they leak.

I have been using this valve for 10 years now. Cant find anything that drives as nice and holds 35psi. Tested with balloon on outlet during dyno pull. I remove the small spring and preload ~ two turns.

They do leak. Not under full boost, but during spool up. I can hear the bypass into my airbox. at first you would think this is a bad thing. Over the years I kept trying other valves that didnt leak during spool and the type S would go right back on. Actually leaking during spool helps spool the turbo faster. I saw a drag car once with big turbo use this fact on his setup. two blow off valves. one operating normally. The second is controlled differently. It is held open during spool up then closed when sufficient boost is reached. Results in much faster turbo spool.

Think about it. Place your hand in front of your hair dyer. What happens? The fan speed slows down. remove hand and speed returns. Well your engine is like your hand. It is a restrictive to the turbine speeding up. You have heard you can over spin the turbo when a coupler pops off. same thing is happening.

I recently was going to switch to speed density on my car. I know the type S would be very loud to atmosphere. So I installed a greddy Type R. no tension on the spring. I spent two hours making it recirculate. My first drive I was shocked. Car just felt sedated. Big Big lack of response and HIT. No leaks during spool up, airbox quiet during spool. I knew what the problem was. Came back home and reinstalled the type S.

I dont have any data . I wish I did to show you what is happening.
If you could measure turbine speed what you would see is at 10 psi with no leaks the turbine is at 50,000rpm. then with the BOV leaking the turbine is at 60,000 at same 10psi boost. Then when the BOV leak is sealed that extra 10,000 compressor speed slams the cylinders with extra air. These are just random numbers I pulled from thin air. But they illustrate well the point I am trying to make.

I like type S valves. Recently had stock of about 6 of them. Sold a couple on ebay for 175 BIN. they both sold in a few days.

 

Awesome. I have two of these that i cannabilized to make one good one. OG purple. best part about this valve is it is almost 100% if not 100% stock dimensions, which means, it fits neatly on most stock framed turbo setups for recirc, or can be vented derr. lol

I have a spare diaphragm, so I should be good to go. I did happen to get one with a stripped out top screw on the top, and the other spare one was garbage on top, something had rubbed it severely in someones engine bay. So I tapped it for a larger screw.\

Are you using the boost reference port to the bottom of the diaphragm?

Are you the guy who wrote the single spring mod webpage that shows up on google? haha

 

never wrote any write ups. I leave the bottom port open

 

people get psyched over the leak factor. I see your logic with slight partial release during spool up, and its the same reason I think its good to have your BPV leaking at idle, keeps shaft speed up and allows smooth throttle response during transient throttle application..

http://www.evomoto.com/tech_info.php?tech_id=7

 

I've had the type s for a year now and it never sounded off correctly, it sounded like the stock at anything over 5psi, and it would sometimes compressor surge. I t'd off the boost controller line (turbo to boost controller) and hooked up a 1/8 in line from the t to the bottom port on the type s, and it sounded off perfectly even at high boost (top set screw is set to 6 threads). Also both springs are inside.

It was then leaking under boost, wouldn't hold over 15 and would taper down to 12. During a boost leak test it would open as well, so I took it apart (super easy just make sure you hold down the purple cap when removing the allen head bolts). I noticed that the diaphragm (black rubber piece) was ripped so I took some black rtv and coated the inside of the rip and the outside (the metal circle piece inside the diaphragm comes out). I let it dry for 24 hours (full cure time) then re-assembled it. I also cleaned/polished the inside of the bov and put a thin coat of oil on the shaft. Now it holds boost and sounds off perfectly!

To summarize:
1. T off the turbo to boost controller line and connect the lower port of the type s to the T.

2. Open the BOV and see if the diaphragm is ripped,
- you can try and repair it with
RTV http://forums.vwvortex.com/showthrea...usted-diafragm

-or buy a new diaphragm for $80. http://www.shopgreddy.com/turbocharg...placement.html

3. Clean the inside of the bov

4. Reassemble the bov (keep both springs)

5. Try setting the adjustment screw to 6 threads sticking out from the top of the nut.