Forge DVs service

[Dippy]

I finally got round to servicing my DVs this afternoon. It turned out to be more just an experience for me than necessarily beneficial. Other than the fact that the original grease was a bit dirty and less viscous than what I replaced it with, they looked fine to me. Nevertheless I replaced the pistons and o-rings on both valves and retested them. Possibly they seem to hold the piston a bit better now, but not by much.

I also remember fairly well examining DJG's Bosch valves a few weeks ago. So I feel I can still compare the two makes. I don't think that the Forge valve should be any slower to open and close than the Bosch unit as the piston is fairly light and its movement very smooth.

Based on what I have been reading on sites like this for the last year or so, I was beginning to have less faith in the Forge valve. However it is now totally restored. IMO the Forge valve should perform as well as the Bosch valve but must be infinitely more reliable.

[s2driver]

Which Forge DVs do you run?

Do you have the aluminium piston or the plastic one?

My DV005 would only work when fitted the opposite way around to the way Audi intended. There have been lots of discussion about this on other forums.

Is there a recomended service interval for these units? MIne has been on for around 20,000 miles and still works flawlessly with the aluminium piston. When I service mine I think that I will lap the piston to the housing just to ensure the seal is still effective. I think it might be worth knocking up a simple rig to asses how well it seals after a service...I don't want my turbo working harder than necessary to generate the required boost.

Lee

[Dippy]

I have the FMCL007P valves which AFAIK were designed specially for the 2.7 biturbo. They have an aluminium piston and can only fit one way. From my understanding of the way these valves work, it is possible that if the boost air pipe is connected to the 'end-of-piston/diaphragm' pipe then the boost could force the piston/diaphragm against its spring. If this were the case then connecting it the other way round might prevent this as the pressure is spread over a larger area. This is the way that it has to be fitted in my S4.

I checked the seal by just blowing into it. I know from experimenting with my boost gauge before fitting it that you can develop quite high pressure with your own breath! My DVs were well sealed - but then I'd expect this because of the way that the piston head is shaped to fit to the body.

I'm also interested to know what the service interval should be as mine didn't really need servicing. I've e-mailed Forge and will post the reply.

[s2driver]

I fitted mine in the same way that the old one came out. Audi fitted them the wrong way around though [img]images/graemlins/confused.gif[/img] ! Now mine is correct after the swap. Before swapping the orientation it would begin to open at only 1 Bar .

I look forward to seeing info about the service interval.

I need to set up a test rig anyway because I need to find out if I should fit a second one when running high boost and high flowrates. Not sure if one will be able to open fast enough and provide enough bypass flow to prevent the turbo decelerating too much during throttle lift off.

I have been told that someone in the states has done this test to characterise dump/diverter valves from several manufacturers. I can't find this site though. Anyone have a link?

Lee

[Doug_RS2]

http://dv.mistertam.com/

Is that the page you were looking for? Or:

http://www.s4biturbo.com/art-dvtests.shtml
http://www.s4biturbo.com/art-dvtests2.shtml

I've had no end of trouble with the forge and just replace the audi one every so often.

[s2driver]

That's the one. Cheers

[Dippy]

The answer is that Forge do not officially recommend a specific service interval, but they suggested either annual or every 20,000 miles. Based on the state of my valves after 15,000 miles, I'll go for 20,000 or even longer.

Those links were very interesting. I have the older style valves so I'll open them up again and smear some extra grease around the seals. At least I can do that with the valves still on the car this time.

I remain unconvinced that the Forge valves have a slower response time than the Bosch ones. That argument seems to be based on their greater displacement. However with the green springs the valve starts moving at a lot lower vacuum, and is fully open at a lot lower vacuum. Therefore since the ECU must be appying a 'Bosch-level' vacuum from a sizeable reservoir (on the S4 at least), I would actually expect the Forge to open as quick or quicker, assuming that there were no air leaks of course!

I guess that due to the weaker spring the closure response may be a bit slower though.

One thing I remain convinced about however is that the risk of a diagphragm tearing in a DV is not acceptable for me. I got the Forge valves for their reliability, and I am totally confident of it. Even if their response is slower, I prefer to have them on my car.

[Joshie]

I was having significant problems with the original forge DV0007 valves. Problem was that I was sufering a drop-off of boost from time to time.

New pistons and seals failed to do the trick and I send the original valves back to Forge. They tested them and said that they were fine but send me a brand new uprated set anyway(these have an additional rubber ring in the head of the unit.)

I fitted the stronger blue springs and and reinstalled the units about 6 weeks ago and I can honestly say that I have not experienced one episode of boost drop-off since.

Doug - don't give up on the Forge units - they are a first class bit of kit.

[Dippy]

I took the heads off my DVs again today and smeared some grease over the seals to be sure.

It seems to me that the problems with DVs seems to be some sort of black art. However I mustn't forget that your car is somewhat older than mine and has different turbos, so where the older Forge DVs failed for you, they might be OK for me.

Forge told me that the green springs are fine for my car, even chipped. I guess that the stronger spring is therefore less to do with boost pressure and more with air flow.

[s2driver]

I have to echo Joshie's post here and can relate experience with the S2. Despite my initial teething problems with the Forge DV which were down to the way Audi implemented it in the first place, Forge ones are great. I have no experience of alternative DVs other than stock so cannot make comparison with other aftermarket ones.

In my case Forge were fantastic to deal with and the valves are very nice bits of kit. Operation has since been flawless for over 20,00 miles and I don't have to worry about split diaphragms.

I am surprised Dougal that you change your DV regularly and are happy with that. They are a pain to change on the S2 becuase the airbox comes out. The first time I did it I dropped the airbox-securing bolt onto the sumpguard (you know the M6 one I mean!). This caused extra agro jacking the car to remove the guard to retrieve the bolt.

Lee

[Doug_RS2]

Right - I'm maybe being a bit harsh on Forge - I'll get in touch and get them to check mine.

Lee - do you have the end of the piston on the high pressure side? (I think this is the standard config - only think this becasue that is the way it was always fitted)

You don't need to take the airbox out(which is a pain). Remove the trim below the headlight(1 screw), the headlight(4 screws and 2 connectors) and the plastic cover behind the headlight and it is dead easy - 5 minute job.

Dougal

[s2driver]

Good point about the headlight [img]images/graemlins/thumbs.gif[/img]. Never tried that.

High pressure to side port I think is best. I will email you my correspondence with Forge if that helps and it should confirm things. It is on my work PC so can't access it from home. PM me an email address if you can.

Lee