Atmospheric blow-off on FC?

[jimmydanny]

How is that working with the original MAF? Or should I get a recirc while I\'m at it? This is for now just cosmetic (in terms of sound), as the original.. well isn\'t making a sound?

Jim

[pdtaylor18]

The blow off valve simply plumbs itself into the intake system, to vent this to atmosphere does not affect the MAF, it will give you a better sound to atmosphere and is what most favour to do with aftermarker valves.  As for no sound when its standard then you will probably not hear it if you have standard plumbing and air box, that thing really does its job well.  As far as the cosmetic side of things then the valve does not need to be where it is, some say better to be closer to the TB as possible, some put this where there is room and others for show and shine purposes, the sound will be the same no matter where it goes in the engine bay, just keep the vac hose as short as possible.

[Brett]

Pete\'s just said most of what I was thinking

Obviously you will need to block the hole left in the inlet when removing the OEM valve. :wave

[Prof]

+2 on what they said ^^

[soldave]

Wouldn\'t it affect the MAF though?  Have had this discussion before on an early Evo site as people were putting on VTA BOVs and wondering why the car was stalling when coming off the gas and into neutral.

The MAF will tell the ECU that a certain amount of air is entering the engine, which then calculates an appropriate amount of fuel taking into account throttle position, intake temperature, random bits of witchcraft etc.  When you vent to atmosphere for a short time the ECU will be expecting a higher air volume than is actually entering the engine.  So it will run very rich for a very short time.  Now I don\'t know how sensitive the FC\'s ECU is to that, but I know the Mitsubshi Evo ECU didn\'t like it at all and most people who vented to atmosphere realised the errors of their ways sharpish.

Now on a MAP sensor car, that\'s another matter altogether...

[Brett]

I ran my old T2 stock bar an atmo valve, never had any issues

[pdtaylor18]

If you think about it the valve works when you are coming off boost, hence the foot is off the throttle and you will be in a leanish state for those few seconds anyway until you plant that foot again. The air entering the airbox from the valve may not be enough to make any difference to the volume of air for those few seconds with the type of MAF installed and maybe the reason why none of us have experiened any problems. A standard ECU does run rich anyway out of the idle area. It would have been interesting though to have mapped that with a wideband at those presise moments and see whether or not the ECU compensates in any way.

[dthebuk]

Why go for a bov? Might aswell just run nothing. It will give better performance than a bov. And it should sound much better. Never heard a TII tub chatter mind

[jimmydanny]

Tell me, where is the valve? Pics please. I found something that should be it, just behind the air filter, there is a hose going back to something looking like the valve, with a hose going into the intake straight after/before the intercooler again. But when I took the original valve and plugged the air filter side, the car wouldn\'t idle, so I guess that can\'t be it.

[jimmydanny]

Why go for a bov? Might aswell just run nothing. It will give better performance than a bov. And it should sound much better. Never heard a TII tub chatter mind

If I run without a BOV or recirc I will blast my turbo. Blasting I dunno how many liters of air @ 0.7-1 bar into the turbo trying to reverse it is no good, TII or V12

[dthebuk]

theres some piping with a valvle in which goes from Turbo - Intercooler piping to the Turbo intake ducting (comes from the air box) Some of the piping has an arrow on it also.


As for the whole BOV argument, I\'ve run turbo car\'s for silly miles with no sort of bov/recirc and they\'ve been absolutely fine. never tried on the fc mind

[jimmydanny]

Try it in longer periods. Might need a new turbo, especially if you run high boost.

Anyways, my car wont idle when the air filter side is plugged (with a screwdriver^^), but when I put the recirc into the air filter side again, it idles perfectly @ 600rpm.

What can cause this? What else does the original recirc do? I mean, it is just a piston in there. Might it be that the vacuum sucks the piston up and makes it stay open or something? Shouldn\'t really matter.

The ONLY difference except having no tubing on the air filter side of the valve, is the angle the valve is staying at. When connected it is horizontal, when I disconnected it, it is vertical. Might this have something to do with it?

[jimmydanny]

Still same issue here folks. When the pre-turbo side is open on the valve (and plugged on the intake ofc. dont want to suck snow into the turbo), there is no idle. It goes to 2k when I start it, and it dies. When I connect the pre-turbo side of the valve to the intake again, it idles. Tried all positions with the valve (ie angle, horiz, vertic and so on).

Also tried by sucking on the vacuum tube from the valve. When I release I hear the spring hit the plastic, so that means the piston is also moving, which means the valve works.

What is this weird thing happening here

[soldave]

Try it in longer periods. Might need a new turbo, especially if you run high boost.

This.  I was running 1.8bar in my Evo and the one time I tried without the BOV the sound scared the bejeezus out when I actually thought about what was making it.

[jimmydanny]

Okay, still, anyone got an answer for me? This is really bugging me. The valve is a normal recirc, I should be able to plug both holes and the car should still run, but it kinda wont without the valve attached to both sides of the turbo.  If I found a picture, I could explain.