DIY Turbo Discussion greddy on a 1.8? homebrew kit?

b.o.v off the intake mani. or turbo?witch is better?

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Old 02-25-2008, 07:48 PM
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Cool b.o.v off the intake mani. or turbo?witch is better?

Well, may seem stupid for some of you miata freaks!!! lol... but i have had my b.o.v on the hot side of my turbo for quite some time now....and have been told to put it off my intake manifold (cold side) what would be the benefit?


should make better sence now. thanks

Last edited by zoomnick; 02-25-2008 at 08:36 PM.
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Old 02-25-2008, 07:51 PM
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you need to clarify what you're asking, your post pretty much makes no sense
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Old 02-25-2008, 07:55 PM
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To me it seems keeping it before your intercooler would be better for the engine. Every time it opens, all that hot air that dumps out is NOT going through your intercooler. That helps keep the IC cooler, and when you do open the throttle, the air it's gonna get will be cooler too. Granted, some will argue this is all insignificant, but it does exist. Some will point out the BOV will last longer on the intake side as it will see cooler air and indeed that is the case. My BOV will be on the hotside of my SC setup.

PS Some capital letter, periods, commas, etc will go a long way. Most that read what you wrote will just ignore you and not answer your question.
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Old 02-25-2008, 08:06 PM
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im pretty sure he's talking about the vacuum line....so tee-ing off the turbo line would be pointless and it wouldn't allow the bov to open properly. you need vacuum to open the valve, no vacuum at the turbo.
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Old 02-25-2008, 08:07 PM
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zoom: yikes.......please reword your question.

mach: yup.

pat: there is a pressure drop when the air cools through the intercooler. i don't think a bov on the hotside is ideal.
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Old 02-25-2008, 08:12 PM
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i try it again

my b.o.v is on the hot side.

is it better on the cold side?
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Old 02-25-2008, 08:15 PM
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doesn't make much difference so whatever you prefer or is easier
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Old 02-25-2008, 08:27 PM
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Originally Posted by zoomnick
i try it again

my b.o.v is on the hot side.

is it better on the cold side?
Ok, start your sentences with a capital letter. You should go back and edit your first post so it makes sense. Clearly state what your asking. Most run it on the coldside.
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Old 02-25-2008, 08:40 PM
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Can we start banning people who can't post in some sort of English comprehension of a 3rd grader on this board? I'm not English teacher, but FFS! (For ***** Sake!) my girlfriend who speaks English as her 3rd learned language is easier to understand on her worst day than half these internet dweebs!
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Old 02-25-2008, 08:55 PM
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Are you talking about BOV placement, or the vacuum line?
I always put my bov between the T-Body and Intercooler with the vacuum line going to the intake manifold.

My FMII has it between the Turbo and Intercooler.

Hope this makes sense... I'd hate to get banned

Here is the BOV placement on my old car with a very old setup. (I forgot I ran a Starion IC for a while)


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Old 02-25-2008, 09:11 PM
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its doesnt matter which side of the charge pipes it's on. as long as its between the TB and turbo.
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Old 02-25-2008, 09:15 PM
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I locate bypass valve over hot turbo side for easier redirection of excess boost to before mass air sensor less plumbing full.

but either way is fine.
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Old 02-25-2008, 09:25 PM
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i always believed that the BOV needs to be in front of the throttle body to release the pressure more efficiently when the throttle closes. but don't take my word for it
https://www.miataturbo.net/forum/sho...=BOV+placement
this may help.
already had a discussion over it.
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Old 02-25-2008, 11:20 PM
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I went before the throttle body to keep gas flowin in the right direction.
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Old 02-26-2008, 09:40 AM
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Originally Posted by musanovic
i always believed that the BOV needs to be in front of the throttle body to release the pressure more efficiently when the throttle closes. but don't take my word for it
https://www.miataturbo.net/forum/sho...=BOV+placement
this may help.
already had a discussion over it.
This guy should win an award, only 133 posts but he clearly has learned the "search first" mindset!
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Old 02-26-2008, 09:42 AM
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i thought that it was well established that the better placement is after IC before throttle body for a few reasons...
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Old 02-26-2008, 09:46 AM
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one may be technically better over the other for various reasons, but does it really matter in the scheme of things, no.
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Old 02-26-2008, 01:36 PM
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The main way in which it matters is the relationship between spring tension and pressure drop. If you have some junkyard plastic valve with an extremely light cracking pressure you will probably want to put the valve after the IC. Or conversely if the valve has a lot of spring tension place it before the intercooler.
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Old 02-26-2008, 07:48 PM
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Originally Posted by y8s
I went before the throttle body to keep gas flowin in the right direction.
Exactly.
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Old 02-26-2008, 10:03 PM
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i agree with Pat on the venting before IC so the IC isn't warming up for no reason when it's venting excess boost. However, with the BOV before the IC, all the pressurized air after the BOV has to travel backward to vent. back through the IC piping and the IC. air does have mass so you're creating an air spring. this theoretically should make it harder for air to get back to the TB once the BOV is closed since it'd first have to overcome the inertia of the backward flowing air. is it measurable? prolly not.

How bout 1 before the IC and 1 after, right before the TB? would solve both concerns, no?

edit: ****, someone just said that.
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