the end all bov thread
the end all bov thread
firstly before any bov thread, please SEARCH.
secondly please anyone that is reading this or reading any future bov threads, link them to this one or the search function. and PLEASE MINIMIZE POSTING IN THIS THREAD!!!
lastly... this thread should contain all the information needed and enough links to end all bov threads. period. if you don't understand something in this thread, SEARCH.
now, on with the show (information)
firstly to quote warrtalon
it is good to know the answers to these questions.
venting to atmosphere is something that should only be done for people running blow through mafs and stand alones that are using speed density to calculate air mass. IF YOU HAVE THE STOCK MAF, VTA WILL GIVE YOU PROBLEMS EVENTUALLY, some will say it runs fine for me... but it is only a matter of time because the fact is you'll be missing air. IF YOU MUST have hte sound then get a dual vent/dual chamber bov.
TYPES OF BOVS:
THE MITSUS.
1g (1g referring to first generation, referring to first generation eclipse, which gave us this factory blow off valve) this metal valve generally holds less than 17 psi, some anamolies do exist, in fact boost pressure holding with these valves is inconsistent to say the least. but they are FLANGED and you can also crush the top of them to increase spring preload and hole more boost. you can also purchase the dejon tools leak stop kit which will give you the ultimate response and pressure holding capabilities. this valve drives like stock.
stock evo8 valve, plastic thing, might hold you boost but might be leaky, also terribly inconsistent, from valve to valve. NOT CRUSHABLE. but there is at least one individual who put screws in it to increase spring preload, not very recommendable but... whatever makes you happy (for free). this valve of course drives like stock.
evo8 jdm mr, aka evo9, aka jdm bov, aka metal evo valve, this valve comes on the jdm evo 8s and now in american is featured in the evo 9. this valve holds lots of boost at least 24psi and is very consistent from valve to valve. its metallic design is of course desireable compared to the plastic evo 8 valve. this valve also drives like stock.
there is a unique feature of the stock type valves and that is a pnumatic assist port under or inside the valve that lets the bottom of the diaphram see boost pressure, this allows the valve to open very quickly even at part boost and part vacuum situations, hence the drives like stock. this port is what is exploited by hte dejon tools leak stop kit.
the greddy type s is basically a 1g clone in purple with a spring adjustment screw. it already has the pnumatic assist port ready to be tapped. do not run this valve with one spring... use the pnumatic assist port! the port is designed for a BOOST source, not a vac source. but of course if you show it boost all the time it will leak, which is why the dejon tools leak stop kit is a pnumatic switch, sending air one way if it's high pressure (boosting) and another way if it's low pressure (vent)
AFTERMARKET VALVES
these fall into several categories. first is the push type valve which is the ever popular hks and maybe one lesser known brand. second is the normal pull type valve which includes everything else.
of the pull type valves there are two main types, adjustable and non adjustable. the adjustable types either have a spring tension adjustor or a variety of springs that you can swap in.
the hks bov is a unique design that holds boost very well but for some reason it does not open under vacuum conditions very well. THIS MEANS IT WILL HAVE PROBLEMS DRIVING LIKE STOCK, but your individual results may vary.
commonly used adjustable valves include: forge, go fast bits (gfb), greddy type rs and the lists go on. the FACT IS many will have problems running bovs as a spring pressure type valve will always have it's benefits and with those come draw backs. more spring pressure for more boost means less giving when you need to vent, this causes turbo surge which is very bad. THIS WILL CREATE DRIVABILITY ISSUES and requires fine tuning to get everything to work smoothly.
a good thread on bov testing, showing why certain valves work and others don't and the inherent draw backs of spring loaded bovs. https://www.evolutionm.net/forums/sh...&highlight=bov
some threads showing common problems
https://www.evolutionm.net/forums/sh...&highlight=bov
https://www.evolutionm.net/forums/sh...&highlight=bov
https://www.evolutionm.net/forums/sh...&highlight=bov
https://www.evolutionm.net/forums/sh...&highlight=bov
ultimate bov thread. https://www.evolutionm.net/forums/sh...&highlight=bov
for bov installation https://www.evolutionm.net/features/.../projectevo/22
secondly please anyone that is reading this or reading any future bov threads, link them to this one or the search function. and PLEASE MINIMIZE POSTING IN THIS THREAD!!!
lastly... this thread should contain all the information needed and enough links to end all bov threads. period. if you don't understand something in this thread, SEARCH.
now, on with the show (information)
firstly to quote warrtalon
Originally Posted by Warrtalon
Ask yourself these questions:
1) What is the purpose of a BOV?
2) How good is my stock BOV?
3) How well does my stock BOV serve the purpose referenced in question 1?
4) What in the world would make me think of replacing my BOV, especially if I don't know the answers to questions 1-3?
5) Why would I even think of touching the BOV first on my brand new IX to begin with?
1) What is the purpose of a BOV?
2) How good is my stock BOV?
3) How well does my stock BOV serve the purpose referenced in question 1?
4) What in the world would make me think of replacing my BOV, especially if I don't know the answers to questions 1-3?
5) Why would I even think of touching the BOV first on my brand new IX to begin with?
venting to atmosphere is something that should only be done for people running blow through mafs and stand alones that are using speed density to calculate air mass. IF YOU HAVE THE STOCK MAF, VTA WILL GIVE YOU PROBLEMS EVENTUALLY, some will say it runs fine for me... but it is only a matter of time because the fact is you'll be missing air. IF YOU MUST have hte sound then get a dual vent/dual chamber bov.
TYPES OF BOVS:
THE MITSUS.
1g (1g referring to first generation, referring to first generation eclipse, which gave us this factory blow off valve) this metal valve generally holds less than 17 psi, some anamolies do exist, in fact boost pressure holding with these valves is inconsistent to say the least. but they are FLANGED and you can also crush the top of them to increase spring preload and hole more boost. you can also purchase the dejon tools leak stop kit which will give you the ultimate response and pressure holding capabilities. this valve drives like stock.
stock evo8 valve, plastic thing, might hold you boost but might be leaky, also terribly inconsistent, from valve to valve. NOT CRUSHABLE. but there is at least one individual who put screws in it to increase spring preload, not very recommendable but... whatever makes you happy (for free). this valve of course drives like stock.
evo8 jdm mr, aka evo9, aka jdm bov, aka metal evo valve, this valve comes on the jdm evo 8s and now in american is featured in the evo 9. this valve holds lots of boost at least 24psi and is very consistent from valve to valve. its metallic design is of course desireable compared to the plastic evo 8 valve. this valve also drives like stock.
there is a unique feature of the stock type valves and that is a pnumatic assist port under or inside the valve that lets the bottom of the diaphram see boost pressure, this allows the valve to open very quickly even at part boost and part vacuum situations, hence the drives like stock. this port is what is exploited by hte dejon tools leak stop kit.
the greddy type s is basically a 1g clone in purple with a spring adjustment screw. it already has the pnumatic assist port ready to be tapped. do not run this valve with one spring... use the pnumatic assist port! the port is designed for a BOOST source, not a vac source. but of course if you show it boost all the time it will leak, which is why the dejon tools leak stop kit is a pnumatic switch, sending air one way if it's high pressure (boosting) and another way if it's low pressure (vent)
AFTERMARKET VALVES
these fall into several categories. first is the push type valve which is the ever popular hks and maybe one lesser known brand. second is the normal pull type valve which includes everything else.
of the pull type valves there are two main types, adjustable and non adjustable. the adjustable types either have a spring tension adjustor or a variety of springs that you can swap in.
the hks bov is a unique design that holds boost very well but for some reason it does not open under vacuum conditions very well. THIS MEANS IT WILL HAVE PROBLEMS DRIVING LIKE STOCK, but your individual results may vary.
commonly used adjustable valves include: forge, go fast bits (gfb), greddy type rs and the lists go on. the FACT IS many will have problems running bovs as a spring pressure type valve will always have it's benefits and with those come draw backs. more spring pressure for more boost means less giving when you need to vent, this causes turbo surge which is very bad. THIS WILL CREATE DRIVABILITY ISSUES and requires fine tuning to get everything to work smoothly.
a good thread on bov testing, showing why certain valves work and others don't and the inherent draw backs of spring loaded bovs. https://www.evolutionm.net/forums/sh...&highlight=bov
some threads showing common problems
https://www.evolutionm.net/forums/sh...&highlight=bov
https://www.evolutionm.net/forums/sh...&highlight=bov
https://www.evolutionm.net/forums/sh...&highlight=bov
https://www.evolutionm.net/forums/sh...&highlight=bov
ultimate bov thread. https://www.evolutionm.net/forums/sh...&highlight=bov
for bov installation https://www.evolutionm.net/features/.../projectevo/22
dejon tools leak stop kit
Just installed my Dejon kit on my remanufactured GReddy RS diverter valve. Replaced the POS broken diaphragm with a new billet aluminum piston and machined the top cap to accept it with 2 O-rings. All I can say is WOW. No more surging or fluttering whatsoever. Drives like a NA car till you kick it in the ***, holds 28 PSI boost and all that unnecessary BS woooosh woooosh cha-cha-cha stuff is gone. 
Dejon Tools
http://evo.dejonpowerhouse.com/ Install is a piece of cake.
Last edited by cfdfireman1; Aug 20, 2006 at 06:01 AM.
Thread
Thread Starter
Forum
Replies
Last Post
SILVER SURFER
Evo Engine / Turbo / Drivetrain
241
May 5, 2011 07:25 PM
Tapeworm
Northwest Region
16
Jan 30, 2007 10:53 PM