I was giving it some thoughts lately, maybe a bit too much. But the stock system dumps air back into the intake when you let off the throttle and so the intake has more air to go into the turbo right? Isn't that a good thing? Blowing off that extra air to the atmosphere gives that COOL sound, but is that the ONLY benefit?

 

Yeah, I really believe that aftermarket BOV's on moderately modified cars are only good for the cool noise. "They" say something about the rpms not dropping as fast so you can shift better, but I think that's just marginal if anything. The noise really is cool though.

There isn't enough air being put back into the intake for it to make any performance difference. I think the stock BOV is plumbed back into the intake to suppress the noise.

If anyone's looking for a cool noise, disconnect that silencer for the ACV. That deep whine it make at 3000+ rpms is cool enough for me, for free.

 

whats the ACV?

 

Air control valve. It's located on the lower intake manifold, and it sends air from your air pump to the catalytic converter.

 

The stock BOV is fine for the stock turbo, but if you're going to run alot of boost with a bigger turbo a good BOV can protect your turbo.

 

anyone have any kind of tips on disconnecting it?
I have an aftermarket exhaust with a high performance cat and I know that it isn't hooked up to the cat so I might as well disconnect it and if it makes a cool noise hey why not?

 

About the blowoff valve question. The reason for them is when you let off the gas and the throttle blades shut there is an excess of air briefly. If this air is not bled off it will dead head the turbo and cause turbulence which stalls the turbo. Stock turbos usually route the air back to the suction side of the turbo to maintain a flow of air through the turbo. So not only do aftermarket blowoff valves sound cool but they actually do have a function.

 

could someone please take a pic and post it of the stock 87 Blow off valve. i just got a turbo 2 and the enigines out with a bad houseing and rest of engine is in box's and i have no clue what the bov is

 

It doesn't effect the catalytic converter anyway since this the silencer is for excess air. I guess you weren't around when we had a post about this. Here's the link:

ACV Venting noise

Some folks like the noise, some don't. I guess that's why they put a silencer.

 

It seems to me that the problem with the big external blow off valves is how do correct for the metered air that you vent outside the system?Using the factory ecu air passing into the intake gets an equivalent amount of to be burned with it.If the air is vented you must end up going very rich.

 

yes but only when you're off the gas so it doesn't really matter. just makes bigger fireballs

FYI, some other cars, talons etc, don't even idle on the stock ecu when you put aftermarket BOV's on cause they need that metered air...

 

I don't have a pic, but its NOT hard to locate it. Its near the Passenger shock tower, close to the boost sensor (that little black box with a vacuum line plugged into it). It plugs right into your intake duct and it has a huge line going from it to your turbo pipes that runs up to the intercooler. Hope that helps...:p