Welcome to the North American Subaru Impreza Owners Club Friday March 6, 2015
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated with bolt-on Forced Induction Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 04-28-2002, 10:40 PM   #1
kid 13
Scooby Newbie
 
Member#: 17603
Join Date: Apr 2002
Location: silver spring, md
Default Bypass Valve vs. Blowoff Valve

which is better..
a bypass valve or a blowoff valve?
* Registered users of the site do not see these ads.
kid 13 is offline   Reply With Quote
Old 04-28-2002, 11:17 PM   #2
HOK
Scooby Specialist
 
Member#: 447
Join Date: Oct 1999
Location: Oh Canada
Vehicle:
1999 EJ22T222B&EVO
Are we racing yet?

Default

its same thing... only difference is where it goes...
HOK is offline   Reply With Quote
Old 04-29-2002, 04:26 AM   #3
HndaTch627
Scooby Guru
 
Member#: 6551
Join Date: May 2001
Chapter/Region: MWSOC
Location: Carol Stream, IL
Vehicle:
'01 GC8 Dinged STM
'09 Concours 14 ABS Black

Default

they are the same thing except bypass valves are used on supercharged systems and bypass the super charger rotors.

jeremy
HndaTch627 is offline   Reply With Quote
Old 04-29-2002, 04:41 PM   #4
giulio
Scooby Newbie
 
Member#: 16040
Join Date: Mar 2002
Location: NY USA
Vehicle:
1998 Impreza RS
Supercharged

Default

I thought that blowoff valves are only on/off devices... either hold the charge or blow it all out.

Bypass valve is variable. It can reroute all/some/none of the charge. For that reason I think it's more correct to compare it to a wastegate than a BOV. Both maintain the boost you want... WG makes sure you dont get too much, BPV makes sure get enough, up to the SC's max. A SC has a definite limit, where a turbo you can overboost.
I guess you can use a BPV to limit the boost like a WG also... if you want to rig it's butterfly to only close up to a certain amount.

I think it's best to say that a BPV does the job of a WG and a BOV at the same time.

It's controlled totally by manifold pressure.
what controls a WG and a BOV?

g
giulio is offline   Reply With Quote
Old 04-29-2002, 04:53 PM   #5
TerenceT
Scooby Specialist
 
Member#: 9510
Join Date: Aug 2001
Location: San Pedro, CA
Vehicle:
04 FX35
Pearl White

Default

i thought they are all the same except for WG

bov/bpv works when your TB is close and the charged air is released/recirculated

WG should be compared with the Acctuator of the turbo

WG control how much boost you are getting from the turbo

Last edited by TerenceT; 04-29-2002 at 06:25 PM.
TerenceT is offline   Reply With Quote
Old 04-29-2002, 06:42 PM   #6
giulio
Scooby Newbie
 
Member#: 16040
Join Date: Mar 2002
Location: NY USA
Vehicle:
1998 Impreza RS
Supercharged

Default

like a WG, BPV controls how much boost you get.
with a turbo, exhaust gases are used to make the turbo spin fast/slower to change boost. a SC is always spinning as much as possible... so the PBV is used to moderate the boost you get. it recirclates the charge. when you open the throttle, vacuum in the intake manifold is gone and the BPV closes, forcing the charge into the motor. when you close the throttle, vacuum is made, and the BPV opens, recirculating the charge again.

what happens with a BOV at partial throttle? a BPV will partially close, recirculating the boost. my understanding was that BOV release it all when you snap the throttle shut... but i dont have any experience with them. I didnt think you can use a BOV to moderate boost... i though it was an emergency release, a safeguard against overboosting/breaking the throttle butterfly.

doesnt a boost controller play with the wastegate? That's why i compared the WG to the BPV... they control boost.

g
giulio is offline   Reply With Quote
Old 04-30-2002, 03:57 AM   #7
HndaTch627
Scooby Guru
 
Member#: 6551
Join Date: May 2001
Chapter/Region: MWSOC
Location: Carol Stream, IL
Vehicle:
'01 GC8 Dinged STM
'09 Concours 14 ABS Black

Default

giulio you are right, i was incorrect before a bypass valve is more accurately compared to a wastegate...they both control the amount of air moving through the compressor.

jermey
HndaTch627 is offline   Reply With Quote
Old 04-30-2002, 09:53 AM   #8
giulio
Scooby Newbie
 
Member#: 16040
Join Date: Mar 2002
Location: NY USA
Vehicle:
1998 Impreza RS
Supercharged

Default Re: Bypass Valve vs. Blowoff Valve

Quote:
Originally posted by kid 13
which is better..
a bypass valve or a blowoff valve?
Well since we shown that they arent really comparable, it's unfair to judge. but if you must... a BPV is 'better' than a BOV since it recylces the charge, making it readily available for the next time you want boost.

And if you want to compate a BPV to a WG, I think the BPV still wins. for the same reason. It's my understanding that a WG just redirects exhaust past the turbine... wasting all that extra energy.

I wonder why turbo systems dont incorporate a BPV. maybe the recycling charge would get too hot to be usable. {shrug}

Someone just told me that there are different types of BOV's... some function just like the BPV. So... who knows.

g
giulio is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Bad oil control valve vs burnt valves. WANTED!! Newbies & FAQs 3 09-15-2009 04:14 PM
Need to buy stock recirc valve, bypass valve, blowoff valve, whatever u call it!! newbie-subie SCIC Private Classifieds 2 02-12-2009 04:35 AM
centralNJ WTB stock bypass valve/blowoff valve funigui Tri-State Area Private Classifieds 0 06-02-2008 03:32 PM
FS:Stock ByPass Valve/Blowoff Valve White_Rex_02 Private 'For Sale' Classifieds 4 10-09-2005 10:57 PM


All times are GMT -4. The time now is 02:49 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2015 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.