makes plenty of sound actually, just depends on how much boost and whether or not the BOV is referencing boost.

Sparky- The BOV isn't used on the exhaust side, but as a compressor wastegate. One of the partitioned ports that is used to open the BOV is used to open it based on boost pressure as you would with a wastegate.

EJ- is your MBC reading boost/vac post-throttle? Was this happening before you got the cams.

As I put in the instructions a couple of posts up, I noticed a significant difference picking up boost-only for the BOV pre-intercooler which seems to pop the BOV earlier and lessen the impact of DV flutter. I want to understand this a bit better to know if why the compressor pressure would oscillate enough at part throttle/high RPM that it would oscillate the valve. In any other scenario, the valve would just be open smoothly when there is a differential in pressure between pre and post throttle, not oscillating.

Wong-There's a no-fabrication vband flange for the Synchronic BOV if you ever want to do a back to back comparo.

 

I figured that this was the case, and that it functions perfectly well as a compressor bypass valve. I was just yanking your chain. Welcome to the club!

EDIT: Incidentally, I'll be vacationing in SoCal over the holidays. Are you going to be in the office? I'd like to see one of these things in person. PM me.

 

Actually, without any controls, it is either compressor wastegate, or DV. However, when used with a GM solenoid on the boost/vac side, it will function as both. Now, just a thought, is that for the guys that have MBC's and no longer use the factory boost solenoid, if you can program it with a MAP to hide boost at a certain overboost pressure level, then you can use it as both as well.

I'm in Europe for Autosport. However, we have a shop in San Diego that is testing out a program for us we're calling "try before you buy." Where you can actually bolt up one of the Synchronic BOVs to test out on your car, no strings attached. They've got 2 units in house that you can test out if you're going to have the car with you.

 

1) I'll have to take a look at it - I'm not sure. Perhaps BoxerSix will remember for me...

2) Cams were installed in April this year. These flutter/surge issues started sometime in June. Additional info - In June when I switched over the intake pipe from the HKS RS to the Buschur, Buschur commented that in the pics I sent them (I was having some fitment issues with their dry filter on the HKS pipe) that my stock boost solenoid should have its nipples capped rather than being open w/ no hoses attached any more. I put separate rubber caps on each nipple. I've seen others with a small piece of hose that spans the 2 nipples. Just want to make sure that doesn't enter into this at all...

 

I am actually running it, i am trying it out compared to the HKS SSQV Version 2 it is definitely better at not surging at lower RPM Ranges like 4k to 6k but at the top end it does tend to surge alittle but i am going to call the Manufacture because the unit has an adjusting knob so i am pretty sure you can fine tune to a particular car. Sound wise it a more sleeper sound you wont hear anything driving around town only when you go over 5k then maybe you will hear something.

 

The test car had both ports open to atmosphere on the solenoid. So with both capped and to atmo and the same issue, I think we can rule that out. BOVs are pretty dumb devices in that there's no intelligence there, just basic logic. I still don't understand what could be oscillating the pressure at the DV enough to make it open and close at frequency. It could be that the intercooler is providing enough of a dampener or time delay for the boost to pressurize the inlet consistently at part throttle/high RPM. Couple that with cams that are potentially high overlap, high consumption rate and you get this weird airflow during those conditions.

All I know is that the condition appeared to have improved significantly when we pulled the boost-only source pre-intercooler at the compressor.

 

Are we talking about the Synchronic unit?

 

yep on the car as we speak

 

evo_ippo - The latest update on the tuning manual for the BOV can be found here and is more up to date from what you have.

http://www.synapseengineering.com/pdf/bov-manual.pdf

I'm assuming that you don't have anything connected to the brass port on the side of the BOV, correct? I need you to start by T'ng off the boost-only source from the compressor and hooking it straight up to the port on the side of the BOV. Bear in mind that the BOV will be much louder, but will perform much much better. Can you post a pic of the install?

 

ohhh ok because i base my install on this youtube video i think was made by Synapse

http://youtube.com/watch?v=Zh5TRE0r2eQ

ok so for the brass fitting on the side you want me to connect to a boost only source ........... where on the evo if a good boosting source???? hahhaha

 

We've updated the instructions. We're always working to develop better tuning setups.

You can get boost only from the vacuum line that is coming off of the aluminum compressor housing, that connects to the wastegate actuator and OEM boost control solenoid. That source is a boost-only source. Tee off that line and run a hose to the side port. Keep us posted on the result.

 

This BOV sounds like it is great. I am going to get one, great price and if it is "better" than a tial I am all it. I like how you can either VTA or recirc, or at least what I understand from that video evo_ippo posted. That means when I put my new turbo on after my rebuild I won't have to change bov's. Awesome work. Synapse, how much boost is it able to hold? Might be a dumb question but I have a BIG turbo going on soon and I need to make sure it will hold 40+. Thanks

 

Each assembly is pressure tested to 100 psi (140 actually, 100 is a nice marketing number) not to leak. We've got a couple of diesels running 50+ psi. 140 may seem overkill, but the seal burst pressures are around 250 psi, and you never know when some tractor puller will decide to use your product so we design to that tolerance.

Jasn- No need to cutoff your Tial flange and reweld, just use the Tial adapter flange and you're done.

The test vehicle that is running the latest configuration to eliminate "DV Flutter" posts here.

http://www.allwheeljunkies.com/showthread.php?t=24205

Sorry for the cross posting, I don't know the user's handle on this board.

 

I was going to go with a tial because they are "top of the line" in the VTA department. I believe this bov should be as good as a tial. I just hope it is loud recirculating or vta. I like to see women and children jump a little, or the great question, "What's wrong with your car?"

 

Synapse,

Erics(EJ) MBC pulls its boost signal from the compressor outlet as OEM. His flutter issue was definitely post-cam install. I will mess around with various setups and will start with the setup you mentioned for the Evo's once the valve arrives.

One thing I did notice is of all the cars affected by this issue that I've worked with.....they're all cammed in one manner or another( I, E, I+E, different cam makes, etc). None of the stock cam Evo's I work on have this issue. I was initially thinking some weird intake reversion crap from the new cams but have been so busy tackling other issues to test that further...

-Adam