Re-circ valve

[Rusty]

That's the spring pre-load adjust, not the aperture adjust Different things Mr. J.

The Turbosmart and Forge products are not as complex as the GFB and so offer less adjustability.

[Rusty]

It would be intresting to know how many of those running a BOV have either MAF on the high pressure side or are running aftermarket ECU. There are a few big hitters on there.

[GazzaG60]

the beauty of GFB is the easy of adjustability.

a few years ago my mate sold a group buy to the 1.8t forum. they were more than happy.

[Rusty]

I only ditched mine as I needed back the £100 or so I'd spent on it... If you can find one on ebay then get it, they're well worth the money.

[bernsaudi]

What's the point of running a split open/closed valve?

[GazzaG60]

the idea is to feed recirc air to the maf to maintain correct conditions but to be able to bleed any excessive air off to atmosphere.

i have seen cars that bring on ckeck engine with a bov but not a split circuit.

[bernsaudi]

So it's to keep the error light away? I understand now, cheers!

[Rusty]

It basically gives you increased noise with a percentage functionality of the original recirculating system, by minimising the amount of air that bleeds to atmosphere, you minimise the drop in AFR on WOT gear change. Obviously, the more air that goes to atmosphere, the louder it is - I wet myself when I went for a run with the GFB on fully atmospheric, the car didn't like it as much.

If you're after some noise then this is a good option as a quick twist can give you full atmospheric to impress your mates down the pub and another twist can give you stealth mode for ferrying the Mother-in-Law to church

[M_GORDON]

[IMG]Best of both worlds

Some time ago I bought this Turbosmart valve and ALWAYS goes sounding. Only if I drive very softly it don't sound.
I put strongest, I put a metalic piece for make stronger, and nothing.
At last I sold to one friend with stock S2 and he goes happily, but I no.

[Thuppu]

What's the point of running a split open/closed valve?

In short way. The only reason to use split on a maf engine is to get louder blow of sound. There is no other reason. Best for the engine is to use fully recirc.

[prj]

Something to keep in mind here while we are on the subject of dumping air from the inlet system, whether it be for the purpose of boost control or for the more usual function of maintaining compressor rpm and avoiding compressor damage when the throttle is closed at boost, is what effect this will have on the air/fuel ratio. If fuelling is metered according to inputs from a speed density MAP sensor based system, dumping air back to the atmosphere will not alter the A/F ratio. However, in any system employing some kind of air-flow meter, remember that once air flows through that meter it has been accounted for. Fuel delivery will then be calculated by the ECU, based primarily on the signal received from that source. Therefore, any time air is released to the atmosphere fuelling will go rich.

So, as Thuppu said. It serves the reason to trade engine performance for a "cool sound".

Also, if you have CAT's, the excess fuel can ignite in the exhaust, melting your CAT.

[Rusty]

On the Forge website they have the following statement at the start of every vent to atmosphere valve description

Suitable for ALL turbo cars without an Air Flow Meter