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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

View Poll Results: BOV location
Cold side before TB 38 84.44%
Hot side near turbo 7 15.56%
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Old 03-21-2010, 11:03 AM   #1
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Default New BOV location

I'm about to get my IC pipes welded up by my friend, now the question is should I place the BOV flange on the cold side before the TB like I used to have it? Or Weld it on the hot side near the turbo? I'm not re-sirculating the air so it's the hot side option pointless?
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Old 03-21-2010, 11:10 AM   #2
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you'll want it as close to the throtte body as posible
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Old 03-21-2010, 11:47 AM   #3
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This is a very debatable subject....I say put it where ever is most convenient. Mine is about a foot from the compressor outlet....whether its right or not is subjective...
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Old 03-21-2010, 12:02 PM   #4
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+1 close to the throttle body.
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Old 03-21-2010, 12:41 PM   #5
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both sides have advantages, but I say where its easiest to install.
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Old 03-21-2010, 01:36 PM   #6
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As I understand it, which may or may not be accurate, you want it close to the TB. Something about the air having to change direction in the pipes, which makes sense.
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Old 03-21-2010, 06:16 PM   #7
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Quote:
Originally Posted by hustler View Post
both sides have advantages, but I say where its easiest to install.
This.

Pressure is pressure. The time difference in reducing it at the TB or the compressor housing from a 'cold-side' to 'hot-side' placement is miniscule and insignificant unlkess you have such a large volume at such high density that the BOV is not large enough to really effectively release it. I doubt anybody here is anywhere near that point.

So put it out of the way. If it were me, with most of the setups I have seen, near the IC outlet would be a great bet.
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Old 03-21-2010, 06:19 PM   #8
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Hey are both easy to do, I just didn't know if one was a better spot than the other and different advantages
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Old 03-21-2010, 08:45 PM   #9
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Since this was in a Honday fail thread....

My car was setup before I purchased with the BOV down in the fender on the passengers side on the cold side. What are the chances of a HKS SSQV bov sucking in dirt down there.... Small animals?

BTW I prefer the "near TB" idea due to reversion on the TB side. Keep things moving.
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Old 03-21-2010, 08:49 PM   #10
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+1 on close to the TB.
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Old 03-21-2010, 08:51 PM   #11
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I dont see how. Any time it is open it's got positive pressure. As long as it is not in the direct path of debris I think it would be fine. I do remember that pic of the Honda though, from what I could see there that thing would get nailed by anything on the road the car went over. Ouch.

If we really want to get nitty-gritty, some pics of the IC and planned tubing paths would be good.
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Old 03-21-2010, 09:02 PM   #12
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Quote:
Originally Posted by Sparetire View Post
I dont see how. Any time it is open it's got positive pressure. As long as it is not in the direct path of debris I think it would be fine. I do remember that pic of the Honda though, from what I could see there that thing would get nailed by anything on the road the car went over. Ouch.

If we really want to get nitty-gritty, some pics of the IC and planned tubing paths would be good.
wrong.

If the BOV is doing its job well, it is opened/cracked whenever there is manifold vacuum. So thats at idle, cruising, and deceleration.
There are plenty of times where you can actually suck air in through the BOV, hence why some people run filters on the outlets of said BOVs.

I wouldnt worry about it if its up in the engine bay, but it could be an issue if its exposed to road debris and whatnot.
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Old 03-21-2010, 09:06 PM   #13
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Have you ever put your hand next to a bov? Even at the highest of vacuum it is still pushing air out. How the **** will anything get in there if it ABSOLUTELY NEVER sucks air in? Ever. As long as the turbo is spinning there is positive pressure in the system exiting through the bov when its open.


That said I don't think it matters much, but seeing how MOST or ALL OEM systems come with one post intercooler I'd stick to that.
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Old 03-21-2010, 09:06 PM   #14
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I put mine rite next to the tb but only because it shortens the length of hose needed for the reference signal from the im and there was room to fit it. I don't think there will be a difference in performance having the diverter valve mounted on either side. Lets see some pics of the proposed routing!
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Old 03-21-2010, 09:10 PM   #15
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I did not know that. I guess it makes sense, since you do have a decent pressure differential from one side of the Tb to the other at idle. I just ASSumed that you needed at least a few psig positive pressure in the IC plumbing to cause any opening. So with vac in the ic plumbing, no open at all.

on my ignant azz.
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Old 03-21-2010, 09:13 PM   #16
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Quote:
Originally Posted by 18psi View Post
Have you ever put your hand next to a bov? Even at the highest of vacuum it is still pushing air out. How the **** will anything get in there if it ABSOLUTELY NEVER sucks air in? Ever. As long as the turbo is spinning there is positive pressure in the system exiting through the bov when its open.


That said I don't think it matters much, but seeing how MOST or ALL OEM systems come with one post intercooler I'd stick to that.
Under idle/light cruise conditions there is probably a bit of vacuum in the ic plumbing. Small, but a bit. How could the BOV then have air going out? That would be a major PITA for tuning with any MAF based EMS, as it would basically cause the car to run rich all the time.
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Old 03-21-2010, 09:18 PM   #17
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Well in my understanding and don't quote me on this one, if I put my BOV by the TB I will get faster spool from shift to shift since the IC would stay charged while the TB is closed. Now if I put it on the hot side I will loose some spool but I will save my turbo a little more from compression surge. Like I said I'm not an expert
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Old 03-21-2010, 09:24 PM   #18
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Quote:
Originally Posted by Sparetire View Post
Under idle/light cruise conditions there is probably a bit of vacuum in the ic plumbing. Small, but a bit. How could the BOV then have air going out? That would be a major PITA for tuning with any MAF based EMS, as it would basically cause the car to run rich all the time.
as long as the compressor wheel is spinning it is moving air.
as long as the engine is on, the compressor wheel is spinning.

The only time I could POSSIBLY see the bov actually sucking in air is for that SPLIT SECOND when you stab the throttle and the car gulps in more air than is already moving through the system and the bov hasn't shut yet. We're talking less than a second worth of "sucking" time.
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Old 03-21-2010, 09:25 PM   #19
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My mom always told me, cold side.
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Old 03-21-2010, 09:30 PM   #20
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This is the cold side where my hand is there a circle I made with a market that's where the BOV would go
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