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26 September 2007

Forge Diverter Valve

One more issue resolved.

At first I was planning on one of the ATP adapters with recirculating valve plumbed into an ATP intake. Then Eurocode came out with a package of the ATP adapter with a fake GReddy valve (or a real one at extra charge). I was unimpressed with Eurocode's marketing of the bundle, and after people tried it and problems became known, I was unimpressed with the technical aspect of it as well.

In looking for a better solution I contacted Forge, and was told that they were working on a solution that would be a fresh design, would have some manner of maintaining computer control over the valve, and would be a robust piston valve with NO rubber diaphragm to fail. Based on their reputation for quality piston-type valves, I decided to wait and see what they came up with. A few people (including me) knew what they were working on, and the design changed a little bit as time went on.

Development of the valve took quite a while, but the end result is a really slick valve that will *not* fail (unlike the clunky stock valve with its gossamer hymen of a diaphragm), works off of pressure & vacuum, and has a clever external solenoid valve arrangement to maintain computer control over what is essentially a mechanical valve. As an added bonus, the vacuum line tap has fittings to accommodate a boost gauge and another device in addition to the valve. Forge's designation for this part is FMFSITV.

When I finally ordered it, it was on backorder for a few weeks. I was really anxious to get it since my stock valve had seen better days.

The contents of the package:

The 3-port vacuum tap. You can see that there are three nipples provided - the largest-diameter one is used for the diverter valve, the smallest-diameter one would be for a boost gauge, and the third one would be for some other device, if needed. If you're just installing the valve, the small threaded plugs shown are used in place of the other two nipples. When making up that assembly, you definitely need to use Locktite Threadlocker (BLUE) to make sure everything stays together (Locktite BLUE is removable, RED is permanent, don't use RED unless you mean it):

In the upper left of the picture is the solenoid valve that controls the vacuum/pressure acting on the actual diverter valve. The thicker black tubing to the left is the used to make up the vacuum tap assembly:

The vacuum tap with the correct nipple + 2 plugs installed:

The valve itself:

It's made up of several pieces - the main valve body, the screw-off cap (ring+top), the piston, and the internal spring, coated internally with a red high-temperature lube.

They provided more than enough silicone vacuum tubing for the install:

Up on ramps, ready to start...

The original diverter valve on the turbo, viewed from below:

Turbo with diverter valve removed, seen from below. There are three bolts on the valve, don't remove the similar one on the oil line bracket just below it:

Always looking for a better way to do things, I decided not to mount the solenoid valve directly to the diverter valve. Forge claims it can be mounted anywhere within reach of the wiring harness that would plug into it, so I relocated it up to where it would be farther away from water, debris, etc. The two lengths of tubing shown attached to the base and cap fittings of the valve are 18" and 22" respectively:

I zip-tied the solenoid to the wiring chase near the ABS controller. It's more protected, easier to keep an eye on, and farther away from the heat of the turbo than if it were bolted to the diverter valve. The two tubes shown above go down to the diverter valve, and then the longer run of tubing goes to the vacuum source.

Here's the vacuum tap installed. It's very subtle when done right, very stock looking, and will be convenient to add a boost gauge later:

The valve installed on the turbo (sorry for the blurry picture, it's not the easiest spot to get a camera into):

When I removed my valve, it completely fell apart as I pulled it away from the turbo. I mean, the piston, the diaphragm, the spring, the pin, the plastic ring.... WIth the new valve in place, it's like a whole different car. MUCH more power, less lurching off the line and during shifts (of course, the dogbone insert helps with that, too). This has been another good mod for me, and highly recommended for anyone with a 2.0T FSI engine.

Subsequent to installing the valve, I asked Forge what maintenance needed to be performed on the valve, and at what intervals. Forge's response:
Valve maintenance is not necessarily a requirement though it can be done at whatever interval you choose based on various factors.

We have a test valve installed on a 1.8T Audi TT 225 in the UK which has been installed and operating for over the last 5 years without having ever been serviced once. It holds vacuum and pressure perfectly fine just as if it were brand new.

With that in mind, however, as dust, dirt or other debris may periodically enter the system, and possibly contaminate the grease inside the valve, depending upon your geographic location and/or other driving conditions, we would recommend at least checking the valve every so often, at least once a year or so, and clean and regrease it if you feel it's needed on your particular car.

We build the valves with Mobil1 fully synthetic bearing grease, however, any other brand of fully synthetic grease should suffice. We do not recommend the use of lithium grease as it can be corrosive to the o-rings inside the valve, nor do we condone using any sort of motor oil, spray lubricants or anything else aside from a fully synthetic bearing grease. The comment on the [motor] oil [is] directly meant to discourage anyone who thinks that motor oil is a "cure-all" lubricant when it is not even remotely suitable for lubricating a component like our valve [instead of the Mobil1 fully synthetic bearing grease].
(Edited for clarity - Len)

(Thanks to local Deldubs member '92rado2.8' for the use of his ramps!)

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