Hey crew,
Let me first clarify: I've been calling guys "ricers" for venting their BOVs since before the Evolution VIII was released in the US.

With that said, I'm trying to decide the most cost effective/efficient solution to my own vented BOV issue. I just bought the car ('06 MR) and it has a Tial BOV sputtering all over the place... drives me crazy! It appears finding a JDM MR BOV can be a bit challenging, and they're not exactly "cheap".

Would this be a more effective solution?

https://www.extremepsi.com/store/pro...cat=390&page=1

Or should I just buy an MR bov and sell this one? It's probably worth knowing that exhaust/mbc/intake is all I intend to do on this car.

I'm trying to get this car ready for a rallyx event in less than 3 weeks, so I'm kind of on a time crunch. Your input is greatly appreciated!

 

That noise you experience (sputtering) is compressor surge. You need a dual port BOV and not a single (top) port like Tial. Essentially, you need to have the IC pipe pressure referenced on the bottom on the diaphragm and the intake manifold pressure referenced on the top of the diaphragm. Not too many companies make such configurations anymore for some reason.

http://synapseengineering.com/compre...ss-valves.html

Synapse used to make a dual port, but I am unsure if they still do so likely option is stock BOV, which is dual port.

 

Tial bov works great if setup properly.

Is the car MAF or SD?

Make sure you have a dedicated 1/4" line with no t's straight to the IM.

 

It's using MAF. I'm leaning toward simply purchasing the stock BOV. Are you suggesting it's fine as-is, or is some work required?

 

It's been a while since I've driven a modified vehicle, so I had to re-familiarize. But it absolutely is compressor surge. Thanks for identifying. Time to throw money at a solution...

 

Might just need to swap to a softer spring. Tial is definitely one of the best BOVs out there, never had issues with it leaking at 37 pounds for me. But yeah, spring rate is based off of vacuum reading so you might need to get a different one.

 

Why not just save yourself a bunch of cash and just upgrade the spring for the bov? If you have serge the spring in the bov isn't stiff enough so see if you can get one thorugh tial or maybe see if a shop can order you one, there like 25 bucks or something like that. I have ordered a bunch of them over the years for my cars and its not that hard to change.


http://www.tialsport.com/documents/w3_tial_qqr_sp.pdf


Theres the info you will need good luck.

 

If you're boosting at or near stock levels then just use OEM.

At part throttle with the Tial (top port only) you are getting more force (boost pressure x surface area) on the top of the valve plus spring pressure vs the force (boost pressure x surface area) on the valve face so the valve is staying shut. However, because it is part throttle your turbo is flowing more air than the engine is taking in so the pressure backs up on the compressor wheel and causes surge.

You can try a softer spring, but because the area of the valve is smaller than the area of the diaphragm and because the spring pressure is also working to hold the valve closed you will likely always have surge issues. With that said, I run VTA Tials on my GTR with MAF (MAF after BOV) and the surge is not too bad. I also run VTA Tial on my EVO, but I can manage the surge because my turbo is larger (GTX 3582r) so harder for the turbo to outflow the engine at lower rpm (1st - 3rd gear) due to increased lag. Even with the GTX3582r the car will surge part throttle as well as full throttle in 4th and 5th gear until the engine reaches an rpm where the engine outflows the turbo.

 

Alright, so:
1 vote for Synapse SV
1 vote for stock BOV
1 vote for checking vacuum line
2 votes for different spring

I love all the support and suggestions, but don't feel it's any more "clear" at this point. I don't mind swapping BOVs and selling the TIAL, but I don't want to deal with having flanges welded on. (It's currently using an OE adapter)

240Z suggested that OE BOV is dual port, but all I can find is JDM MR which appears single port?

 

I have a stock bov and I can tell you its not dual port. 25 dollar spring call it a day. Just check your vac at idle and make sure you order the correct spring.

 

Sounds like a plan. Better get a boost gauge connected then...

 

All you need is the right spring. The valve doesn't come with an appropriate spring for the evo, you need the white one. I have track tested with three different springs on stock turbo, and the white spring will drive exactly like stock. I have never had any surge in my car, ever.

Swap the spring when you swap the bottom half and your good to go

 

Evo.matt - Killerpenguin have it spot on.

I was exactly facing the same problem when i was using HKS SSQV.

Installed TIAL Q Bov - with 11 Psi spring but the turbo was still fluttering . Did a boost leak test , fixed all the leaks and now bov is opening as it should.
My other evo required a softer spring . After installing the white spring which i think is 10 psi solved the issue .
Don't use the Teed Vacuum source , use a direct source from intake manifold.

 

You realize it will change he has cams right? It goes of vacuum not what size turbo you have. Different cams will make the vacuum in the system different.

 

Synapse has always made their DV; probably one of their best-selling products, I don't see it going away any time soon

@OP go with anything that recirculates. I'm partial to synapse but a stock 9 valve will do just fine also