Removing a dump valve.
22-05-2007, 02:02 PM
#41
Originally Posted by Billabong
In my experience, removing the dump valve does sharpen up throttle response when going back on the gas. The theory behind that is you haven't just dumped most of the pressure from the IC (which would then have to re-pressurise).
Obviously in some turbo / high boost applications, you'd ideally need to run a dump valve to prevent catastrophic turbo stall to due a massive pressure reversal.
If there's a difference after removing the DV such as increased boost, then that's probably as Chip said re: leaks. That doesn't necessarily mean that it had a leak when the boost was set, as up to a point, a turbo will do its best to supply the pressure it's set for - which in the case of a leak, could mean the turbo overspeeds whilst trying to supply the set boost level (which again is a danger point)
Obviously in some turbo / high boost applications, you'd ideally need to run a dump valve to prevent catastrophic turbo stall to due a massive pressure reversal.
If there's a difference after removing the DV such as increased boost, then that's probably as Chip said re: leaks. That doesn't necessarily mean that it had a leak when the boost was set, as up to a point, a turbo will do its best to supply the pressure it's set for - which in the case of a leak, could mean the turbo overspeeds whilst trying to supply the set boost level (which again is a danger point)
Also the pumping losses will be different during that leak, so the engine wont be emptying its cylinders as well, so when it was mapped to the correct AFR, if you remove the leak then you have a situation where it will lean out and also may detonate due to the timing now being too agressive.
All in all a VERY dodgy sitation to be in, really you need to remove the leak and have it remapped.
22-05-2007, 02:09 PM
#43
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Originally Posted by Chip-3Door
All in all a VERY dodgy sitation to be in, really you need to remove the leak and have it remapped.
22-05-2007, 02:17 PM
#45
Originally Posted by Billabong
Originally Posted by Chip-3Door
All in all a VERY dodgy sitation to be in, really you need to remove the leak and have it remapped.
22-05-2007, 02:27 PM
#47
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My apologies, I should have put the latter part of my original reply in a different paragraph and made it clearer that I was simply talking about the dangers of a damaged DV, and not the misfire.
Of course there's always the possibility that someone could have tweaked just the boost after noticing a drop in boost level, without actually finding the reason for the boost drop. Then at some point, the DV is removed/replaced and then boosts higher than previously as there's now no leak.
Of course there's always the possibility that someone could have tweaked just the boost after noticing a drop in boost level, without actually finding the reason for the boost drop. Then at some point, the DV is removed/replaced and then boosts higher than previously as there's now no leak.
22-05-2007, 02:38 PM
#50
Originally Posted by Chip-3Door
At any other time you dont want the entire boost of the turbo to squueze past the throttle.
That's what I was trying to say That's how I understand it anyway. 
22-05-2007, 02:39 PM
#51
Originally Posted by cozmeister
Originally Posted by Chip-3Door
At any other time you dont want the entire boost of the turbo to squueze past the throttle.
That's what I was trying to say That's how I understand it anyway. 
24-05-2007, 05:26 AM
#53
Originally Posted by Chip-3Door
Originally Posted by cozmeister
Originally Posted by Chip-3Door
At any other time you dont want the entire boost of the turbo to squueze past the throttle.
That's what I was trying to say That's how I understand it anyway. my cars got a recirculating dump valve.but it does still chatter
even on the lowest boost setting ?
found this on wikipedia
Dump valves are fitted to the engines of (usually older) turbo charged cars and sit between the turbo outlet and the throttle body. When transitioning from a boosted state to a closed throttle state (as in between shifts), due to inertia, the turbo continues to pressurize air, but the closed throttle prevents the compressed air from entering the engine. In this case the pressure exceeds the preset spring pressure in the dump valve and the excess pressure is bled off to atmosphere.
Even with a dump valve the compressed air acts as a brake on the turbo (slowing it down), because the pressure on the backside of the turbo is at a higher pressure than on the front side (and the air actually wants to flow through the turbo backwards).
i know the chatter noise is the air passing backwards through the turbo blades.but im still confused
25-05-2007, 01:14 AM
#54
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chatter sounds gooooood.
i dont know anyone on here in person but i can be satisfied in thinking tis Mr Ford is this phil person. Chip-3dr has put some very valid and technical advice but mr ford denies them or ignores them and its obvious to pf users that theres some kind of problem between the two.
i think chip 3drs posts on technical issues are very helpful so as a new comer why would mr ford just write him off
Very sad, a grown man acting like a child
i dont know anyone on here in person but i can be satisfied in thinking tis Mr Ford is this phil person. Chip-3dr has put some very valid and technical advice but mr ford denies them or ignores them and its obvious to pf users that theres some kind of problem between the two.
i think chip 3drs posts on technical issues are very helpful so as a new comer why would mr ford just write him off
Very sad, a grown man acting like a child
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