I have a FD upper on an FC engine.
My Vacuum port on the Upper manifold,facing front...The BIG one of the 3 located by the TB is giving me TOO much vacuum and keeps the BOV open on Idle.(noticed this especially on start up)
The BOV is a JGS 50mm.
I am wondering IF there is another Port that can be used OR is my Spring too weak on my BOV?.(I can change springs.)
Thanks Gentlemen.
STYX.

 

Spring is too weak. Being open at idle is not necessarily a bad thing though.

 

The bov isn't adjustable? ...could always pick up a used greddy bov

 

DOH! If it does not have a filter on it, then it can suck in dirt.

Get real.

 

At idle air is pushed out of my BOV, no filter needed.

 

Renesisfd is correct, it is not a bad thing at all, in fact Synapse has a BOV designed to do just that yours is currently doing. They claim it improves throttle response cause the motor can momentarily pull air through while it waits for the turbo to start flowing enough air to overcome the vac. However if you want to correct this and your BOV does not have a adjustment screw you will need to put a harder spring that the BOV should have came with.

 

I have to disagree. You dont want a BOV open at idle. When the primary is trying to spool up, it will take longer to get to positive pressure, as the open BOV acts as a boost leak that the turbo must overcome. Thus boost takes longer to come.

I would use a stiffer spring or adjust yours harder. The thing is, manifold vacuum *should* be equal within all parts of the UIM and its runners. I'd be skeptical that the manifold vacuum could be different in different parts. More than likely something is not hooked up correctly causing the issue.

I'm not familiar with the FC UIM, but try taking the vacuum signal hose you are trying to use, and putting a bolt in the end. Start the car. Observe the idle speed.
Now take the bolt out while still idling. Does idle speed increase? If not, then that is not a vacuum source appropriate to operate a BOV.

 

In actuality it helps the spool of the turbo. The fast response to throttle in turn creates more exhaust pressure, and what are turbos spooled with? Exhaust pressure. The BOV works off of vac, so in theory as soon as you crack that throttle you drop vac, however the open BOV feeds air directly into the TB instead of trying to pull it through a turbine. So once that surge goes through your exhaust it will actually spool you faster. This is all explained and tested by Synapse. I was skeptical as well however after the tests they ran its very clear it helps spool time.

As for the location of the vac line you are correct the vac should be identical throughout the manifold after the TB.

 

Why would I want a used blow off valve when the one I got is NEW?
The blow off valve is a JGS 50mm.It comes with different rate springs.
It is open like all the way at idle though.I noticed this especially on start up.I can't SEE it on driving..heh,heh!
I need a c clip plier set to take the spring out though.
Sa3R,I am using the UPPER FD manifold on an s5 Lower,so really it is the same setup as an FD all the way UP to The TB.It just has **** blocked off,and Properly too.I made Damn sure nothing was gonna leak,using Vac Caps AND clamps.
I'll try another spring.Even if I can get it to close half way,it will a lot better.
Right now I just drive the car without the BOV hooked up.I get some compressor surge but it runs Real good!

 

Your spring is too soft for your application.
That is why good BOVs are either directly adjustbale or use shims.

 

Why is it too soft? If air is pushed out then it is fine. The stiffer spring made the compressor surge.

BTW, It is only open about 1/2 way and shuts once the throttle is opened.

It is a Tial Q BOV is that a good one?

 

Lol nice

 

15,000 posts and makes a thread about BOVs...

 

He is allowed, with how much time he spends moderating the new member section I don't know how he has time for anything else, I forgot he had a car.

 

He's an FC guy with an FD UIM. And his post count is because he's a mod. What's your point?

 

the point is if you search BOV you get a million hits.

which bov is best?
what bov sound is this?
no bov is bad?
how do i put a bov on my stock t2/ fd?
this BOV vs that BOV
BOV is leaking?
still have compressor surge with bov
bov leaking at idle!!?? HELP!
bov placement


with 15,000 posts surely you have your own opinion on BOVs. and being in the new member section as you say im sure gets pounded with BOV questions.


however my contribution to the thread would be to find a medium, to hard of a spring and it wont vent, too soft and you get open on idle.

my experience was a light spring that was open on idle but snapped shut with the slightest throttle input. and worked well for a cheapo bov.
my FD wont have a bov on it. but its an s366 that has the ported shroud. but may go BOV if the sound annoys me.

 

^His thread wasn't asking any of those questions. He 's got an unusual situation with a hybrid intake and wondering about vacuum supply for the BOV, not a BOV recommendation.

Search "Car won't start" and you'd get a million hits too. But that doesn't stop them from coming....does it?

 

For the average car owner who is somewhat of a mechanic, it would not be a problem.
He does not have the KNACK.

He could be a government official.

 

Yeah...I know what you mean. I see people talking about guns and Sniper rifles who have little first hand knowledge too.
I just think he's a guy who's worked hard helping others and deserves a little courtesy for a reasonable queston.

 

Lol LIKE BUTTON!!!

 

442 posts and still knows Zilch about posting etiquette.
Search "thread crap"..it will show your last post.
.So kindly post elsewhere.

I get 2 minutes to post a thread and I get a heckler..Nice place...is thing thing on?
..........
Ok,does anyone know if the Vac nipples on the FD upper show as ALL Vac?..or some Vac/boost?..
As Sarge stated I have been an avid FC owner for 8 years.,so this FD Upper mani is something that I am not familiar with.
Thanks again.

 

I replaced the spring...helped a lot.Needs a slight adjust though,and I found the way to do it.They hide the adjustment IN the bov itself (this BOV has NO diaphragm).
Thanks to those who posted some advice.

I May not have "The Knack".(lol)..,BUT I Do have the First Led Zeppelin album..
Woodstock is not a Shotgun Butt...