WTF? im building mad boost in neutral!?! [Merged 12-7]

[98TsiAWD]

I want to test my pcv valve under boost. Is there anyway I can get the turbo to boost by reving the engine under the hood?

I recently blew out my dipstick, I did a leakage test and my intake valves are sticking open a little so that would mean boost is getting in there when it shouldnt be right? Causing excess crankcase pressure.

My valve cover breather works fine, I pulled the pcv valve, I can blow through it easily, I also pulled the hose that goes from the pcv to the intake. I make sure it and both fittings where not clogged.

So, basically i want to have the engine under boost just for a second to see if the pcv blows off excess crankcase pressure. But being as there is boost in the intake that will keep the pcv from opening wont it? So my intake valves sticking open is what is causing excess crankcase pressure?

 

[thefisl]

the reason is because he has the hks bov.. that bov is a pull type not a push type like most other bov's. because of this it will blow off with any pressure change which allows it to sound off even in neutral with little to no boost..... also because it is a pull type while at idle it will not open so it does'nt have a rough idle like others would, but it will still mess with you a/f ratio during shifts (i doubt you care though ) hope this answers your question

 

[exzercist]

greddy bov sound too and the hks. stock bov will to just not loud. wrx, srt4s and 3000gt all do to.

 

[Generation1JeY]

alright thanks thefisl that was exactly what i was trying to undersatand. I know that he cant build boost by just barely tapping the throttle, cause thats what i was doing just barely pushing down on the throttle lever and it would swoosh when i dropped it no matter how high it was, but of course the higher i revved it the louder and longer the swishhhhh sounded.

Alright my mind is made up i want that bov in the future or another one that does that. I love my rfl because when i'm actually building boost and i let go it is the loudest one out there. But i like to show my turbo off like most people, and as lame as it might sound that would be fuxoring awsome to just rev and sound the bov.

 

[exzercist]

get the hks ssqv i have it and how it is designed it is not suppose to open under any boost pressure. more you boost more it holds!

 

[AWDGrayBird]

Sounds like you might have low compression or your turbo is going out cause everyone that i know can build boost in nuetral except the kids with low compression. I could build 15psi on a 6k launch and my stock bov was loud a shit but i don't know now because my car is not running but even with the SBR GT13 i bet i can build boost. So check your compression before you waste money on a Bov you might need to replace some rings.
TMO Good Luck

 

[SilverMitsu]

i can build boost in neutral, and power braking...but i'm an auto. So to answer ur question, if ur buddy is an auto, yes he can build boost from powerbraking or in neutral. i have no clue about 5sp.

 

[crankbender]

This has little to do with the exact turbo or BOV. What is happening here is most likely 2 different things that you are not noticing. Before I do into this for educational purposes I have some experiments for everybody out there with this going on.

Do exactly what you were with your hand over the exhaust of the bov. Put your hand in front of it and then just hit the throttle a little bit. Then keep your hand over the bov at idle and see if you can feel any air going in .

After doing this think about what is going on a little and see if you can figure it out. I will be back.

Noise isn't always good :thumbdown

 

[Defiant]

Is it the T-25 That allows him to Neutral Boost?

Why the hell would you want to? Is the one who blows up first the "winner"?

 

[Generation1JeY]

ok forget about the boost. there is no way he is boosting by just revving it for half a second to 2 grand and just dropping the throttle. Ok i realize hes not making boost, so now that that factor is out lets stop talking about idle boosting because i know thats bad.

I pretty much already have the answer to my question, the reason he can do this is because of the HKS SSQ BOV, its a pull kind so the more u boost the more it holds, and yet it opens no matter what if u release the throttle, even when u have vacuum, and even when it opens during vacuum it still sounds. That is the only explanation, but my question now is directed towards everyone who has ever owned an hks ssq or any other kind of pull bov.

Do they sound even if u dont make boost? if u rev a little does the bov open up and sound. The easiest comparison i can make to this if anyone is having trouble understanding is the way the SRT-4s do it. If u have ever heard an srt-4 u know that if they rev a little bit their bov always sounds. Even ones with different bovs. There were about 10 of them at the races on friday and about half of them had aftermarket bovs, they still all sounded by just revving, it doesnt mean they were building boost, i mean theres no way that a turbo can spool up that fast and give u reasonable top end power, so it MUST be their BOVs. But ya anyone here with HKS pull bov or any other kind of pull bov, does it always open and sound by just revving?

 

[yoshimitsuspeed]

It builds some boost just not very much. When I rev my motor with the BOV off it blows a good amount of air out. If you have a BOV that is designed to make noise it is deffinatly enough to do so. If you hooked a whistle up to it it would be pretty damn loud but it may only be 1 or 2 psi. Think about the how many PSI you can blow with your mouth. I don't know how much it is but I can't even get a boost guage or a tire pressure guage to move, but I could get a pop out of a BOV if it opend quick enough and a pretty good woosh to boot.

 

[EPSYCHOBOB]

I can't even get a boost guage or a tire pressure guage to move, but I could get a pop out of a BOV if it opend quick enough and a pretty good woosh to boot.

i blew an autometer carbon fiber boost gauge and got 1psi

 

[98spydert]

I build 10 PSI in neutral on my Big16G.

Me too, with a "stutter box" mod on my chip.

 

[exzercist]

that little blow off test wont work becasue the stock ones are open at idle so there always blowing air out ven at idle and no throttle. i pretty sure all blow offs sound on 2gs cuz of how they are hooked up to the throttle body. my supra doesnt sound and its hooked up different so i really think that the diff unless it could be the actuaotors that let it.

 

[Defiant]

that little blow off test wont work becasue the stock ones are open at idle so there always blowing air out ven at idle and no throttle.

Well, no. In fact, hell no. You're miles wrong. IF the BOV opens at idle, it only lets the engine suck in a little air without having to draw it through the turbo and intercooler, and most of the piping. So long as you're not boosting, an open BOV is actually a slight benefit.

i pretty sure all blow offs sound on 2gs cuz of how they are hooked up to the throttle body. my supra doesnt sound and its hooked up different so i really think that the diff unless it could be the actuaotors that let it.

Your random guesses are appreciated, and thank you for playing.

Now, back to reality.

 

[jmakado]

Your random guesses are appreciated, and thank you for playing.

Now, back to reality.

that was funny......i hate random guesses :laugh:

 

[exzercist]

your tryin to tell me there not open at idle. thats funny becasue mine was on my 2g so and when i gave it throttle it closed so yeah thanks for the random stupid remarks! :laugh:

 

[my95tsi]

damn highschool kids and their loud bov's!!!

 

[sonicnofadz]

I am definitely no expert on BOV's, but I thought that the exhaust from the BOV remained closed until the pressure between the turbo (going from the throttle body to the IC pipes back to the turbo compressor outlet) and the throttle plate increased too high (the pressure in this area builds up REALLY fast when someone closes the throttle plate really quick because the turbo is still spooling and the air has nowhere to go). Am I wrong in this assumption? The above described function of the bov implies that it remains closed until it vents, and when it vents it either recirculates the dumped air into the intake (past the MAS sensor) or vents it to the air (which makes it much more audible) in which the volume of escaped air escapes the computers calculations (in a normal stock mas setup). Isn't this normally how it works or am I being just as silly as the kid Defiant busted on?

From what I understand (which could be VERY VERY wrong) when the engine is idling your reading negative on the boost gauge (relative to the atmospheric pressure) because your pistons are causing a vacuum when they pull downwards on the intake part of the piston cycle. At idle the pistons are the only things causing a vacuum. But when you rev an engine on a turbo car the exhaust gases spin up the exhaust turbine on the turbo which spins the compressor blades and centrifuges air from your intake filter to the IC pipes to create a positive pressure in the intake (instead of negative). So when your vaccuum suddely jumps from -25 to 0, and doesn't create any "boost' (where boost is a postive pressure relative to the atmosphere) the turbo actually DID spin up. It just didn't spin up enough to create a few more pounds of pressure to be considered "postive" (and hence see a positive reading on the boost gauge). To get the turbine really spinning hard (like when launching from 1st gear) to create even more boost requires the transmission to be in gear and the engine getting plenty of air (putting a load on the engine).
So closing the throttle really quick while building 0 psi on the boost gauge (revving it pretty hard) could really cause the BOV to activate since the pressure behind the throttle plate (as in NOT in the intake manifold) increases rapidly for a second while the turbo is still spinning. Why can some cars build more boost than others at neutral? I think this depends on the turbos condition and the condition of the engine, and what type of turbo it is (lighter turbos spin up with less exhaust force).

 

[98spydert]

Here's a very good visual explanation of a blow off valve. Also a good explination of the "lower nipple" that everyone argues about on the Type S.
http://dsmtalk.com/showarticle.php?threadid=51052

Someone needs to explain the fact that while driving and your vac/boost gauge reads 0psi, there is actually positive pressure in the charge pipes created by the turbo...

I just can't explain it very well

 

[leet]

your tryin to tell me there not open at idle. thats funny becasue mine was on my 2g so and when i gave it throttle it closed so yeah thanks for the random stupid remarks! :laugh:

I'm going to go slow here, as I've noticed you can't read.

He stated that it will open at idle, and the engine will SUCK in air through it.

Got it?

 

[sonicnofadz]

Here's a very good visual explanation of a blow off valve. Also a good explination of the "lower nipple" that everyone argues about on the Type S.
http://dsmtalk.com/showarticle.php?threadid=51052

Someone needs to explain the fact that while driving and your vac/boost gauge reads 0psi, there is actually positive pressure in the charge pipes created by the turbo...

I just can't explain it very well

Thats what i just said ^
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[98spydert]

What you said came off as "The blow off valve opens because there's pressure between the turbo and the closed throttle body and that pressure pushes open the valve" The blow off valve is there to releave that pressure, but that pressure doesn't cause the valve to open, the vacuum "signal" from the intake manifold does. If I misread your post, I'm sorry.

 

[sonicnofadz]

I didn't know the pressure from the intake manifold activates the valve opening. I stand corrected.

 

[Generation1JeY]

yes and my original question has been solved, pull type bovs are the salvation to all show turbo guys who like to just rev and sound their bov.

 

[draxus83]

i can bulid up around 12-16 psi on my 1g evo 16 i got to rev it pretty hard but she is more then willing to build the boost I LOVE MY TYPE-S !!!! SHE SCREAMS LIKE MY GURL :laugh: