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View Full Version : Greddy Type-S BOV in stock location problem



Pepperoni
11-24-2004, 08:28 PM
I've tried searching for days (not only here but on other forums as well) along with trying out different things. I have the turbo (t25) set at 9psi.

Basically, I have a greddy type s blow off valve with an RX7 flange/pipe. I decided to mount it in the stock location seeing that i had extra hoses and such. I also wanted to keep the stock look (california). Heres a pic of what it looks like

http://img114.exs.cx/img114/967/09170019.jpg

first off, i kept getting compressor surge no matter how i adjusted the bov. I read that people take out the bigger spring of the two springs inside, so i did. After i did this, I eventually got to the point of no more compressor surge after the adjusting screw is in about half way.

SO heres my problem:
If i boost UP to 3000RPM and let off the throttle, i get no compressor surge. But anything over 3000RPM, i get surge. Either situation im at full (9psi) boost.

Adjusting the bov screw barely does anything apparently; i even took out the screw entirely and it did nothing (engine idle-wise). I thought it was supposed to leak without the screw.

I have the upper (bigger of the two) nipple connected to the corresponding nipple on the throttle body. I also tried connecting the lower nipple to the wastegate, reason being that i read this would help get rid of the compressor
surge; i still got compressor surge with or without connecting the lower nipple.

Should i cough up the money and just get a flange/pipe for the hotpipe and plug up the SMIC, or is there something i can do about this? Im out of ideas. http://forums.freshalloy.com/images/graemlins/tear.gif

cosmoworks
11-24-2004, 10:25 PM
Adjusting the bov screw barely does anything apparently; i even took out the screw entirely and it did nothing (engine idle-wise). I thought it was supposed to leak without the screw.



It does leak. At idle, the larger nipple will draw in outside air due to vacuum. On boost, the larger nipple will leak boost. But because the diameter of the nipple is relatively small, you probably wont notice the leak.




Should i cough up the money and just get a flange/pipe for the hotpipe and plug up the SMIC, or is there something i can do about this?



Get the flanged pipe. I almost went the RX7 adapter for my BOV setup, but the inlet diameter of my adapter was only 3/4" inch. I ended up buying the greddy flange, popped a 1.25" hole in my cold-pipe and welded the flange on.

My guess is that because of that restriction of the RX7 adapter (and the fact that your BOV outlet hose is kinked), I think that's there's the source of your flow restriction, and thus surge.

-Cosmo

Pepperoni
11-24-2004, 10:35 PM
Thanks for the reply.

I hadn't thought about that; i did notice the rx7 pipe was smaller, but it never came across my mind that this would cause me to have compressor surge.

Do you know where I can find a flanged pipe?

Pepperoni
11-25-2004, 06:30 PM
Thanks again cosmoworks, u hit it right on the head. All the stores were closed today, so I ended up cutting the RX7 flange, to get rid of the bottleneck design

For those that don't know, it looks like this
http://img127.exs.cx/img127/2123/09170004.jpg

and after i cut the little end, it's now like this
http://img8.exs.cx/img8/9517/9220005.jpg

I also ended up rerouting everything to the engine bay, by the air filter. So now the hose from the BOV to the Intake is only about 3-4" and now the BOV is much louder than before, when the hose used to be a good 10" length at least.

Now im finally happy with this blow off valve http://forums.freshalloy.com/images/graemlins/smile.gif

Hugh
11-25-2004, 06:57 PM
So your BOV vacuum source is coming from the throttle body?

I always hooked mine up to the Intercooler piping. This usually gives it quicker response, helping to reduce that surge.

cosmoworks
11-26-2004, 12:46 AM
Thanks again cosmoworks, u hit it right on the head. All the stores were closed today, so I ended up cutting the RX7 flange, to get rid of the bottleneck design

Now im finally happy with this blow off valve




Hmmm, I never thought about cutting the adapter back... that'd work too. I ended up selling my adapter off, and just welded a Greddy aluminum flange onto the pipe. Glad to hear the cut back adapter worked out for you. http://forums.freshalloy.com/images/graemlins/smile.gif



So your BOV vacuum source is coming from the throttle body?

I always hooked mine up to the Intercooler piping. This usually gives it quicker response, helping to reduce that surge.



How's that work Hugh? The Type-S needs to see the plenum vacuum on the larger nipple when the throttle body closes to help pull the valve open.

-Cosmo

Hugh
11-26-2004, 01:37 AM
Thats a really good question... but I've always hooked mine up to the intercooler piping and it seems to work pretty well. http://forums.freshalloy.com/images/graemlins/smirk.gif

Maybe I'm crazy...