Difference between a recirc valve and a Blow off valve.

[NathWraith]

Hi guys,

Was browsing Forge's website earlier and came across these 2 products:

Recirc Valve
http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=190105DV&product=FMDVRTSi

Blow Off Valve
http://www.forgemotorsport.co.uk/content.asp?inc=product&cat=190105DV&product=FMDVATSI

Now I thought these 2 items serve the same purpose?

What is the difference between these two? In terms of performance, sound (if any) and which would be the best choice on an Stage 1 Cupra.

Cheers

 

[psycho6285]

Sound wise the blow off will sound like you standard dump valve with the load noise

Recirc will not be as loud unless you have an open cone

Performance wise, not sure on your engine but the 1.8t doesnt like blow off as it classes it as having a boost leak.

 

[Dan Cupra R]

if anything will be more noise on the blow off valve

 

[VRSfab]

one is open the other closed but those are reinforced Piston controlled versions of the OEM one .

the OEM one is the Membran version . Faster reaction but tends to fail on Tuned engines

the Forge one is a Piston controlled Valve wich is a bit slower in Reaction but can handle high preasure well.
you will also need the right Spring setup.

going to order mine next month but i need to test wich spring works best for 0.6bar preasure

 

[queen]

General difference between a blow off valve and a recirculation is that the blow off releases the air to the atmosphere, the recirculation directs the air into the intake and it's being released by the filter. Sound wise like others said the blow off is noisier but the recirculation when paired with a short intake pipe will make the same noise. Performance wise the only difference you will see is if you release and then suddenly step on the gas pedal. If you have the blow off the engine will need to suck in the air that was lost when you let the gas off (to spool the turbo) when with the recirculation the engine will not need that much air because some remains in the intake. To sum it up with the blow off you'll have a bit of lag but I don't think it will be that noticeable.

 

[NathWraith]

Ah cheers for the replies guys.

So a blow off is better for sound but a recirc is better for performance?

 

[queen]

You're welcome.
Well, it comes to what are you gonna do with the intake? And if you race your car hard. I don't think it will be a noticeable performance difference but bare in mind that our car comes with a recirculation one and I wouldn't change the valve type.