02-04-2012, 12:29 PM #1
BOV Spring Rate and Reference Line Diameter
Ok...here is what I've come up with and have yet to water test these changes. When I initially built my conversion, I installed the Tial 50mm Q BOV. On the application chart the smallest spring I saw available was the 6lb spring. Thats what I ordered. The reference line I used was T'd off the map sensor which fed the R&D multiport boost adapter. Initially, the lines and fittings I used off the adapter was basically the same diameter as stock line. The inside diameter is roughly 4mm. I used that to feed not only the BOV, but the FPR and boost gauge as well. The ski seemed to hit pretty hard when I first took it out, then I read where the supply line to the BOV should be 6mm (1/4") according to Tial. I changed the fitting off the R&D adapter to a larger diameter barbed fitting for the appropriate 6mm hose. Since then it seemed like the valve actually slowed, the ski didn't respond as quick and boost didn't seem to want to hold up top. I'm thinking, out load basically lol, that I was expecting to much out of the stock 4mm line off the manifold originally for just the MAP sensor to supply the reference to the MAP sensor, FPR, boost gauge and larger BOV line was to much and couldn't supply an accurate signal fast enough with the increased volume needed to flow the larger line. Since then, I changed to the 3lb spring recommended by Tial for all supercharged applications. I also tapped a seperate reference line off the manifold for the 6mm line and the valve literally snaps closed. Another thing I noticed is before the changes, the ski really wouldn't build boost on the trailer with the hit of the throttle. As you can see in the video that changed as well. I went to test this morning but the fog was horrible, so I wasted almost two hours sitting at the launch HOPING to be able to test. Has anyone else experienced similar results regarding this? Thanks in advnace. Keith
02-05-2012, 12:32 PM #2
Is the 3lb spring made by TiAL because I also don't see it on there website.
02-05-2012, 01:01 PM #3
02-05-2012, 06:10 PM #4
02-05-2012, 07:02 PM #5
02-05-2012, 07:07 PM #6
02-05-2012, 11:04 PM #7
Interesting....This may help me. Thanks.
02-12-2012, 02:14 PM #8
***UPDATE*** Just took the ski out, it went 96.0mph at 8540. I have video and pics that I will post this evening. I have some family things to do first. I'm beyond excited to say the least.
Also, the ski has ZERO and I mean ZERO surge. There is not even a hint of a sound of surge.
02-16-2012, 07:39 PM #9
Ok so I'm just posting this info I found on a website up for anyone who wants to install a TiAL 50mm Q BOV.
First some commonly over looked facts about the unit:
- the spring ratings have nothing to do with boost
- the bov is a pull type valve - the vacuum sucks open the valve (which is why we have different spring settings for different vacuum levels)
- you need to put a washer on each side of the air fitting, they come with both on the inside so they don't fall out
- we have a -3psi spring for superchargers
the valve can be open or closed at idle depending on your air meter setup:
- if you are metering air BEFORE the BOV you will need to have the BOV shut at idle, unmetered air will be EXITING the bov and cause a rich condition because less air is entering the engine than previously recorded by the MAF sensor
- If you are metering air AFTER the bov it does not matter one way or another if the valve is open or closed at idle, since the air exiting the bov is before the air meter on the car you are going to get a correct mix of air fuel. - if your air metering system is like this i would suggest a step lighter spring than the car is rated for, that will ensure you lightning quick response.
Is vacuum line size important?
Hell yes it is, if the line size is too small you will be restricting flow, which could cause problems. I've seen a LOT of evo owners get the required 1/4" ID line and attach it to the very small very restrictive connector right by the valve cover. the proper way to run the BOV is this: 1/4" ID reinforced line (brake line from autozone...it's cheap) running from the BOV ALL THE WAY to the intake manifold with NOTHING ELSE T'd into that line.
How do i know which spring i have?
It's on the box the unit came in
But i bought it used!
give me the SN on the top of the unit and I'll look it up
I hear you offer free bov spring swaps if my vacuum changes
Yes this is true, requirements are you must provide a picture of your unit and the SN from the top...some bozo's have tried to send us knockoff springs - we aren't stupid here guys, i can smell a fake from a mile away. you pay shipping, i turn the springs around the same day they come in
you must also include a note in the box with all of your contact info and what we are doing i deal with about 50-60 turbos/gates/bov's a week, when i open your box i need to know exactly what needs to be done, and will not ship back to the UPS store or the like.
03-15-2012, 09:45 PM #10
Josh (BAYOU FZR) brought me a couple of Riva Power Coolers to make a block off plate for the existing HKS flange and install the Tial flange. He had mocked it up in his ski and showed me where it needed to be placed. Here are a few pictures of the valve mounted for those who wanted to see them on the FZR platform.
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