nice stuff...

 

OK, fair enough, but does pressure under the valve from the UICP keep the valve closed or does it push it open? I would prefer the former. Of course it could be installed 'backwards' to do either, but how was it designed? Or is that what you are referring to when you mention that it can be installed as push or pull? In the video, it appears that it is being installed where the pressure from the UICP would keep the valve closed...is that correct?


Thanks

 

I may end up picking one of these up.

 

real nice, if i ever move to cali i may need to swap to the DV...well i'd need to swap a lot out probably

 

I currently have a Forge DV and get what I describe as an awful 'bucking' under certain conditions - most common is going up a hill, with mild throttle, vacuum to boost (0 to 10 psi). I have been told this is 'common' but never happened with the stock DV. Will the new Synapse DV solve this issue ? Thanks

PS - I am in socal and would be happy to test the product

 

I have never had that issue with part throttle 0-7 psi boost going up hills with my SB style, and I do that a lot on the hills around me, so if they function the same then this DV will probably cure your problem.

 

Yes, in the video, the DV was installed as "Pull", because we felt "Pull" worked better for this particular Evolution 9.

Depending on how you run the setup (Push or Pull), the pressure may act as pushing force to open or keeping the valve close.

Here's the tuning manual for the DV, this may give you more information about how to properly set up the DV to suit your driving style and preference.

http://www.synapseengineering.com/su...ual_webres.pdf

Hope this helps.

 

This BOV is not available at no limit yet. when is this thing coming out and available to public?

 

According to our conversation with Master Distribution, the products are in transit this week. No Limit should receive their shipment soon. I would keep checking with them often to ensure a unit is allocated for you when their shipment arrives.

 

Thanks for the link to the manual...that's what I was looking for.

 

A quick question for you, after taking a look at the manual:

If installed in pull mode (to keep the valve closed under pressure the best), there is no provision to have it open under part throttle lift-off. Port C on the SB enabled this. Or am I missing something here?

I would like the valve to open smoothly when there is pressure UICP, but still pressure in the IM, but less. For example, coming off of 30 psi boost, to part throttle, where the IM may have 10 psi boost...or simply accelerating at part throttle, where the pressure differential is greater in the UICP than the IM. In the pull configuration, there is no way for the valve to open, resulting in possible compressor surge.

For this scenario, it appears that the 'push' configuration would have to be used so that the pressure from the UICP would open the valve.

 

Can you tell me what the surface area for the boost reference for port A, port B, and the two inlets are (push pull inlets)?


Thanks

 

Hello this is David from Synapse.

If i understood your question correctly..... If you're going from 30 psi to 10 psi without lifting your foot completely off the accelerator, then the TB technically should still be open. In that case, the boost is still being consumed by the engine, and the air flow in the charge pipe should still be going in one direct, regardless 30 psi or 10 psi. Compressor surge happens when airflow is being forced back towards the opposite direction when the TB closes, so as long as your TB is still open, there shouldn't be any surges. Theoritically.

The purpose of the Synchronic SB and DV is for the valve not to open under boost, otherwise, it would be considered as boost leak just like some of the other units on the market.

Now running in Pull mode, the pressure in the charge pipe being put on the valve's back side, plus the boost pressure going into A and B will keep the valve close. When boost disappears (from the valve's back side), the vacuum in A and B will pull open the valve to release the air.

The same philosophy was employed on the SB. However, the valve opening of SB does not solely rely on Port C, but rather all 3 (A, B, and C). In the case of SB, port C HELPS opening the valve quicker considering that the SB is heavy duty and larger, and designed to hold 100+ psi of boost pressure. Hence having port C will help opening the valve more efficiently when running high boost. There are however, plenty of users, running 10 psi or less and not use port C on the SB, and it still worked perfectly fine.

(The later versions of SB had port C eliminated does not mean the actual function of port C is gone. The function of Port C was simply built internally into the SB rather than having an external port)

Back to the DV. If the DV is installed as Push, then the sampling pressure facing the face of the valve should equal to A + B. In addition, with the aid of the preload spring and depending on how much pressure the preload puts on the valve, the down push force will keep the valve close under boost.

A+B+preload > valve surface pressure

When the pressure on the valve surface decreases (when your foot is off the accelerator), A and B pressure will go from + to - (boost to vacuum). The amount of pressure is left in the charge pipe will push open the valve when working together with the vacuum from A and B. Hence opening the valve.

Now previously I mentioned that Port C is there to "aid" the opening of valve and piston in the SB. The valve/piston size (mass) on the DV is much smaller than the valve + piston in the SB. It is determined by testing data that Port C is simply not needed in the DV (to achieve the response time) due to the size of DV is much smaller than the SB.

If you must compare, then SB's reaction time is still a few milli-seconds faster than the DV. However, the few ms time difference should not be significantly enough for users to notice the performance difference, or in the respective of causing any compressor surge.

All in all, it is difficult to determine which mode would work best on a vehicle, but rather leaving it to the individual to test out the different configurations to suit personal preference.

 

David,

Thanks for the thorough explanation. I'm already very familiar with the function of DVs. I was simply curious as to what the area of actuation of A+B was in regards to the valve seat itself. You answered that (A+B=valve seat, so the spring preload is the difference).

However, I disagree with you on the below quote:

If you have the DV installed in a pull configuration, then anytime there is more pressure in the UICP than the IM (my example was part-throttle lift off where there was 30 psi vs 10 psi, but it can be part-throttle acceleration as well), there is no way for the DV to open to release that pressure, causing it to back up and cause surge in the compressor.

The full amount of airflow isn't being consumed...that's the whole point to my question really. The pressure builds faster in the UICP because it can't be consumed quick enough past the partially open throttle plate. In this scenario, in the pull configuration, there is no way for the DV to open, since it's needs vacuum to pull it open from the IM. Any positive pressure, even 1 psi (or even less due to the spring preload) will keep the DV shut. The compressor surge happens because this airflow and excess pressure is being forced back towards the compressor.

While this isn't compressor surge in the true sense of a quick spooling lage turbo operating past the surge line on the compressor map, the same thing is happening. If the DV is installed in a push type configuration though (like stock), the pressure build-up in the UICP eventually overcomess the spring preload and the A+B pressure and you get DV flutter. This is what is commonly experienced with people accelerating in a high gear at partial throttle when entering the freeway, for example.

Basically, all I'm saying is that your 'pull' configuration is just like installing the stock DV backwards, which is very good for holding boost, but there is no way to relieve pressure in a sitation where there is more pressure in the UICP than the IM, which can and does happen. Perhaps for racing applications, this is the best setup.

But, for daily driving, I would probably have to recommend the push configuration, just like the stock DV. My question on A+B ports and the surface area was simply for my own knowledge to know their relation to the pressure from the UICP if installed in this way. Some DVs use a greater surface area above the valve to help keep the DV closed in this configuration and to help vacuum acttuation. Since your DV has adjustable preload, this isn't necessary though, but I just wanted the information for my own purposes.


Thanks,
Eric

 

Hello Eric, thanks for the clarification. Based on my theory of the air flow direction in the charge pipe going from 30 to 10 psi, you were correct, Pull would work better. Indeed, Push perhaps would work better with the situation that you have described above. The same reason that the engineer has described that you may choose to use B, or A+B setup for Push if you have Fast Spooling turbo and MAF Recirculate Discharge. Using B only, the charge pipe pressure may eventually be greater than B plus preload (depending on the setting of preload), and push open the valve to release the excess pressure that may cause surge.