RB20 aftermarket BOV questions

[Boyscout]

remove it and dont use a BOV

[DreadedFist]

remove it and dont use a BOV

sssssSSSSSHHHHHH tu tu tu tu tu tu

[quadracer111]

I still cant believe someone bought that car! hahaha
j/k lol I was the one who made the video for this car and as far as I remember the BOV was really nice but really expensive. Sequential BOVs are up there in the splerge department but worth the money if you have it.

What do you mean you can't believe someone bought the car??
Thats something that doesn't sound to good...

[BurlyR32]

Run full atmospheric and tune the car properly.

[trickey1991]

hittin up an old thread but.. I currently run a Tial 50mm BOV -Non recirc. I relocated it the front of the engine bay in the charge piping. I removed/ plugged the previous recirc piping. If i decide to buy a recirc BOV like the Tial Alpha Q does anyone have a diagram of where to recirc the BOV to?

[BongRips]

The one problem I was having when I was trying to run a Greddy Type RS VTA is either at idle and vacuum the bov diaphragm would be open allowing air to come in through there and get in but when throttle was applied it would close and release fine with no compressor surge, OR if I tightened it enough to not allow air to leak in at idle and vacuum, then I would get compressor surge instead of it releasing properly. My question is this; Once I do front facing plenum, and haltech with conversion to map sensors, will I be able to use this bov and have it work properly as in stay closed until I need it to release boost? Or do I misunderstand how bov's work and need to buy a synapse bov with anti-stall valve if I wanna run VTA?

[trickey1991]

I think I might go with the TiAL QR BOV, its a recirc and is rated well

[Skym]

BOV is designed to release pressure that reverses direction when throttlebody closes. BOV should be closed under boost.

With diaphram BOV it's like pushing a balloon against a bin, the balloon is going to collapse before bin moves, hence valve is slower to open. They work around this by increasing valve size. Wastegates are the same (diaphram) hence why you can get overboost problems and have different size valves. Also diaphrams are affected by engine bay or exhaust manifold heat (known problem).

Synapse BOV being a piston type BOV (no diaphram) is designed to react as fast as the plate inside throttlebody and being a pull type BOV means the BOV is kept closed by the boost pressure (not going to leak). It uses a boost source feed (Port C) which helps incase of an overboost, where it can force the valve open and helps BOV open quickly.

Testing like this in link below for Synapse BOV shows how fast BOV opens (faster = better) which removes the pressure, that if not released or not released fully would reverse direction and go across compressor blade (slowing turbo down) creating the flutter sound out of podfilter -

http://www.youtube.com/watch?v=71L1w77xC-M&feature=relmfu

That's one of the reasons why I run a Synapse BOV on my car, as there is proof that it releases quickly and no flutter sound when fitted to car. Also because it does this, when getting back onto throttle, turbo is already spooled up, so engine reacts quicker (increases transient response / hp). Also Synapse BOV releases below 0 (where there is some pressure and most aftermarket BOV's wouldn't do this) on boost gauge, so improves offboost transient response / hp and this is something I did notice in reallife on my car.

With push type factory BOV, once spring and boost that is fed via vaccum hose to top of BOV is overcome, valve opens (around 10psi on GTS). It's a way to protect engine from overboost. Also there's a boost feed hole next to main valve that helps stock BOV to release quicker at lower boost levels. If this is hole is blocked, stock BOV doesn't release pressure until above 1-3psi on boost gauge and when BOV does, can hear flutter sound. Also doesn't leak at 10psi. Factory always put multiple failsafes (BOV opens at 10psi, boost cut on ECU) to make sure engine last's the 100,000km or 3 year? warrenty period.

With push type aftermarket BOV, adjusting spring preload (soft or hard on top of BOV via nut) makes BOV valve stay closed longer (when set to hard setting which makes spring shorter / adds more spring preload that pushes on top of valve) before spring, vacuum get overcome and valve opens when releasing throttle at lower boost levels and keeps valve closed at higher boost levels. Basically when set on harder setting BOV opens at around 1-3psi+ when throttle is released, not at 0 on boost gauge if set on a softer setting (spring is longer / adds less spring preload that pushes on top of valve).

[BongRips]

The one thing I don't understand is the difference in operation while using a map setup. I know with stock mafs you wanna recirc or get the anti-stall valve with the synapse if you wanna vta properly. Obviously the nipple for a bov is tapped into a boost source so at vacuum it stays open and boost it closes, but isn't it bad for the valve to be open at vacuum (ie idle) because wouldn't that cause a leak and then cause stalling even on a map setup? If so, what's the point of diaphragm bovs then???

[Skym]

MAP sensor is mounted at intake manifold, so what air is left over after VTA BOV has released enters intake plenum. The MAP sensor measures this air and ECU selects correct load cell on fuel, ignition map with correct fueling, timing.

With MAF the air is released behind MAF by VTA BOV and ECU has no way to know the amount of air has changed, so ECU selects fuel, ignition cells to match what MAF measured (which is too rich) and engine stalls or pops flames from exhaust or could have a rough idle. But o2 sensor picks up on this rich problem and ECU adjust's fueling to make engine run leaner, then rich again, then lean, which when combined with idle stabilisation adjusting ignition timing to suit, creates the rough idle. Recirculating air to infront of and back through turbo keeps same amount of air in intake piping, so engine doesn't run rich.

Also can run into reversion (air reversing direction and heading towards MAF) problems when turbo slows down too much with VTA BOV, which makes engine run richer and is usually the cause of engine stalling.

A way around this problem with VTA BOV is running a blow through MAF setup or moving MAF further away from front of turbo (to reduce reversion problem which works).

Or fit a HKS EIDS which allows you to adjust leaner or richer and for how long -

http://www.hksusa.com/products/?id=2175