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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,265
"JFairman, that T between the most beautiful intercooler ever and the AAV, is that going to the decel valve? And do you have your decel valve going to intake or atmosphere?"

Thanks, I bought a used Kokeln long neck intercooler a few months ago and then sanded it down and polished it. Took some time and I like the results.

There are 2 T's in the hose going to the AAV because there is no deceleration valve hose fitting on a long neck Kokeln intercooler.
The bigger T goes to a 32mm black anodized chinese copy of a Turboxs type blow off valve I found on ebay. With shipping it was only $41

I clear silicone glued a small stainless steel mesh air filter I had into the BOV horn because sometimes during low speed decelerations like coming down a hill or approaching a stop sign when the turbo is spining slowly and not making air pressure, intake manifold vacuum opens the BOV a little and slight vacuum in the intercooler sucks in some air. The horn that is there to amplify the pfwooosh noise when the valve opens under boost unscrews and can be removed from the BOV if you want.

That is not causing any drivability problems and it leans out the AFR a little at medium to low rpms during slow speed decelerations. I can see it happening on my AFR gauge.
I know that sounds funky but with 3 of the 6 shims that came with the BOV installed under the spring inside it, it works great.

I also installed a vacuum solenoid I had sitting around in the vacuum line that opens the BOV so I can flip a switch and disable it making it stay closed all the time if I want.
I installed a small rocker switch in the front left side of the glove box to operate that vacuum solenoid.
The vacuum solenoid is open at rest letting vacuum pass through and operate the BOV and it closes when 12 volts is applied to it disabling the BOV.

The smaller T and 3/8" hose thats hard to see in the pictures goes to a 10mm vacuum solenoid I mounted on the right rear side of the CIS airflow meter housing and it opens and bypasses some air around the throttle body when the AC compressor turns on so idle speed stays the same and doesn't drop at all when the AC compressor kicks on.

When I first installed this intercooler I installed the deceleration valve vented to atmosphere under there on the end of that hose but I removed it and installed the adjustable BOV in place of it and sold the deceleration valve.
The adjustable BOV works better for this application and you can add or remove washer shims under the spring to adjust preload to control when and how far it's brass piston opens from intake manifold vacuum when you close the throttle.

There is also a 25mm or 1 inch Turboxs compressor bypass valve/BOV installed sideways in the rubber C2 elbow hose recirculating turbo boost from the back of the intercooler into the turbo air intake when you close the throttle. The 25mm recirculating CBV has no shims under the spring and it's brass piston opens a little before the 32mm BOV. I think more boost pressure is being recirculated than vented to atmosphere between upshifts or when you close the throttle under boost but there is no way to measure that.
The CBV and BOV are both opened by the same intake manifold vacuum port on the top left side of the throttle body - the same place the deceleration valve activation vacuum line was.

It might seem kinda silly to have 2 blow off valves working together but I like it, enjoyed installing it, and it works great.
The BOV vented to atmosphere makes a nice little fwoooosh between upshifts under boost that isn't very loud because some of the turbo's air pressure is being recirculated quietly at the same time but you can still hear it.
You can't see the BOV under the intercooler unless you look for it.
There doesn't seem to be any boost leakage from them and I'm running between 1.1-1.2 bar boost with no problems.

Pics of the 32mm BOV while the intercooler is removed when I still had the stock air cleaner housing installed.


Old 07-23-2011, 09:28 AM
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