2g bov leaking after 10~ psi or so...should I buy this crushed 1g bov?

[91rtstealth]

I just got a dsm (finally) and it's my first turbo car, so this is all pretty new to me.

I did a boost leak test recently and found that my stock 2g bov (96 talon, pretty much stock) leaks after about 10-12 psi. A lot of people recommended getting a 1g bov. I found one for 20 bucks on craigslist near me. It's already crushed the the guy selling it said it worked fine on his car with 22 psi. I plan on running about 16. Should I buy this or is there something else you guys would recommend. I'm not totally sure what factors to consider when buying a bov or bpv. Do you want one that will handle well beyond what you plan on running, or do you buy one that handles CLOSE to what you plan on running? I don't get it.

also, what are my options for installing it. So far I"ve found that I could buy a flange adaptor or buy Dave Brode's UIP. What do you think?

 

[renovatdkitchen]

1g Bov's are great for the price. Go ahead with it unless you want to spend more on a tial or something. Possibly look into a FMIC. Great upgrade and you can have it come with a 1G BOV flange.

 

[forumboarder154]

Buy a stock 1g. Crushed is for around 20+.

 

[91rtstealth]

yeah...this dood has one crushed for 20 bucks and he said he used it on his car with 22psi without problems. He just decided to get a tial.

What are you really looking for when you buy a bov? do you really want that overhead of it being able to handle much more boost than you plan to run, or is that overkill?

 

[renovatdkitchen]

overkill with a BOV could be a bad thing. Like if it doesn't open at lower pressures.

 

[NHerron]

I wouldn't buy the CRUSHED 1g bov from a random guy just because he may not have crushed it properly which might cause you some problems like, compressor surge.

Taken from http://www.jumptronix.com/2g_go_faster/Stages/details/BlowOffValve.htm:

Crushing the BOV, in short, entails placing the BOV in a vice and slowly crushing it (making it shorter, not skinnier). The trick is to use a vacuum pump (hand pump is fine) and gauge and crushing the BOV until it remains closed at about 20 mmHg. So don't just stick it in a vice and crush it 0.x inches. You have to use a vacuum gauge to do it right.

20mmHG is just rule of thumb, the specific engine should be tested with a vac gague to see it's lowest reading at idle. You only want enough spring pressure to hold the valve closed at idle.

Contrary to popular assumption, the spring does not hold down boost. It's to hold the bov closed during highest -idle- vacuum. Under boost, the pressure in the intake piping, and the bov signal line (intake manifold) is equal. In other words, pressure on each side of the valve is the same and boost pressure actually keeps it closed. When the throttle plate is quickly shut, it's the combination of manifold 'vacuum' and intake piping pressure that allows the spring to open. AKA pressure diffential

*UPDATE** ^^Actually the spring does assist in a round about way, to hold boost. Typically, you choose a BOV spring according to your lowest manifold vacuum at idle. For example, that could be a 20inHg spring. 20inHg also equals 9.8psi. With 9.8psi below atmospheric pressure (or 20inHg) being applied to the BOV vacuum line, the spring will begin to compress (valve opens). So the spring resists 9.8psi below atmospheric pressure right? Well it also resists 9.8psi ABOVE atmospheric pressure too. BUT that's on the other side of the valve. So the 20inHg spring can also hold 9.8psi boost pressure on it's own. Now, hook up the BOV vacuum line and you now have boost on both sides of valve to keep it closed PLUS the 9.8psi spring to keep the valve from "floating"

Another way to see it is, if you were to disconnect the rubber line going to the bov, the bov would open early, around 10psi. Same with an aftermarket BOV, with the signal (rubber line) disconnected you can tighten the adjustment as far as you want but it won't have much adjustment to it. Tighten too much, you may cause turbo failure from compressor surge.

The jist of why aftermarket BOV's are 'better' is because they are sealed better for higher boost, they provide a bigger passage for massive psi volume to pass through quickly, adjustable to any vacuum, and can be rebuilt. Oh and they look swweeeettt.

In short, for your goals you'll be fine with a 1g BOV UNcrushed. It's been proven to stay sealed for your goals and they can be had on the DSM classifieds. Usually once a week for around $20. Make sure to keep it recirculated.

By the way, our 'BOVs' are not technically blow off valves. Since blow off valves are vented to atmosphere and ours are recirculated

More info (with pics),
FrozenBoost BOV

TIAL BOV spring finder:
TIAL BOV

Hope that helped!

 

[awdtalon4451]

I have a uncrushed 1g for $20 .Works great only reason I took it off is I upgraded to Turboxs. Pm me if your interested

 

[HaveBlue83]

send u a PM bud. Hope to see you in philly so I can get ya squared away.

 

[91rtstealth]

Cool. Thanks everyone for the help. So what's the real difference between crushed and uncrushed?

And I was actually going to ask....if someone wanted to blow off sound couldn't they just eliminate the recirc tube? What would happen if you did this? I don't plan on doing it but I'm curious if you can do that.

 

[Maverick4g63]

Eliminating your recirc tube and venting to the atmosphere will allow metered air to escape. Since the maf sensor has already calculated the volume of air entering the system for combustion and how much fuel is required, a temporarily rich condition will occur once your BOV vents to atmosphere. In short, run your recirc tube unless your running speed density.

 

[2GbTalonGuy]

yes, you can get a louder BOV sound by removing the recirc tube, but it is a bad idea to run without it. Allowing metered air to escape into the atmosphere will cause a rich condition and possibly idle problems, poor performance, and worse gas mileage.

 

[91rtstealth]

Yeah that makes total sense. But at the same time it sounds strikingly familiar to the effect of putting an after market ACTUAL bov that blows into the atmosphere. Would they both have the same effect?

 

[NHerron]

Exactly yes. Removing the tube will have the same effect as having an aftermarket bov vented to atmos. If you want a slightly louder *whoosh* sound, you can replace the factory airbox with a k&n cone air filter

 

[spydreclips6]

Yes, it will have the same effect. The ecu believes the air that is being released from the bov is being put back into the intake. So the air out of the bov plus the air being drawn past the maf equals the total air the ecu thinks is being stuffed into the engine. So with out the bov recirculation it will cause the engine to run rich, ruff, and possible die. This is why some people(who want to vent the bov) switch to a gm maf and maft, because the gm maf will be installed after the bov closer to the intake so the lost air from the bov wont be taken into account when the air reading is being sent to the ecu. However, it is pointless to switch to the gm maft for just the venting because the 2g maf is good up to 400hp.

 

[91rtstealth]

Okok. This def all makes sense. Thanks so much for the info. I actually do have a cone open air filter so I do get a blow off sound. If I ever want to be a ricer for a minute I'll pull over and rip off the recirc tube. Haha. Juuuuust kidding

 

[NHerron]

Its all good, glad everything makes sense

Welcome to the Tuners by the way

 

[91rtstealth]

Thanks. I fear I'm going to put more time Nd money into this car than I had planned. It seems addicting

 

[romeen]

Depending on how much you're willing to spend I would consider a stock EVO 8/9 MR or EVO X BOV (the metal ones). For ever day driving there is more to consider than just the maximum amount of boost that a BOV will hold. How rapidly a BOV responds during part throttle operation affects driveability, BOV chatter and transient boost response.

From researching on the evom forums it appears that these BOV's (not crushed or otherwise modded) typically hold boost into the upper 20's. I have tested my own EVO X BOV to 30psi with no leaks. I love how quickly my BOV responds during part throttle driving.

I've seen used ones for as low as $50 but usually they are closer to $80. Keep in mind that a 1G BOV will require the extra expense of an adapter or an appropriately flanged UICP. An EVO BOV will be a direct fit in place of your 2G BOV.

What the EVO BOV lacks is the bling factor which, admittedly, is important to a lot of guys (I'm saying this sincerely, not sarcastically).

 

[NHerron]

Cool info I didn't know they were direct to bolt on^

 

[deanmeon2]

I think romeen just convinced me to upgrade to an evo9 bov... that's awesome that they are a direct replacement! Will the bov sound any different coming from a stock 2g bov to a evo9 bov?

 

[NHerron]

I doubt it but maybe! I haven't seen what one looks like

 

[romeen]

I think romeen just convinced me to upgrade to an evo9 bov... that's awesome that they are a direct replacement! Will the bov sound any different coming from a stock 2g bov to a evo9 bov?

I don't know. It's been a long time since I've heard a stock 2G BOV. But compared to most aftermarket BOV's, the EVO unit sounds very sharp and crisp as opposed to a more prolonged, lazy whooshing sound. I've never heard any chatter between shifts with mine which is something I've heard some 1G BOV's do. I don't recall if the 1G BOV's that I'm referring to were crushed or not.

 

[91rtstealth]

ohhhh reaaaallllly? Hmm. Maybe I will look into that. That way I don't have to buy the flange adaptor or the UIP pipe. That would be much easier to install. How many different evo bov's are out there? Or will any of them do the trick and bolt right on?

 

[romeen]

ohhhh reaaaallllly? Hmm. Maybe I will look into that. That way I don't have to buy the flange adaptor or the UIP pipe. That would be much easier to install. How many different evo bov's are out there? Or will any of them do the trick and bolt right on?

You want one of the metal BOV's which are found on the EVO 8 or 9 MR as well as all EVO X's. The non-MR EVO's have plastic BOV's (similar to the 2G's) with supposedly weaker springs than the metal units, although I've never actually tested one.

The only difference between the EVO 8/9 MR and EVO X BOV's is the orientation of the nipple for the vacuum/boost reference line. If directly replacing a stock 2G valve then the EVO 8/9 MR unit will have the nipple pointing back towards the passenger side strut tower. The EVO X BOV has it's vacuum/boost nipple rotated 180* so it will be pointing towards the thermostat housing.

 

[fonzi90Tsi]

Wow I didn't know they were that good and worth that Mich. I have one for sale for a lot less!

Maybe I should keep it!