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Guest Message by DevFuse
 

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blowout valve


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11 replies to this topic

#1 Nick Leigh mtb

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Posted 19 May 2004 - 09:18 PM

is there anyway i could make my own blowout valve?

#2 calebz

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Posted 19 May 2004 - 09:26 PM

If you mean 'blow off valve', I don't know of anyone that has made their own.. and with stock boost its not really necessary. your car is equipped with a dash pot that stop the throttle plate from slamming shut.

I am using a blow off valve from an RX7.. others use Saab and Volvo BOVs.. they are cheap and plentiful in junk yards.

Fliip through my photo album here
http://usmb.net/gallery/albuo11

and you will see the BOV, boost controller, Intercooler and hood scoop. It will give you an idea on how it all goes together

Note: Subarus do not like to have their BOVs vented to the atmosphere.

#3 Nick Leigh mtb

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Posted 19 May 2004 - 09:44 PM

how did you make all of that?

#4 bajavwnsoobnut

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Posted 19 May 2004 - 10:05 PM

Caleb just the older Subies don't like it cause of the MAF sensor involved gets the hiccups if the charge is blown out into the atmosphere (read: blow-off valve) that's why a recirulating valve is perferable in this case which blows the charge back to in front of the turbo intake, The later ones that use a MAP sensor instead of a MAF can use the BOV cause of the measurement of airflow is done with pressure instead of the amount of air sucked through a sensor.

So Nick Leigh mtb it would be a good idea to look out for a Recirculating valve from like an Audi/VW, Mitsibushi/Eagle, or even from a WRX cause most guys that have WRX's that hop them up just get rid of them and might just try e-bay or even here (but on the marketplace) for someone that is selling a WRX intercooler and just make sure that you get the RV with it also
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#5 calebz

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Posted 19 May 2004 - 10:16 PM

Caleb just the older Subies don't like it cause of the MAF sensor involved gets the hiccups if the charge is blown out into the atmosphere (read: blow-off valve) that's why a recirulating valve is perferable in this case which blows the charge back to in front of the turbo intake, The later ones that use a MAP sensor instead of a MAF can use the BOV cause of the measurement of airflow is done with pressure instead of the amount of air sucked through a sensor.


Yes.. I know, I made the generalization based on the fact that is the old gen forum, the car in question is an old genand as far as I know, no one here is running a MAP system on their old soob(yet). I didn't feel a need to confuse the issue with newer information that wasn't relevant to his current needs. You are 100% correct though.

#6 calebz

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Posted 19 May 2004 - 11:25 PM

Nick .. all the stuff in my pictures is a result of time, patience, imagination, help from friends and a whole lot of looking at what others on the board have done.

1) Boost controller: This was made by another board member based on instructions available online. I will look later to see if I can find the link. It takes about 10 minutes to install... and thats with an 8 minute smoke break. It does require a boost gauge and a little time to properly calibrate.
2) Intercooler and BOV(recirculating) :The IC and BOV are both from a Gen 2 RX7. I made the mounts myself. All of the plumbing for the IC is from the RX7 and from a Dodge Conquest Turbo. The only modifications to the plumbing parts I made were, cutting one of the soft hoses and reattaching at a different angle.. And having a small tube welded on for the BOV. The BOV itself recirculates back into the intake boot behind the MAF (see above conversation) This was done by drilling a hole in the small 'silencer' that sticks off the intake boot and venting the BOV into there.
3) Cone Filter: The cone filter is easy. Go to Autozone and buy the MAF adapter they carry for nissans.. it will bolt right on to your MAF. Cone filter attaches directly to that.
4) Hood scoop: I used a circular saw with a metal cutoff wheel to cut a 16x7 hole in the top of the hood above the IC. The scoop itself attaches with double sided foam tape.. for now.

I've done tons of other stuff to the car, but none thats relevant to yours, because you are starting with an RX, not a shell of an automatic turbowagon:)

Any questions?

#7 nkx

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Posted 20 May 2004 - 04:26 AM

this info is all very good, but what the hell is a dash pot? ive heard the term a few times, but i have no idea what it is! im going to crank the boost up on my buggy, but i need a way to vent it before the TB so that i dont kill my turbo when i let off the gas under boost.

#8 Scrub2k

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Posted 20 May 2004 - 09:59 AM

The Dash Pot is Subaru's Own BOV it keeps the Throttle Plate Open just enough for the Air Still coming from the turbo to pass the Plate instead of Bouncing back to the Turbo.

#9 Nick Leigh mtb

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Posted 20 May 2004 - 10:34 AM

with doing an intake, boost controller, and possibly the IC and BOV, would i want to look into a custom exhaust?

#10 All_talk

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Posted 20 May 2004 - 11:05 AM

Yes, in fact the exhaust should probably be the first thing on your list.

Note: some have noticed boost creep at sustained high RPM with a high flow down pipe (typically cat-less) and the stock wastegate control, so you may want to do the exhaust, boost control and boost gauge as a package.

Gary

#11 Nick Leigh mtb

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Posted 20 May 2004 - 11:45 AM

Would i be best off getting a custom pipe bent for me, or is there one that i can buy that will fit my RX? Also what would be the best boost gauge to use?

#12 All_talk

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Posted 20 May 2004 - 12:49 PM

Custom, as far as I know nobody makes a off the shelf exhaust system for the EA82 Subies. I talked to my local exhaust shop and he quoted me about $200 for 2 ½” from the turbo back with no cats and an open muffler.


On the boost gauge, the more you spend the more accuracy you get, but incredible accuracy isn’t really needed, you just need something to tell you where you’re at. Most of the time you are going to tune to detonation anyway. Pick one with the 0-20psi boost range (not the 0-30), the stock turbo isn’t much good above 14psi and you might as well have the larger sweep.

Gary




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