Great convo on vortex on DV relocation and why NOT to do it...
11-14-2003, 10:05 AM
#1
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Great convo on vortex on DV relocation and why NOT to do it...
1. You needlessly push air through the intercooler (warming it up) that would otherwise have recirculated before it ever reached it back to the turbo inlet (keeping the intercooler colder).
2. Since the intake manifold controls the open/closing of the DV, it shouldn't make a difference where you place it, except that you ACTUALLY put less stress on your piping and IC the closer you place the DV to the turbo output since in recirculates immediately after exiting the turbo instead of running through all the piping and all the way back to the turbo.
3. Recirculating hotter air (OE DV position) means the turbo will spool more easely since it will have less air mass to push. By this I mean that the air being hot, is less dense and thus the turbo will have less friction on the compression side. This will result in a higher rotational speed VS the relocated DV sending cooler=more dense=heavier air back to the turbo inlet.
This would mean that you would get less lag when getting back on the gas after a shift.
Then some replies:
...makes no sense to me why people are doing this. I thought the purpose of the bypass valve was to relieve pressure when the tb is closed in order to eliminate compressor surge and/or stall ? With this being said, wouldn't you want it to relieve pressure at it's closest point to the turbo to eliminate any pressure build up the quickest and most efficient way possible? I would have to agree that the shortest route is the best...
More:
Well, let's try this theory as well.
With the DV near the turbo outlet...The TB closes and the DV opens.
When this happens, the pressure is bleed...But a fairly large mass of air stops moving. All the air downstream of the DV and upstream of the TB now becomes static (I'm thinking, "shifting gears" type of pedal operation) momentarily. As soon as you are back on the gas, pressure must then "push start" the static air mass. (yes, the cylinder vacuum "suck starts" it too. I do know this.)
With the DV near the TB...The air mass in the intake tract continues to move towards the TB, with only a minor "static" area. The laws of inertia being what they are, this should make it easier and thus quicker, to recover airflow after the TB closure.<ul><li><a href="http://forums.vwvortex.com/zerothread?id=1109489">DV relocation threat on Vortex...</a></li></ul>
2. Since the intake manifold controls the open/closing of the DV, it shouldn't make a difference where you place it, except that you ACTUALLY put less stress on your piping and IC the closer you place the DV to the turbo output since in recirculates immediately after exiting the turbo instead of running through all the piping and all the way back to the turbo.
3. Recirculating hotter air (OE DV position) means the turbo will spool more easely since it will have less air mass to push. By this I mean that the air being hot, is less dense and thus the turbo will have less friction on the compression side. This will result in a higher rotational speed VS the relocated DV sending cooler=more dense=heavier air back to the turbo inlet.
This would mean that you would get less lag when getting back on the gas after a shift.
Then some replies:
...makes no sense to me why people are doing this. I thought the purpose of the bypass valve was to relieve pressure when the tb is closed in order to eliminate compressor surge and/or stall ? With this being said, wouldn't you want it to relieve pressure at it's closest point to the turbo to eliminate any pressure build up the quickest and most efficient way possible? I would have to agree that the shortest route is the best...
More:
Well, let's try this theory as well.
With the DV near the turbo outlet...The TB closes and the DV opens.
When this happens, the pressure is bleed...But a fairly large mass of air stops moving. All the air downstream of the DV and upstream of the TB now becomes static (I'm thinking, "shifting gears" type of pedal operation) momentarily. As soon as you are back on the gas, pressure must then "push start" the static air mass. (yes, the cylinder vacuum "suck starts" it too. I do know this.)
With the DV near the TB...The air mass in the intake tract continues to move towards the TB, with only a minor "static" area. The laws of inertia being what they are, this should make it easier and thus quicker, to recover airflow after the TB closure.<ul><li><a href="http://forums.vwvortex.com/zerothread?id=1109489">DV relocation threat on Vortex...</a></li></ul>
11-14-2003, 10:48 AM
#2
Haha....
Ask those that have done it, not the theorists...
<img src="http://images2.fotki.com/v18/photos/7/7305/201596/prerelo-vi.jpg">
<img src="http://images2.fotki.com/v18/photos/7/7305/201596/postrelo-vi.jpg">
<img src="http://images2.fotki.com/v18/photos/7/7305/201596/DSCF0074-vi.jpg">
<img src="http://images2.fotki.com/v18/photos/7/7305/201596/prerelo-vi.jpg">
<img src="http://images2.fotki.com/v18/photos/7/7305/201596/postrelo-vi.jpg">
<img src="http://images2.fotki.com/v18/photos/7/7305/201596/DSCF0074-vi.jpg">
11-14-2003, 11:05 AM
#3
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Re: Great convo on vortex on DV relocation and why NOT to do it...
a DVs sole purpose in life is to reduce turbo lag between shifts.
Slamming the throttle shut causes flow reversal, and slows down the compressor wheel. DV allows the turbo to freewheel, reducting spoolup time when the throttle is reapplied. The best place for the DV vent is as close to the thottle body as possible, absoloutely no doubt about it.... the closer to the source of the flow reversal the better. All of the other considerations in that crosspost are insignificant, because they have nothing to do with the DV's sole purpose in life. Schwing got it right.
A BOV is even better because it avoids reheating the already hot air when its recompressed in its second trip thru the turbo compressor. Too bad BOVs cause a rich condition on MAF cars. There is no good reason to run a DV vs BOV in a MAP sensor equipped car, other than unwanted noise.
Slamming the throttle shut causes flow reversal, and slows down the compressor wheel. DV allows the turbo to freewheel, reducting spoolup time when the throttle is reapplied. The best place for the DV vent is as close to the thottle body as possible, absoloutely no doubt about it.... the closer to the source of the flow reversal the better. All of the other considerations in that crosspost are insignificant, because they have nothing to do with the DV's sole purpose in life. Schwing got it right.
A BOV is even better because it avoids reheating the already hot air when its recompressed in its second trip thru the turbo compressor. Too bad BOVs cause a rich condition on MAF cars. There is no good reason to run a DV vs BOV in a MAP sensor equipped car, other than unwanted noise.
11-14-2003, 11:57 AM
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the last argument is my contention....
less mass to move after the bleed. If you look at may other manufacturers, tuners, etc, you'll see that they place the bov/dv right before the tb.
And basically what TTinTO said.
And basically what TTinTO said.
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11-14-2003, 12:54 PM
#10
Do it! I've been in Vortex "Discussuions"....>>
I'm well known over there, but don't feel like jumping in cause it will go around in circles for days! Post the link...Dat's OK!