Blowthrough MAFT installed! Pics inside>

[tsitalon1]

Funny thing about a bov.... I pressure tested mine to 21 psi. However upon venting to atmosphere the damn thing would open under partial boost and the car would buck violently.... So it was opening and it still is

 

[LucidEclipse]

I pressure tested the system w/ the blow off valve vented, there should be no difference whether the turbo is pushing the air or an electric compressor is pushing the same (or higher) amount of psi. Agreed?

 

[Black95TSIawd]

Thats a 1g bov u have right?

 

[tsitalon1]

I have a 1g bov yes

 

[Green93TalonTSi]

Have u done the BOV mod yet ? so that it holds 30psi ? If not, u know the stock bov only holds 16psi. And you said u were pressure testing at 18-19psi ? I bet there is a leak , but u dont here it. I found a small leak when doing a test and I didnt even here it, I felt around for exscaping air. You should re-test it to make sure the bov isnt leaking.

 

[LucidEclipse]

My 1g bov has never been modded, It is holding all the way up to 19 psi no problem, When I pressure test, I always read the boost gauge and it read a steady 19 psi for about 35 sec. then the pvc endcap blew off (I guess I didn't tighten it enough) I have one of those good 1g's i guess. Oh and funny thing, my stock bov held 16-17 psi. no problem. Go figure, I was pretty amazed myself after reading review after review on how much the 2g bov's suck.

 

[tanner261]

My unmodded 1G BOV opens at 20 psi, to fix this I'm going to perform the Dejontool fix, as should anyone trying to run 18+ psi on a 1G BOV. You can get the Mac Valve from http://www.fierofp.com/ part number 111A-1111

 

[LucidEclipse]

thanks for the info, I'll be running ~20 psi in the next month of so (if funds allow) I'm just happy I don't need safc anymore cuz theres another 280 bucks I can use for the injectors and pump. One question though, Can I run a 190 lph pump with stock wires? I've heard that running bigger wires will give it a steadier flow but I have also heard that it is bad, there was a reason I just can't remember what it was now.

 

[tanner261]

Larger gauge wire will supply more voltage to the pump, thus more pressure is supplied. I feel this mod is not required and just adds another vaiable to fail in your fuel system. You need to first determine if you have a voltage problem before trying to fix what isn't wrong.

 

[JayHass]

Originally posted by LucidEclipse
Holy crap DC, that makes perfect sense (after i read it like 5 times ) Yea my bov isnt leaking, The whole system held ~18-19 psi without any problem until it shot the PVC end cap I was sealing the system off with out of the compressor side. I was gonna run it up higher but I didn't feel like putting the end cap back in (19 psi. is enough anyway) JayHass and Tsitalon1 wheres my 150 bucks? (j/k)

Damn sorry for the delay, I forgot about this post. :laugh:

Lucid, pressure testing and the way your BOV acts in the real world sometimes are not the same. Believe me, I pressure tested the crap out of my SE-R but when driving down the road, my TiAl wouldn't open (Divorced) yet I couldn't build more than 12-14psi. My boost controller acted all screwed up and I was pulling my hair out.

I blocked off my BOV, and the TiAl opened up with a nice BLAHHHHHHH and all was well in the world. My BOV was controlling boost! I called and got a much stiffer spring in the HKS BOV, cranked it down and away it went with normal operation.

Now I'm not saying it's 100% your BOV but they are friggen notorious for causing problems, even when they check out "okay". Try blocking it off with something and go for a rip and see if you get your boost back. If not, no harm no foul, if so...you know the drill.

DCJ98GST: I agree with a lot of what you said. Thanks for the dissertation.

 

[LucidEclipse]

you want me to block the BOV completely? That will cause compressor surge! I don't completely understand your reasoning either saying that
"pressure testing and the way your BOV acts in the real world sometimes are not the same. " I'm not saying that i disagree with you, however the way I see it 18 psi is 18 psi, whether it comes from the turbo or an external source.

 

[tsitalon1]

He's right ! Blocking it off temporarily just to boost once or twice is not gonna kill your turbo ! It will help diagnose if the bov leaks... If blocked off and you get more boost then there you go !
James

 

[pneumo]

During a pressure test the air is not flowing, so all parts of the intake system have exactly the same pressure. But, in a running car at boost there is a pressure drop all along the intake piping. The manifold will see less pressure than at the BOV, and the BOV is made to open when the pressure at the BOV is a certain ammount higher than the pressure at the manifold. Since you added the MAFT after the BOV there is more restriction between the BOV and the manifold, which gives you enough pressure drop to make the BOV open.

 

[LucidEclipse]

So what to do? I love my 1g bov. Its all polished and everything and I think the sound is awesome. I guess its time to do the mod to it? I know that no other part of my system is leaking cuz I would've heard it hissing somewhere. So I guess most likely it's the bov, right?

 

[pneumo]

So just crush the BOV. That's the easiest way, and it's been proven to work. Basically it just tightens the spring in the BOV. All you do is put the BOV in a vice with the flange base on one jaw and the top of the "hat" on the other jaw. Carefully squeeze the top down until the clearance between the manifold/BOV line pipe is a pennies width away from the case below it. It should only take 1 or 1.5 mm worth to do it right. If you're unsure about it, ask for details. If you crush it too much the BOV won't open early enough, and you'll get compressor surge.

 

[LucidEclipse]

I was thinking about that, but I don't want to screw up the nice polished look to this one, I would rather just sell it and get a hks ssqv or a blitz dd super sound. Funny thing, I get compressor surge with my 1g bov if I boost it at low rpm (below 2400) and let off the throttle quick, I get the che che che sound. Eh, maybe a little crushin' wont hurt.

 

[Green93TalonTSi]

Dont crush it, it puts more stress on the spring. THeres already a high amount of stress on the bov the way it is now, and if u crush u run the risk of making it leak even more. Just do the mod on VFAQ, its a lot easier, u drill 1 hole and use 2 set screws and ur done. once u do that, u can hold 30psi, and it wil start releasing hard, and the noise kinda sounds like rally car, it chatters a lil bit and it gives a loud tttthhhhhhrrrreeeeewwwwww type noise. Good luck.

 

[JayHass]

Originally posted by LucidEclipse
you want me to block the BOV completely? That will cause compressor surge!

Yep, just block that bad boy off. It's the easiest way to diagnose it. Compressor surge won't kill your turbo instantly. As a precaution just don't snap the throttle closed after you boost it.

As for crushing the BOV, I just used a spark plug socket (The small one) and a mallet. Started tapping it down lightly until it was at the level I wanted. I personally crushed the crap out of it and I get a *small* amount of surge at lower rpms. I also have mine vented to atmosphere with a one way valve system I made myself. It seals tight at idle and goes "POOOOooooosh" when I let off. (Yea that's my big ricer outlet. )

You don't have to remove the thing to cap it, just plug the outlet with something. Even a hose with something clamped in the end. (Just be sure to clamp it tight or you will make a cannon. )

Good luck.

 

[chaye]

question about this set up ....im looking to do the same..
where did you buy the MAF..dejon or the junk yard..and does the connector from your dsm MAF plugs right in to the GM?
and what piping did you use..stock snorkle with custom everything else??
thanks man..
i just bought the HKS BOV today and i was thinking of doing this but for like 400 of piping i might get the upc with hks flange and custom make the other stuff.
thanks ..

 

[chaye]

no answer.........

 

[LucidEclipse]

Junkyard,
no, you need the translator, then it does.
new dejon 3" pipe (look at pic)

 

[jpolizo]

Originally posted by tanner261
Larger gauge wire will supply more voltage to the pump, thus more pressure is supplied. I feel this mod is not required and just adds another vaiable to fail in your fuel system. You need to first determine if you have a voltage problem before trying to fix what isn't wrong.

RRE has some good info on this. Keeping the pump voltage at 14 results in more fuel flow; the stock wiring is pretty danged small and you get a voltage drop that cuts pump flow. The rewire will give you more flow out of whatever pump you have.

http://www.roadraceengineering.com/fuelpumpflowrates.htm

 

[jake98gst]

i get what feels like compressor surge right around 3000 when at wot. im a completely stock 98 GST A/T with removed stock bcs. is my bov f'd up and not opening early enough? also. during the "stutter" i sometimes get a cylinder misfire CEL ...bov problems or what? thanks.

thanks for the fuel pump link ive been wondering about that.