Blow off valve on the hot side

[95blackGsTurbo]

I am going to be making my new intercooler piping for my intercooler and going with a MAFT setup so no need for recirculating but is anyone on here running thier blow off valve on the hot side of the intercooler. I have been waiting to do this for a while as I have seen HUGE success with some friends that are running it on thier cars. I know it is the best place to put it and is hard to do on a stock car but with no recirc. I am gonna try it. Just wondering if anyone else was doing it and where they put it on thier piping.

 

[brute]

How can they have huge success? Because it works? Or did they test intercooler efficiency and intake air temperatures? It seems like a lot of extra work to me, and I don't see any gain from doing it other than to say you did. But I do a lot of stupid stuff that only I care about, so whatever floats your boat.

 

[DSMunknown]

I am going to be making my new intercooler piping for my intercooler and going with a MAFT setup so no need for recirculating but is anyone on here running thier blow off valve on the hot side of the intercooler. I have been waiting to do this for a while as I have seen HUGE success with some friends that are running it on thier cars. I know it is the best place to put it and is hard to do on a stock car but with no recirc. I am gonna try it. Just wondering if anyone else was doing it and where they put it on thier piping.

Adam, I am sorry to say that I am unable to find the link to support my next sentance, but in the wave of "MAFT" and "MAF-T" threads, I would be here all night. I remember somewhat recently where one of the five-star generals commented that even when running with the MAF-T setup, the turbine wheel "likes" the extra air pressure that comes into the air inlet pipe when one recirculates.

How can they have huge success? Because it works? Or did they test intercooler efficiency and intake air temperatures? It seems like a lot of extra work to me, and I don't see any gain from doing it other than to say you did. But I do a lot of stupid stuff that only I care about, so whatever floats your boat.

I would also be skeptical about the added length to the vacuum hose that connects the BOV to the intake manifold. It seems that with the increased length of the hose, there may be a delay time in the responsiveness of the BOV.

 

[95blackGsTurbo]

I would also be skeptical about the added length to the vacuum hose that connects the BOV to the intake manifold. It seems that with the increased length of the hose, there may be a delay time in the responsiveness of the BOV.

I was wondering about that myself but it won't be that much farther away because it is going on a huge stock located LICP for my big sidemount. And I tapped the manifold as close to the TB as I could so it is only 3" more of line. That was my big worry too. But with SS line from manifold to BOV it shouldn't be a problem. And If I want to recircualte, which I might, the location will allow me to wend a little pipe onto my intake pipe that will recirculate the BOV so it is shooting straight into the turbo instead of straight down into the intake pipe.

 

[Boosted98gsx]

Colder air = denser air. that means that the BOV has to let off less volume to discharge the intake system when put on the cold side, because all the air has to go through the intercooler and cool off before exiting the system.

What you are considering is risking compressor surge.

 

[95blackGsTurbo]

Actually if you read the advantages of it, its risking it less. The BOV by the TB allows air that has already started back into the compressor to get there. This way there will only be 1-2ft of piping instead of 8 or so. Denser air doesnt really have anything to do with it. I got the idea from a local performance shop that does this on all of thier sub 8 second cars and 10 second street cars. They explained it to me and showed it to me with sensors measuring the amount of air getting back to the turbo and the BOV on the hotside was considerably less.

 

[Boosted98gsx]

That doesnt make any sense. If you put it closer to the throttlebody, the aircharge will continue moving towards the TB and instead out the valve so you have less air moving towards the compressor, aka less risk of compressor surge.

If you put it at the compressor, you have ~8ft of charged air instantly rushing backwards towards the compressor, and if the valve gets overrun, it's going right to the turbo.

 

[95blackGsTurbo]

You have to think of it in milliseconds. There is a big gap of time from when the throttle plate closes and the BOV opens. There is a LOT of air that hits the throttle plate and starts back to the turbo. That air has no where to go in that time so it starts the air coming from the turbo back to the turn so there is a small amount of surge. But putting it by the turbo it releases all of the air coming back and coming out of the turbo so that no air can be moved through the system until the bov closes. I will see if I can get his graphs and the test he did that measures how much air was rushing back with the BOV in both places. It wasn't a significant amount but there was more air going back with the turbo with the BOV closer to the TB. It's not gonna hurt anything and I'm not saying one way is better than the other because I don't fully understand it myself but the guys that do it understand it and have the proof to back it up.

 

[nikkeebabee]

those 8 second cars, arent usually running intercoolers thats why the bov is on the "hot" side...There isnt a cold side!!!!

Look at shep he runs twin tials stil close to the t/b

i understand the need to be different hell theres cars that run without bovs, just because you can do doesnt mean you should...thats what started the lambo door tread....

too bad the bov on the hotside wont be a bling...

 

[GVR4592]

Actually if you read the advantages of it, its risking it less. The BOV by the TB allows air that has already started back into the compressor to get there. This way there will only be 1-2ft of piping instead of 8 or so. Denser air doesnt really have anything to do with it. I got the idea from a local performance shop that does this on all of thier sub 8 second cars and 10 second street cars. They explained it to me and showed it to me with sensors measuring the amount of air getting back to the turbo and the BOV on the hotside was considerably less.

What sensor are they using that measure the amount of air that is returning to the turbo? That would be almost impossible to measure.

 

[95blackGsTurbo]

Nope they run an intercooler. And you can run it on either side and it will be fine I was just wondering it anyone was doing it. As far as the sensor, they used a basic resistor like in a MAF sensor but cut a brass pipe in half to block off it getting a reading coming from the turbo, just a reading from air coming back, read in HZ just like the MAF. Very basic but it worked.

 

[mavisky]

Everything I've ever read states that closer to the TB = better. Mine's about halfway between the ic outlet and tb though as apparently having the MAFT setup too close to the tb can be bad as well.

 

[Kevin Jewer]

I ran a tial BOV on the lower IC pipe on the 2g simply because I had no choice. With a 3-3.5" UICP with nice gradual transition, there was no room for it on the UICP. Pics here. There was a bit of a delay in it opening, but I never got around to finding out why. It could have been from it's location, or from too stiff a BOV spring for my cams, etc. At the track I don't lift when I shift, so the BOV isn't used, so I never bothered to look further into it. It worked for what I was doing.

 

[JOEY A]

Meh my buddy isnt even using a bov on his GT30 sti swapped wrx


Keeps the car in boost alot better between shifts, go ahead and tell me its wrong and doesnt work, and try explain to me why blah blah

It works, alot of race cars dont use bovs..

 

[project_tsi]

Look at shep he runs twin tials stil close to the t/b

No he doesn't.

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Your probably thinking of Albert of DV/DT Fab

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[Boosted98gsx]

Yes, well abert is the engineer, I would tust what he does over anyone else.

 

[delta448]

That doesnt make any sense. If you put it closer to the throttlebody, the aircharge will continue moving towards the TB and instead out the valve so you have less air moving towards the compressor, aka less risk of compressor surge.

I'm no expert, but I think it would be better to think of it as a pressure wave or a pulse, instead of visualizing a volume of air moving, -that is until the BOV actually opens and there is a volume discharged. When the plate closes, there is a pressure spike at the plate that moves back toward the compressor incredibly fast. The compressor is still packing more air in, and there is a collision between the incoming air and the pressure wave right at the turbo. No matter where you put the BOV, this interaction will occur. It just happens way too fast. The BOV needs to open only quick enough to not allow the turbo to add pressure to the point where the pressure actually makes air start to flow in the wrong direction. If the BOV is right at the outlet and if the BOV opens quickly enough, the air being added by the turbo has a shorter route to the BOV outlet, but this also requires air to flow backwards from the plate which leads to...

~8ft of charged air instantly rushing backwards towards the compressor, and if the valve gets overrun, it's going right to the turbo.

But I don't totally agree, because the turbo is still pushing air. The valve is key. I don't think it'd be easy to overrun any decent BOV, because it -minimally speaking- only has to be able to flow enough to not allow overall pressure to remain the same or increase.

I really think that BOV placement is nothing more than your own personal preference. But sometimes it may actually be beneficial to have it on the hotside. More of the air blown out will be from the turbo and will allow some of the air already cooled by the intercooler to remain. I think this is the only real benefit, if there even is one.

 

[herblove]

My tial BOV is mounted on the hot side to the my intercooler intank. It was not my plan to mount it there. The guys that work on my car mounted it there when they were making my 3 UICP. They said that is where it should be to releive the most pressure off of the turbo. I do notice what sounds like compressure surge if I slowy let off of the gas under boost. It was real bad until I change springs the BOV. I think that maybe having the BOV on the UICP give you a faster response.

 

[95blackGsTurbo]

Faster response it one of the advantages of putting it closer to the TB. And you don't think that the guys that are putting this type on aren't engineers? If it is good enough for a 6 second car it should be good enough for mine.

 

[mavisky]

Meh my buddy isnt even using a bov on his GT30 sti swapped wrx


Keeps the car in boost alot better between shifts, go ahead and tell me its wrong and doesnt work, and try explain to me why blah blah

It works, alot of race cars dont use bovs..

It's a great setup for that, also most people who do that replace their turbo's every event as well. It's a different spending league than the average street car. Eventually compressor surge will have its way with his turbo's bearings. There's simply no escaping that.

 

[nikkeebabee]

I have seen Alberts twin BOV setup but if you go to ShepRacing and click on his mods he lists Tial bovs....

maybe an old mod list? but it sounds pretty current...I havent personally looked at shep's car so I honestly dont know. But they are listed on his site...

 

[nikkeebabee]

here's ams's set up....

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[95blackGsTurbo]

I saw that and wanted to ask them about the reasons they did it like that. I will call tomorrow and see what I get from them.

 

[nikkeebabee]

you'll notice the one on the intercooler and the one on the upper i/c pipe too...interesting set up, make sure you share your findings after talking to them

 

[herblove]

here's ams's set up....

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This is somewhat how mine is mounted on the intercooler end tank.