Dual port vs Single....comparison
09-11-2010, 11:30 PM
#16
You should be testing transient lag (in and out of the throttle, while above the full-boost threshold), not so much the WOT boost response to redline. Running from below the boost threshold with something like a Tial is mostly a test of how quickly the turbo will spool; running a test from above the boost threshold, and going in and out of the throttle, will show the true ability to control the wastegate quickly.
If you have a gain setting on your EBC you can set it to its most agressive setting, then see how the wastegate is able to actually control boost (it will overshoot and boost spike as its fail case). You can dial the gain back until the boost no longer overshoots. You should test this ability in single and dual port modes, and that will show you the real advantage of a dual port setup.
The dual port advantage should reveal itself in transient response. With a steady WOT setup from under the boost threshold you're really just riding the turbo's ability to spool up - unless you have just a killer turbo. When you're above the threshold and stabbing in and out of the throttle, the turbo is basically kept spinning (as it's venting out the blow off), and you're really testing the wastegate's ability to manage "instantly available" boost. A dual port should be able to open and close the wastegate faster than the single port setup, so if you have all of the other parts in the system you should see increased transient throttle response.
If you have a gain setting on your EBC you can set it to its most agressive setting, then see how the wastegate is able to actually control boost (it will overshoot and boost spike as its fail case). You can dial the gain back until the boost no longer overshoots. You should test this ability in single and dual port modes, and that will show you the real advantage of a dual port setup.
The dual port advantage should reveal itself in transient response. With a steady WOT setup from under the boost threshold you're really just riding the turbo's ability to spool up - unless you have just a killer turbo. When you're above the threshold and stabbing in and out of the throttle, the turbo is basically kept spinning (as it's venting out the blow off), and you're really testing the wastegate's ability to manage "instantly available" boost. A dual port should be able to open and close the wastegate faster than the single port setup, so if you have all of the other parts in the system you should see increased transient throttle response.
09-12-2010, 08:31 AM
#18
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that was the one in 20 posts on here written by a man who knows. Good work, never understood it like that function at all, couldn't work out why you'd wasn't to be able to force open the watergate under normal running. Now it makes sense
09-12-2010, 06:19 PM
#20
09-13-2010, 09:52 AM
#21
Drive-by provocation guy
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You should be testing transient lag (in and out of the throttle, while above the full-boost threshold), not so much the WOT boost response to redline. Running from below the boost threshold with something like a Tial is mostly a test of how quickly the turbo will spool; running a test from above the boost threshold, and going in and out of the throttle, will show the true ability to control the wastegate quickly.
If you have a gain setting on your EBC you can set it to its most agressive setting, then see how the wastegate is able to actually control boost (it will overshoot and boost spike as its fail case). You can dial the gain back until the boost no longer overshoots. You should test this ability in single and dual port modes, and that will show you the real advantage of a dual port setup.
The dual port advantage should reveal itself in transient response. With a steady WOT setup from under the boost threshold you're really just riding the turbo's ability to spool up - unless you have just a killer turbo. When you're above the threshold and stabbing in and out of the throttle, the turbo is basically kept spinning (as it's venting out the blow off), and you're really testing the wastegate's ability to manage "instantly available" boost. A dual port should be able to open and close the wastegate faster than the single port setup, so if you have all of the other parts in the system you should see increased transient throttle response.
If you have a gain setting on your EBC you can set it to its most agressive setting, then see how the wastegate is able to actually control boost (it will overshoot and boost spike as its fail case). You can dial the gain back until the boost no longer overshoots. You should test this ability in single and dual port modes, and that will show you the real advantage of a dual port setup.
The dual port advantage should reveal itself in transient response. With a steady WOT setup from under the boost threshold you're really just riding the turbo's ability to spool up - unless you have just a killer turbo. When you're above the threshold and stabbing in and out of the throttle, the turbo is basically kept spinning (as it's venting out the blow off), and you're really testing the wastegate's ability to manage "instantly available" boost. A dual port should be able to open and close the wastegate faster than the single port setup, so if you have all of the other parts in the system you should see increased transient throttle response.
09-13-2010, 03:19 PM
#22
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If it wasn't such a PITA to get it off, I would take my dual port off and see how it worked. I am still not completely clear how the dual port works exactly.
For the longest time I ran my dual port Tial in single port mode and it worked great. Now that I have switched to dual port, I am having more issues.
In single port mode the tial I had a manual bost controller. Basically, until it flowed air, it didnt open the wastegate. No signal meant the wastegate stayed closed.
Now, no boost signal means that it runs off of spring pressure or about 6psi boost.
So with the tial hooked up as a single port, doesnt seem to open at the set spring pressure.
So, the constant signal that is sent to the wastegate in dual port mode opens the wastegate. The top port adds pressure, to keep it closed. In essence, if both the top and bottom ports are seeing manifold pressure, then it is closes because pressure on both side of diaphragm are equal and then there is 6psi pressure keeping it closed.
Tial sells additional springs. What does going with a stronger spring do for me? My boost curve doesnt seem as smooth in dual port as single port (i.e. it drops a psi or two when the valve opens, then it closes and the boost builds, then the boost drops off..think of a little sine wave action going on). I am thinking this has to due with only having the 6psi spring in the wastegate, and the wastegate is not fast enough in this situation (or it is too fast). Here is an example of the cyclic boost curve.
I need to play around, but i really want to get the boost smoothed out like when i was running in single port mode.
-Dana
For the longest time I ran my dual port Tial in single port mode and it worked great. Now that I have switched to dual port, I am having more issues.
In single port mode the tial I had a manual bost controller. Basically, until it flowed air, it didnt open the wastegate. No signal meant the wastegate stayed closed.
Now, no boost signal means that it runs off of spring pressure or about 6psi boost.
So with the tial hooked up as a single port, doesnt seem to open at the set spring pressure.
So, the constant signal that is sent to the wastegate in dual port mode opens the wastegate. The top port adds pressure, to keep it closed. In essence, if both the top and bottom ports are seeing manifold pressure, then it is closes because pressure on both side of diaphragm are equal and then there is 6psi pressure keeping it closed.
Tial sells additional springs. What does going with a stronger spring do for me? My boost curve doesnt seem as smooth in dual port as single port (i.e. it drops a psi or two when the valve opens, then it closes and the boost builds, then the boost drops off..think of a little sine wave action going on). I am thinking this has to due with only having the 6psi spring in the wastegate, and the wastegate is not fast enough in this situation (or it is too fast). Here is an example of the cyclic boost curve.
I need to play around, but i really want to get the boost smoothed out like when i was running in single port mode.
-Dana
09-14-2010, 02:30 AM
#23
You want to run a spring that will run just below your normal boost if all electronics fail. if you were running 16 psi you'd do well to have a spring that will get you 13-14, etc.
Handling a small delta between base and target boost will be easier for whatever controller you're using. And if it ever packs up completely (e.g. in a race at the track) you don't want to retreat to 6psi ;-)
Handling a small delta between base and target boost will be easier for whatever controller you're using. And if it ever packs up completely (e.g. in a race at the track) you don't want to retreat to 6psi ;-)
09-14-2010, 11:33 AM
#24
You're right that the Tial flows backwards compared to the stock unit, but the Tial valve also moves in the opposite direction. It moves into the body whereas on the stock unit, the valve travels out of the body. I believe that in both cases, the exhaust pressure pushes the valve toward the open position.
This is overall a pretty good thread.
Learn something new every day!
