I was at a friends house last weekend helping him install a dual core radiator. He has the KW kit and is quite happy with it. About the time we pulled the fans I noticed something unusual about the recirc valve installed on the hot side intercooler pipe.

My old man was a Porsche guy and over the years replaced a number of these recirc vavles as a matter of routine maintanance.

Here's the Bosch recirc vavle on an '86 944 turbo:



The valve is sitting on top of the rubber boot that leads to the turbo inlet. Coming in at 90 degrees is the boost from the cold side intercooler pipe about six inches from the throttle body.

Here's a diagram of the same Bosche valve and it's recommended installation:



Here's an install diagram from the older Forge Motorsports billet version of the same vavle:



Here's how Kraftwerks has the Bosch part installed on their S2000 kits:



OBVIOUSLY it will function in this configuration. But could it function better if it were installed as Bosch has suggested? As it is- boost pressure is pushing directly on the diaphragm seal. In the above installs boost pressure hits a brick wall. The valve can only be opened by manifold vacuum. Here's the specs on the Bosch 0 280 142 108 diaphragm valve that comes with the KW kit and some possible alternatives:



If you install the valve as KW suggests you (might) consider upgrading to the Bosche 0 280 142 (110) diaphragm vavle so that you can be sure you're getting a full 10 psi out of your blower.

It's also very easy to "flip" the valve around into the normal config and be quite happy. You might need to install a rubber vacuum "elbow" because of clearance issues or consider the latest Forge Motorsports "lifetime" billet valve which has a 90 degree vacuum inlet that will solve the clearance issue as well.

Hope this helps.

Louis

 

I had heard about this as well. Thanks for posting this up! This could quite possibly be quite useful for some KW owners!