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Old 11-17-2009, 09:04 PM   #21
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Does air even get sucked into it? I'm pretty sure the airflow is always out the BOV never in.
The BOV is open when your boost gauge reads Vacuum, in other words that puts "a hole" in your system between the turbo and the throttle body. So yes air gets sucked into it when the turbo hasnt spooled yet such as at idle. In that case the turbo is a bottle neck since its stopping the air from freely flowing into the intake. If you have a bottle neck with a hole, it will suck in air from the open hole to bypass the bottle neck.

If you have a air flow sensor and no recirculation system you will have a quite crappy idle since you have tons of unmeasured air entering the system due to the open bov. Thats besides the fact that you will be getting 9a/f when shifting gears when in boost..
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Old 11-17-2009, 09:27 PM   #22
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The BOV is open when your boost gauge reads Vacuum, in other words that puts "a hole" in your system between the turbo and the throttle body. So yes air gets sucked into it when the turbo hasnt spooled yet such as at idle. In that case the turbo is a bottle neck since its stopping the air from freely flowing into the intake. If you have a bottle neck with a hole, it will suck in air from the open hole to bypass the bottle neck.

If you have a air flow sensor and no recirculation system you will have a quite crappy idle since you have tons of unmeasured air entering the system due to the open bov. Thats besides the fact that you will be getting 9a/f when shifting gears when in boost..
It's partially open because the signal to the BOV is under vacuum, thus pulling the diaphragm slightly up.

Just because your vacuum/boost gauge says vacuum doesn't mean the entire intake track is in vacuum. The intake manifold and it's hoses are in vacuum because the throttle plate isn't open very much, causing a pressure difference since the engine is an air pump.

Your turbo is still spinning and still compressing air, so guess where that goes? Don't believe me? Go to you car and check.
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Old 11-17-2009, 09:31 PM   #23
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Any body has a pressure gauge installed before the throttle body?
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Old 11-18-2009, 06:57 PM   #24
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Ok si I just picked up a t28 wastegate of a Garrett for $10 on CL. I'm going to mod it, install it and re-do the hose to the Ic pipe. I'll update you guys when I'm done
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Old 11-20-2009, 07:00 PM   #25
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Ok so I just Re-routed the wastegate hose to the coldside in the IC pipe and installed the t28 wastegate after a little mod. Split the rod into two pieces threaded both sides with a 1/4 20 dye. Added a treaded rod and bolted them up. Anyways just took it for a spin and holy **** what a difference! Holds boost like a champ and it spools up way faster. Best mod I've done for $10
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Old 11-20-2009, 09:04 PM   #26
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Sweet. Im going to try this!
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Old 11-20-2009, 09:17 PM   #27
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You should have looked at how mine is plumbed when you had the chance...



The nipple just before the TB feeds the waste gate actuator. My boost is so steady you can rest your drink on it.
So did I miss all the threads saying waste gate signal should come from a post intercooler source? I thought I read through those and it was determined that there were more drawbacks than benefits. But if you're getting dead steady boost, I'm switching to the throttle body, I just freed up a barb there after removing my o2 clamp.
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Old 11-20-2009, 09:29 PM   #28
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at idle my car is forceing air out of my blowoff valve, its slightly open and even if i take it totaly off, you can still feel it forcign air out of the intake tract

this is with a begi-s with the 2560
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Old 11-20-2009, 11:00 PM   #29
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So did I miss all the threads saying waste gate signal should come from a post intercooler source? I thought I read through those and it was determined that there were more drawbacks than benefits. But if you're getting dead steady boost, I'm switching to the throttle body, I just freed up a barb there after removing my o2 clamp.
don't do it in the manifold! Do it on the cold side IC pipe right before the TB
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Old 11-20-2009, 11:32 PM   #30
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Right right, I was referring to the two hose barbs on the throttle body, directly pre butterfly valve. I'll switch to one of those asap. What kind of space age rubber seals the compressor barb without melting though?
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Old 11-21-2009, 04:57 PM   #31
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Right right, I was referring to the two hose barbs on the throttle body, directly pre butterfly valve. I'll switch to one of those asap. What kind of space age rubber seals the compressor barb without melting though?
I thought those two nipples were after TB could be wrong tho. I used a regular rubber cap that you buy at any auto part store, it's fine for me buy since you track your car I don't know if it will melt
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Old 11-21-2009, 05:22 PM   #32
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You're talking about how to plug that fitting up after you switch the source on the intake side? You can buy a cap and stick it in there, i dont know if you can take out the barb and put a screw in there to block it off.
DSCF0043.jpg
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Old 11-22-2009, 02:12 AM   #33
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Yes they are both after the throttle body. Braineack seems to have perfect boost, yet Miataspeed2005 says to put it before the throttle body. Who to trust, who to trust....

I did go for drive today with the wastegate signal coming from one of those two hose barbs. Didn't really find out if it worked, as my overboost was set to 1.5psi, and my laptop was at home. Oops.
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Old 11-22-2009, 02:42 AM   #34
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Originally Posted by curly View Post
Yes they are both after the throttle body. Braineack seems to have perfect boost, yet Miataspeed2005 says to put it before the throttle body. Who to trust, who to trust....

I did go for drive today with the wastegate signal coming from one of those two hose barbs. Didn't really find out if it worked, as my overboost was set to 1.5psi, and my laptop was at home. Oops.
Both Braineack and Miataspeed2005 are saying to put it post intercooler pre throttle body.
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Old 11-22-2009, 05:47 PM   #35
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Both Braineack and Miataspeed2005 are saying to put it post intercooler pre throttle body.
Correct
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Old 11-22-2009, 06:04 PM   #36
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Originally Posted by curly View Post
So did I miss all the threads saying waste gate signal should come from a post intercooler source? I thought I read through those and it was determined that there were more drawbacks than benefits. But if you're getting dead steady boost, I'm switching to the throttle body, I just freed up a barb there after removing my o2 clamp.


I'm sourcing it PRE-throttle. It's said the wastegate doesn't like vacuum. Plus the spots on the TB are very turbulent.

on the BOV ingesting air...It's a tiny, tiny, tiny little crack. The biggest source of air on the intake is the idle valve. The second you crack the throttle the BOV closes shut.
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Old 11-22-2009, 11:16 PM   #37
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on the BOV ingesting air...It's a tiny, tiny, tiny little crack. The biggest source of air on the intake is the idle valve. The second you crack the throttle the BOV closes shut.
how much vac does the bov require to be open? 20-25?
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Old 11-23-2009, 10:14 PM   #38
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I figure this should help anyone wanting to make their actuator adjustable:

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Old 11-23-2009, 10:53 PM   #39
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Originally Posted by Braineack View Post
I'm sourcing it PRE-throttle. It's said the wastegate doesn't like vacuum. Plus the spots on the TB are very turbulent.
Oh gotcha, I didn't see where those TB lines were routed, figured once went to the waste gate since I hadn't noticed the extra one before that last coupler. Guess I'll be drilling/tapping my intake for a 3/8" hose barb. Thanks!
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Old 11-23-2009, 11:51 PM   #40
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^^

why dont you just buy a right waste gate and enjoy boost with a gate thats suppose to open at whatever psi you want it to open?

What the above would do a lot of time is boost creep since it doesnt open all the way or if youre using one for too much psi it will always be loose and have a lot of lag since the waste gate will not be shut completely.
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