fitting forge DVs

[dhali]

just been looking at a picture in the gallery ( favourites 465) and noticed that they are fitted at 90 degees to the oem. Any reason for this?

[Dippy]

Not sure which picture you mean. Forge DVs have exactly the same orientation as OEMs - couldn't be otherwise without modifying the pipework.

[Nige_RS4]

Not sure which picture you mean. Forge DVs have exactly the same orientation as OEMs - couldn't be otherwise without modifying the pipework.

I think he is referring to the orientation of the actual DV itself - the Forge units fit better with the vacuum hose point up, whereas OEM has it to one side.

Nige.

[dhali]

thanks NigeS4. i was refering to PhilT RS4 album pics 9-17. Also just noticed in same album they are fitted other way round

[Nige_RS4]

I think technically, they should be the OEM way around, but I've tried both and they still work OK.

Nige.

[bobjebb]

while we're on the subject can anyone give a brief lesson as to exactly their job (I know the basic principle) and the benefits of fitting forge ones?

[Dippy]

I can't even remember the OEM ones, but if so, that's only the vacuum nipple orientation. Forge do DVs with a side orientation too.

Whilst in theory the other two ports can be either way round, in practice they should not. The face of the piston should be on the bottom connection which is connected to the pressurised side of the turbo (outlet). I'm not quite sure why, but I believe that some users have had performance problems fitting them the other way round. In my case I have had to get the right spring to avoid hesitation problems, and I'm sure that connecting them the wrong way round would make the problem worse. The only cases of fitting them the 'wrong' way making it better have been on the 1.8T engine. Again, no idea why.

Bob,
They need to open quickly so that air is recirculated and the trubos don't stall, but also close quickly to avoid hesitation. Normally that would mean light diaphragm valves are good (i.e. OEM), but the downside is that they can tear causing leaks which are BAD. The only reason to fit solid piston valves (e.g. Forge) is reliability. You may even get a loss of response. The decision is not easy. Some people stick with the newer OEM valve and replace regularly (or keep spares), whereas others like me prefer the 'fit-and-forget' confidence the Forge valve gives.

[ChrisG]

Forge are now doing a diaphragm version made from a strong material that implies the reliability of the solid versions with the speedy response of the diaphragm - not sure what size they are , they may be too large for the space in the V6 engines

[PhilT]

IMHO the orientation I have used reduces piston slap due to the boost pressure not being against the side of the piston..... Releasing the pressure on the bottom allows the piston to move more smoothly.

That's my story and I'm sticking to it