SR20 & Tial BOV

[Mysterious Driver]

Ok so for awhile i haven't been too happy with my BOV i'm running a Tial 50mm BOV on my redtop SR it doesn't hit as hard or normal in my opinion. I have a Stock motor and Stock turbo the pressure sounds no different from when i ran a T25 or the T28 at 11psi it sounds low and on 17psi it sounds to a medium It is mounted on the cold side pipe instead of the hot side as i was told originally it wouldn't make a difference.

Here's the crazy part Originally the spring inside wasn't opening much so i ended up getting a 9psi spring for it. It ran bad and started to leaked where car kept shutting off. We cut and mixed both springs together and the car ran fine and left it at that.

It's really weird cause my friend had a S14 SR swap with same turbo and same size injectors (550's), he ran the Tial BOV as well only his sounded VERY loud when in boost and loud while shift cruising. A tech told me that his version was probably a MAF as most common one's sold in the market are MAP versions so to go buy a Tial that's recirculated instead which would be the newer style ones. Can anyone vouch for this or know what could be the issue?

I'd really hate to buy the QR if it doesn't fixes the problem If i can't figure out what the issue is then i'm probably going to go with a SSQV

Newer style QR
http://www.tialsport.com/index.php/tial-products/bovs/47-tialbvqr

[KAT-PWR]

So your "problem" is the blow off valve isn't that loud?
I have a tial Q that vents from all sides and it is plenty loud. I'm also running a big turbo on 20psi.
If you want loud and bought a BOV that vents from a large area i would imagine it would be quieter than a Recirc style bov that vents from a smaller, single port.

[Mysterious Driver]

Tail BOV's in general pressure out pretty loud, they work perfect on JZ motors and other engines i heard it's hit and miss on SR motors just to me it doesn't sound normal.

at shift cruising the turbo surges while the BOV barely opens

[Kingtal0n]

Closer you get it to the turbo the faster it will open, respond, and the better it will protect your turbo as well. You also want a bypass that hangs open at idle as much as possible to keep the wheel spinning as fast as it wants to all the time (decreases "turbo lag"). If you have a maf you need to recirculate it no matter what for best results.

[jr_ss]

What spring do you have in your Tial? What is your idle vac? Perhaps you have the wrong spring in there? I have had no issues with my Tial on my SR.

[cotbu]

Closer you get it to the turbo the faster it will open, respond, and the better it will protect your turbo as well. You also want a bypass that hangs open at idle as much as possible to keep the wheel spinning as fast as it wants to all the time (decreases "turbo lag"). If you have a maf you need to recirculate it no matter what for best results.
You can always argue the location of the bov/bpv when people have issues. Most bov/bpv operate via vacuum so "the it will open and respond" is an untruth! Turbo lag usually is more apparent when the bov/bpv is leaking, including a correctly recirculated setup, boost is still leaking out of the system until the pressures equalize, I know you don't consider this a leak, but it is. That jolt of air when the throttle plate closes is best vent from the colds side when bov/bpv are sprung stiff, loose or low boost setups bov function better on the hot side close to the turbo and recirculated. Protecting the turbo is not the only job it has, (bov/bpv) its there to protect the entire system under pressure.

Op whats your vacuum like, try swapping vacuum lines.
I was going to stay out of this because, it's really a ricey type if question but...!;)

Sent from a Highly Tuned Note 4.5!!!

[Kingtal0n]

You can always argue the location of the bov/bpv when people have issues. Most bov/bpv operate via vacuum so "the it will open and respond" is an untruth!

push-type bypass open because pressure from under neath opens them, not only the vacuum source.

The pressure is higher on the hot side.

furthermore the "response" is simply the "activation of the feature", nobody can tell you that an opening is any kind of "response" to anything. The "activation of the feature" is the drop in pressure of the plumbing in front of the compressor. Simply put, the less volume there is, the faster it will empty from the hole in the bypass. Imagine you had an intercooler that held 500 gallons of air, and you put the bypass after it. Now when the bypass opens, the pressure will never drop in time to save the turbo, because there is too much volume to to relief.


Make a graph of pressure drop per time, for a ballon or an intercooler or any kind of plumbing in the world. Make a hole and chart the time amount of time it takes to drop the pressure. The larger the volume, given the same size hole, the slower the drop in pressure.

If there was no engine on the cold side, then it wouldn't make a bit of difference where you put the bypass. However, because the engine is still breathing as long as it is spinning, there is no significant reverse flow through the intercooler as there would be if you shut it off and stopped it to 0rpm at the same instant that you opened the bypass.


Protecting the turbo is not the only job it has, (bov/bpv) its there to protect the entire system under pressure.

actually protecting the turbo is the only job it has. Otherwise you could just remove it completely? Why even install one?

[pebecavi]

they work perfect on JZ motors and other engines i heard it's hit and miss on SR motors just to me it doesn't sound normal.http://goo.gl/eycghd

[cotbu]

push-type bypass open because pressure from under neath opens them, not only the vacuum source.

The pressure is higher on the hot side.

furthermore the "response" is simply the "activation of the feature", nobody can tell you that an opening is any kind of "response" to anything. The "activation of the feature" is the drop in pressure of the plumbing in front of the compressor. Simply put, the less volume there is, the faster it will empty from the hole in the bypass. Imagine you had an intercooler that held 500 gallons of air, and you put the bypass after it. Now when the bypass opens, the pressure will never drop in time to save the turbo, because there is too much volume to to relief.


Make a graph of pressure drop per time, for a ballon or an intercooler or any kind of plumbing in the world. Make a hole and chart the time amount of time it takes to drop the pressure. The larger the volume, given the same size hole, the slower the drop in pressure.

If there was no engine on the cold side, then it wouldn't make a bit of difference where you put the bypass. However, because the engine is still breathing as long as it is spinning, there is no significant reverse flow through the intercooler as there would be if you shut it off and stopped it to 0rpm at the same instant that you opened the bypass.


I do keep forgetting that people actually build slow cars, and justify the slowness for reliability.

But... here we go. There are many different types of bov/bpv you have to choose the best for your application, a push type is great for being close to the compressor housing, and low boost situations or when your on and off throttle quick but not building a lot of boost.
The cons of a push type bov/bpv for me is we have to shim them or run a super stiff spring, that defeats the purpose of that type of valve.

Pull types work best, for the type of engines I build, and they work much better than a properly sprung push type and I've used them on the hot and cold side without any ill effects.
My current engine has the bov on the cold side, recirculated and I have zero flutter and fast spooling, I make decent power and push the cat pretty hard. I know that not what everyone wants, so yeah.

Many of these types come in combination with each other meaning you could have a Push or Pull type Piston or a Push or Pull type Diaphragm or a Pull type Sequential or a Pull type Synchronic. I will simply explain each type individually to keep things simple.

Push Type. In this configuration, pressure is pushing against the valve and inherently wants to open it. The spring pressure is what keeps it closed and it's operation is triggered by both the pressure on the valve and the vacuum assist to overcome the spring pressure and ultimately pushes the valve open, hence the name Push Type. This type of valve is less desired in high boost/flow applications but is ideal for stock level and moderately modified applications. With this type of valve you don't need a strong vacuum source to successfully operate the valve and its reaction time is very quick. It lends itself well to applications utilizing large cams and is useful in driving situations that see many large throttle deltas in a short amount of time such as in an autocross event. It is also least likely to cause compressor surge but you risk leaking boost under high boost pressure applications.

Pull Type. In this configuration, pressure is pushing against the valve and inherently wants to close it. It's operation is triggered by the vacuum assist combined with the spring pressure and ultimately pulls the valve open, hence the name Pull Type. This type of valve requires a stronger vacuum signal to operate and its reaction time is slower. This type of valve lends itself well to high boost and flow applications and is better suited for 1/4 mile and 0-60 where shifting is quick and concise. There is a higher propensity for compressor surge with this type of valve how ever the higher levels of residual pressure that remains inside the intercooler piping is desired when racing the quarter mile. This will decrease spool time because the piping does not have to fill with so much pressure during the onset of power. Some of it is already there. With a pull type valve you have a balance between pressure release and surge

Diaphragm Actuated. These can be seen in both push and pull type configurations. It is constructed using a shaft attached to a disk that seals against a o-ringed surface or a precision machined surface and is actuated by a sealed chamber diaphragm at the other end. This type of valve tends to be durable and will maintain a seal over a good deal of time. The vulnerability is in the diaphragm. This component is subject to ware.

Piston Actuated. This valve is generally only push type though pull type piston valves exist such as in the Synchronic valve by Synapse.. It is constructed using a hollowed out piston like actuator that, when closed, seals against an o-ringed surface while the body of the piston blocks the outlet port. A spring is applied to the opposite side of the piston that sits inside a sealed chamber. when pressure is present in the intercooler and enough vacuum is present to overcome the spring pressure, the valve is actuated. Over time the piston tends to ware due to lack of lubrication and the valve may bind and/or leak.

Sequential. In this configuration the construction is much like a pull type diaphragm valve with one exception. The disk that makes up the valve is a two stage device consisting of two concentric disks with one inside the other. It is essentially one valve with in the other and consists of a main primary valve and an initial low level valve. During normal and moderate performance driving, the initial valve activates first to relieve the low volumes of pressure. As your level of performance increases, the primary vale then opens to relieve the higher pressures generated. This is a great idea because it behaves much like a push type valve but with the advantages of a pull type. The valve will remain sealed under extreme pressure and the sequential design is less susceptible to surge. So you can have your cake and eat it to.

Synchronic. Synchronic valves are pull type multi tier piston actuated valves and are operated by both a vacuum and boost pressure signal. This valve is designed to leak (remain slightly open) during vacuum only conditions. This is meant to significantly improve throttle response by bypassing latency restrictions of the turbo and piping prior to the throttle body. Instead the air entering the engine enters through the valve and not the intake. If using this type of valve on a MAF car you must use it as a BPV and must route the valve to the intake. This way when the valve is open during vacuum only conditions, the air will still pass the MAF sensor and be metered by the ECU. If you simply must have the sound and want to vent to atmosphere, Synapse has developed a Synchronic valve that can be configured as a BOV with the use of an Anti Stall Adapter. Though adding this adapter kind of defeats one of the main purposed of a Synchronic valve. This type of valve is fully capable of eliminating any and all compressor surge by precisely manipulating the vacuum and pressure signals in combination with spring pressure and the multi tier piston. This is the ideal solution for any valve application and can be ideally set up in both BOV and BPV configurations. It is one of the most precise and responsive valve configurations out and is the only type of valve that can actually increase performance by significantly improving throttle response.

actually protecting the turbo is the only job it has. Otherwise you could just remove it completely? Why even install one?
And I already said they protect piping, couplers and gaskets, that's just the protection part, they can help with lag, but this guy also installed one because of the sound.
Not all turbo engines have a bov or bpv, iirc
And we are not talking about the surge line on a compressor map here so...?

Sent from a Highly Tuned Note 4.5!!!

[Kingtal0n]

1. ya cant tell there are no ill effects. just because it doesn't explode or hold up a red flag that says "ouchie" doesn't mean there are no ill effects.

2. The manufacturers of TURBOCHARGERS are putting the bypass ON THE COMPRESSOR. Now if anyone even has the slightest idea of truth that the cold side was a better place, then that would mean these turbo manufacturers are literally putting the bypass at the worst possible location, as far from the cold side as possible. It would be like putting the trigger for a gun at the end of the barrel.

3. the pressure does not spike significantly when there is no bypass installed because the compressor acts as a bypass in those situations, it has no choice, and the compressor map clearly shows you that there is no way it could hold against any significant pressure rise because the flow rate is off to the left side (SURGE) of the map when you lift your foot. Have you ever checked your map sensor voltage on a car without a bypass and watched it during a throttle lift? It does NOT spike up and rupture gaskets, if it did nobody would ever even think about not running a bypass, and at least one guy would have mentioned it. Instead it just falls right back as if it didn't care what kinda plumbing you had.

4. as to turbo lag. I suggest you install a turbo wheel speed sensor and collect some real world data. Turbo lag is reduced anytime you get the turbo wheel speed moving faster. If you open the exhaust behind a turbo at idle the wheel speed increases. If you open a bypass at idle the wheel speed increases. If you spray nitrous into the engine, the wheel speed increases. Anything that speeds up the wheel reduces the lag of the turbo, and an open bypass at idle does exactly that.

[KAT-PWR]

I'll spray nitrous in your turbo