Hi,which is the best type of dump valve(BAILEY) for sierra cosworth?
1)single piston
2)twin pistons or
3) with diaphragm?
Which are from three dump valves works correct?
thanks a lot.

 

All three will work correctly.
BAILEY DV's have given a lot of people a lot of trouble, diaphragm ones tend to be louder, but can split diaphragm's but last years before this happens and spares are cheap and easy.
Saying that piston ones especially BAILEY can jam.
tabetha

 

If your going for a single piston or a diapraghm dump valve then get one with a filter as the cossie's lay out tends to suck the dumpvalve open at idle allowing unfiltered air into the inlet. Im using a twin piston Forge...have done for a few years with no problems.

 

I have GGR diaphram on mine and its good.