Forge DV Spring?

[A80Avant]

if that is the case,should i also change to a yellow spring instead?If im boosting with a yellow spring,wont this mean that if the boost reaches the 1.6bar,then the DV will open,and isnt it possible that this way i wont be able to reach the estimated overboost value?

for example,if i have a program to reach 1.8bar overboost,and 1.4steady boost,which spring should i use?blue or yellow?

With the DV i have now,with the blue spring,i do hear hissing sound on gear change.Doesnt that mean that the DV is working properly,opening to let excess air out?

[newsh]

The DV is mostly operated by the small gauge vacuum pipe. When the car is on boost, as well as getting pressure on the input side of the DV the small pipe is pressurised too and holds the DV shut (along with the spring). When you close the throttle you get vacuum in the inlet which overcomes the spring and the DV opens. So the spring really affects speed of operation of the DV it would seem. With a bigger spring it would snap shut sooner as the throttle is opened again. If there was more boost pressure at the output of the turbo than in the IM (say large pressure drop across the IC) then you would need a larger spring to help the vacuum pipe close the valve. Big turbos on part throttle might exhibit this symptom too as there would be a pressure drop across the throttle body.

[Jamo]

The DV is mostly operated by the small gauge vacuum pipe. When the car is on boost, as well as getting pressure on the input side of the DV the small pipe is pressurised too and holds the DV shut (along with the spring). When you close the throttle you get vacuum in the inlet which overcomes the spring and the DV opens. So the spring really affects speed of operation of the DV it would seem. With a bigger spring it would snap shut sooner as the throttle is opened again. If there was more boost pressure at the output of the turbo than in the IM (say large pressure drop across the IC) then you would need a larger spring to help the vacuum pipe close the valve. Big turbos on part throttle might exhibit this symptom too as there would be a pressure drop across the throttle body.

It uses the same principle as a wastegate spring. When the top of DV is pressurised the spring should not open if it's strong enough.

When vacuum is applied it's boost pressure that then pushes open as there is a vacuum on the top chamber i.e no resistance.

You can see this with a stock that the spring diaphram is weak and can actually be opened by vacuum just by sucking on the top pipe. On an aftermarket DV with a strong spring you won't be able to do it.

[Efini]

It uses the same principle as a wastegate spring. When the top of DV is pressurised the spring should not open if it's strong enough.

When vacuum is applied it's boost pressure that then pushes open as there is a vacuum on the top chamber i.e no resistance.

You can see this with a stock that the spring diaphram is weak and can actually be opened by vacuum just by sucking on the top pipe. On an aftermarket DV with a strong spring you won't be able to do it.

The way my DV is mounted now, the boost pressure is pushing against the side of the piston. I assume that boost pressure won't be able to force it open then?
Perhaps mine is mounted the wrong way..
When the pressureside is on the side of the piston does it really matter what spring I use? The piston will then only be activated by the top vacuum/boost pipe I guess.

[Jamo]

Thats why you can get different characteristics / results of the DV when installed the wrong way round.

Sometimes it will hold pressure better sometimes it won't open correctly.

[A80Avant]

so the DV only opens in the vacuum position? i still havent got around understanding the workings of it...

I always thought that by using a spring that accepts pressures up to 2.0bar with a map ECU that takes only up to 1.6bar,then it is possible to achieve the boost you have on the ECU program you have.If i had a spring that could hold the pressure up to 1.2bar,then although i have a program for 1.6bar,it would only go up to 1.2bar then,the DV would open up and release the extensive pressure thus not allowing me to achieve the 1.6bar.

am i wrong in this assumption?

[Jonas_R]

Jamo:
Iam a bit pussled here. But anyhow, if your running 1.6 bar peak and then 1.2-1.3 bar redline. Would you use green or yellow? Currently using yellow with my 1.4 peak and 1.1 bar redline, does seem to work fine and I can here the DV realease pressure.

/Jonas R.

[A80Avant]

im working 1.6 with 1.2bar to the redline.Which one should i use?

[newsh]

so the DV only opens in the vacuum position? i still havent got around understanding the workings of it...

I always thought that by using a spring that accepts pressures up to 2.0bar with a map ECU that takes only up to 1.6bar,then it is possible to achieve the boost you have on the ECU program you have.If i had a spring that could hold the pressure up to 1.2bar,then although i have a program for 1.6bar,it would only go up to 1.2bar then,the DV would open up and release the extensive pressure thus not allowing me to achieve the 1.6bar.

am i wrong in this assumption?

Yes, because the boost pressure is on BOTH sides of the valve.

To be honest I think you're confusing the job of the Wastegate and the Diverter
Valve..

Look at a 2Bar Wastegate spring and then at a DV spring, its pretty obvious the DV spring isn't made to withold 1 or 2 bar of pressure.. If it wasnt for the small pressure drop between the turbo and the IM you wouldn't need a spring in the DV. Also the car will run perfectly well without a DV, All the 10V Quttros had no DV. The DV just helps the turbo not to slow down so much between gear changes. Keeps it spooling so the boost is still there when you put you foot down.

I suggest you phone or email Forge and ask them what spring to use for your level of boost.

[A80Avant]

newsh,
forge told me when i bought the DV that the ideal spring would be the blue one for me,and for the pressures applied.I dont understand though what you say about the toughness of the spring.If it is not made to withstand the 2bar pressure then why does it say that the blue is for 30psi? the yellow for 1.6bar etc???
Are they reffering to the actual pressure the turbo is working on?

[Jonas_R]

I just talked to Forge and the say I should use the blue spring, and that it normaly comes with the 006 DV.

/Jonas R.

[newsh]

newsh,
forge told me when i bought the DV that the ideal spring would be the blue one for me,and for the pressures applied.I dont understand though what you say about the toughness of the spring.If it is not made to withstand the 2bar pressure then why does it say that the blue is for 30psi? the yellow for 1.6bar etc???
Are they reffering to the actual pressure the turbo is working on?

Yes, absolutely, the ratings refer to the boost you are running not the actual strength rating of the spring.

[A80Avant]

Im a bit puzzled with the DV/s ... again so i bring up a couple of questions.As you can see in the picture,my forge DV is mounted the 'wrong' way.This means that whenever boost is up,the air reaches the side of the dump valve,not the actual piston from the top of it.However it is this setup that i hear most of the noise and not the other way around.

Here in this site:http://dv.mistertam.com/2.htm it explains how it works.Here according to this picture i have it the right way on though!!!
Also same thing i read at the SJM troubleshooting page!!!!

Im puzzled as to what reference have the DV springs that forge offers in regard to the boost pressure that the ECU is working on.I read somewhere here that these ratings refer actually to the boost pressure that the car is making and not the actual spring pressure.Agreed!

But what pressure are we talking about?Overboost?Steady boost to the red line?

When i remaped the car,in between we replaced the blue spring to the red spring.We wanted to make the car boost to 1.8 and drop to 1.3 to the red line.

At first,my remapper noticed that i had the DV the other way around(meaning the 'right' way,as i had done it myself before the trip)I must say that during the trip it sounded funny,more like a clunk rather than a psssshhhhh....

Then we changed the spring as well.

now that im reading all these info about the DV,im puzzled again.The small tube that connects on the DV which is coming from the IM,produces vacuum on idle and deceleration,thus workgin against the spring's tension is forcing the piston to move backwards and opens the DV.So pressure is escaping from the pressure side to the MAF side.RIGHT?

OK.On WOT,the vacuum small tube,also sees boost.So it forces the piston along with the spring(working with it now) to close the pathways of the DV so as to produce a leakless pressurised aera for the boost to build up.RIGHT?

If during boost the spring is working along with the vacuum tube,then why is there a need of different springs for different boost levels that the car is workgin on?Any spring would help close the system since it also gets extra effort from pressure itself.

So it would seem that the spring tension has relevance on idle or deceleration,whre vacuum is supposed to work against the spring.Then why are there different springs in the first case?All our cars vacuum aroun -0.8bar!!! Why the different springs???

These thoughts apply mainly when the DV is mounted the 'wrong'way.

But really,if you mount it the right way,you have a piston with the spring and you also have 2 tubings,one towards the IM(vacuum small tube) and the other on the opposite side to the pressure side,both receiving the same pressure on WOT.So the piston should remain in place since on both sides there should be the same pressure eg 1.8bar overboost 1.3bar steady boost.The dv should not open!

So why are there different springs?what is their purpose???

[A80Avant]

i tried mounting the valve the other way around as well today....Didnt notice any difference...So i tried usein the blue spring along with 2 washers.

The funny thing i get now is on 3d gear, WOT,turbo climbs to 1.5bar then as rpm goes up aroun 4000,it makes a slight jump to 1.7bar for a little while,then begins it's drop to terminate on 1.2bar on 6000 to 7000rpm...

do you think the DV has anything to do with this??

[Matt_D]

Hmm i no expert and if i have this wrong then please fell free to tell me where to go
...but i think if you have added 2 spacers the 'gap' the air is trying to rush through inside the dump valve is now smaller and more restrictive ?!?
This might by why your cars peaking at 1.7 bar as its trying to make boost ?

Dump valves confuse me too, perhaps emailing Forge with your problems might be the best thing ?