Fat Blerk

Have a Forge VTA valve on my 99 RB5 - had it for about a year - just get a lot of chatter, no real whoosh. I read on a thread a couple of days ago that changing the spring will change the noise. I got in touch with Forge, who had a blue spring out to me next day (impressive!)

I fitted it at lunchtime..... and am quite....bemused!! I get a LOT of whooshy dump valve noise, but on every gear change also get a pop or bang from the exhaust.

Now - I know there are overfueling issues caused by dump valves blah blah blah but if we did everything sensibly we wouldn't have scoobies in the first place. I am guessing that the spring is now too soft, and It'd dumping too easily, leading to massive overfueling.

Am I right? I spoke to someone at Forge and they said that was probably about right and to pack the spring up with some spacers of some kind.

Has anyone else heard of or had a similar issue? Was it cured with spacers or should I put the original spring back in and shout "Whoosh" every time I change gear? Any opinions gratefully received (by evryone on my route to work as well no doubt!!!)

Fat Blerk

Oops forgot to mention - car is fully decatted with induction kit - running 1.1 bar boost................

buzzerboyroy

dont fret matey,

most vta dump valves with an induction kit and full decat pop and bang,,i am surprised you havent seen the flames in your rear veiw mirror?????!!!!!

i am going to replace my forge re-circulating dump(on my my99) valve very soon to a forge vta type to get the pop and bang !!!!!!!!!!!!!!!!

i am surprised i havent seen you around as i dont live that far from you and am traveling around your end quit a lot lately.

all the best
roy

[Edited by buzzerboyroy - 12/20/2002 4:09:35 PM]

Fat Blerk

Roy,

Nice one...... the concerning thing is that its EVERY gear change, unless I really monster it.... also, I noticed that if I blip the throttle while idling, I get a stutter which was never there before..... d'you reckon more spring tension would take some of this away? I've only driven it for half an hour but it's getting on my t*ts already!!!

ScoobyJawa

All normal! The pop and bang is as the ECU overfuels on lift off due to the DV and its great - flames galore

As for the judder - yep - thats a feature too!! There are other springs, yellow and green IIRC, John Banks went with the yellow I think to stop the judder on his car with a Forge recirc. Or learn to drive round it

buzzerboyroy

if its annoying you then take it off!!!
its no good driving a car that has somthing annoying under the bonnet.
either replace the spring or get a re-circ dv like mine,,it is quieter than an atmospheric dv but still has the little whooshes and chatter.
you seem to have the correct spring in it now as its popping and banging as it should,where as before it had the wrong spring in it .
i will do you a swop if you want!!!!hehehehehehe

[Edited by buzzerboyroy - 12/20/2002 5:06:00 PM]

Fat Blerk

Right chaps - after a little bit of tinkering have cracked it.

The blue spring is TOO soft on its the valve is dumping too much too early and causing huge overfueling - pop on every gear change. This might sound like fun, but it also means the boost isn't building very quickly when the throttle is opened again (making car slower - NOT GOOD!!!)

I've put some fibre washers under the spring to give it a bit more tension - BINGO!!!!

The valve makes the lovely whoosh that we young men love so much. The turbo is spooling up quickly again (3 or 4 times quicker than without the washers in fact) There is also no stutter from idle, and no judder from lift off....

Bonus : no bang UNLESS YOU WANT IT..... by stepping on and off a couple of times, you can pop and bang all you like.

So..... if you've got a forge VTA with a blue spring and it pops and bangs all the time, you're probably not getting the best performance........ worth playing with!!!!

Thanks for the input guys!!

Dark Blue Mark

I just fitted mine (MY 99) blue spring, dawes at 1 bar and full decat. The noise I get from the DV is quite a quick short Pshhh. At full boost its a bit longer, but still short. At half boost its very short. I had one on my 96 and it was a lot longer noise than this.

It gives pops and bang on around 3k rpm overrun, if you floor it, build up a bit of boost and then let off.

Does it sound ok?

MB

Fat Blerk

DBM - sounds like its working just right.....

On the red spring mine would never dump unless it was under full boost at 6000Rpms or more - 1.1bar boost. Below that you'd just get the chattery wategatey type noise (sounded like a horse snorting was how my mates described it!!!)

The blue spring, now I've put the spacers in dumps whenever theres more than half a bar boost running - it's a quick "psssssht" - not the drawn out "look at me, I'm in a shoebox" pppsssssssssssshhhhhhhhhhhhhht of the reanult turbo boys....

I assume the quick dump is more efficient than a drawn out one... but I'm only guessing. Sounds to me like yours is set exactly the same as mine if you have to consciously make it pop and bang......

Cool!

Dark Blue Mark

Thanks Berk,

Good to hear it sounds right! My 96 had bad idle problems so I suspect the spring was too weak, and on boost, it made a longer noise as it was staying open longer.

My loudest bang is in 4th at 50mph, add some boost, let off and... scared pedestrain! When its really hot it gets better

MB

sillysi

Got a little bit to add on this one. I have a MY01 WRX which I tried a Forge VTA DV on and found it would not hold boost over 5K RPM. I have spoken to Forge and they are sending out some machined 'spacers' (read washers) to fit under the spring, they assure me there is no design fault with the DV but these 'spacers' will cure the problem. This seems to be in line with Fat Blerks findings.

Si.