Yeah I know, this comes up every week and you all must be sick of it... but I'll ask anyway.

I was bored earlier today and decided to see how the stock BOV would sound if it dumped to the atmosphere. I disconnected the return hose and pinched and sealed it so no unmetered air can get past the MAS.

The thing sounds great, but of course the idle is pretty messed up. If I let off the gas and coast in neutral the revs drop to 400-500 and then climb back up. The engine doesn't stall, but it comes close. When the car is idling in the driveway, the revs stay between 700 and 1100, slowly climbing and falling.

My question is, what exaclty causes this? Does the BOV leak too much air, even at idle? Would some kind of 1way valve fix this somehow? I need ideas... I love the sound, but I'm not prepared to blow hundreds on a new BOV when the stock one is perfectly fine... and yes, I'm aware that the car runs rich when I let off the gas and accelerate again, but I don't think that makes too much difference. As for spooling, it's the same.

Like you said, you're stalling because the BOV is leaking at idle. You can crush the BOV to make it stop leaking.

It'll probably still stall when you're driving though. I'd recommend you just leave it the way it is.

[ November 18, 2001: Message edited by: Jeff Mitchell ]

It's too late to go back now... I've had a taste of the wooosh.

I'm gonna try to rig up some kind of one way valve so it holds the pressure in at idle but still lets the BOV vent at higher than a few psi or something.

I've heard that the reason it stalls is because the stock bov sucks in air aswell. There was that stupid device selling on ebay for $50 someone made with a check valve and he said it worked and prevented stalling. You can try to make one yourself for $15 or so.

lol someone tried selling it for $50? Ouch. Hope nobody fell for it...

I figured it would keep the valve from leaking any air up to 1psi... after that it would open and let the BOV function as it should. Since it's a 1way valve it would also keep the air out so it works both ways.

I'll try it tomorrow and report back with my findings.

Well, it looks like the idea works... just not the way I made mine.

I went to CT and picked up a 1" gated 1way check valve from the plumbing department, and a barbed fitting to go with it. I cut about 2 inches of hose from the BOV return line and attached one end to the BOV outlet and the other to the barbed fitting which is attached to the check valve.

The valve is not supposed to let any air back in, but the problem is that it doesn't swing shut fast enough, and it doesn't stay sealed.

What I tried after I realized it doesn't work is to put my finger in the valve (its a big whole, and you can snap the gate shut with your hand) and rev the engine manually... I revved up, let go, and the gate swung open releasing air, then when all the pressure was almost gone I snapped the gate shut with my finger. The idle dropped normally to about 800 (I could hear it) and it didn't fluctuate one bit.

Basically now I gotta go back to CT and buy a good spring loaded valve that will snap shut at the right time and keep a good seal.

Just get an aftermarket BOV, it gives the nice whoosh followed by a bang (<-just my car). The bang comes from running rich and then backfiring...hahaha

Heh... $400 for a new BOV or $30 for a simple valve which will make the same sound... lemme think about that one for a minute.

I'll be able to adjust the sound mine makes too with the end fittings... certainly beats buying a new BOV just for the sound.

Darko, I'd like to know how your project works out. I'd be interested in doing something similar to my car if your findings are satisfactory.

Hell, you could probably even SELL it to people who wanted it.

I have the answer for all yous guys that love the WOSHHHHHHH...and that is get a new blow off valve i put the turbo XS racing BOV valve on and I love it it does not idle bad att all it is one of the only BOV'S that close on idle to keep the idle right and you can get this at JRP in toronto costs about 300 bucks but way worth it to see the peoples faces when I go by them and let of the gas to get the big bang..... keep on boosting.


Jer.....

You may also be interested in this thread -
http://www.dsmtalk.com/forums/showthread.php?threadid=29543

Although this is a discussion about a certain type of TurboXS BOV, it also includes venting to atmosphere. (Be patient, sometimes DSMTalk is real busy and times out).

Gates, it works wonderfully.

I just got back from Home Depot an hour ago. I picked up a "2 stage check valve".

Basically it's a long tube (maybe 5 inches) with 2 plastic inserts. Each plastic cylinder has a spring operated piston that opens at a certain psi. I took out the second stage piston and left the insert in there. The first spring was too tight so I cut in 2 thirds away and replaced the parts. I used a small part of the dump tube to connect to the blow off valve, and the other side connected to the valve by a barbed 1" fitting.

I played with the spring for an hour, slowly cutting away at it and testing the sound. Right now my idle is ROCK STEADY at 800rpm. It dips below if I rev up really high and let off, but that's because the spring is too short. The sound of the stock BOV is great and pretty damn loud. I had my buddy stand out on the street and he heard my 1-2 shift from about 500 feet away. With the check valve on, he told me I lost about 25% of the sound but it's still nice. Im gonna continue tweaking it to get the most sound out of it, but I'm very happy that it works as it should.

The only downside is that the 2 stage valve costs $39.99... I'm a crook and I put the valve in a box which had a normal gated valve in it originally and got it for $10. What can I say... I was desparate.

If you can find a regular spring loaded valve it should run ya $20 tops.

This is an email I received from another DSM guy who did almost exactly what Darko did.

I have yet to try this though.


Sent: Friday, November 02, 2001 6:33 PM
Subject: bov check valve


Hi,


I designed this valve to use on my car which is a 1992 AWD Talon. I don't see any reason that it shouldn't work equally nice on a second generation car, as the basic design of the bov is the same although the 2nd gen leaks at high boost. This valve will not prevent any bov from leaking pressure at high boost, what it will do is allow you to vent your bov to atmosphere without suffering idle problems. It is a one way valve(exit only) so it makes it impossible to introduce unmetered air into the intake tract. The reason this works, is because the bov is wide open at idle, or any time there is negative manifold pressure. (vacuum) any time there is vacuum in the manifold, the check valve will be completely sealed. So in conclusion, you get to experience the sound of a vented bov, and retain the streetability of a stock setup. If youve never heard a vented bov, you will be very pleased with this. it sounds like a semi releasing its air brakes every time you shift. Here it is:

This thing is made of 3 basic pieces. 1. Check valve 2. male adapter 3. rubber coupler
Screw the male adapter (nipple fitting) into the end of the check valve with the nut and spring.(inlet end) There is an arrow stamped on the check valve showing direction of flow. Use a piece of rubber hose about 3" long that is the same diameter as the stock bov dump tube to attach the assembly to the stock bov outlet. Plug the dump tube opening on the turbo inlet hose using a 35mm film canister, or something similar. I drilled some large holes around the perimeter of the check valve outlet to diffuse the exiting air. (more flow and noise.) I bought the parts at Menards. They are made by a company called Water Source. (they are well pump parts). The check valve is part number cv100, and cost $9.88. The male adapter is ma100 or mar100, and cost $6.49. Pretty cheap, Huh? If your local building company doesn't stock them, I got their address and phone number for your convenience. Water Source P.O.Box 7615 Des Moines IA, 50322 1-800-346-7611 : If you have anymore questions, don't hesitate to ask. For those of you who suggested that I charge for this, I'm content providing this for free as it didn't cost me anything to think it up. I just hope that all of you will do the same if you come up with something cheap and fast!


Corey

Damn... I didn't think anyone else thought the same idea up. Oh well, great minds think alike.

I'm real happy with the way it's working... although the BOV sounded incredible without any valve or hose attached to it. I'm gonna experiment with different springs and outlet tips to get the loudest sound.

Cool, I just ran outside and tried it

It's nice to finally know the exact sound people are always trying to describe. The Idle thing does suck though

Not sure if is't for me though, well maybe in the spring

I have a question though, does the $300 BOV do anything better than my stock one except make the noise and hold more pressure (more pressure than I will ever need)

If I just wanted the sound why would I pay $300

That's my mentality... the stock 1G BOV is excellent, and it can hold plenty of pressure and even more if it's crushed.

I'm very happy with this little contraption... sure a new BOV would dress up the engine bay and make a louder sound but for $300 I could get a downpipe and a uic pipe and get some REAL gains.

Darko, good work! Also, check your private messages.

An aftermarket BOV can hold more boost, can flow more air, close more quickly after blowing off, don't leak at idle, and they are fully adjustable. Most of these things don't really matter much until you're fairly up there in terms of modifications.



The 1G BOV is very good for a stock piece, but for alot of us (i.e. 2G owners) it's *not* the stock piece. So if we're going to change it, why not get something even better? I'm sure alot of the people you hear talking about aftermarket BOVs are 2G owners. I personally wouldn't change it if I had the 1G BOV stock, but I didn't, so I found a cheap used HKS unit.

Oh, and keep in mind that the aftermarket ones are usually much louder. I'd be interested in hearing one with the check valve though, to see how loud it is.

Jeff Mitchell

Hey Darko, where do you live?
Would you help me do thae same mod?

Jakub,

I'm in Mississauga, about 5 minutes away from Square One.

I'm still looking for a better valve to use. The one I used is totally unnecessary and too expensive.

If you know any plumbing shops or any place other than canadian tire or home depot then we could go together and get you the parts you need. It's really only a 5 minute job with 30 minutes of tweaking.

I'm free until 2:00pm today... I'm not sure about tomorrow. I'm on-call so I probably won't know until later today. Call me at 416-873-0655 or email me at darko@ako.ca and lemme know when you want to do this.

Hey, Drko can you get some pics up?

I'm going to work at 2:30 so I'll snag the digital camera and take some detailed pics when I get home. The job I did is far from clean though... I used electrical tape to twist the original bov return line shut, and the valve I used is twice as long as it needed to be (2 stage instead of 1), but it will give you the idea of what's goin on.

Look for it later tonight.

You've got mail!

Darko, you think you can do some sort of a final write up with pics? A VFAQ?

Getting the right spring/checkvalve combo is the only obstacle here. We need a spring that will stay closed when coasting or driving at slight deceleration but will still open when e let off the gas after boost.

Because if some air leeks out (the check valve opens)while cruising down the highway we will always run rich because the ecu is adding fuel for the air we lose during these situations.

I posted the same thing on dsmtalk

Vince:

Do yuo have any recommendations as for combinations of spring/check valves?

[ November 20, 2001: Message edited by: Gates Perry ]

I'll try to do a formal write up tomorrow if I have time. If I get the pics taken tonight I'll get started on it.

Mine stays sealed at idle and opens even when I let off the throttle under hardly any boost. It's all about experimenting.

I went to another store just now and couldn't find any spring loaded valves. It might be hard to find the right one for a low price since mine is expensive.

Rafal and Jakub are gonne get together with me so we can do the same on their cars. Rafal has a logger so we might try it on my car to see if there are any sideeffects. My assdyno tells me everything is okay though.

That sounds like a great winter project. When I took the dump tube off my BOV the idle was not to bad but I put it back on so the idle was perfect. I would not spent $300 for a new BOV and all you get is sound. Also Jerry, where did you get the body kit? or is it another car's modded to fit yours?

sorry Jeremy, what was i thinking?

I just finnished experimenting with using a film cannister and PCV valve sitting vertical. It holds perfect idle but the sound is not so good (warbley laser beam) because of the bearing bouncing around I think.

Hey Check this baby out
http://www.takakaira.com/accessories/nightpager/nightpager.html

I found this site while researching.

Stupid, Stupid, Stupid!

Yeah I stumbled upon that a while ago... we all had a nice laugh about it.

I hope nobody is stupid enough to waste their money on it... but then again.

That simulated sound sounds like a the cracking of a bottle of pop....I see a lawsuit coming on from Coke/Pepsi.

JR did you have a chance to hear my valve?

so any more updates? Did anyone find a good check valve to use?

We're still looking for the right valve. I found the part number and all that but NOBODY carries it.

The mfg. part # is 101-305, it's a 1" single stage spring loaded brass in-line check valve.

[ November 25, 2001: Message edited by: Darko Miodrag ]

and the manufacturer is B&K.

I'm going to look through our inventory at work, we carry all sorts of valves, fittings, maybe I can borrow something from them.

mabye Keith can get it from Niagara Plumbing?