There was a bunch of theories on it, and i've been determined since my turbo install to get the sucker properly opening AND recirculating, FULLY preventing compressor surge. Didn't expect it to take so long to figure out (it's in a nasty spot also).

I hooked up the BOV with the recirc piece as instructed and with the included hose. I think over time i'd tried every possible setting with both springs in, only one in, screw setting all the way loose and all the way tight in both cases. Always surge!

Several months ago, I managed to get the BOV venting to the atmosphere. Pretty much done like any other BOV. The setting for anyones reference was:

-- Both springs installed
-- Tightened to several threads from all the way tight

Worked real nice, releasing at 0-1 PSI and sounded awesome!! But this caused driveability/idle issues for me because of the air having already been metered, and besides, I did ultimately want to get it recirculated. On the exact same setting with the recirc piece back on it was surging again!

The IAP kit's Greddy-RS comes with the 19mm recirculating piece, and crankcase vent-sized hose for recirculating tube, with a nipple on the turbo pipe that can't be any bigger than 12-13mm. Herein lies the problem!

On a hunch, I bought a $21 34mm RS-BOV recirculating piece, along with the somewhat standard "Home Depot" (and rather large) flexible plumbing, ready to do some not-so-fun custom work & fabrication.

Attached the new 34mm fitting to the BOV. Plumbed the line upwards (cutting a bit more out of the body...) back into the engine bay. Made a new custom pipe from turbo compressor to air filter with a new extension/adaptor/nipple almost 2x as wide as the IAP one. Attached hose with clamps. Doing this took the better part of a day, but hey that's alright.

After first test drive, got surge, but with a hint of air. Setting was only one spring inside, screw quite loose. So I tightened it a whole bunch to test.

Was all surge. So I unscrewed that screw ALL the way out, and finger-tightened it slightly.

FINALLY!

Just a little PFFF... sound! It sounds great and is actually pretty quiet!

---
To recap/summarize how to recirculate the Greddy RS:

-- Get 34mm adaptor for RS
-- Get large hose for plumbing
-- Use larger inlet for turbo compressor pipe
-- Only one spring in BOV, loosened as much as possible
-----

So anyhoo, here are some pics of the working set up!

DARE TO COMPARE - 19mm vs. 34mm!

Initial look at the area...

New fitting and hose attached to BOV:

Some shots of the set up:

At last, I can sleep at night again.

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ATMOSPHERE:
-- Use full-size vent piece
-- Make sure both springs are in the BOV (comes already like this when bought)
-- Tighten the BOV adjusting screw down to about halfway or a bit more
-- Loosen more if you're getting surge above 1-2 PSI of throttle release
-- Tighten more if it's making a long bird-singing noise after releasing or if your vacuum reading is low

RECIRCULATED:
-- Get 34mm adaptor for your Greddy RS!
(example - http://www.motiongarage.com/st...id=70)
-- Get large hose for plumbing that JUST fits over the fitting
-- Get some clamps also to ensure air tight and secure
-- On pipe between turbo compressor and MAF, weld on/create a much larger nipple (probably somewhere around the 34mm..)
-- Run plumbing from BOV to new nipple (obviously)
-- Only one spring in BOV (larger one), loosened as much as possible
-- Or make slight adjustments as needed to eliminate the surge

Thanks for the comments! I was very happy as well!! I love you too AZ lol!

EDIT: Broguht ADAPTER! WOOHOO!

Modified by GEO at 9:11 AM 7/19/2006

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Click the above image to check out my ride!

NICO NITE KREW

Good work finding a solution for it

I'll see if my bro's willing to do some filming again, then maybe I could upload the sound of it..

Truth is Treason in the Kingdom of Lies - Ron Paul

1992 Nissan 240sx KA24DE-Turbo: The "Showcar"
Stock internals
532whp/486ft.lbs-30psi
12.6@122.3mph-22psi
http://ka-t.org/cory_b.php

Anyways, the pipe is actually 3 inches, about the same size (if not exactly the same) as the IAP one. The couplers are sized correctly...and I figure this is a pretty standard size for the pipe, no?

Is that what you meant? Let me know..

And thanks WDRacing!

I was really picky with exactly when mine opened when I was vented, so it took me 5-6 test runs to get it just right.

Your setup looks good, make sure the seal is good on the BOV's gasket. Also, get the vacuum feed for the BOV from your FPR or some other source near the intake manifold...that's about it.

Good luck.

"gregatnico"

Cheers.

http://www.gofastbits.com.au/i..._info

I have been dealing with this foul sound since mine was finished - I didn't think I'd need to do this modification but I now see that I do!!!

Also didn't realize I needed to open up the BOV and remove a spring - This is good news.

Bad news = My beautiful polished SS intake pipe will now need a larger port (or maybe I'll make a "tee" and just drill another port so the BOV charge enters the intake in 2 seperate places).

Guess I know what I'm working on this weekend!

you need it connected to somewhere after the TB so that vacuum is applied once you let off and the difference in pressure allows the BOV to open....

GT42R powered KA-T
http://www.ka-t.org/ryan_k.php

Leave the nipple 3" from your BOV for a dedicated wastegate connection instead of for the BOV. That will open your external wastegate when it sees the boost. This is an important connection obviously so make sure it's secure!

Then, run a nice long vacuum line from your BOV all the way to your intake manifold vacuum source, preferrably fed off of the FPR.

That's how mine is set up, and that almost indefinitely will get your RS opening up happily.

Now with the above configuration, you may find both springs necessary to get it working. I did. With 1 spring in there was a large vacuum loss through the BOV's opening to atmosphere on idle. Basically, to vent, the BOV likes to be tight.

Let me know.

P.S. AZHitman -- Good luck on your project lol....let us know how it goes for ya for sure!

I was only implying avoiding bolting the hotpipe tee to save time and prevent too many tee's on your FPR, but i'm sure it'll be fine.

Let us know..

The 5-tee thing might be suspect, make sure there are no vac leaks..

But man what a nuisance they can be until "just right" though....I feel your pain...hang in there, it's worth it!

Good luck man, let us know.

Works fine. Loud as hell tho!

And yeah, the atmospheric RS is kinda loud...but it sounds great if ya ask me.

Wait till I upload some vids of the recirc'd setup i've got! It's quiet but has an interesting sound...

kay, I tightened mines all the way down, comp. surge through all psi... loosened it all the way out... still compr. surge...

WTF?

I took it apart and took out one of the springs, it seems to be working ok now... don't hear much, but at least I don't hear the "flutter" now