boustie.sti

any one know if a standard re-circ valve can be used as an external vent to atmosphere, by blocking off the recirc pipe and removing the flange going to it. A friend of mine tried it and said it worked but intermittantly back-fired.

silent running

Well yes theoretically you could just disconnect the exit side of the valve and let it dump outwards, and then block off the return hose to the turbo inlet pipe.

Your mates one probably backfired because doing this would **** up the ECUs air flow calculations, throwing the fuelling off and messing up the throttle response.

But if you want an atmospheric dump valve that badly...

Jolly Green Monster

iTrader: (4)

the springs are usually too weak to be used to atmoshpere and it will open on cruise and possibly on idle..

better stick using it at recirc or getting a decent dump to atmosphere..

Simon

boustie.sti

Would the engine management system still mess up if i fitted an atmospheric valve, i dont want to end up with back firing and dodgy noises etc.

thanks for help new to this

dan83590

The standard Dump Valve does its job very well. I have tried various other valves and always go back to the standard one, I personally think the car runs far better with it. With the aftermarket part fitted fueling was all over the place, idling was awful, start-up was difficult. However, if you really want the noise from dump valve I would think about a twin piston type, a Baileys DV26 may be one to look at, I did'nt try one of these so can't say how well they work. I'm sure someone here can tell you.

If a dump valve did mess up the fuelling could a re-map sort it??

Jolly Green Monster

iTrader: (4)

as said the standard one works best when still on the standard intercooler etc.. but with fmic etc you need to find an alternative.. the after market recirculate ones work well and some of the atmospheric ones work well.. the HKS, and baileys are usually good.. if using a TD series turbo then my personal choice is no dump valve at all.. but that's another discussion.

You cannot map around it although a MAP based ecu will mask it but the problem will still be there.
The air entering the engine is metered by the MAF and the ecu injects the fuel required due to the maf reading but the air is not entering the engine but leaving through the open dump valve. Usually on a light throttle cruise and sometimes on idle.

Simon