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Choosing a blow off valve, what should I be looking for?


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Alright, Ill start this by saying I am a cheapskate. Screw paying 250 bucks for a valve that dumps air into the atmosphere!

 

I don't much care about sound honestly.

 

I am considering the Tial, but at 210 shipped its not cheap! But I never hear anything bad about them.

 

Has anyone ever used a Forge motorsports BOV? they seem to be very popular in for the german car crews. Seems you can get shims and springs to make it vent when you want it to. They also have a sock like filter to keep debris out.

 

My one hesitation is not knowing wether or not it will have enough flow to vent off all the air coming back. This is on an RB25DET with a t3/t04e. I expect low 400s for HP at the rear wheels.

 

The inlet is about 1.5" from what I can see. The kicker is that its only 125 on amazon.com and I have a gift card from there that will drop the price to 70 bucks or so.

 

http://www.amazon.com/Forge-Motorsport-FMDVF005-pol-Piston-Filter/dp/B000ED0BJS/ref=sr_1_1?ie=UTF8&s=automotive&qid=1201906806&sr=8-1

 

Any thoughts? Or am I barking up the wrong tree? I know its a noobish question but I have trouble bringing myself to pony up big bucks for a part that seems to deeply involved in fashion!

 

Thanks guys - Evan

 

BTW, I have been running a blow through setup since I built this car, so don't worry about me having trouble there!

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I'm sure it will flow enough air to keep your turbo happy. My only warning is to beware of buying from wholesale places. They will usually have the best price but really crappy customer service. If you ever have a problem with the product getting some kind of support could be tough.

 

Brandon

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What kind of fuel management are you using? do you have afm or maf style sensor? If you do, it is preferable to have a "bypass" valve and not a "blowoff" Something that can vent the released air back into the air intake so it does not confuse the air flow sensor. If you just realease the air, you will get a very rich condition causing black smoke or even flammage out your exhaust pipe between gear shifts.. LOL

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What kind of fuel management are you using? do you have afm or maf style sensor? If you do, it is preferable to have a "bypass" valve and not a "blowoff" Something that can vent the released air back into the air intake so it does not confuse the air flow sensor. If you just realease the air, you will get a very rich condition causing black smoke or even flammage out your exhaust pipe between gear shifts.. LOL

 

I run a blow through setup with a maf, so thats not a concern.

 

Thanks for the advice on the SS autochrome. The forge looks good because I have a gift certificate that will cover most of it.

 

Thanks! - Evan

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I run a blow through setup with a maf, so thats not a concern.

 

Thanks for the advice on the SS autochrome. The forge looks good because I have a gift certificate that will cover most of it.

 

Thanks! - Evan

 

Blow through huh? I thought about doing that as well. I ended up finding a AEM ecu and am gonna run a map sensor instead. Just out of curiosity, how do you like that setup? Any issues? I was thinking that you could not use the factory PCV setup and would have to get a catch can.

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Evan,

 

I plan on going the SS Autochrome route. $100 vs $200+.

 

Stony did a great comparison thread and it seems for a lot less money you can have the exact same quality part minus the "name".

 

Good Luck,

 

Jon Taylor tried a ebay 50mm wastgate and it was junk. outside looked pretty good but the parts inside were pure junk. It leaked from the get go and never worked right. Right now I have a greddy type S. Its ok for now but I will be going Tial when I redo all of my intercooler piping. If you do decide to get the SSautochrome unit.. Let us know how it does..

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The SS autochrome unit has me somewhat interested. Problem is, I have already had a knockoff BOV that leaked and caused problems. I don't wanna go there again.

 

I have an HKS SSQV that I am almost 100% is a knockoff. Its so quiet you can't hear it. I don't mind it, I just don't trust it. I don't want a damn chirp! So annoying.

 

Yeah, I am running blow through, it works fine. Map would be better of course. I am running a catch can and all that jazz.

 

Thanks guys, maybe I just go ahead and try the Forge, then report back. Worst case scenario I loose a few bucks and we all know they suck!

 

Evan

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I have an ssautochrome tial knock off and it works fine but I have no way of knowing what spring is inside it. Looking at my vacuum at idle I ordered the correct one. Once I open it up I'll post pics of the whole tear down but for now it works fine. Boost is about 13 currently

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First gen DSM BOV, they hold 17psi stock and you're able to mod them (not crushing) to hold 30+psi... Need more air movement?? use 2? they're cheap enough and can be polished/painted to be classy-like.

 

Just make sure you put a filter on them, they're open at idle.

 

Shane

 

 

http://thedodgegarage.com/turbo_bov_mod.html

 

Dude that is awesome! Maybe Ill go this route, I wish those contraptions didn't have the goofy DSM flange on em!

 

I can tell you, Ill be doing that to my buddys DSM.

 

Evan

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Stay away from the 'loud' valves. They use high flow rates across the orifice to make the noise. That actually disrupts flow, so they need to oversize the valve orifice to get it to flow what it does.

 

Listen to a Porsche next time he shifts, and tell me what you hear. Then take a look at how big their valve is...

 

The blowoff should sound like a big sigh more than anything else. i liked the old Indycar Blowoffs: Nothing then WHOOMP! Just blow open,vent and close as soon as the throttle was reopened. Never heard a 'woosh' or a 'chirp' just the sound that felt like someone hitting you across the kidneys with a cricket bat! Man, I miss 47" Hg Turboboost and manual shifts off turn 11 at Long Beach...

 

I digress!

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Stay away from the 'loud' valves. They use high flow rates across the orifice to make the noise. That actually disrupts flow, so they need to oversize the valve orifice to get it to flow what it does.

 

 

Wow, I did not know that. Very good tidbit of info there for sure.

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I bought a Forge unit after looking into various unit with little objective information at hand, despite much searching. I have a MAP based EFI and run my BOV as open, but got a recirc unit to ensure that the outlet was solely designed for flow and not noise generation. You can certainly hear it from inside the car as a whoosh but nothing loud, which was my goal. Had it for over a year now and can recommend it. Came with 3 springs and hence good adjustability, solid built and excellent customer service. My friend got a similar unit for his supra after my positive experience and is also very satisfied with his purchase.

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