Greddy RS compressor surge problem???

[kicknurass4fun]

Ok so I have a greddy RS bov and I have been trying to get the thing set up properly and im having some problems that I am curious as to if any one else has had? When boost testing my car the bov will leak if I dont have the spring tension set pretty high. The problem with this amount of spring tension is I get compressor surge when ever I shift with less then 5psi of boost. Now I know the Greddy type S bov had a lower nipple that you could hook up a second boost/vacume source from inbetween the the turbo and the bov. This made the bov react faster to help at low boost levels with high spring tension. The RS doesnt have this. It just has a hole for the air to vent through. My first question is has any body else had this problem with the RS? Second has anyone drilled and tapped that hole to put a fitting in so that it can be made to have a boost/vacume line attached to make the bov quick release? Thanks

 

[suicidal2af]

Ok so I have a greddy RS bov and I have been trying to get the thing set up properly and im having some problems that I am curious as to if any one else has had? When boost testing my car the bov will leak if I dont have the spring tension set pretty high. The problem with this amount of spring tension is I get compressor surge when ever I shift with less then 5psi of boost. Now I know the Greddy type S bov had a lower nipple that you could hook up a second boost/vacume source from inbetween the the turbo and the bov. This made the bov react faster to help at low boost levels with high spring tension. The RS doesnt have this. It just has a hole for the air to vent through. My first question is has any body else had this problem with the RS? Second has anyone drilled and tapped that hole to put a fitting in so that it can be made to have a boost/vacume line attached to make the bov quick release? Thanks

You have it too tight if it isn't leaking under a normal leak test with the throttle plate closed. I'd wager that if you perform the test with the plate open, you'll find it's not leaking at all.

Normally, you want to plug your bov when you perform a boost leak test.

Edit: To elaborate, imagine this scenario: You are at WOT with about 15psi(just an example). You let off the gas completely and the throttle closes. What's the BOV do?

Edit 2: A better way to adjust it is to loosen tension at idle until it starts to flutter open while idling, and then tighten it down 2 threads or so so that it tightens down. Reason being, under Boost/WOT conditions, you have equal pressure on either side of the diaphram. When you release, this setup will give you the greatest pressure differential(boost on bottom of valve, vac on source nipple), resulting in the fastest possible release.

 

[DGajre777]

Reason being, under Boost/WOT conditions, you have equal pressure on either side of the diaphram. When you release, this setup will give you the greatest pressure differential(boost on bottom of valve, vac on source nipple), resulting in the fastest possible release.

^^^ only happens if you have a Type S type BOV with the lower nipple connected to a pressure source. Without the lower nipple connected, there will not be equal pressure on either side of the diaphram under boost and WOT conditions. The Type RS has a small hole.


kicknurass4fun - Try the suggestions in these 2 threads below:
http://www.dsmtuners.com/forums/showthread.php?t=232961
http://www.dsmtuners.com/forums/showthread.php?t=225223
A search for "Greddy+RS+leaking" will give you more threads.

If the above doesn't work, drill a small hole, put a small fitting in there and connect it to a intake side pressure source (like the type S).

 

[kicknurass4fun]

Thanks for the link. I did search for about a good half hour before i made this thread and Ideffenitly never found the second link which was helpful. Everything I found was about a greddy S and how people just keep hooking up the lower vacume fitting when they have this problem. Im gonna dril and tap out that whole and run a second vacume souce to it. I will let you guys know how it goes. Thanks for the help.

 

[suicidal2af]

^^^ only happens if you have a Type S type BOV with the lower nipple connected to a pressure source. Without the lower nipple connected, there will not be equal pressure on either side of the diaphram under boost and WOT conditions. The Type RS has a small hole.

The diaphram pushes down on the piston, which has pressure underneath of it. At WOT, you have equal pressure in your manifold and intake tract. Hence, yes, there will be equal pressure.

The lower nipple is not intended to be connected. That's per GReddy themselves because it causes premature diaphram wear. The reason for the vent is to allow free motion of the diaphram. People didn't listen to the instructions, so they removed the nipple and left a blank vent.

Follow the instructions I gave you and then give it a try.

 

[DGajre777]

The diaphram pushes down on the piston, which has pressure underneath of it. At WOT, you have equal pressure in your manifold and intake tract. Hence, yes, there will be equal pressure.

The lower nipple is not intended to be connected. That's per GReddy themselves because it causes premature diaphram wear. The reason for the vent is to allow free motion of the diaphram. People didn't listen to the instructions, so they removed the nipple and left a blank vent.

The Type S has a lower nipple air volume. Drilling a hole in the Type RS and putting a nipple in there would create a lower nipple air volume chamber, which will (like in the Type S and the second picture below) reduce flutter and compression surge. The downside is that it will make the BOV hold less boost.

See pics below.

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[daren_p]

The diaphram pushes down on the piston, which has pressure underneath of it. At WOT, you have equal pressure in your manifold and intake tract. Hence, yes, there will be equal pressure.

The lower nipple is not intended to be connected. That's per GReddy themselves because it causes premature diaphram wear. The reason for the vent is to allow free motion of the diaphram. People didn't listen to the instructions, so they removed the nipple and left a blank vent.

Follow the instructions I gave you and then give it a try.

This isn't completely true, if you refer to the above diagrams under boost yes there will be pressure ontop of the diaphragm & also pressure opposing this from the bottom of the valve. Now if we say that the surface area of them both is completely equal (which Im not sure of) that would give you equal pressure but you forgot there will also be a vacuum created on the backside of the valve if you have the bov recirculated (from the turbo sucking in air)

As for the origional posters question, tapping the vent hole & connecting it to a pressure source will probably eliminate your problem (then the bov will operate like factory) but are you sure you are getting compressor surge? It sounds like you are just seeing a little bov flutter under light throttle conditions.

 

[kicknurass4fun]

Ok so i put the fitting in the lower part of the bov and it helped a lot but now the bov doesnt hold boost for anything over 16psi haha. So That is deffenitly not going to work. Now what is the difference between your bov fluttering and compressor surge. Because with the bov tightend as it should be, it does make a flutering sound at anything below 5psi but isnt that still not haveing the bov functioning properly and is causing compressor surge? Thanks agian for the help guys!!!

 

[DSMSpyder99]

when i had the Type-RS (sorry its a POS went through 2 diaphragms in one year) i couldnt get it too blow off. So i took it apart and took out the little spring inside.

 

[kicknurass4fun]

when i had the Type-RS (sorry its a POS went through 2 diaphragms in one year) i couldnt get it too blow off. So i took it apart and took out the little spring inside.

Ya i'm starting to think the same thing about it. I also took out the smaller spring and it then opened as it should, but then no matter how much I tightend the spring tension it leaked still and it still started to compressor surge. It just doesnt seem like there is a happy medium. Im pretty much ready to rig my lightly crushed 1g bov back on. That thing held strong up to 25psi on a boost test and opened properly all the time. Does anyone else have any advice or suggestions before I put the 1g bov back on?

 

[daren_p]

Ya it seems hard to get a "happy medium". If you tapped the lower port to a pressure source you will more then likely have to tighten the spring tension to get it to hold the higher boost levels. You will want both springs in. Basically tighten it just enough to hold the amount of boost you want to run. This fluttering sound you are getting a low boost levels seems to be common with this valve & isn't compressor surge. For some reason at the lower boost levels it just doen't seem to want to blow off in a solid burst.

 

[suicidal2af]

Ya it seems hard to get a "happy medium".

If you follow the method I posted, getting a happy medium is easy.

That method has been around for at least 4 or 5 years on the Type S. The only different here is the size of the valve, but all that means is you might need an extra thread or two of tension.

They don't have it up anymore on the new website, however:

"How do I set the adjustment? The top nipple on the top section will connect to the intake manifold (behind the throttlebody, so it reads both vacuum and pressure. Make sure it does not get bled off to anything) while the lower fitting is a vent for the internal diaphragm. The lower nipple should be left open and not be connected to anything. Make sure when you adjust the stiffness of the valve that you first loosen the lock nut before you adjust the setscrew. Adjustment will very from car to car, so you will need to use trial and error to find a good setting. Generally you want to valve as tight as possible, without getting any compressor surge. (Compressor surge will sound like a stutter.)m You don't want it too loose or it can open too early and you will loose boost. The valve should make one clean blowing sound, it should not stutter. It should also not open before the throttle is shut. "


"What is the lower nipple for? The lower fitting is a vent for the internal diaphragm. The lower nipple should be left open and not be connected to anything. Do not plug up this opening. "

People didn't follow the instructions, and it caused premature diaphram failure, so when they made the RS, they took the nipple off.

 

[kicknurass4fun]

Yes i did this and it does that fluttering thing when i let off at low boost levels. Isnt this still causing damage to the turbo?

 

[suicidal2af]

Yes i did this and it does that fluttering thing when i let off at low boost levels. Isnt this still causing damage to the turbo?

If it's bov fluttering, no. If it's compressor surge, yes.

 

[kicknurass4fun]

Problem solved!!! I put my lightly crushed 1g bov back on. Opens when its supposed to and held over 25psi on a boost test yesterday. It might not sound as cool as the greddy but thats not what im after any way. Thanks for all the help guys!!!!

 

[oldman]

You have it too tight if it isn't leaking under a normal leak test with the throttle plate closed. I'd wager that if you perform the test with the plate open, you'll find it's not leaking at all.

Normally, you want to plug your bov when you perform a boost leak test.

Edit: To elaborate, imagine this scenario: You are at WOT with about 15psi(just an example). You let off the gas completely and the throttle closes. What's the BOV do?

Hate to pick on you but think about what you're saying. Throttle position have absolutely no effect on the BOV during a static test, there are other air passages which will allow pressurization of areas behind the plate even when it's closed.

Problem solved!!! I put my lightly crushed 1g bov back on. Opens when its supposed to and held over 25psi on a boost test yesterday. It might not sound as cool as the greddy but thats not what im after any way. Thanks for all the help guys!!!!

Good old 1g BOV.