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I mean atmospheric or recirculating ...
Been considering the way the dump valve works and I have a couple of postulations for discussion.
On a twin piston dump valve even on idle the valve is firmly closed.It only opens when
1. there is positive pressure in the hose
2.there is a vacumm diferential between the plenum and the hose
If this is the case then on light throttle openings the valve will remain closed (as it should ) now if the compressor wheel wants to spool up and it pushes air through faster than the engine pumps it away then the hose pressure ncreases but eventually the compressor wheel will slow stall
Now consider what would happen with a recirculating (Single Piston ) valve
This will open as above with the addition on idle it will open as there will be a pressure differential across the throttle flap and will close gradually as the pressure difference disappears
Now in this case on partial throttle the turbo pushes as before but this time the valve opens venting the excess air back into the system
But...In this condition the turbo is still spinning and on WOT there will be significant pressure and spool up is already there
so in theory throttle response should be better with a simple recirculating valve ..or am I missing something ?
I happen to have one to hand so I will give it a go tonite ...
Been considering the way the dump valve works and I have a couple of postulations for discussion.
On a twin piston dump valve even on idle the valve is firmly closed.It only opens when
1. there is positive pressure in the hose
2.there is a vacumm diferential between the plenum and the hose
If this is the case then on light throttle openings the valve will remain closed (as it should ) now if the compressor wheel wants to spool up and it pushes air through faster than the engine pumps it away then the hose pressure ncreases but eventually the compressor wheel will slow stall
Now consider what would happen with a recirculating (Single Piston ) valve
This will open as above with the addition on idle it will open as there will be a pressure differential across the throttle flap and will close gradually as the pressure difference disappears
Now in this case on partial throttle the turbo pushes as before but this time the valve opens venting the excess air back into the system
But...In this condition the turbo is still spinning and on WOT there will be significant pressure and spool up is already there
so in theory throttle response should be better with a simple recirculating valve ..or am I missing something ?
I happen to have one to hand so I will give it a go tonite ...