Blow-off Valve

[Vader's Fury]

http://www.shopatron.com/products/productdetail/part_number=1047225-S/532.0.1.1


Been thinking about adding one of these to my build. Since I have a 6 speed manual I believe that it will add life to my turbo. Especially since I tend to have a heavy foot.

Does anyone have any experience with blow-off valves on there diesels? On gas engines? Any experience you can tell be about or details on how they operate beyond they release air when you get out of the throttle would be appriciated.

 

[Whytry]

The link didn't work for me. I will tell you what I remember been a while since I have read on these but I am pretty sure they can be controlled. They release a lot of air very quickly. Other than that I can't remember. Some of the ones I have looked at work off vaccum I don't know if everyone does but it release pressure when it detects vaccum in the intake. Hope that gets you started

 

[Vader's Fury]

Fixed it.

I know that the purpose of a blow off valve is to rapidly release the pressurized air in the intercooler tube. I also know that they are proven in the gas world.

What I believe is that this could prevent the "surge" or loud "bark" that is common when hard into the throttle and then all of a sudden dumping the throttle. Being as I have a 6 speed this would happen alot as I row through the gears, especially when pulling a load or trying to shift while climbing a grade.

Here is another product that is similar.

http://www.turbosmartonline.com/index.php?id=592

 

[Vader's Fury]

Ok...... So I have been doing some more research on these and it seems that they use a controller to read voltage to the tps and use that to control when the bov releases pressure or seals up to retain pressure in the intercooler tube. I found this video on You Tube.

http://www.youtube.com/watch?v=lXi79kLz6dM&feature=player_embedded

Seems to work pretty well. You can hear around 14 sec mark that he quickly gets out of the throttle and right back into it and the valve shuts just as quickly. This was one thing that I was worried about. Seems that in a DD set-up the slight delay that is present(if any at all) is so minimal that it wouldn't affect the boost coming back up.

 

[bigbadford01]

subed

 

[RedSmokey]

The only people that I have noticed using BOV have a twin turbo setup. Otherwise AFAIK it wont really help you. Just like in the video its a 6.4 (twin turbo)

 

[Vader's Fury]

Why do you think it wouldn't help. I believe the problem would be the same with a single turbo as you would see with twins, just a lower pressure. You still get a Loud "Bark" when you get out of the throttle quickly. That is what I am trying to prevent as I am sure that the turbo really doesn't care much for this.

 

[RedSmokey]

Why do you think it wouldn't help. I believe the problem would be the same with a single turbo as you would see with twins, just a lower pressure. You still get a Loud "Bark" when you get out of the throttle quickly. That is what I am trying to prevent as I am sure that the turbo really doesn't care much for this.

With gassers they NEED the BOV as they have a throttle plate that traps the boost when it slams shut, leaving it no where to go. For us it just escapes back out the filter. Im not saying for sure it would do nothing, but I dont see it helping much or almost at all. I would be interested to see if I was wrong though. If you do mess with it, please post results. And where would you plan to plum it, in the CAC tube right before the intakes or maybe right next to the turbo on the hot tube?

 

[Vader's Fury]

I was thinking of plumbing it in on the hot side intercooler tube. I figure this is the best place for it. I want it to prevent air from causing the turbo to stall, so place close to the turbo makes the most sense.

I have added this to my list of things to do for my truck. I don't see it happening for a couple of months though as I already have spent my truck budget as of right now but I do plan to add this once I get the coin together. Planning to use the Turbo Smart one.

 

[TARM]

There is something the OEM are setting up on the new turbo systems or maybe its upcoming ones but its to control the surge back thru the comp wheel when there is sudden rapid throttle let off during boost. I only briefly skimmed over it while doing some reading so I do not know any of the technicals. IIRC it feed the pressurized air around the comp wheel and back into the intake tube between filter and comp inlet. Was triggered by boost and TPS I think.

 

[2stangs8689]

I don't have any experience with them on a diesel, but I used Tial's on my turbo car. They were vacuum actuated, but the springs could be changed out, so they only would open at a certain vacuum level. They were closed all the time, except for when I would come out of "hard" boost, but would close up very quickly as well.

 

[Big Bore]

I notice the barking under throttle and upshift. This has always concerned me. That can't be good for the turbo shaft and considering its a BB could be expensive if it snaps. This blowoff valve interests me. I've already been researching wastegates for the compounds and run across them a lot at the same time.

 

[Tree Trimmer]

we just had this topic over in psn. it went something like, that bark you hear is the turbo wheel stalling and the air coming backwards out. you need to think the compressor wheel spinning somewhere around 80k+ rpm to 0 in less than .1 secs, with the turbine wheel still being driven by exhaust. to me personally, that does not sound like a good scenario.

if you have that bark, or wheel stall, and a bov will fix it, then why not put one on? i realize that most ppl probably are not running one, and their turbo probably has X thousand miles on it. this is where you make up your mind, if you want to chance being "that guy".

 

[2stangs8689]

I ran all Tial stuff on my 1000hp turbo car, and not one problem. I've been reading of some issues with the Precision gates.

If you were to call a Tial dealer, tell them what you are after, they should be able to recommend a spring for the BOV that won't completely open the valve the whole way, just enough to release the pressure and take the load off the compressor wheel.

 

[littleredstroker]

i just dont buy the whole wheel stopping/ going backwards thing.

 

[2stangs8689]

It's definately not stopping dead, but it does fight to slow down, that's for sure.

 

[juniort444e]

Isnt that what a waste gate is for, or am i miss understanding something here. I know when i let off the throttle on a harder run or even from a 50psi spike it makes that sound, and i dont mind it, kind of sounds kool, but i know it cant be good either.

TT... Thats what scares me is the sudden difference is spinning the wheels go through. I want to drop down to a smaller housing and put a waste gate on for quicker spooling, but i can imagine that making it worse.

All i know is a waste gate helps with back pressure. To me that sounds pretty close to a bov.

 

[2stangs8689]

A WG is supposed to bleed off the "unwanted" exhaust gas that would otherwise spin the turbine passed a desired point, a BOV on the other hand relieves the pressure from the cold side compressor, once the throttle is lifted, and motor sees vacuum. Absolutely necessary on a gasser with a throttle blade snapping shut, giving the compressed air an escape route.

The sound you are hearing is compressor surge, which is basically the turbo fighting to slow down.

 

[juniort444e]

Ok, that clears it up for me.

Would it help on a bigger single turbo truck. Im running a gt4202.

Also would having both be a good thing, or not really needed.

 

[2stangs8689]

That's the debate, atleast as far as the BOV goes.

Personally,I don't like the idea of running a turbo without atleast a WG, which is why I opted for the 38R, for now, until I can swing one of Jake's T4 mounts, WITH a WG. A WG will give you alot more control over the turbo, especially with a larger turbo, with a change of a spring you can dial in your target boost number you want, as not everybody is either set up for, or wants, say 50#'s of boost.