Jump to content
  • Welcome to AutoLanka

    :action-smiley-028: We found you speeding on AutoLanka Forums without any registration! If you want the best experience, please sign in. Safe driving! 

Blow Off Valve For B4 Tt ?


CARBON

Recommended Posts

Hi All,

I just got registered on this , but i have been reading most comments , which has been very helpfull. So big thank you for everyone...

Need some advise as I am thinking of getting a blow off value for my B4 , I have heard many contradicting views and appreciate if anyone could help me out in making a informed decision.. Here goes....

a) Is it true that a blow off value will reduce fuel economy ?

B) Is it only the noise or will it actually improve performance ? if so by what percentage ?

c) Will I need 2 units as its a twin turbo or is one enough ?

d) How much will a good unit cost and where can I get one ?

e) Will I mess up the ECU or should any change needed to the ECU ?

I know the list is long.... Sorry...

Thanks.

Link to comment
Share on other sites

  • Replies 71
  • Created
  • Last Reply

Top Posters In This Topic

According to what I've heard from a AL member owning the earlier model of the same car:

a) yes it will reduce fuel economy- Debatable on the performance issue. no access to devices used to measure hp changes

c) Optional

d) Advertising on the forum not allowed 20k +

e) No

Link to comment
Share on other sites

Hi All,

I just got registered on this , but i have been reading most comments , which has been very helpfull. So big thank you for everyone...

Need some advise as I am thinking of getting a blow off value for my B4 , I have heard many contradicting views and appreciate if anyone could help me out in making a informed decision.. Here goes....

a) Is it true that a blow off value will reduce fuel economy ?

B) Is it only the noise or will it actually improve performance ? if so by what percentage ?

c) Will I need 2 units as its a twin turbo or is one enough ?

d) How much will a good unit cost and where can I get one ?

e) Will I mess up the ECU or should any change needed to the ECU ?

I know the list is long.... Sorry...

Thanks.

its always recomend to keep the stock BOV, there are various types of aftermarket blow off valves, on type is the VTA = Vent to Atmosphere, this relese the excess presure to the Atmosphere and makes a noice, other type is the React , this is like the stock bov, the presure relese back to the intake (recirculate), other type is Duel Port type, this has VTA and React in one, can also use 50% 50%

a) when u shift the air fuel ratio will be bit rich and u will not notice even there is a different in fuel consumption

b,) BOV is there to relese the presure out when the throtle is close, so VTA types have different noices, with any type there will be no performance increse at all

c) one

d) HKS SSQ, Blitz DD and greddy Type S are the best avilable, u have to buy from ebay, i also heard TiAL Sports have some gud BOV's

e) no

Edited by GihanFX
Link to comment
Share on other sites

gihan got is spot on. but i'd like to add there will be tiny lag period of lag when u get on the power after a shift (could say its not even noticable as it happens only for a milisecond or so). this can be justified with the sudden blob of black smoke given out from the exhaust momentarily because of the rich mixture as gihan said. but its a worthy trade off for the durability of the turbo and various other components.

the technical side of this is rather boring. but you may query about it B)

personally i'd go with the hks unit as it makes the best noise... and yes i know im very rice :P

Link to comment
Share on other sites

gihan got is spot on. but i'd like to add there will be tiny lag period of lag when u get on the power after a shift (could say its not even noticable as it happens only for a milisecond or so). this can be justified with the sudden blob of black smoke given out from the exhaust momentarily because of the rich mixture as gihan said. but its a worthy trade off for the durability of the turbo and various other components.

the technical side of this is rather boring. but you may query about it B)

personally i'd go with the hks unit as it makes the best noise... and yes i know im very rice :P

Last year i had a Blitz DD bov and this year i fixed a HKS SSQ, HKS sounds awesome and im lovn it, HKS SSQ is different from other types, you cant edjest is cus it not a spring type one, yes technical side is very boring

BOVs are to protect the throttle rite?

No, thats what normaly people think, what really hapend is if the BOV didnt work "Compressor surge" occurs, when the throttle plate of a turbocharged engine closes and the pressurized air is forced back into the turbocharger’s compressor housing causing the turbo to slow down. Compressor surge not only decreases the spool of a turbo but can also damage its center cartridgethe air will go backwards,

Link to comment
Share on other sites

Heard this on some other forum and just want your opinions;

"you can't have a BOV on a diesel engine because it operates at higher psi than a patrol engine"

- How valid is this remark?

Link to comment
Share on other sites

i look forward to being enlightened, so if someone could go into the nitty gritty of BOV's please?

well, imagine a turbo spooling up pushing air continously into the throttle body. when we take our foot off the throttle (to say, shift) the throttle valve closes bringing that massive air flow to a sudden halt. this causes a huge pressure build up. a pressure which could be bigger than that can be maintained by the turbo. possibly sending the air bouncing back through the still spinning turbo. at this point the strain on various components of the turbo system is huge; the pipes, intercoolers and the turbo itself. in most cases you can hear is mashing noise (most noteably in diesels i'd say) as this back flow brings the turbo to a shuddering halt. this could cause various mechanical failures such as fatigue. so for example one day the main shaft of your turbo will just snap.

a bov is designed to limit the maximum pressure that can built up before the throttle valve. as soon as the pressure is higher than its deemed safe by the device it opens a valve and releases the excess pressure. and usually the case is there's a tiny pressure drop in the system as air is released.

so when you get back on the throttle the air flow anticipated by the ecu is not met. so the a/f mixture turns out quite rich for a moment. if you watch a big powerful turbo'd car driven at full beans you'll see a tiny amount of black smoke given out after a shift as a result. but this results varies greatly on the size of your turbo or the psi u r running at, the valve release pressure, how hard you get off the throttle, and what sort of tune your engines running at.

if it is not fitted by the manufaturer and your engines running stock you don't really need one. fitting one may increase the life of various components. but i believe they are already engineered to last quite a long time under stock tune.

fitting one may also raise certain social issues as fake bovs are fast becoming major rice add-ons. i think you are safe in sri lanka but you can still fit a quieter bov if you want to keep a low profile.

Heard this on some other forum and just want your opinions;

"you can't have a BOV on a diesel engine because it operates at higher psi than a patrol engine"

- How valid is this remark?

well i agree with you to a certain extent as im yet to see a bov fitted to a diesel.

however i dont quite understand what you meant by the psi's. turbo's fitted to diesels are much smaller than one fitted to a same sized petrol engine. if you meant the the diesels run on higher compression than petrol you are quite right. but as for turbos on diesels i think they are rather mild.

Link to comment
Share on other sites

well i agree with you to a certain extent as im yet to see a bov fitted to a diesel.

however i dont quite understand what you meant by the psi's. turbo's fitted to diesels are much smaller than one fitted to a same sized petrol engine. if you meant the the diesels run on higher compression than petrol you are quite right. but as for turbos on diesels i think they are rather mild.

i think hes saying Turbo diesel cars runing High boost, i was bit suprise too cus in Sl we mesure boost in BAR, ( 1BAR=14.5038PSI)

Link to comment
Share on other sites

Pressure release valve or more commonly known as a "Blow Off Valve", releases turbo pressure when the throttle plate is closed. The turbo is still spinning and still creating pressure. The forced air will hit the throttle plate and return where it came from. When a BOV reads vacuum from the manifold, it either opens a valve, or softens the valve. Which lets the pressure escape from it's opening. In order to work correctly the air must go back into the intake before your turbo because the Air Flow Meter has accounted for it. If not you will have a temporary rich condition which will upset your idle slightly. Proper tuning can get around this hassle. Most choose to vent to the air, as they love the sweet sound the air makes when it runs to the atmosphere. If the pressure release valve (as some call it) contains a horn or small holes/vents it will cause the air to make a louder/higher pitched sound depending on what is used.

Q: What is the difference between a blow off valve and a bypass valve?

A: A blow off valve will release pressure to the air, while the bypass valve will release the pressure into the intake system between the turbo and AFM.

Q: I installed a blow off valve, it sounds really cool but my car stalls when I let off. Why?

A: First of all, the reason this is happening is because the Air Flow Meter on our cars measures the air coming in through the flapper door. It senses this air and adjusts the fuel mixture accordingly. When you let big rush of air out of the intake system, you are letting out a bunch of air that was just measured. The fueling will still dump the fuel associated with that air and cause an over rich condition. This will cause your car to stall momentarily or in some cases actually turn off. Once the BOV has closed and the intake system will return to it's normal state and work again.

To fix this, you need to adjust your BOV. Most BOVs have a screw or nut to adjust the tension. You can turn the screw/nut to the right and increase the tension. Do this several times with a test drive in between. If your BOV stops letting out the pressure, you have adjusted it too tight. You will then need to start adjusting soft again. You must keep playing with this adjustment until you get it just right. A good adjustment will allow the BOV to release pressure after slight boost, and not stall afterwards. It is not necessary for the BOV to release pressure when you rev the car.

Q: How can I make my blow off valve LOUDER?

A: There are a few possibilities. The first thing to remember is that there is more boost located in the piping between the turbo and intercooler, yet most blow off valves are placed near the throttle. Now, you want it by the throttle for response, but you can place it closer to the turbo for a louder sound output. Another thing to consider is to amplify the sound. You will notice that blow off valves with basic air holes are not as loud as blow off valves with horns (blitz) or air splitters (HKS). If you have a greddy type S, the most common BOV out there, you can find something similar in style to the horn on a blitz BOV and that will make the sound output far greater. Finally, if you (or the people on the street) to hear your bov, then you need to place it in a location that would let the sound travel out. In most cars the sound is muffled by the hood lining. Placing them out side of the engine bay on intercooler piping or similar methods will make your BOV loud and scary!

Q: Where do I get the vac/boost feed for my BOV?

A: While using the small nipples on the left side of the intake manifold may work, I suggest that you use the larger A/C idle adjuster hose. This will increase the response and thus the sound of your BOV. In addition to this, this hose is much closer to your BOV location.

Q: Can I use my new BOV in conjuction with my stock type BOV

A: Yes you can but it requires some fancy fabrication. This would be the ideal setup. The stock bypass valve could handle low boost / flow situations. Which means you can tighten the main blow off valve so that it only opens under high boost. This way you have created a "double valve" system. This is not as necessary these days since twin valve designs exist.

Edited by GihanFX
Link to comment
Share on other sites

i think hes saying Turbo diesel cars runing High boost, i was bit suprise too cus in Sl we mesure boost in BAR, ( 1BAR=14.5038PSI)

psi is the imperial unit for measuring pressure. we are more acquainted to it as americans use it (so does uk, just thought i'd mention it ;) )

BAR is the metric unit, so thats what we should be using. japan and non english speaking speaking euro nations use metrics units as well.

anyways whats funny is the other day i was reading something about volkswagen's new tsi engine. and they've qouted the boost as 1.8 BAR and 2.5 BAR which is closer to drag racing terrotiry. i almost fell off my chair when i saw it. but what they've done is mention the actual pressure whereas in forced induction culture we qoute the gauge pressure i.e. the actual pressure generated by the turbo minus atmospheic pressure (1 BAR). this is critical as i've noticed some people dont take take this into consideration when turning out custom made piping and stuff. well namely rice boys :lol:

however that gives us with our n/a cars an oppertunity to brag about our boost pressures. cos all n/a cars are running at a 1 BAR boost. its just we are qouting the actual pressure and not the gauge pressure :P

Link to comment
Share on other sites

its always recomend to keep the stock BOV, there are various types of aftermarket blow off valves, on type is the VTA = Vent to Atmosphere, this relese the excess presure to the Atmosphere and makes a noice, other type is the React , this is like the stock bov, the presure relese back to the intake (recirculate), other type is Duel Port type, this has VTA and React in one, can also use 50% 50%

a) when u shift the air fuel ratio will be bit rich and u will not notice even there is a different in fuel consumption

b,) BOV is there to relese the presure out when the throtle is close, so VTA types have different noices, with any type there will be no performance increse at all

c) one

d) HKS SSQ, Blitz DD and greddy Type S are the best avilable, u have to buy from ebay, i also heard TiAL Sports have some gud BOV's

e)

no

Hi Gihan,

Thanks machan , So in summary what you have said is

The B4 currently has a stock BOV ? and there seems to be no real benifit in getting an aftermarket BOV as the only benifit it will give out is the nice sound .

If there is no improvement in the turbo lag I guess there is no point investing in one....

Thanks Again.......

Link to comment
Share on other sites

Hi Gihan,

Thanks machan , So in summary what you have said is

The B4 currently has a stock BOV ? and there seems to be no real benifit in getting an aftermarket BOV as the only benifit it will give out is the nice sound .

If there is no improvement in the turbo lag I guess there is no point investing in one....

Thanks Again.......

Yes, if u want loud noice then go for a aftermarket bov, yes the B4 currently has a stock BOV and u will not get any benifit by replacing it with a aftermarket one

Link to comment
Share on other sites

I came across a BOV for diesels on the net. The seller confirms that they have tested it on Mitsu 4D56, 4M40 and Toyota 1KZ. After the technical explanations I get that there is no such restriction on using a BOV, as long as it doesn't vent the intake air too soon.

Thanks to the Gurus for awesome explanations on how these things work.

Link to comment
Share on other sites

Looks like its already been said- there is not performance gain from an aftermarket BOV. All modern turbos come with stock units that do the same job.

As for reliability, my car is on its 10th year in stock configuration. No reliability issues.

In the end, its a question of noise/no noise.

Link to comment
Share on other sites

  • 2 weeks later...

Hi Friends,

I am using 2002 B4TT, I need to know whether should I use a BOV or not? In this thread it was said that it decreases fuel economy...! If so what is the point of using BOV? Btw, I am using an Octane Booster per every full tank and mine does 7 to 8 a liter in Colombo and definitely 10 outstation. however if I aggressively drive it does say around 6.

Hope you would help me out with my BOV concern. Tx in advance!

Link to comment
Share on other sites

Hi,

The effect on the fuel economy will be very small and you will hardly notice... Anyway most of the answers to your question seems to have been answered above

I am very suprised to note that your car does 7 to 8, which is very good for this car. Assume this is the facelift version as its a 2002 car ?

Could you let me know whats the brand of octain boost you are using ? I have heard that it is best to stick to one octaine value like 95 rather than changing it which will confuse the ECU .... Will anybody be able to share some knowledge on this ?

Thanks

Hi Friends,

I am using 2002 B4TT, I need to know whether should I use a BOV or not? In this thread it was said that it decreases fuel economy...! If so what is the point of using BOV? Btw, I am using an Octane Booster per every full tank and mine does 7 to 8 a liter in Colombo and definitely 10 outstation. however if I aggressively drive it does say around 6.

Hope you would help me out with my BOV concern. Tx in advance!

Link to comment
Share on other sites

Hi Friends,

I am using 2002 B4TT, I need to know whether should I use a BOV or not? In this thread it was said that it decreases fuel economy...! If so what is the point of using BOV? Btw, I am using an Octane Booster per every full tank and mine does 7 to 8 a liter in Colombo and definitely 10 outstation. however if I aggressively drive it does say around 6.

Hope you would help me out with my BOV concern. Tx in advance!

based on whats been said in this thread there doesn't seem to be any logical reason for someone to want to install an aftermarket BOV :mellow:

that fuel consumption figure is mighty impressive - your car isn't a manual by any chance is it?

Link to comment
Share on other sites

based on whats been said in this thread there doesn't seem to be any logical reason for someone to want to install an aftermarket BOV :mellow:

afaik aftermarket bovs are only really useful for noise and their wide operating parameters.

no offence but im not suprised u asked that question cos u got 2 cars mostly famous for their turbos but they are both n/a :P

Link to comment
Share on other sites

Hey there,

Thanks for the reply...Yeah its the facelift version RSK.

Well talking about the Octane Booster, I am using Wurth (dunno telling a brand name in the forum is allowed :) Well, anyway I have been using this since day one, so that the RON should always be between 98-100 (as spec says) since I am using octane 95 fuel. Also buddy, make sure that you fill up at Laughs or Ceypetco gas stations...these IOC ppl are having 95 Octane but in real that is 93 Octane (One of my friends is having the test results with him)

On the ECU affects side, I am blind there...if an expert can answer us please....?

Link to comment
Share on other sites

based on whats been said in this thread there doesn't seem to be any logical reason for someone to want to install an aftermarket BOV :mellow:

that fuel consumption figure is mighty impressive - your car isn't a manual by any chance is it?

Hi,

Mine is Tiptronic with Peddle Shifts...Generally I drive to my office and back home, not daily though coz I mix my trips also with my other car (a Honda Integra, that does around 10-11)

Well, frankly speaking I am not an expert in terms of mechanical but I believe that the secret should be with the Booster. there must be other ppl those who use Octane Boosters with every tank like me...if someone out there please share your experience as well!

Link to comment
Share on other sites

Hi,

The effect on the fuel economy will be very small and you will hardly notice... Anyway most of the answers to your question seems to have been answered above

I am very suprised to note that your car does 7 to 8, which is very good for this car. Assume this is the facelift version as its a 2002 car ?

Could you let me know whats the brand of octain boost you are using ? I have heard that it is best to stick to one octaine value like 95 rather than changing it which will confuse the ECU .... Will anybody be able to share some knowledge on this ?

Thanks

even my STi do 7 to 8 with 1 bar boost on 95, most of the octain boost are just junk, as i rember we discussed abt these octain boost in AL, i have run with 98 octain by mixing my trustfull toluene, it never confuse the ECU, anyway we planing to run bit high octain on a RSK this weekend so i let u know the results

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


AutoLanka Cars For Sale

Post Your Ad Free [Click Here]



×
×
  • Create New...