John McLaren

Hi All,

I've just a 2005 WRX. It's standard at moment but was looking to fit a HKS blow off valve or something similar.

I asked a similar question on the pistonhead forum and they basically said you don't need them on a 2005 scooby. I thought that the trapped air in the pipe caused the turbo turbine blades to slow down - hence more lag, cos you have to get the turbo to spin a ful again! But they said that the excess gas is reciculated back into the system, so doesn't 'stall' the turbo.

If this is true, do people buy them just for the noise they make?

Cheers,

John

andythejock01wrx

Yes, folk buy 'em for the noise alone (just went back to std recirc, LOL).

Bob Rawle

You already have a perfectly good one fitted as std and there really isn't any technical need to change from it.

bob

funkyspider

Lots of info on dump valves on this site if you use the search function. You currently have a recirculating one bolted to the front of the intercooler and there is no reason to change it for a Atmospheric one.

corradoboy

This forum must have saved you a good 400 quid tonight alone Put some of that towards suspension and chassis products which will make your car faster without being less reliable

Donkster

They produce a nice sound and that's about it. I fitted one for a while before removing it ... the wife kept asking what's that farting sound when I first fitted it (and no, it was the dump valve, not me!)

John McLaren

Thanks everyone for your reply's - Saved me loads of dosh :-)

Cheers,

John

IJE71

Does this mean that all pro rally drivers, not just scoobs, fit BOV's for the noise? I would have thought that a vent to atmosohere would lose more pressure than a recirculating valve venting to a pressurized system.

Davros 1979

iTrader: (56)

IIRC rally cars do not use BOV's at all.

Means a shorter life span for the turbo though.

silent running

Cars with MAP sensor based systems can run atmospheric dump valves perfectly fine and in this case an atmospheric can always dump out a lot more charge and faster too, than a recirculating. On a MAF sensor based car like a Subaru, only a recirculating should be used.

andythejock01wrx

MAF = Mass Air Flow

MAP = Ermm, "Starter for Ten !" ?

mickywrx

iTrader: (29)

MAP = Manifold Absolute Pressure

silent running

My old Clio 16v was based on a MAP sensor system. It basically measures manifold pressure and air temperature and calculates the air volume from that. When I turbocharged it, it could therefore run an atmospheric dump valve with no problems at all.

andythejock01wrx

The winner ! And now for 5 points, how does a MAF work ?

Fixel

Mass airflow sensor

andythejock01wrx