Educate me on a few things
Thread Starter
Registered User
Joined: Mar 2003
Posts: 280
From: San Francisco, CA
Car Info: '03 WRX Yellow
Educate me on a few things
"JDM"...wtf does this mean?
BOV's...what do you gain by adding an aftermarket one to your car? Why do you need to adjust them?
thx!
BOV's...what do you gain by adding an aftermarket one to your car? Why do you need to adjust them?
thx!
The weal amewican hewo!
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From: Hayward, BAIC
Car Info: 02 Aspen White sedan
JDM = Japanese Domestic Market, so basically anything that is manufactured in japan, including "JDM" girls lol...
and as for the explanation for the BOV...here is one from Autospeed...
"Psssht!!
A throttle-closed blow-off valve is designed to vent any pressure build-up between the turbo (or intercooler) and the closed throttle blade. This pressure build-up occurs when the car is on boost and then the throttle is suddenly shut. To allow simple valve triggering, the blow-off valve (BOV) is opened only at high manifold vacuums (ie light loads - especially on the over-run). Manufacturers fit BOVs to reduce the turbo surge noise that otherwise occurs when the throttle is suddenly snapped shut while the turbo is still spinning, while in some applications they can also help keep the turbo on boost during gearchanges. However, the main reason that most people change the factory valve to an aftermarket unit is to get a "pssssht" noise when backing off or changing gears. This noise occurs because the valve is configured to dump air to the atmosphere, rather than feeding it back to the intake of the turbo, as all factory blow-off valves do.
It should be noted that if a relatively normal sized turbo is being used and the factory valve isn't leaking under boost, fitting an aftermarket blow-off valve will not transform performance in the same way that winding up the boost or fitting a large exhaust will.
Ascertaining the effect that the blow-off valve is having (eg if it is leaking and limiting boost) can be easily determined by blocking it off and then going for a drive. But don't just pull off the BOV's vacuum hose - it will then open more easily and will almost certainly drain away boost.
Externally venting valves give the loudest noise, but can cause some engine running problems. This is the case because the air that has been measured by the airflow meter is exhausted to atmosphere, rather than passing into the engine. To attempt to overcome this problem, some aftermarket manufacturers sell valves that return ("plumb-back") most of the air to the turbo intake, while still venting enough to make the noise. (Others dump high load air externally and recirculate low-load air.) Another problem of an externally venting BOV is that, if the valve is open at idle, the engine will run badly as air is drawn in through the BOV, bypassing the airflow meter (and also the airfilter!). Some manufacturers allow adjustment of the BOV opening vacuum, so that the valve can be configured to be shut at idle, but still open on the over-run. Cars fitted with aftermarket MAP-sensed management will not experience either of these engine running problems when fitted with externally-venting BOVs, though the lack of filtration when the valve is open at idle is still a concern."
- Daniel
and as for the explanation for the BOV...here is one from Autospeed...
"Psssht!!
A throttle-closed blow-off valve is designed to vent any pressure build-up between the turbo (or intercooler) and the closed throttle blade. This pressure build-up occurs when the car is on boost and then the throttle is suddenly shut. To allow simple valve triggering, the blow-off valve (BOV) is opened only at high manifold vacuums (ie light loads - especially on the over-run). Manufacturers fit BOVs to reduce the turbo surge noise that otherwise occurs when the throttle is suddenly snapped shut while the turbo is still spinning, while in some applications they can also help keep the turbo on boost during gearchanges. However, the main reason that most people change the factory valve to an aftermarket unit is to get a "pssssht" noise when backing off or changing gears. This noise occurs because the valve is configured to dump air to the atmosphere, rather than feeding it back to the intake of the turbo, as all factory blow-off valves do.
It should be noted that if a relatively normal sized turbo is being used and the factory valve isn't leaking under boost, fitting an aftermarket blow-off valve will not transform performance in the same way that winding up the boost or fitting a large exhaust will.
Ascertaining the effect that the blow-off valve is having (eg if it is leaking and limiting boost) can be easily determined by blocking it off and then going for a drive. But don't just pull off the BOV's vacuum hose - it will then open more easily and will almost certainly drain away boost.
Externally venting valves give the loudest noise, but can cause some engine running problems. This is the case because the air that has been measured by the airflow meter is exhausted to atmosphere, rather than passing into the engine. To attempt to overcome this problem, some aftermarket manufacturers sell valves that return ("plumb-back") most of the air to the turbo intake, while still venting enough to make the noise. (Others dump high load air externally and recirculate low-load air.) Another problem of an externally venting BOV is that, if the valve is open at idle, the engine will run badly as air is drawn in through the BOV, bypassing the airflow meter (and also the airfilter!). Some manufacturers allow adjustment of the BOV opening vacuum, so that the valve can be configured to be shut at idle, but still open on the over-run. Cars fitted with aftermarket MAP-sensed management will not experience either of these engine running problems when fitted with externally-venting BOVs, though the lack of filtration when the valve is open at idle is still a concern."
- Daniel
Thread Starter
Registered User
Joined: Mar 2003
Posts: 280
From: San Francisco, CA
Car Info: '03 WRX Yellow
awesome explanations
thx
as for BOV's
what do people here say is a good one?
that is interesting about the problem of letting air come in at idle...is there a brand that people here like that handles the WRX well without the driver having to mess around with it?
thx
as for BOV's
what do people here say is a good one?
that is interesting about the problem of letting air come in at idle...is there a brand that people here like that handles the WRX well without the driver having to mess around with it?
GFB stealth is the most adjustable. you can adjust the pressure at which it opens to tune your idle as well as the amount of air that is recycled. another cool thing about the gfb is you can move the vacuum nipple for the best fit so you don't have to cut/stretch/tuck the hose.
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as a person that has gone through the purchasing of three BOVs the HKS is one of the best. the two i had before were a GFB BOV, the problem with this valve is that is was not adjustable and caused compressor surge at low boost (my turbo is probably going to **** the bed now because of it), it only vented at high boost or high rpms, the other that i had was the Blitz DD BOV. this valve works better than the GFB but the spring inside the WRX model is stiffer than that of the non-WRX Blitz BOVs. So there is some compressor surge still! now, the HKS has been nothing short of perfection for me. this valve will vent as low as 1100rpm's and very little boost if not some vacuum (were turbo is spooling however is not creating pressure). this valve makes a great sound and is worth every penny. I am sure there are other valves out there that do just as good of a job as the HKS but I did no such research on them...
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Oh! and the HKS is adjustable however HKS says that you do not need to adjust it out of the box, it is already set from the factory. The GFB that "gordy" is recommending different than the GFB that I had, the STEALTH is adj. and alot better valve. Mine was the first design that GFB had.
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Joined: Apr 2003
Posts: 174
From: Las Vegas
Car Info: 2005 STI
yeah... i have the HKS too... it really is great. if you need one, i have a friend who deals with a lot of HKS stuff. he sold me mine for $225 shipped. its a pretty decent price IMO.
Last edited by wonton2049; Mar 4, 2004 at 02:41 AM.
^
my stock BOV sounds like that
JDM ver6 motor with apex power intake aircleaner.
HKS's high pitch sound bothers me, I wanna get one that sounds similar to WRC (although WRC doesnt have one) but not sure which one is closer.
my stock BOV sounds like that
JDM ver6 motor with apex power intake aircleaner.
HKS's high pitch sound bothers me, I wanna get one that sounds similar to WRC (although WRC doesnt have one) but not sure which one is closer.
Last edited by go go go; Mar 6, 2004 at 05:25 PM.
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hey special-k,
totally random, but are you like the short bus of cereals? (end of random transmission)
totally random, but are you like the short bus of cereals? (end of random transmission)
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