tinydelete

was thinking of going over to scooby sports to have a forge motorsport vta dump valve fitted love the sound will this cause any harm to my 01 any comments appreciated

thanks darren

planky

Yes No Yes No could be either,its a bit of a hot issue on here.
btw you already have a DV but a quite one

BruceWarne

Make sure you fit one that vents at least some of the air back into the system.

Fitting a vent to atmosphere-only one can lead to problems.
The MAF sees an increase in airflow, fuelling gets adjusted, but the air never gets to the engine (it was lost into the atmosphere, remember). This can cause driveability issues, increased fuel consumption, blah blah blah. It is however only a transient condition, so I wonder what effect it can really have on consumption. I had serious idling problems when I had one of these fitted.

You get nice hybrid ones (vent to atmosphere, and recirculate in one unit)

Dark Blue Mark

Bruce is right, they screw things up and are pointless apart from the noise. I don't see the point in aftermarket re-circs either, unless they make a better noise??

I had one, took it off and got more power on a dyno run.

MB

Pete Croney

Oh dear, this old chesnut again

First, it won't do any harm at all.
Second, if its a good one, it will help you build boost more quickly
Third, it won't make ANY difference to peak power
Forth, you will get exhaust flames if you have a full de-cat
Fifth, by not recirculating hot gas which is full of rebreathed oil vapour, you are less likely to suffer MAF failure.

Oh, nearly forgot, a vent to atmo will keep your turbo speed much higher during gear changes as there is much less resistance for the air which is being vented and so less load on the turbo compressor.

Marc R

Don't know about technical type stuff and won't even try but I have forge VTA on MY97. Sounds excellent which is one of the main reasons I got it (although MY97's are known to have faulty dv's). I have no problems with erratic idling or starting and car runs fine, fitting afr shortly so don't know if fuellings affected much. Very happy with it. When driving softly there is no noise, cruising you see no difference, floor it and let off or change up and big whooooooshhhhhh

Marc

nom

Listen to Pete here. No, there's no power gain. But drive a car with a good DV & then go back to the standard one - there is a very noticeable difference to the actual drive, especially if you play with the gears - it feels (& I think it probably is) much harder to keep the car 'on the boil' with the standard DV over a good aftermarket one. Oddly it even seems to make gear changes quicker...

tinydelete

even more confused, now anyway thanks for all the comments it has helped me out, anyway as i spoke to paul at scoobysports today and they have none in stock anyway at least this gives me another week to ponder!!

Big Goon

I have a SS Forge D/V on my 01, makes no difference to car in most respects other than the PSSSSSST when changing gear.
And if you find you dont like it, they sell like hot cakes 2nd hand and are pish easy to remove/refit old one.

mega_stream

I agree that its when you take a VTA valve DV off you notice a change in gear change oompff, I was running a forge for a bit, took it off and there's some lag now that wasn't there before.

Can't say it made mine run bad or increase the comsumption though.
I always get 100 miles on £20 of Optimax.

Dark Blue Mark

Pete, I agree that it will help bring boost quicker on gear changes but it is undeniable they **** the idling up on many cars.

Ok, it won't do any harm but I personally don't like them. Apart from the noise and flames!

Will they really make any difference to a non modified car? I imagine you could justify it if you were running high boost etc. Also, ive always wondered what the point of a non standard recirc dv is? Is it just for noise or is there a capacity issue?

Advice appreciated.

Don't want any B/S either - im a mechanical engineer...


MB

chrisp

Just one question then if they are so much better and have less wear and tear on the turbo and the car then surely Subaru would fit them as standard or offer them as part of the PPP wouldnt they ???

planky

Atmo DV are to noisy,that why Subaru dont fit them.

[Edited by planky - 6/15/2002 11:05:54 PM]

Jamie Whitfield

I am in total agreeance with Pete, as good dump valve will keep the turbo on the boil and that is the reason I have just fitted a Blitz SSDV to mine. Makes no difference on power, and sounds like a bus door, but I love it!

Also it must be noted that I have no idling issues, although the car is running richer and probably using more Optimax.

Jamie

www.j-w-racing.com

StanS

iTrader: (3)

SS fitted a VTA Forge d/valve yesterday and it has made a noticeable difference to the performance - far better going up through the gears to the extent I gave a biker a shock from the traffic lights (he was still a couple of car lengths infront at 70 - doh!) - but slightly noisier (only just audible "chatter" over the SS exhaust system). Can't wait to drive it again.
Maybe the difference is more noticeable if you are running higher boost (peaking about 20-21psi on Optimax + Proboost).
Thoroughly recommend it. No difference to idle speed. Not noticed any flames yet though.
Stan
(editted to say UK98)

[Edited by StanS - 6/16/2002 11:52:33 AM]

Shorla

Not one to stir it up or keep an argument going but I sopke to Graham Goode and they said the forge dump valve will damage your engine over time. My '96 Sti has big iddling probs with it but it sounds the best so who cares.

planky

He would say that he ONLY sells GGR ones but im shocked he said they damage engines!!!!!!.
If you buy ANY double piston Dv you should have NO engine or idle probs.

P1Fanatic

Pete - do Scoobysport have one on a demo car as Id have to hear one in the flesh before buying?

Simon

BruceWarne

It would probably only make a difference to older <96 cars, they had very small DV, and actually benefitted from aftermarket ones.

Other than that, they do sound nice, but if you think they have any advantage over OE, you're fooling yourself.

As far as fouling the MAF sensor is concerned...last time I checked there was nothing before the MAF sensor other than my air-filter...and the BOV opens on a vacume (manifold pressure <0)...so how any oil could end up on the MAF sensor,pointing away from the engine that is sucking in contaminated air from behind it, is beyond me.

nom

They DO make a difference, only one that involves driving rather than looking at graphs.
Honestly

BruceWarne

Delta Dash should be able to pick it up.
Plot MAP vs Time.

Pete Croney

Bruce

My comment on MAF's is based on the fact that a recirc sends a jet of air back into the pipe between the turbo and the MAF. This air is laden with the oil vapour that has been vented from the crankcase, for burning.

To vent this oily gas away from the MAF seems much safer to me. And if there is no risk, explain why a certain P1 demo car which saw a lot of track use suffered 3 MAF failures, using the stock air filter and dumpvalve.

You couldn't fit one as OE, as the noise would fail new vehicle tests.

P1Fanatic, we have them on every staff Impreza, you are welcome to come along for a demo.

BruceWarne

I agree with this statement, but can't see how this can foul the MAF. The oiled air will be sucked straight back into the engine, missing the MAF by miles. For it to get pushed back to the MAF would require the air pressure to be lower at the filter inlet (aka the atmosphere) than at the engine inlet - meaning air would be sucked out back through the turbo? Yes, I think not.

These days it is rather common knowledge that MAF failures have a whole lot more to do with vibration than with oil contamination. To tell the truth, I think even if you cover your MAF film with oil, it will still work when you clean it - whilst it is dirty it won't work, obviously.

And loose you a lot of air already in the system. And it sounds common.

I don't think anyone having to shift gears for the first time with a large BOV burping away in the background will be able to make an objective decision as to its effectiveness.

I hate them, they are an attempt by the truck driving fraternity to make their scoobies sound like lorries.

nom

Drive your car with one (drive, not stick on a RR or watch numbers through DeltaDash) for a couple of weeks to get used to it & then replace it with the standard one. If you didn't know that you'd just swapped back to the oem bov, you'd think there was something really wrong - a leak somewhere, for example, because there's a lot more apparent turbo lag between gears. I say 'apparent' because I haven't actually looked at a log to discover this, that's what it feels like - and I don't really care if a log doesn't show it 'cos the log isn't driving the car.
I don't like the 'gshhh' noise either, but it's worth 'putting up with' because of the 'better driving experience' it gives.

Katana

Can you do my homework for me?

Pete Croney

The force of the air comimg out of a 15mm pipe, into the large intake pipe, is enough to send it in both directions. I'm not saying that using the standard DV will definitely foul your MAF, but using a VTA definitely takes this out of the equation.

For years I also had my head buried up my 4rse over these. I was well known for hating them. But to prove to myself that the (anti) hype was correct, I tried one. I have never taken it off, because the car drives better

David_Wallis

Well youve convinced me... gimme gimme gimme

David

StanS

iTrader: (3)

Thanks Pete for advising me to go for the VTA and the fitting job on Saturday - its what you said - noticeably better driving experience with very little increase in noise (over your exhaust !)
Stan

tinydelete

looks kike i will be at ss on saturday,spoke to knowlsey today they now have them in stock,will post after fitting to let you know what i think

yoza

Ive just fitted a FORGE dump valve and K&N induction kit to my MY01 WRX.Im no expert here so hear me out,my dump valve is fitted as a direct replacment for the original one,I dont think its a VTA valveit vents thru the filter I think,is this a re-circullating valve or have i lost the plot?Makes the right noises anyway