Tuning dump valve part 2!

[smoo]

have had a chat to one of the guys at L & M regarding what is the best dump valve for a 20VT, he says that the best is a recirculating one as opposed to a atmospheric one as the later brings muck in to the engine through the intake? Is the views from you guys the same as the views from L & M??

Thanks

Chris

 

[custard]

not really heard that TBH.suppose in theory you could argue there could be an ingress of dirt when it dumps or if it had a poor seal but its negligable i would think.

 

[hmallett]

I think that realistically there's no difference. However, the MAF sensor measures the amount of air entering the system, and sets various ignition properties based on that. If you are dumping some of that already measured air on each gearchange, then for a brief moment, the calculations will be wrong. So I prefer a recirculating dump valve on the Coupe. That and the fact it's more subtle. I have a Bailey DV30, which seems OK.
H

 

[smoo]

what noise is the dump valve supposed to make?? just fitted a baileys to my coop, and it makes more of a spinning noise than a wooshing noise?? is it a faulty one???

 

[custard]

should be the sound of air being released suddenly when you lift of the throttle with boost pressure.
been described as a pshhht or a wap tish kind of noise

 

[sammiboo]

which baileys? if it is a recirculating one you should barely be able to hear it.

 

[HP]

have had a chat to one of the guys at L & M regarding what is the best dump valve for a 20VT, he says that the best is a recirculating one as opposed to a atmospheric one as the later brings muck in to the engine through the intake? Is the views from you guys the same as the views from L & M??

Thanks

Chris

Under vacuum a non recirculating dump valve will be open, so it will draw unfiltered air in.

If the dump valve is after the mass air flow meter, this will cause you bother.

 

[pinin__prestatyn]

Not heard that one. I've heard that K+N intakes can block the air sensor as the filtering oil is drawn in over time. If you like the whap-tisch, get a atmos, if you are a little more conservative, go for the recirc. Apparently the atmos DV causes the coupe to overfuel for a fraction of a second on the overrun as the engine is expecting the dumped air back into the system. If you run a de-cat this can mean flames every gearchange

 

[smoo]

dont know what sort it is, but after taking the fiat dump valve from the engine, i have had to block of one of the pipes with a bit of a broom stick, which i am assured is the right thing to do?? you can hear it, fairly well, when changing gear, and when you ease off the accelerator, but its a spinning sound, not a single woosh, sounds the nuts though!!!