.

StickyMicky

yes lol
i fitted a TAS piston alloy recirc one as my standerd plastic one was leaking

its set at 18psi
its good
thats all u need to know
none of this gay "wwwwwwwwwssssssssst" stuff here thanks

Bob Rawle

"I think you may find that vibrations cause maf failures as well, on the my99"

Sorry I consider this a "given" as its been well documented many times on this bbs.

bob

Dan J

All interesting stuff! My MY00 that I've only had a few weeks now came with a Forge VTA dumpvalve and a Ramair induction kit. From reading all the horrors of MAF failures on here I've bought an original Subaru airbox and will be fitting that back on asap with a standard panel filter. With regards to the VTA though I was thinking of getting a standard Subaru dumpvalve back on but was told that the VTA is harmless so may as well leave it on. Reading this thread though it seems that the car may not run quite as well with a VTA on it. To be honest I could live without it sounding like someone's opening a can of coke under my bonnet all the time too! So noises aside and just in terms of how the car runs would you recommend I get the original Subaru part back on there and lose the VTA???

Dan.

Leviathan

Just get a decent forge, or the like, re-circ Dan

sg72

janaid

I have a BLITZ SUS induction kit fitted to mt car with no probs so far.
I used to have a K+N panel vefoe but MAF sensor went faulty and when ECU reset after battery disconnection. ECU couldn't adjust
and caused lean run and quick BLOW UP.

I have BLITZ. TIE WRAPPED to I/C pipework to avoid vibration.

sg72

Forgot to say .

Also have FORGE re circ ( Which you can still hear).

Dan J

Ok thanks for your replies. So you think that swapping the Forge VTA I have is definitely the thing to do but for a Forge re-circ instead of the standard Subaru part??? And reasons why please? Sorry but like I said only had the car a few weeks and it's my first Scoob, still a lot to learn!

One thing I've noticed though is all the one's I test drove in the past had a really noticeable shove when the turbo kicked in but my one doesn't. It speeds up rapidly of course but there's no shove at all just a smooth delivery. Could that be caused by those 2 mods and if I get rid of them should it feel different??? I want that kick in the back!

Thanks, Dan.

Leviathan

Dont get a standard Suburu valve, they're crap.
As Bob said above, they have weak springs in them and arnt upto the job.

beamer

So in your opinion what would be the better DV to buy as I'm thinking of getting one also

nomad

thats not the low down , thats your opinion, very interesting points raised in your low down,
"1. When you lift of the throttle the inlet butterfly closes, meaning the compressed air from the turbo charger is trapped and this causes the compressor wheel of the turbo to stall.

What this means is that there is more turbo lag as the turbo has to spool up again "
i would have thought it was the other way round, if the air is not allowed to escape then most of its still there when you come back on throttle, i would have also thought that when you lift off you are no longer on boost and you are now on vacuum ( vacuum means suction )the air is going the opposite way hence flutter as the air hits the butterfly.
"2. In the instance above the turbo bearings come under a lot of stress and over a period of time can wear causing turbo to seize "
i thought lack of oil caused the turbo to seize, ive seen turbos that have done 120.000 miles still going strong with only slight play fore and aft,
"If you want the sound of a dump valve, and still want to use the original Subaru set up.
Do the following ,as I am going to do

Fit an MRT inlet plenum pipe and a Blitz metal sus induction kit

1. The mrt inlet plenum pipe gives an increase in induction noise (so the Subaru dump valve can be heard better)
It also increases low end torque and significantly improves high RPM throttle response

2. The blitz dry sus metal induction kit, in my opinion is the best one on the market for the following reasons

1. Its free flow metal mesh design allows a unique induction ROAR to be heard as well as the Subaru dump valve.

2. Many filters on the market have oil on them or need oil,
This oil can go on the MAF sensor and burn. The result of this is the car will run very badly and if you’re running higher boost your going to be in trouble a few miles down the road."
surely if you fit an induction kit you are going to drown out the sound of your standard dumpvalve (which you omitted to tell us how to sort out), why lose a perfectly good airbox that subaru spent thousands of pounds to perfect ? does it not rely on cold air supply from outside the hot engine bay ? is the dry sus an enclosed box that wont allow hot engine air into the filter ? (hot air equalls less power) .
the inlet pipe ? is it different diameter ? please tell me how it improves the things you say it does , you make some fantastic claims about increased throttle response at high rpm and lowdown torque, i trust you have your dyno sheet to prove these claims ?cheers nomad ( sees things as they really are)

nomad

"Forgot to say .

Also have FORGE re circ ( Which you can still hear). "
recirculating means all the air should be going back into the turbo inlet pipe, if you can hear something then its not all going back in there, try fitting the original dump valve back on and see if you can still hear something, if not then you have a leak. cheers nomad

Dan J

So what do you run with then Nomad? You on the original Subaru part or have you changed yours and if so for what?

nomad

i do not run a dumpvalve anymore, the reason for this is to improve throttle response whilst changing gear, this is on a T34 fitted to a cosworth, i would have to do some research to see if this can be done a scooby, cheers nomad

WREXY

Just to let you know that MAF failures on MY99/00s are common on cars with the standard airbox as well. My mates, (also a member on here), MAF went on him 3 times. There have been many more with MAF failures on here with the standard setup.

Cheers,

George.

Paul_M

You can hear recirc dump-valves, although nowhere near as loud as VTAs. Depends a lot on the induction setup as well, but basically the air passing through the valve will make a sound it's just that most of it is muffled out. With a "louder" filter setup you're more likely to hear it.

I can hear my OE recirc valve making a slight "psst" noise in some circumstances since fitting an ITG filter cos it lets out more noise - the turbo suction noise when on boost can also be heard more with the ITG. I'd imagine it would be still more audible with something like a blitz stainless cone filter.

Eddoe

I have a MY99 that has just had a MAF failure with the standard setup, the air box has just been replaced with a blitz SUS kit and in my opinion it is superb, and yes i can now hear my standard dump valve! tsssshhhhhh!!

nomad

hmm, its weird how you can now hear the dump valve after fitting a filter, i suppose there's no need to vta it if you can already hear it. interesting point about the dust particles , it would be nice to hear from people who have cleaned them ? does it have a recommended cleaning interval ? does much dust come out ? how do you clean it ? the standard filter is mint but once you use it the filtering degenerates, ideally it would be best to fit new filter after every journey but this is not possible lol, chees nomad

MorayMackenzie

The original blitz SUS filter was not good at filtering dust particles. I am not sure if they have changed the design at all since I had one. Sure, it makes some interesting noises and flows pretty well, but that is because it provides a lower level of filtration then other filters. After using one for a while, I inspected my intake ducting, there was a lot of dust particulate matter stuck to the duct wall. Not good. From then on I have used K+N filters.

As to dump valves: I have tried running the car setup with and without a dump valve. The car is more responsive when running without a dump valve. I don't have a dump valve on my current setup, but I would considering running one set to vent only at boost levels over 1.1 bar or so, if I wished to run significantly more midrange boost than I do now, mostly for peace of mind as I am fairly sure that this turbo is capable of running without one.

doaney

Have Blitz SuS on Stiv5, however I've bolted it down and tie-wrapped it as much as possible to stop any vibrations. With this induction kit fitted event the OE dump value can be damn noisy, however I do not know if my import OE DV is the same as UK ones.
Happy whooooshing !!!

nom

Just my own opinion, but I'd stay well clear of a Blitz filter. They flow very well, yes; that's because they don't bother too much with the 'filtering'... instead of coating the MAF with oil, the dust particles just eat away at it. And the compressor blades. And the engine in general.

[Edited by nom - 7/9/2003 12:44:47 PM]