?Blow off valves?

NVJAY775

NVJAY775

Married with children
Joined
Jun 16, 2007
Messages
94
Hey guys. I am curious about BOVs. Does anybody run them? Why and why not? It sounds kinda wrong when you have to get out of it, for whatever reason. It sounds like a 50 pound dove bird taking off under the hood. Any input guys? Thanks in advance.
Jay
 
BOV's are not really needed in a diesel application, unless you are prone to going from WFO to idle at a fast pace. Unless your going for the ricer sound, then there is some bad BOV's for That!
 
BOV are needed for some trucks. They are great for the Duramax with big tunning. If you chop the pedal under load it will dump the excess pressure out to atmosphere so the compressor doesn't have to see that load. I have one and it works great !

Here is a link to mine!

http://www.youtube.com/watch?v=T7zQHag-FSQ
 
C.A.P said:
BOV are needed for some trucks. They are great for the Duramax with big tunning. If you chop the pedal under load it will dump the excess pressure out to atmosphere so the compressor doesn't have to see that load. I have one and it works great !

Here is a link to mine!

http://www.youtube.com/watch?v=T7zQHag-FSQ
Click to expand...


If you dont mind me asking, what boost were you at when that popped off? I am assuming by 50mm it is a Tial similar to the one in the BD turbo guard kit? I ask because I recently purchased a turbo guard, and I got it to work ok at low boost however at higher boost it wont seal. I put in the larger spring and it won't pop, (to stiff). I want to cut the larger spring, but dont know where to start, dont want to cut it to short. Any recommendations on where to start? I am running an industrial Injection Silver bullet 66 at about 55psi with supporting fueling mods (dodge). I dont want to screw it up and have to buy a new spring. Anyway I was just wondering because that sounded a whole lot louder than mine, when I had it working at 40psi it was barely noticeable. Also, if your not running the turboguard system, what are you using to control it.
Thanks in advance,
Alex
 
x3! I try not to chop the pedal at full boost but sometimes it happens, and it seems really hard on the turbo.
 
I was curious as to what signal you used to get that to pop. I thought a BOV used vacuum to tell it when to open.
 
I end up chopping the pedal occasionally too. Loss of traction usually. It doesn't sound the greatest. BOV setups anybody?
 
This is the BD kit. It . For Cummins you will probably need to experement. The softer spring is good for the Duramax. The heavier one is for the Cummins. If it will not seat back make sure the valve walls are clean. I use a tiny bit of petroleum jelly. Not on the Viton seal, but the inner aluminum. If it stays open you may have to adjust the settings on the controller. It is a tricky deal but once you get it right its set. As for boost I see 47 lbs with the GT4094. It is WAY louder live than in the video.


1 A BOV(blow off valve) is not a boost controller.
2 It is not a waste gate
3 It is not a boost increaser
4 It is not a device that will give you any power.

What it will do, and does well is save your turbo.

Typically diesels do not have turbo surge(Bark) at stock levels. However with todays bigger turbos and heavy fueled tuning we get a turbo to light and create excess of 45 to 65 lbs boost. when all that boost is in the engine and the turbo is pushing through the cooler you have positive pressure.

Now when we have 45 + lbs of boost and you chop the throttle , all that positive pressure has to go some where ! The engine is slowing down and the turbo is still spinning at excess of 120,000 rpms. You are not gonna force the engine to take it, so it heads right back up the stream. This is the sound you hear WOOOP ......WOOOP.....WOOOP....... , Better known as Turbo bark or properly known as "SURGE" . That is the air trying to force it self back through the turbo compressor wheel . The sound is the wheel chopping the turbulent air at 120,000+rpms. Now some of you think this is cool. Until you break a center shaft from to much stress on the turbo.

This is where a BOV comes in. YES, DIESELS DO NEED THEM TOO. Get that misconception right out of you GAS MINDED HEAD.

As soon as you chop the pedal on big boost the BOV opens and releases the pressurized air from returning to the turbo and barking it. Thus the big air rush you hear. It only opens when you chop the pedal. Unlike a gas engine where it may open between shifts, a diesel has no vacume and always has positive pressure.

Now some of you are wondering how , with out vacume can we get a BOV to work. Well we use a spool valve and a voltage switch that is wired into the TPS(throttle position sensor) that measures the intake boost and senses the immediate voltage drop when the pedal is chopped. This allows the spool valve to divert the air to the BOV as it pressurizes the spring inside and releases the boosted air before it gets back to the turbo. Thus it save the turbos eventual life.

This is not a Mod for the every day enthusiast. It is a mod for big power tunes and big turbos. Why spend $4500 on a turbo and not help it live longer by pairing it with a protective device.
 
Nice info! Greatly appreciated. My turbo isn't near that cost mentioned, but I do want it to last as long as possible. I need the truck to be reliable. It's mainly a work / tow rig. Any input on products and or setups. Maybe some install info as well? Can't thank you guys enough for the input.

Jay
 
C.A.P great write up, I always appreciated when guys take the time to really convey some good info.:clap: There is far too much confusion on alot of diesel sites about a device with such a simple purpose. Its the implementation and making it work that confuses people, I think. Anyway, Im glad to hear that yours is even louder in person. I have a very loud exhaust (dual 5in straight lake pipes, they exit right behind rear window) and the way mine sounds it is literally inaudible. I think this is mostly because I have not yet had time to properly tune it and I have several boost leaks I have not had time to fix due to the fact that I bought the Turbo guard just before I left for college and had just enough time to do a rough install and a boost leak check which resulted in me finding several. So I am hoping that once I get that all straightened out it will at least be loud enough so I can hear it working. Like yourself I didnt care much about the sound but instead my $2000+ investment (which I got used).

As soon as I get it all to work, I will try to remember to report back so all you other fellas interested in getting one of these can have another first hand experience.

Again thanks for the great info, much appreciated!
:thankyou2: Alex
 
GRotman said:
BOV's are not really needed in a diesel application, unless you are prone to going from WFO to idle at a fast pace. Unless your going for the ricer sound, then there is some bad BOV's for That!
Click to expand...

it's not that BOV's are not 'needed' in a diesel truck, they most certainly are..
it's that BOV"s are vacuum operated, and diesel engines don't historically make vacuum..

some of the newer diesel engines have a throttle plate for emissions reasons, and this may or may not provide enough manifold vacuum for this to work.. my 04 came with a throttle plate in my elbow which i have since removed..

i am actually in the process of trying to design a BOV for my truck. i know that there is a company that is making a BOV kit for the duramax kit that is electronically operated, and microprocessor controlled ( i believe it uses boost reference and TPS inputs to know when to open)..

i think i will install a vacuum gauge on my manifold and maybe even reinstall my throttle plate (which was only for egr purposes and i no longer have an egr system).. if i can get my SCT to control the throttle plate, then maybe i can get something to work.. or maybe i can come up w/an electronic one too..

BOV's are important because they release the pressurized boost charge into the atmosphere upon releasing the throttle (usually for an upshift, or any time you are under boost and release the throttle)

on our PSD's you notice you will usually only hear this surge (turbo fart) when releasing the throttle rapidly while under boost.. this sound is actually created by the pressurized intake charge in the boots/intercooler/manifold suddenly having nowhere to go and being forced back into the turbo the wrong direction.. this actually 'backspins' the turbo and the sound you hear is the turbo shaft actually changing directions several times back and forth..
this is MURDER on the turbo, and eventually can lead to turbo shaft failure.
 
AOsipower said:
If you dont mind me asking, what boost were you at when that popped off? I am assuming by 50mm it is a Tial similar to the one in the BD turbo guard kit? I ask because I recently purchased a turbo guard, and I got it to work ok at low boost however at higher boost it wont seal. I put in the larger spring and it won't pop, (to stiff). I want to cut the larger spring, but dont know where to start, dont want to cut it to short. Any recommendations on where to start? I am running an industrial Injection Silver bullet 66 at about 55psi with supporting fueling mods (dodge). I dont want to screw it up and have to buy a new spring. Anyway I was just wondering because that sounded a whole lot louder than mine, when I had it working at 40psi it was barely noticeable. Also, if your not running the turboguard system, what are you using to control it.
Thanks in advance,
Alex
Click to expand...


is this the electronically operated BOV you guys are talking about.. if not, most vacuum operated ones such as tial have several ports on them.. there is a boost reference port that sends boost pressure to the other side of the diaphragm to keep the valve closed under boost, that way the spring pressure won't be over-ridden.. actually this is the same one that opens the BOV also.. i'd have to see what kind you are working with.. but look and see if there another reference port somewhere..

are you hooking up the engine side of the vacuum line to the upstream or downstream side of the actual "throttle plates" ... because this can affect the amount of vacuum (if any) you will register.
 
C.A.P said:
This is the BD kit. It . For Cummins you will probably need to experement. The softer spring is good for the Duramax. The heavier one is for the Cummins. If it will not seat back make sure the valve walls are clean. I use a tiny bit of petroleum jelly. Not on the Viton seal, but the inner aluminum. If it stays open you may have to adjust the settings on the controller. It is a tricky deal but once you get it right its set. As for boost I see 47 lbs with the GT4094. It is WAY louder live than in the video.


1 A BOV(blow off valve) is not a boost controller.
2 It is not a waste gate
3 It is not a boost increaser
4 It is not a device that will give you any power.

What it will do, and does well is save your turbo.

Typically diesels do not have turbo surge(Bark) at stock levels. However with todays bigger turbos and heavy fueled tuning we get a turbo to light and create excess of 45 to 65 lbs boost. when all that boost is in the engine and the turbo is pushing through the cooler you have positive pressure.

Now when we have 45 + lbs of boost and you chop the throttle , all that positive pressure has to go some where ! The engine is slowing down and the turbo is still spinning at excess of 120,000 rpms. You are not gonna force the engine to take it, so it heads right back up the stream. This is the sound you hear WOOOP ......WOOOP.....WOOOP....... , Better known as Turbo bark or properly known as "SURGE" . That is the air trying to force it self back through the turbo compressor wheel . The sound is the wheel chopping the turbulent air at 120,000+rpms. Now some of you think this is cool. Until you break a center shaft from to much stress on the turbo.

This is where a BOV comes in. YES, DIESELS DO NEED THEM TOO. Get that misconception right out of you GAS MINDED HEAD.

As soon as you chop the pedal on big boost the BOV opens and releases the pressurized air from returning to the turbo and barking it. Thus the big air rush you hear. It only opens when you chop the pedal. Unlike a gas engine where it may open between shifts, a diesel has no vacume and always has positive pressure.

Now some of you are wondering how , with out vacume can we get a BOV to work. Well we use a spool valve and a voltage switch that is wired into the TPS(throttle position sensor) that measures the intake boost and senses the immediate voltage drop when the pedal is chopped. This allows the spool valve to divert the air to the BOV as it pressurizes the spring inside and releases the boosted air before it gets back to the turbo. Thus it save the turbos eventual life.

This is not a Mod for the every day enthusiast. It is a mod for big power tunes and big turbos. Why spend $4500 on a turbo and not help it live longer by pairing it with a protective device.
Click to expand...

so true !! i wish more people understood this !! it's not that we don't need BOV's , the reason we don't have them is because of the fact we don't make the vacuum required to operate them..

do you know anyone making a similar setup for 6.oh's ?? i've been thinking of designing one myself to save my turbo too.. what about the "vacuum pump" and reservoir that we have for operating things like the HVAC system and the automatic hubs ??

is it possible to tie into this vacuum system w/a line to the BOV and have it electronically signalled to let the vacuum open the BOV due to TPS sensor volgage input ??? my PSD uses an electronic throttle also...

you could run a boost line to it to keep it closed so you wouldn't need too stiff of a spring, and another vacuum line going to the vacuum tank (w/some sort of control valve in line) to operate the thing ??

anyone have some ideas...
i've been working on some new charge tubes for my buddy's diesel, and we've got the BOV, just still trying to figure out to actually get it all to operate correctly.:
CIMG0128.jpg
 
is it possible to tie into this vacuum system w/a line to the BOV and have it electronically signalled to let the vacuum open the BOV due to TPS sensor volgage input ???
Click to expand...



That is a great idea Ihave an extra procharger race gate that would be great for a diesel if the vacuum setup would work. I am not sure how to wire it with electronic throttle but with a 12v all you would need is a micro switch and a solenoid valve. Thanks for the idea that will give me a weekend project to try:thankyou2:
 
ford69557ci said:
That is a great idea Ihave an extra procharger race gate that would be great for a diesel if the vacuum setup would work. I am not sure how to wire it with electronic throttle but with a 12v all you would need is a micro switch and a solenoid valve. Thanks for the idea that will give me a weekend project to try:thankyou2:
Click to expand...

did you get around to trying that out ??
i also thought about a simple microswitch and solenoid valve, but since i have an electronic throttle and "fly by wire " i was hoping i could come up with something that would open when it sensed the voltage drop from TPS sensor or the actual throttle sending unit ??
 
SinCityDiesel said:
did you get around to trying that out ??
i also thought about a simple microswitch and solenoid valve, but since i have an electronic throttle and "fly by wire " i was hoping i could come up with something that would open when it sensed the voltage drop from TPS sensor or the actual throttle sending unit ??
Click to expand...

This is exactly how a turbo-guard operates...tps voltage drop...you could just buy one or maybe call BD and see if you can talk to one of their engineers or techs, however I doubt they will share much on how to build one yourself. It does utilize an electronic solenoid valve too...which is controlled via a little computer box with four adjustments for apps, pulse, time and reapply.

-Alex
 
Also you mentioned a Micro switch...this is how they are operated on the 12v cummins...so either solution is viable, however the micro switch would be far less involved electronically speaking.
-Alex
 
or you can get a dual chamber bov and plug drive pressure into bottom side and boost on the top side

So when your boost drops, drive pressure opens the BOV

It works exceptionally well unless your drive pressure under boost are on the order of 15-20+ more than your boost is

KISS lol
who needs electronix
KTA came up with this one
 
Have you tried that setup? I'm guessing their is a quick spike in drive pressure when you chop the throttle? I'm gonna have to go watch my gauges and see this in action!
 
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