I have the same problem with my Tial, that's why I'm switching back to stock this weekend. I want my drivability back!!

 

Synchronic has a good design, but I ask the question: 20 milliseconds from WHEN does it open? 20 milliseconds from the occurence of the pressure wave? 20 milliseconds from the driver starting to let up on the throttle (will give street driveability issues)? I notice the synchronic in youtube apparently 'bouncing' as the pressure wave reverberates, does this mean the surge is not properly vented to start with? Or the aperture is not being fully used due to the rarefactions in the pressure wave? Can the frequency of the pressure wave cause the valve to duty cycle 'float' rather than snap open/shut, thereby compromising the operation of the venting?

I have done a great deal of research on the matter and I am interested in seeing a manufacturer give real performance data and not just claim performance. Synapse says its a matter of milliseconds, that is correct.

Perhaps Synapse can share the graph of BOV open/shut performance vs pressure change in the intercooler during the sub 1 second of a gearshift while in boost.

I have seen the GFB valve deliver a LARGER pressure spike than a stock BOV in order to hold a high I/C pressure for performance. This leads to flutter/flow reversal/ MAF transient problems at possibly high boost levels.

I am an engineer with a turbo car and while I can find real data on all my components for building performance, BOV performance & sizing still seems to be in the dark ages of hearsay and marketing claims. Can you help me Synapse?

 

Unfortunately, much of what we're working on today is under contract development and in an NDA. However, there is a 3 sigma analysis on the response of the Synchronic geometry at various pressure levels that I can share.

Most OE systems moving forward will be using a solenoid to control the BOV via the ECU, so response will be critical. Almost all aftermarket BOV manufacturers will tell you to eliminate & bypass the solenoid because their device will not be able to respond quick enough.

From the time the winding in the solenoid energizes to the time the Synchronic BOV has enough lift to release pressure and neutralize the pressure wave is ~20ms. You have to factor in that the solenoid takes 4-6 ms to energize and you quickly realize that Synchronic is operating in the ~16ms range. This is at only 10 psi. There is no way in hell that vacuum alone is what is actuating the Synchronic valve. Especially considering that the transition from 10 psi of boost to full -12 psi of vac takes at least 175 ms. Tial will be lucky if their valve is even actuating sub 200ms, regardless of spring.

For a turbo, sizing doesn't matter as much as response time hysterisis.

 

Synapse was my original choice, but I heard so many different stories. Tial was already proven so I thought I would go with them.

I would love to come by the facility in Miramar and try this BOV out.

 

Synapse, you have confirmed something I have been developing over the past 18 months.
Your data is similar to mine.

I am about to bring to market an after market electronic control upgrade for any BOV. Which can deliver not only the 20 millisecond response time you mention, (19.8 ms to be precise), but can deliver a trigger within 6 ms from the moment the driver starts to lift his foot. This will give a fully open BOV before the surge even spikes as it takes about 60 to 80 ms for the surge to build as the throttle closes.

The product also incorporates quite a few other capabilites and comes in a standard gauge form factor. It is fully TUNABLE for both sensitivity and DURATION from inside the cabin for unsurpassed drivability.

It contains some proprietary logic and control technology for instantaneous (microsecond slew rates) responses. From the description of your expected response times, this aftermarket controller would interface quite nicely with a Synapse BOV to deliver unparalleled flexibility in the marketplace.

I am currently exploring licensing and manufacturing options as the product is only waiting on its packaging at the moment. If this interests you my contact is mosaicmerc@yahoo.com

 

Your problem will be any BOV other than Synchronic that will respond sub 200ms from the time your controller fires off the solenoid

We already do sub 100ms without any electronics involved at all. Our focus is progressively towards OEM, and those guys do that from the ECU anyhow.

 

Fair enough, I do have all electrics which will be fully open a full 40 ms before surge develops.

But then that is in competition with regular BOV. But if I can't find a recommended fast acting mechanical, I will support an all electric option.

Audi & Volkswagon already run their BOV with ECU control. The future is e control and I plan to provide an option for all those vehicles whioc are out there with no e control performance.

Good luck with your valve, I hope it is an option for non oem performance adders.

 

TIAL,

Back on topic, I am experiencing actual surge (not compressor surge) with my new re-circ QR on my EVO X. I ordered it with the unpainted spring which is 11 psi I believe. Currently, I am T'd off of an existing vacuum line.

Will it without a doubt make a difference for me to run a 1/4 inch line directly off the intake manifold? Under very light load, when I let off of the gas, I am getting crazy flutter as the compressor blade must be chopping up the backlash

I have also heard of certain EVO X people going down a spring to avoid this. Your thoughts?

Thanks!

Lou

 

on throttle or off? if it's on throttle line size won't make a bit of difference for that - and the bov doens't have anything to do with it.

but yes, you NEED 1/4" ID line from the bov to intake manifold with no T's. if you do not have the proper volume/flow you will get flutter and surge because you are restricting the flow and the BOV can't react quickly enough

 

Flutter is with closed throttle.

I will try the 1/4" ID line tonight and report back. If that doesn't work, maybe a spring change will be necessary. Have you guys had to switch out many EVO X owners' springs because of this issue, even with 1/4" direct line?

Lou

(BTW, thanks for the fast response!)

 

Off throttle flutter is the business of the BOV and its mechanical Latencies. The larger BOVs have larger latencies and are a bit more prone to the problem u mentioned. To keep using the BOV u have u may need a BOV controller to enhance its response beyond what a spring change can give.

On Throttle flutter is the business of your Turbo flow exceeding the engine capacity and requires
1) A smaller compressor wheel , or
2) A larger Turbo Housing, or
3) A smart/programmable recirc vent valve to allow the rpm to rise past the surge region, or
4) A smart boost controller that can limit/ map boost to rpm.

Item 3 is hard to come by but is the best option. It allows marginally better spool up than item 4 as boost is not inhibited. If u have an aftermarket ECU u can drive a solenoid valve to produce item 3.

 

I just put the QR on my 8 and it has great drivability the only issue I have is when I let of throttle it flutters and I am going to try a new spring to fix this issue.

 

are you line sizes correct? with no T's?

 

B4 u diddle with the spring.....ensure the BOV 'sees' good vacuum. No leak in the hose etc. A direct hose to the vacuum nipple, not branching at all.

After that, u can go for a softer spring.

 

I wonder if porting the throttle body or getting a larger one would allow the little amount of air normally recirculated by the leaking oem bov a way to flow in better at any given throttle position reducing surge. Hope I dont get partial throttle surge on my turbo set up I'm currently peicing which is gt 2871 stock head cams and throttle body evo 8 . with bov / recirculated.