Post your Synapse DV config and results
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Joined: Feb 2008
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From: Falls Church, VA
When I let off the throttle after being in boost the car BUCKS really hard...
idk if that's the right word for it... but basically feels like the car is being pulled BACK... like boost comes on, then take foot off of throttle, and the car flys back... it really throws off the balance of the car. I want to take my car to the track but I know this would cause problems... I've tried nearly every single setting I can think of...
Pull mode/push mode with a, b, a+b, abys spring, no preload, some preload
Should I just get a different dv? I thought this was supposed to be the best DV on the market yet there's a whole thread dedicated to the problems that arise with it lol...
idk if that's the right word for it... but basically feels like the car is being pulled BACK... like boost comes on, then take foot off of throttle, and the car flys back... it really throws off the balance of the car. I want to take my car to the track but I know this would cause problems... I've tried nearly every single setting I can think of...
Pull mode/push mode with a, b, a+b, abys spring, no preload, some preload
Should I just get a different dv? I thought this was supposed to be the best DV on the market yet there's a whole thread dedicated to the problems that arise with it lol...
for me, I spent the past two weeks (and two tanks of gas) trying pull mode, b only with the following preloads in this order:
1 - Better than push, a+b
2 - Better than 1
7 - Terrible
3 - A little better
2.5 - A lot better (BEST)
1.5 - A little less better
2.25 - Like 2.5, very good.
But I had read this also:
But I also have Aby's spring sitting on the shelf waiting to try, I'll give it a whirl when I come back from vacation in a week.
Last edited by wjamyers; Mar 4, 2012 at 07:38 PM.
When I let off the throttle after being in boost the car BUCKS really hard...
idk if that's the right word for it... but basically feels like the car is being pulled BACK... like boost comes on, then take foot off of throttle, and the car flys back... it really throws off the balance of the car. I want to take my car to the track but I know this would cause problems... I've tried nearly every single setting I can think of...
Pull mode/push mode with a, b, a+b, abys spring, no preload, some preload
Should I just get a different dv? I thought this was supposed to be the best DV on the market yet there's a whole thread dedicated to the problems that arise with it lol...
idk if that's the right word for it... but basically feels like the car is being pulled BACK... like boost comes on, then take foot off of throttle, and the car flys back... it really throws off the balance of the car. I want to take my car to the track but I know this would cause problems... I've tried nearly every single setting I can think of...
Pull mode/push mode with a, b, a+b, abys spring, no preload, some preload
Should I just get a different dv? I thought this was supposed to be the best DV on the market yet there's a whole thread dedicated to the problems that arise with it lol...
How does your car behave with the oem mr/metal bov?
fwiw, how much w/g preload are you running & what type of boost control method are you running?
can you post a pic of your engine bay? where are you getting the bov source signal from? is it a direct line or do you have anything "T"'d into the source line?
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From: Tri-Cities, WA // Portland, OR
...
So today I finally tried it and it's by far the best, the car will not buck not matter what I try and it's also (BONUS) a little quieter, sounds cooler and seems faster.
...
Originally Posted by Aby@MIL.SPEC:
my favorite is pull mode, a-port (closest to the adjusting screw), zero preload with the factory spring.
my favorite is pull mode, a-port (closest to the adjusting screw), zero preload with the factory spring.
...
Code:
Push configuration (charge pipe pressure pushes the valve open)
Port A Port B Valve
Equivalent Surface Area (mm^2): 491 766 755
"Pull" configuration (charge pipe pressure pushes the valve open here also with the listed surface area)
Port A Port B Valve
Equivalent Surface Area (mm^2): 491 766 502
Last edited by mrfred; Mar 5, 2012 at 12:06 PM. Reason: Incorrect analysis of DV operation
Evolved Member
Joined: Feb 2008
Posts: 1,171
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From: Falls Church, VA
to be sure, I didn't really account for "in-between shift spool" in my analysis, BUT, I'm certain I can hear the DV doing it's job, although it does it much less agressively. the car is running like a champ, easy to drive smooth at partial throttle, quick to spool and pulling hard with 26 psi to 6500 rpms.
If I am missing out on beneficial effect, how will that manifest itself? How can I tell?
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From: Tri-Cities, WA // Portland, OR
the beneficial effect should be keeping my turbo spooling between shifts and/or preventing compressor surge, is that correct?
to be sure, I didn't really account for "in-between shift spool" in my analysis, BUT, I'm certain I can hear the DV doing it's job, although it does it much less agressively. the car is running like a champ, easy to drive smooth at partial throttle, quick to spool and pulling hard with 26 psi to 6500 rpms.
If I am missing out on beneficial effect, how will that manifest itself? How can I tell?
to be sure, I didn't really account for "in-between shift spool" in my analysis, BUT, I'm certain I can hear the DV doing it's job, although it does it much less agressively. the car is running like a champ, easy to drive smooth at partial throttle, quick to spool and pulling hard with 26 psi to 6500 rpms.
If I am missing out on beneficial effect, how will that manifest itself? How can I tell?
Last edited by mrfred; Mar 5, 2012 at 12:07 PM. Reason: Incorrect analysis of Synapse DV operation
The reason why its not bucking is because the valve likely isn't opening. And it may not be allowing any pressure relief when letting off from WOT. Here are the surface areas that drive valve movement. (I got these from Synapse.):
In Pull mode, Port A has slightly less surface area than the valve. In a best case scenario which is with no spring in the DV, the only way for the valve to open is if the vacuum in the IM exceeds the boost pressure in the UICP. The strongest possible vacuum is -14.7 psig, so in this scenario, pressure in the UICP has to drop below 14.7 psi before the valve will open. Account for imperfect vacuum (say 13 psi), throw the spring back in the mix (with no preload), and my guess is that pressure in the UICP has to drop below 8 psi before the valve will open. I don't think the valve is providing any beneficial blow off effect in that configuration.
Code:
Push configuration (charge pipe pressure pushes the valve open)
Port A Port B Valve
Equivalent Surface Area (mm^2): 491 766 755
Pull configuration (charge pipe pressure pushes the valve shut)
Port A Port B Valve
Equivalent Surface Area (mm^2): 491 766 502
The reason why the Synchronic technology reacts so fast, is because the valve is nearly balanced under operation. As soon as the port A/B side of the valve looses a bit of pressure due to the throttle plate closing, the forces on the valve become unbalanced, and cause the valve to accelerate open (and very quickly).
The valve is opening for sure. I would not be concerned about running this configuration on evos.
-Chad-
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From: Tri-Cities, WA // Portland, OR
The math above is incorrect. The values for equivalent surface areas above don't tell the entire story. Port A and B with positive pressure keep the valve closed, and the "Valve" equivalent surface area causes the valve to open with positive pressure. The force vector for the "valve" equivalent surface area should be negative, or you can look at the surface area being negative.
The reason why the Synchronic technology reacts so fast, is because the valve is nearly balanced under operation. As soon as the port A/B side of the valve looses a bit of pressure due to the throttle plate closing, the forces on the valve become unbalanced, and cause the valve to accelerate open (and very quickly).
The valve is opening for sure. I would not be concerned about running this configuration on evos.
-Chad-
The reason why the Synchronic technology reacts so fast, is because the valve is nearly balanced under operation. As soon as the port A/B side of the valve looses a bit of pressure due to the throttle plate closing, the forces on the valve become unbalanced, and cause the valve to accelerate open (and very quickly).
The valve is opening for sure. I would not be concerned about running this configuration on evos.
-Chad-
* UICP pressure holds the valve shut
* Spring holds the valve shut
* IM vacuum pulls it open
I understand that once the valve cracks and removes the valve surface area from consideration, then it will open rapidly, but it looks to me that UICP pressure has to drop pretty low before that would happen with the valve in Pull with Port A only.
Sounds like you are talking about the valve in Push configuration, but he is running in Pull configuration where the charge pipe pressure is holding the valve shut. I'm assuming Pull mode is as straightforward as it appears:
* UICP pressure holds the valve shut
* Spring holds the valve shut
* IM vacuum pulls it open
I understand that once the valve cracks and removes the valve surface area from consideration, then it will open rapidly, but it looks to me that UICP pressure has to drop pretty low before that would happen with the valve in Pull with Port A only.
* UICP pressure holds the valve shut
* Spring holds the valve shut
* IM vacuum pulls it open
I understand that once the valve cracks and removes the valve surface area from consideration, then it will open rapidly, but it looks to me that UICP pressure has to drop pretty low before that would happen with the valve in Pull with Port A only.
This is assuming pull mode, as shown above by the "Inlet Flange"
If you look closely at the picture above, the O-ring separating port B from the inside of the DV has a larger diameter than the O-ring that seals the valve to the DV Body. This means, under positive pressure, there will be more force acting in the up vector, and causing the valve to leak once the equivalent surface area * pressure overcomes the spring preload force affecting the valve.
-Chad-
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From: Tri-Cities, WA // Portland, OR
I understand how this can be confusing. The way the piston/valve is designed, it will open in either configuration without either of the ports connected.
...
This is assuming pull mode, as shown above by the "Inlet Flange"
If you look closely at the picture above, the O-ring separating port B from the inside of the DV has a larger diameter than the O-ring that seals the valve to the DV Body. This means, under positive pressure, there will be more force acting in the up vector, and causing the valve to leak once the equivalent surface area * pressure overcomes the spring preload force affecting the valve.
-Chad-
...
This is assuming pull mode, as shown above by the "Inlet Flange"
If you look closely at the picture above, the O-ring separating port B from the inside of the DV has a larger diameter than the O-ring that seals the valve to the DV Body. This means, under positive pressure, there will be more force acting in the up vector, and causing the valve to leak once the equivalent surface area * pressure overcomes the spring preload force affecting the valve.
-Chad-
Still loving my b port only, Mil.Spec spring and stock preload. 
http://www.verociousmotorsports.com/...R-Black-Silver
I bought my universal version from them and was pleased with the price and transaction
http://www.verociousmotorsports.com/...R-Black-Silver
I bought my universal version from them and was pleased with the price and transaction
Evolved Member
Joined: Feb 2008
Posts: 1,171
Likes: 1
From: Falls Church, VA
I'm testing my AbyAtMil.Spec spring right now.
I had found a happy place with Aby's recommendation with the stock spring (pull mode, a-port only, zero preload) but now I'm working my way through testing preloads in push mode with B port only and 2, 1, and now, 3 turns of preload. I still haven't matched or surpassed the stock spring yet, but still many different configs to try. It's pretty much impossible to make adjustments when the engine is hot with the DV in the stock location in push mode, with the controls on the side under the hot-*** radiator hose right next to the scalding exhaust manifold. In pull mode (controls on top) I can drive, adjust, drive, adjust, all day long.
This weekend I also switched my vacuum hoses to standard (from the leaky quick-release ones) but I'm not completely convinced that the hose is tight enough on the barbed nipple so I may have to go to the autoparts store AGAIN for a slightly smaller hose, just for piece of mind (especially considering the actual hose I used has been sitting in my tool kit for literally 20 years).
Also, on the DV, I switched from cheesy worm clamps to SS t-bolt clamps, to not take chances. I've only got two more worms on the intake system to replace, the 70mm TB and the outlet-to-DV from the ETS UICP, ordered those t-bolts (3" and 1.5") from silicon intakes on Friday. I have almost achieved parts nirvana.
I had found a happy place with Aby's recommendation with the stock spring (pull mode, a-port only, zero preload) but now I'm working my way through testing preloads in push mode with B port only and 2, 1, and now, 3 turns of preload. I still haven't matched or surpassed the stock spring yet, but still many different configs to try. It's pretty much impossible to make adjustments when the engine is hot with the DV in the stock location in push mode, with the controls on the side under the hot-*** radiator hose right next to the scalding exhaust manifold. In pull mode (controls on top) I can drive, adjust, drive, adjust, all day long.
This weekend I also switched my vacuum hoses to standard (from the leaky quick-release ones) but I'm not completely convinced that the hose is tight enough on the barbed nipple so I may have to go to the autoparts store AGAIN for a slightly smaller hose, just for piece of mind (especially considering the actual hose I used has been sitting in my tool kit for literally 20 years).
Also, on the DV, I switched from cheesy worm clamps to SS t-bolt clamps, to not take chances. I've only got two more worms on the intake system to replace, the 70mm TB and the outlet-to-DV from the ETS UICP, ordered those t-bolts (3" and 1.5") from silicon intakes on Friday. I have almost achieved parts nirvana.