To Blow Off Valve or not to Blow Off Valve??

[Lukezen27]

Hey Guys

To Blow Off Valve or not to Blow Off Valve that's the question?

GReddy kit 11550021A

Motor D16Y1

Intercoolers upgrade

Pro?
Con?
Type?

Any advice would be great

Thanks Guys

Luke

[Joel The Mole]

u might aswell, but plumb it back into the system, unless u get off on the 'PSSHHTTTT' noise. they help stop compressor surge, so it will help ur turbos longevity(sp?) turbo smart make good ones.

[mku01]

either way u like... having a plumb back BOV prolongs the life of your turbo but doesn't give as much sound as ones that vent to atmosphere.. so if you're asking whether you should have a BOV installed or just have a big hole on ur piping... i'd say bov... because u're gonna wave ur turbo byebye if u don't

[Lukezen27]

OK

Is I'll get one

$85
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=120148685759&ssPageName=STRK:MEWA:IT&ih=002

$261
http://cgi.ebay.com.au/Go-Fast-Bits-GFB-Hybrid-Blow-Off-Valve-BOV-Red_W0QQitemZ120149375197QQihZ002QQcategoryZ43807Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem

Second hand Turbo Smart
http://cgi.ebay.com.au/TURBOSMART-BLOW-OFF-VALVE-BOV-WITH-PIPE-SR20DET-BOLT-ON_W0QQitemZ110158601681QQihZ001QQcategoryZ43807QQ ssPageNameZWDVWQQrdZ1QQcmdZViewItem

So are BOV like turbos, never buy second hand?

Thanks Guys

Luke

[[ricer]]

My friend bought 2 2nd hand ones from ebay and they're both fine
his got a hks SSQV for cheap if ur interested PM me

[DLO01]

Why does it need to be plumed back to stop surge?

Any Bov can eliminate surge.

Get one. Have one to atmosphere if you like the sound. Or plumb it back if you don't like the sound or to make it legal. :thumbsup:

[Lukezen27]

Why does it need to be plumed back to stop surge?

Any Bov can eliminate surge.

Get one. Have one to atmosphere if you like the sound. Or plumb it back if you don't like the sound or to make it legal. :thumbsup:

So only plumb back's are legal in OZ?

[DLO01]

So only plumb back's are legal in OZ?

Pretty sure in all states that an atmosphere Bov is a defect.

Maybe someone can confirm.

[Klayemore]

Pretty sure in all states that an atmosphere Bov is a defect.

Maybe someone can confirm.

Thats what Ive heard.

It's not like a turboed Honda is legal anyways :p

[DLO01]

What do you mean Klay, mines fully legit. :p

[Joel The Mole]

^^sounds right, in qld neway

its a 450 fine and 3 points for noise pollution aswell. mate got done in his 32.

[Sexc86]

My opinion is deffinately run a bov.

Bov both have asthetic and practical uses. Firstly they have a massive range of sounds which sound pretty cool as well as your basic stealth ones. (whatever floats your boat)

Practically they are designed to protect your turbo from backpressure when your throttle body shuts. This backpressure after time can reduce the life of your turbo to the point where is may even fail. (depends on running boost, driving style, turbo etc etc). also Bov reduce your boost lag inbetween gear changes, as your compresser wheel is still able to spin freely, if the air is going fowards and escapeing, but not if its compressed backwards thought the turbo (wording could be a bit off, make sense?) do to haveing nowhere else to go.

If your in it for the practicallity (not a fan of a wankish "cha ching" noise every time you change gears) i would think get a basic stealth bov (no big trumpet ends), mount it just after the cool side of your cooler in your front bar, in front of your wheels, that way its out of site and cannot be seen if you open your bonnet.

lol at people who think turbo hondas are illegal..

also has anyone ever though of putting a Breather style mini pod filter on the outlet of your bov? so then air would not be leaving your engine system unfiltered? possibly a way of gettting around legallities? (doubtfull though)

thats about it :)

Regards Lyle

[DLO01]

also has anyone ever though of putting a Breather style mini pod filter on the outlet of your bov? so then air would not be leaving your engine system unfiltered? possibly a way of gettting around legallities? (doubtfull though)Regards Lyle

I think the legal side of things is more, keeping it a Closed System, and Noise Polution.

[Klayemore]

And emissions? Surely that's an extreme difficulty in making it legal.

[Lukezen27]

Pretty sure in all states that an atmosphere Bov is a defect.

Maybe someone can confirm.

So is this one a plumb back?

http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=002 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=120148685759&ssPageName=STRK:MEWA:IT&ih=002)

[Klayemore]

"Compatible to Turbo & N/A Cars"... lol

And no I don't think so. It will say it in the description if it is.

[DLO01]

So is this one a plumb back?

That picture is an Atmosphere valve.

[Lukezen27]

That picture is an Atmosphere valve.

Can you point me in the direction of the legal type?

[Sexc86]

mate, its not so much what bov "Type" is illegal and what isnt its how they are "installed" is what determines the legality of them.

Venting the compressed air strait to atmosphere - Illegal
Plumbing the compressed air back into your intake ( just after your air filter before your turbo) via a seal tube / pipe - Legal (this is how most if not all factory turbo cars are setup)


ps. lol good old ebay... a bov to suit n/a!

[Lukezen27]

mate, its not so much what bov "Type" is illegal and what isnt its how they are "installed" is what determines the legality of them.

Venting the compressed air strait to atmosphere - Illegal
Plumbing the compressed air back into your intake ( just after your air filter before your turbo) via a seal tube / pipe - Legal (this is how most if not all factory turbo cars are setup)


ps. lol good old ebay... a bov to suit n/a!

OK

This is my fisrt turbo setup and I'm a noob

SO what one should I get and what other parts ie hose do I need?

[Sexc86]

thats allright mate, do you want this part as a purely functional accessorie to your setup? or do you want it for a bit of fun to ? make a cool noise? (although illegal)

[Lukezen27]

thats allright mate, do you want this part as a purely functional accessorie to your setup? or do you want it for a bit of fun to ? make a cool noise? (although illegal)

Cool

functional and legal :thumbsup:

But I like the cool noise but I'll take functional and legal over cool any day..

Shame though I was looking forward to that shzzzzzzzzzz sound :(

[Joel The Mole]

u can still hear the noise, but its not as loud as a atmospheric one, sounds more like induction noise, but its pretty good neway.

[string]

Run no blow off valve for the best sound and completely legal! Bring on the evidence of no blow off valve causing turbo damage...

[Sexc86]

hmmm, well if you want it plumbed back.... get a bov with a circular strait flat outlet... (not a bell mouth or trumpet). This way you can get a hose made up (similar to a radiator hose) to go from the outlet of the bov back to a inlet flanges on your intake pipe between your air filter and turbo.

here is my ghetto diagram

http://i12.tinypic.com/4u3kqvo.jpg

[Joel The Mole]

paint FTW, good explanation though.


Run no blow off valve for the best sound and completely legal!

how does it have the best sound??? and running a plumb back BOV is completely legal. and having one does prevent damage to the turbo, because every time u take ur foot off the gass, the air gets forced back onto the compressor wheels, which creates more stress, and some lag, as the air is forcing against the spin of the compressor wheels.

so BOV does have some fuctionality, instead of just sounding good.

[string]

paint FTW, good explanation though.



how does it have the best sound??? and running a plumb back BOV is completely legal. and having one does prevent damage to the turbo, because every time u take ur foot off the gass, the air gets forced back onto the compressor wheels, which creates more stress, and some lag, as the air is forcing against the spin of the compressor wheels.

so BOV does have some fuctionality, instead of just sounding good.

IMO it's the best sound. I like the chattery sound. And that's not a proof of damage, that's called a theory. Here's another one. Bearings and compressor blades are quite strong. Intake charge air might have a mass of let's say, 100grams. Clearly you are completely correct in saying that there will be "more stress and some lag", but i'm looking for some evidence which says that this stress is more than completely negligible.

[Sexc86]

Run no blow off valve for the best sound and completely legal! Bring on the evidence of no blow off valve causing turbo damage...



mmm, running no bov what so ever, physically doesnt sound too bad but seriously does have long term repircussions. Dont really need to show evidence, just go ask any manufacture why then run a bov type device standard? because they are made to last. i mean i dont think most if not all leading car manufactures run a bov just for the hell of it? or because it sounds good ahah. feel free to rebut

[string]

I believe that manufacturers run a blow off valve (plumbed back) to avoid noise pollution, and in mass air flow systems, avoid the rich backfire on gearchange/throttle release.

If there was any actual physical evidence derived from a real test, every blow off valve manufacturer on the planet would be pimping it till their last breath. Though, i'll admit, I don't keep up to date, so there very well could be a test floating around somewhere, which is why I asked for 'evidence'.

[Joel The Mole]

IMO it's the best sound. I like the chattery sound. And that's not a proof of damage, that's called a theory. Here's another one. Bearings and compressor blades are quite strong. Intake charge air might have a mass of let's say, 100grams. Clearly you are completely correct in saying that there will be "more stress and some lag", but i'm looking for some evidence which says that this stress is more than completely negligible.

yeah thats cool on the sound, everyone has there own opinion on it.

can't really provide any evidence on damage, i can only base this on info i have read, and like sexc86 said, that manufacturors(sp?) fit these on stock cars. but in theory, it does seem completely logical that not having a BOV will cause more damage than having one fitted

[Lukezen27]

OK guys I got the theory down!!

Its very easy to understand but what make/model is eazy to make legal buy running a hose back through the lop..

Just like my PC water kit :wave:

[Joel The Mole]

u want a plumb back BOV, try GFB or turbosmart, there pretty good brands

[Lukezen27]

u want a plumb back BOV, try GFB or turbosmart, there pretty good brands

Hows this one?

http://cgi.ebay.com.au/Go-Fast-Bits-GFB-Basic-Blow-Off-Valve-BOV-Red_W0QQitemZ120149374998QQihZ002QQcategoryZ43807Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem

This one looks like what I need
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=110157458443&fromMakeTrack=true&ssPageName=VIP:watchlink:top:au

[Joel The Mole]

i'd go the second one, as the first one looks like an atmospheric one.

[aimre]

mmm, running no bov what so ever, physically doesnt sound too bad but seriously does have long term repircussions. Dont really need to show evidence, just go ask any manufacture why then run a bov type device standard? because they are made to last. i mean i dont think most if not all leading car manufactures run a bov just for the hell of it? or because it sounds good ahah. feel free to rebut


Dont get a BOV. If BOV are so good. Why dont race cars use them??

Ever watch the Bathurst 1000 back in the early 90's?
Those sierras ran 40 psi racing and 60 for quilifying. Dont hear them going PSSSSHT when they shift

[Sexc86]

Dont get a BOV. If BOV are so good. Why dont race cars use them??

Ever watch the Bathurst 1000 back in the early 90's?
Those sierras ran 40 psi racing and 60 for quilifying. Dont hear them going PSSSSHT when they shift


I thought they would be setup with flat shift, so their throttle bodys would be alwayes open (even gear changes, ie dont have to remove foot from gas peddal) therefor they would never loose boost pressure inbetween gears nor need a way to vent it?... please correct me if i am wrong

[TEGZOTIC]

Dude if u like the sound of it then get a atmo bov. when turboing a honda i realy dont think your thinking much about being legal. there wont be 1 part under the hood thats legal unless engerneered. So what ever you chose at the end of the day it is illegal on a honda.
So the whole idea is not to get pulled over, so imo id get the pump back so u dont get cop attention. it is tempting tho, they do sound mad and im trying to decide my self which way to ago 2 for my setup as well.

[Lukezen27]

Dude if u like the sound of it then get a atmo bov. when turboing a honda i realy dont think your thinking much about being legal. there wont be 1 part under the hood thats legal unless engerneered. So what ever you chose at the end of the day it is illegal on a honda.
So the whole idea is not to get pulled over, so imo id get the pump back so u dont get cop attention. it is tempting tho, they do sound mad and im trying to decide my self which way to ago 2 for my setup as well.

Mine will be completely legal for insurance cover and will be engineered

[Sexc86]

i would beg to differ, in qld anyway it really isnt that hard to make it legal. Just put aside $80 to go to an engineer to get a blue mod plate pop riveted to your engine bay with the appropriate code for a forced induction conversion. As long as it looks relatively clean/ secure, maybe might need to pass an emmisions test. your fine ;) why spend thousands on a turbo conversion and then be stingy on $80 for a mod plate so you dont have to worry about legalities? it would be the same case for an engine conversion... would be just as illegal as a turbo converion if it wasnt mod plated... in qld anyway im not sure about anywhere else.

[aimre]

i would beg to differ, in qld anyway it really isnt that hard to make it legal. Just put aside $80 to go to an engineer to get a blue mod plate pop riveted to your engine bay with the appropriate code for a forced induction conversion. As long as it looks relatively clean/ secure, maybe might need to pass an emmisions test. your fine ;) why spend thousands on a turbo conversion and then be stingy on $80 for a mod plate so you dont have to worry about legalities? it would be the same case for an engine conversion... would be just as illegal as a turbo converion if it wasnt mod plated... in qld anyway im not sure about anywhere else.

In sydney its over $400

[aimre]

I thought they would be setup with flat shift, so their throttle bodys would be alwayes open (even gear changes, ie dont have to remove foot from gas peddal) therefor they would never loose boost pressure inbetween gears nor need a way to vent it?... please correct me if i am wrong


They still gotta let go to brake. They dont use bovs.

Another reason they put BOVs in factory cars is becoz normal ppl would buy a car from factory that sounds like a pigeon fluttering. They'll b like WTF?


In Part 2 of our interview, we speak to a leading industry expert Simon Gishus about Nissan engines, Holden Gen 3 V8s, and directions for modifications...
What are some areas where people often make errors modifying their turbo car?

http://us1.webpublications.com.au/static/images/articles/i14/1457_2lo.jpg
"The classic blow-off valve.
"The blow-off valve is designed as an emissions control device for OE manufacturers. It came about when smaller engines made more and more power using larger turbochargers and bigger intercoolers. As you close the throttle, the build up of pressure and the larger volume inside the intake has to go somewhere; it can't go into the engine because the throttle is shut. Instead, it has to do a U-turn and it comes screaming out the airflow meter. That creates the 'gobble-goggle' sound.
"The gobble-gobble sound is something the public has grown to love.
"The airflow meter is not all that smart and does not realise the air is going in the wrong direction; it therefore measures the air twice (once going into the engine and again going out in the wrong direction). The computer now tips in twice as much fuel as what's required, making it run rich - making it not pass emissions.
http://us1.webpublications.com.au/static/images/articles/i14/1457_3lo.jpg
"Therefore, manufacturers fit a blow-off valve - or a recirculation valve as they are actually called. A recirculation valve opens when it senses manifold vacuum, returning the air trapped at the throttle body to between the airflow meter and the turbocharger. As such, the airflow meter does not take a double reading - the car now passes emissions.
"Unfortunately, we've had people ringing up and wanting the "audible gear change alarm".
""What audible gear change alarm?" we ask. "You know, when the Sierras were running around and just when they went to change gear it used to go whoda-whoda-whoda" they tell us.
""No pal, that is the dump valve..."
http://us1.webpublications.com.au/static/images/articles/i14/1457_4lo.jpg
"Some people do think that at the absolute upper extremes of boost levels - about 30-plus pounds - the blow-off valve does, somewhat, save the compressor wheel and shaft from trying to rotate backwards. It doesn't actually rotate backwards at all - all you're hearing is cavitation. What happens is, you've shut the throttle, the turbocharger is doing 100,000 rpm and now has a boost spike of 50 psi. Because it's working in a higher region than what it's designed for, it slips; it basically does a skid like a car tyre does when you dump the clutch. That's the noise you hear - the whoof-whoof-whoof is the air doing a skid."
Is there any performance gain to a blow-off valve?

http://us1.webpublications.com.au/static/images/articles/i14/1457_5lo.jpg
"We've tested one on a manual gearbox performance car run at Winton Raceway. I think it was running 1 minute 40s back then, but it would lose 2 seconds a lap putting the gobble-gobble valve on. When you look at data acquisition, what you find is - as you change gear - the blow-off valve dumps all the pressure built up through the intercooler and pipes. It then goes back to zero manifold vacuum when you get back on the throttle, you have to build all that boost back up.
"The fact that people think that they keep the turbo spinning is a problem. The people that suggest this have never had an engine on the dyno and never had a turbo tacho in their hands. What people don't realise is, when you shut off the throttle, you shut off the air supply to the engine - this shuts off the exhaust gasses coming out of the engine. When there is no exhaust flow, there is no energy to keep the turbine spinning - the turbo slows down at an alarming rate.
"If you change gears at quite a good speed, you can actually get a boost spike on changes; if you're trying to hold a constant 30 pounds, when you do a racing change you'll get 32-33 pounds when you crack the throttle open again. If everything's working well, you've got a full head of stream waiting to go into the throttle as soon as it's opened.
"I've done this on a rally car and it was quicker through every timed section without a dump valve. You'll never hear a World Rally Car going pssshhht because they don't use a dump valve - you get the woof-woof-woof noise instead."

[destrukshn]

Dont get a BOV. If BOV are so good. Why dont race cars use them??

Ever watch the Bathurst 1000 back in the early 90's?
Those sierras ran 40 psi racing and 60 for quilifying. Dont hear them going PSSSSHT when they shift
who said they don't?
lol.

well depends on what race car.
look at the japanese ones.
lol.

[Sexc86]

In sydney its over $400

geeze you serious? that sux! spose $400 is better then an equally heavy fine/defect + points


$400 is steep!..... ehheheh gobble gobble

[string]

There's always someone who'll do it cheaper, you just have to know the right people. I don't know the right people and I know a guy up the road from me who does engineering certificates for $250.

[Lukezen27]

There's always someone who'll do it cheaper, you just have to know the right people. I don't know the right people and I know a guy up the road from me who does engineering certificates for $250.

In Sydney?

[albii]

Bov are used on factory cars (plumbed back to meet adr) to eliminate lag between gears from the throttle being snapped shut and pressure being applied to the compessor blades .
It is for performance only ,it does not kill the turbo not to have one.

Factory turbo cars are set up so that you feel almost instant boost and grunt from the lower to mid rev range where most people do their driving.
That is why factory turbo cars such as the WRX feel grunty mainly from 0-120kmh but not much after due to turbo sizing etc .
The venting of excess gasses keeps the blades spinning between gearshifts therefore the turbo is ready to boost again next gear with minimal acceleration.
Think of this.The factory bov on a WRX is good for standard boost and not much more, telling you that the bov spring tension is good for stock boost so when it vents ,it vents most of the gasses.
Anything more than stock would see the bov leaking under load ,not being able to hold boost.

[string]

In Sydney?

No i'm not from Sydney but I don't see why a capital city discounts the posibility of cheaper than arse raping prices.

[kazam]

aimre speaks from the heart about this matter it seems haha

[TEGZOTIC]

wtf,, 80 to 400 buks for a turbo eng certificate, thats NOTHIN... if thats the case who wouldnt do that then. last time i looked into it, it was over 1000buks to get it engerneerd in melb.

[aimre]

Bov are used on factory cars (plumbed back to meet adr) to eliminate lag between gears from the throttle being snapped shut and pressure being applied to the compessor blades .
It is for performance only ,it does not kill the turbo not to have one.

Or to eliminate noise, or pass emissions.

There are a few reasons why they do it. Read what i posted before.

Also if u change fast enough, u can actually get a boost spike. Due to the throttle closing and the turbo still compressing for a second. When the throttle opens again, all the still compressed air in the piping rushed into the intake manifold, u can get like 2 psi spike, so u get no lag at all.

[aimre]

who said they don't?
lol.

well depends on what race car.
look at the japanese ones.
lol.

yeah ok, Lets look at a jap car

http://youtube.com/watch?v=roLBHcw8eKA

:D


O look, here a concept car, so no ADR to adhere too

http://youtube.com/watch?v=bR96aWfpWN0

from TopGear, although jeremy incorectly describes whats going on

[kazam]

lol that S2000 got pwned

and that P2 is insane

[aimre]

wtf,, 80 to 400 buks for a turbo eng certificate, thats NOTHIN... if thats the case who wouldnt do that then. last time i looked into it, it was over 1000buks to get it engerneerd in melb.

400 is just to get it looked at once. If for some reason u dont pass, the price only goes up. So it might end up $1000

[Lukezen27]

yeah ok, Lets look at a jap car

http://youtube.com/watch?v=roLBHcw8eKA

:D


O look, here a concept car, so no ADR to adhere too

http://youtube.com/watch?v=bR96aWfpWN0

from TopGear, although jeremy incorectly describes whats going on

Hm now I've heard that sound I like it :thumbsup:

Sounds mean

[DLO01]

I asked a turbo manufaturer/repairs workshop some questions in regard to Bov's and thier effect on Turbos. Hope this clears up any misconceptions or myths that we may have. This is their response:

I asked **** here the same questions as you've asked me, and although he has seen no 100% positive sign of damage due to no BOV, he still recommends using one for over 10psi of boost pressure when using a Ball Bearing turbocharger.

As for the BOV helping keep the turbocharger spooling, I can definately say this works, as turbocharger reversion would definately cause the turbocharger to reduce spool speed quite rapidly. There may only be a small difference in response time, but there is definately a difference.

[aimre]

I asked a turbo manufaturer/repairs workshop some questions in regard to Bov's and thier effect on Turbos. Hope this clears up any misconceptions or myths that we may have. This is their response:

I asked **** here the same questions as you've asked me, and although he has seen no 100% positive sign of damage due to no BOV, he still recommends using one for over 10psi of boost pressure when using a Ball Bearing turbocharger.

As for the BOV helping keep the turbocharger spooling, I can definately say this works, as turbocharger reversion would definately cause the turbocharger to reduce spool speed quite rapidly. There may only be a small difference in response time, but there is definately a difference.

But im saying without a bov, u can get a spike between changes, so ull never actually fall out of boost.

Try it one day, remove ur bov, and eye ur boost gauge while changing gears

[DLO01]

Thats ok, I was not targeting anyone. Would never do that. Everyone has thier own opinions.

Just wanted to ask questions to the people that actually repair turbos to see thier thoughts. :thumbsup:

Just wanted to share the info with everyone.

[Aza]

i no when my old bov was jammed i had major problems :) honestly why wouldnt u BOV it, its not like its expensive, and it can be done legally. at least then u dont have to be paranoid about it.

[Sexc86]

i just find it amazeing that different states have these outragous prices for mod plates i mean $1000!!!! wtf do they do?

but i guess we have to pay $2200 for prestige number plates where as in vic its only $400.00 go figure dam goverment and their "non profits"

[aimre]

i no when my old bov was jammed i had major problems :) honestly why wouldnt u BOV it, its not like its expensive, and it can be done legally. at least then u dont have to be paranoid about it.

Becos its another thing that can go wrong. I dun wanna be driving and the piston get stuck in the up position, or it simply just leaking.

What major problems did u have. Ther are hundreds of cars running no BOV and they go fine

[[[d a n n y]]]

any plumback with a pod will make a noise

[Blue]

Hey guys,

So in a nutshell,

I would go BOV on a everyday car and no bov on a race car.

Plumback for legality, insuarance etc and

Vent to Atmosphere for the fully sick "Audible gear change" sound.

Gotta love that sound, I go past pedestrians and they pooh their pants, its hilarious.

Thats my summary of this, and that if you really need to worry about it their are some decent brands like GFB which make BOV's that make no noise and can be adjusted to vent to atmo.

[xenonkuraz]

For 100% increased performance and up to 300kw instant gain (proven!), just buy one of these bolt-on BOVs! Will work with N/A cars!

http://www.takakaira.co.jp/accessories/nightpager/nightpager.html

:cool:HOW COOL!:cool:

[Lukezen27]

For 100% increased performance and up to 300kw instant gain (proven!), just buy one of these bolt-on BOVs! Will work with N/A cars!

http://www.takakaira.co.jp/accessories/nightpager/nightpager.html

:cool:HOW COOL!:cool:

Now that's just silly:eek:

[xenonkuraz]

Those Japanese will never cease with their silly (but 100% LOL) products.

http://www.takakaira.co.jp/accessories/nightpager/type2.wav

LOL @ the sound.

[dudeling7]

check out the synapse BOV. supposed to have new technology in it and be the fastest bov on the market atm.

[strafe]

But im saying without a bov, u can get a spike between changes, so ull never actually fall out of boost.

Try it one day, remove ur bov, and eye ur boost gauge while changing gears

You may actually find that you get a raise in boost because as you take your foot off the accelerator, the throttle flap closes, and the air stuck between the turbo and the throttle body has nowhere to go (well, except for back through the turbo).

Also, there are also a few problems when not running a blowoff valve. I have listed them below:

As the air has nowhere to go except through the turbo, it is in fact slowing the turbo down. This is counterproductive performance wise, as you want the turbo to be spinning as much as possible.

Pushing against the normal direction of airflow is bad. Why? Well, air going backwards through the turbo backwards is adding additional load on the turbo bearings (remember, it will be fighting against the air going through the exhaust turbine). Also, the air exiting the turbo is already hot from being pressurized, so the additional heat can cause unwanted expansion (even enough for the impeller to touch the housing sometimes!).

Air rushing back through an airflow meter will cause one of two things. It can either slow down any air already passing through it, causing the engine to run lean (not fun), or rush back though the airflow meter over a short time, causing the engine to run rich. In some cases, this can cause the airflow meter to 'max out' (too higher reading), causing the ECU to get grumpy, go into limp mode, etc. This is generally not an issue if your vehicle uses a map sensor to determine airflow.

As far as legalities are concerned, my understanding is (and I'm more than likely wrong, but anyways...) that vehicles with airflow meters require them to be vented back for emissions purposes (big puffs of black smoke and crackling from the exhaust are frowned upon by the RTA :)). Cars without airflow meters can have the bypass valve vent to atmosphere, but the noise must be under a certain level (which is near impossible). This would more than likely vary from state to state, too.

[Bludger]

i would happily replace a turbo every year just to hear that dose.

TUUUUUUu, tuuuuuu tuuuu tuuu tuu tu

[kerim]

i would happily replace a turbo every year just to hear that dose.

TUUUUUUu, tuuuuuu tuuuu tuuu tuu tu

haha, yeah cant get enuf of the dose,
wif mine, i change it around every now n then, when i wanna dose sound, i just disconnect the BOV, but if i want to hear BOV, just re connect it, you can sorta feel a diff though when BOV is connected

[DLO01]

Air flow meter?

[Blue]

that synapse thing is crazy.

and -

dose, gotta love dose, commonly refered to as cooler dose

[aimre]

You may actually find that you get a raise in boost because as you take your foot off the accelerator, the throttle flap closes, and the air stuck between the turbo and the throttle body has nowhere to go (well, except for back through the turbo).

Also, there are also a few problems when not running a blowoff valve. I have listed them below:

As the air has nowhere to go except through the turbo, it is in fact slowing the turbo down. This is counterproductive performance wise, as you want the turbo to be spinning as much as possible.

Pushing against the normal direction of airflow is bad. Why? Well, air going backwards through the turbo backwards is adding additional load on the turbo bearings (remember, it will be fighting against the air going through the exhaust turbine). Also, the air exiting the turbo is already hot from being pressurized, so the additional heat can cause unwanted expansion (even enough for the impeller to touch the housing sometimes!).

Air rushing back through an airflow meter will cause one of two things. It can either slow down any air already passing through it, causing the engine to run lean (not fun), or rush back though the airflow meter over a short time, causing the engine to run rich. In some cases, this can cause the airflow meter to 'max out' (too higher reading), causing the ECU to get grumpy, go into limp mode, etc. This is generally not an issue if your vehicle uses a map sensor to determine airflow.

As far as legalities are concerned, my understanding is (and I'm more than likely wrong, but anyways...) that vehicles with airflow meters require them to be vented back for emissions purposes (big puffs of black smoke and crackling from the exhaust are frowned upon by the RTA :)). Cars without airflow meters can have the bypass valve vent to atmosphere, but the noise must be under a certain level (which is near impossible). This would more than likely vary from state to state, too.

I know why the spike happens, but if u open up the throttle quick enough, the air rushes back in your plenum, before its gone "back out" the turbo.

Also, wtf airflow meter? Plz stop your copy/pasting mate

[Muzz]

My opinion - If the 90% of turbo oem cars come with a recirculation valve, when the manurfactures are all focoused on keeping costs down, then theres obviously reason for them using one. They dont just go sticking random parts in there cars, they do testing and evaluating, if it was worthless it wouldnt be there.



BOV on a everyday car and no bov on a race car.


Tons of top level race cars use a BOV, for example:
http://i106.photobucket.com/albums/m263/muzz1987/jkm.jpg

If they didnt believe the benifits out weighed the extra weight, they wouldnt run one, simple.
Its a car by car basis, on some it may be basically completly pointless, while on others it plays an important part.

Heres a good read, seems unbiased, unlike alot of other BOV talk - http://hrc.s10.forumsplace.com/viewtopic.php?p=15

IMO this argument is completly and utterly pointless, unless youve studied fluid dynamics to a very high level, and you can actually understand how this surging air acts on the turbos mechanicals, which none of us have.

Aimre, you seem dead set trying to convince everyone theres no benifit, do you understand how the surging air effects the turbines mechanicals? Im guessing not, which really dosnt make what your saying any more than an uneducated opinion, the worst kind there is.

To run one, or not to run one, simple question.

Run one if you like the noise or you want your turbo to be working in the best possible conditions, and the extra cost dosnt bother you.

Dont run one, if you dont like the noise, are super paranoid about weight reduction, are scared of it malfunctioning, you like the dose sound, or your happy to risk maby reducing your turbos working life, to save some cash.


Statement :- Compressor surge will not damage a turbocharger. It's only air being chopped by the compressor wheel!

Fact :- DEAD WRONG! People who state this fact should have their licences taken off them for being a danger to a perfectly good car. Compressor surge is one of the leading reasons for premature turbocharger failure. It runs a close second place to problems such as poor oil delivery to turbo bearings, high boost with ceramic coated wheels and hitting a turbocharger with a 9 pound hammer because it's too big for the space in the engine bay. But regardless of how many BOV companies put special notes on their turbo spec sheets and their websites, people who believe that the fluttering sound coming from their turbo when they back-off is only air being chopped by the compressor wheel, continually destroy turbochargers and then blame the turbo for being either too small or not built well enough to handle their engine. Believe me, I've seen stock standard CA18DET's with a bit more boost and no BOV destroy turbo bearings, shafts, wheels and in some extreme cases even the housings for one reason, COMPRESSOR SURGE.

That fluttering noise isn't just the excess pressurized air trying to rush back past the compressor wheel in the wrong direction. It does some horrible things that a lot of people aren't aware of. This is a tech article on BOV's not compressor surge so I will outline the other hazards here but leave the full explanation for the Compressor Surge article.

Hazards associated with compressor surge :-

1 - The air rushing back through the compressor wheel actually applies end load to the shaft. Although a turbocharger can handle some end load their primary direction of movement is spinning around. When this compressed air hits the wheel and creates the fluttering noise it actually pulses against the wheel. This pulsing at speeds reaching over 100,000 rpm causes the shaft to hammer backwards and forwards on the thrust plate. Eventually the plate wears out and the wheels hit the housings. How does it do this when th air is coming from one side of the wheel? Well providing the wheel dosn't completely stop it's still trying to push air into the inlet tract, the air trying to get out forces it's way around the front of the wheel pushing it back, onto the thrust plate.

2 - When a compressor wheel is being spun by the turbine wheel it has air being sucked into the smaller side of the wheel and being pushed out the larger side. Where it comes out of the comrpessor wheel it's at a tangent to the wheel itself, which means it's coming from one side of the wheel, not the middle. When this compressed air rushes back into the housing it hits the side of the wheel and creates a lot of side load against the wheel and shaft. This side load is what causes bush bearing turbos such as the T25 and T25G to destroy themselves rather quickly when subjected to compressor surge. The amount of side load on the shaft actually chews into the bush, regardless of how good the oil feed is. Ball bearings aren't as prone to this problem, but it does mean that eventually the bearing will have to be replaced, and a lot sooner than they realistically should be.

3 - When this air rushes back into the comrpessor wheel in the wrong direction it actually starts working the same as an exhaust brake on a truck. It puts pressurised load on the wheel and slows it down. Depending on the boost this slowing down effect can be very quick. There have even been instances where the compressor wheel has come to such a sudden stop with so much reverse pressure that it will try to spin backwards. Not a good thing to happen. It will result in a shattered wheel or snapped shaft and in the worst case an exploded turbo housing due to one of the previous two outcomes.

4 - When you back-off, if the car is fitted with a boost controller (be it electronic of mechanical) the wastegate will start to close. This means that the turbine wheel will begin to increase speed. Now knowing that the compressor when hit with this excessive back pressure of compressed air slows down rather quickly, we can clearly see that if one end of the shaft is trying to speed up and the other is slowing down, eventually something has to give. Normally after it does, it's the hip pocket that starts giving the most.

5 - This is a problem which isn't as big as the others, but it's a problem none the less. On Nissan's and some other vehicles fitted with "hot wire" AFMs, the air coming back through the compressor housing has sometimes reach the AFM. This can result in damage to the sensitive resistors which measure the air coming into the engine. AFMs are not really designed to handle pressurized air although some American cars do have "blow through" AFMs which are in the inlet tract after the turbocharger outlet. AFM's aren't a cheap item to replace if it does get damaged though. If it doesn't damage the AFM then you've come out of it not too bad, but now we see another problem involved in this as well. If air comes through the AFM the opposite way to the proper direction of air flow, then it can in some cases actually cancel out the incoming air flow. This will result in the AFM reading no flow what so ever and suddenly trying to shut down the injectors to stop the engine from over-fuelling. Due to safe guards such as knock sensors and O2 sensors the quick instanance of this happening won't normally damage an engine. So as I said, it's not a major problem, but still a problem you need to be aware of.


To Fit or Not To Fit, That is the question!

[Bludger]

sorry, my brain doesn't function as well as your brain, i just love dose

LOL:)

[Muzz]

honestly why wouldnt u BOV it, its not like its expensive, and it can be done legally. at least then u dont have to be paranoid about it.

Exactly my thoughts, i got a stock recirculation valve from an s15 with 25k on the clock for $9, for my future setup, cheap piece of mind.

If somone were to get a nice new expensive turbo, i think its definatly worth the slight extra cost, to get a bov, so your not trying to surge air back through it. Treat it right and give it the best possible working conditions.

The only reasons i can see to skimp on this part, is because your doing a setup on the cheap, and are using a cheap 2nd hand turbo.

EDIT: Or cause you love dose^^^:p:thumbsup:

[Lukezen27]

Exactly my thoughts, i got a stock recirculation valve from an s15 with 25k on the clock for $9, for my future setup, cheap piece of mind.

If somone were to get a nice new expensive turbo, i think its definatly worth the slight extra cost, to get a bov, so your not trying to surge air back through it. Treat it right and give it the best possible working conditions.

The only reasons i can see to skimp on this part, is because your doing a setup on the cheap, and are using a cheap 2nd hand turbo.

EDIT: Or cause you love dose^^^:p:thumbsup:

I'm going to buy one for these just to be on the safe side plus I want my setup completely legal
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=110163803524&fromMakeTrack=true&ssPageName=VIP:watchlink:top:au#ebayphotohosting

[aimre]

Aimre, you seem dead set trying to convince everyone theres no benifit, do you understand how the surging air effects the turbines mechanicals? Im guessing not, which really dosnt make what your saying any more than an uneducated opinion, the worst kind there is.


Ok so does this guy you quoted have this super fluid dynamic knowledge u speak of?

How can u say im uneducated? i have also shown articles saying that the use of a BOV is pointless. You must know it all cos u quoted some guy off some forum, and i just quoted the guy that owns nizpro and is responisble for this.

http://youtube.com/watch?v=6RpGKP_FsTc

Im sorry


Btw, luke, if ur gonna buy a bov, dont buy them cheapies, they leak.

[Lukezen27]

Ok so does this guy you quoted have this super fluid dynamic knowledge u speak of?

How can u say im uneducated? i have also shown articles saying that the use of a BOV is pointless. You must know it all cos u quoted some guy off some forum, and i just quoted the guy that owns nizpro and is responisble for this.

http://youtube.com/watch?v=6RpGKP_FsTc

Im sorry


Btw, luke, if ur gonna buy a bov, dont buy them cheapies, they leak.

I don't so much care if they work or not but want my setup to pass whatever tests needed to make it legal?

They are required are they not?

Man that's red hot

[aimre]

O, lets not forget the people on calaisturbo who have had their cars dosing for 4 years without rebuilding turbos.

[Lukezen27]

Is it or is it not legal to run without a BOV?

Can anyone just answer that?

[aimre]

VL turbos run NO bov from factory. As do CA18DET's too, supposedly

[aimre]

but hell, what do i know, im uneducated

[Muzz]

What do i know, im uneducated

So you feel you can explain to us how surge effects the turbocharger? :p
Im not saying your uneducated, your not, im saying that you have nothing to show that surging wont effect turbo life, while there is plenty of SOLID PROOF out the from the top manurfactures that it is infact bad for the products they are engineering.

Here, directly from turbobygarrett.com

Surge Line
Surge is the left hand boundary of the compressor map. Operation to the left of this line represents a region of flow instability. This region is characterized by mild flutter to wildly fluctuating boost and “barking” from the compressor. Continued operation within this region can lead to premature turbo failure due to heavy thrust loading.
Surge is most commonly experienced when one of two situations exist. The first and most damaging is surge under load. It can be an indication that your compressor is too large. Surge is also commonly experienced when the throttle is quickly closed after boosting. This occurs because mass flow is drastically reduced as the throttle is closed, but the turbo is still spinning and generating boost. This immediately drives the operating point to the far left of the compressor map, right into surge.



Surge will decay once the turbo speed finally slows enough to reduce the boost and move the operating point back into the stable region. This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve. A BOV functions to vent intake pressure to atmosphere so that the mass flow ramps down smoothly, keeping the compressor out of surge. In the case of a recirculating bypass valve, the airflow is recirculated back to the compressor inlet.

And..


What is compressor surge?
The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side.
Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself.
Common conditions that result in compressor surge on turbocharger gasoline engines are:
A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body
The outlet plumbing for the bypass valve is too small or restrictive
The turbo is too big for the application

[Muzz]

You must know it all

No, not at all.
Infact, id even go as far as to say that out of us, im the only one who understands how very extreemly little I actually know.

The engineering involved when talking about turbochargers, is WAY WAY beyond crazy, none of us here can even BEGIN to understand how that surge of high pressure is going to effect everything within. What extra forces are being introduced, where are they distributed, what are the effects?

This is the exact reason i would rather listen to what manurfactures say is bad for their turbos. Garret states that compressor surge is bad for their turbos, what have you got to show them to be wrong?

[aimre]

My opinion - If the 90% of turbo oem cars come with a recirculation valve, when the manurfactures are all focoused on keeping costs down, then theres obviously reason for them using one. They dont just go sticking random parts in there cars, they do testing and evaluating, if it was worthless it wouldnt be there.





What about a cat converter? Its there for emissions, so is a recirculation valve.


Garret states that compressor surge is bad for their turbos, what have you got to show them to be wrong?

People who have not rebuilt their turbos after 4-5 years of dosing.

Im not saying it doesnt do any damage, im just saying its so little, its not worth worrying.


Also, you keep neglecting my evidence.

Nizpro doesnt use them, responsible for the 1153hp xr6t, and you would think at those heat levels, premature wearing should be exaggerated.

Prodrive, the guys that run the subaru WRC car, and various other race cars, seem to think its unnecessary in the road going concept.

The guys responible for the Aqua subaru dont seem to think that its needed.

Many people on calaisturbo have been dosing for years without rebuilding turbos. Youd think they would stop dosing if it was so clear that it damaged turbos.

O, and my friends, have been dosing for years now, i we've yet to rebuild a turbo.

[string]

LOL Muzz, you're taking this too far. Garrett says it themselves, CAN cause damage when in CONTINUOUS or LONG PERIODS of time in the surge region. Surging under no load quickly between gears is neither of those things. Generalized FAQ answers is not SOLID PROOF of anything. Consider the forces involved between continuous operating in the surge region versus a little bit of chatter from your charge pipes filled with some boost. Got negligible?

Also please get off your high horse about everyone's knowledge. You've done one fluid mechanics course and you think you know it all? Please... Leave your comments on education at the door and concentrate on the discussion not those discussing it.

[gReY-oNe]

seriously reading this has made me more confused then wen i started LOL

[Lukezen27]

seriously reading this has made me more confused then wen i started LOL

I do you think I feel, I asked the question lol

[gReY-oNe]

I do you think I feel, I asked the question lol

HAR HAR HAR ive been following this thread
cos i was wondering the same thing
now im confused and have no idea wat to do LMAO

[aimre]

o btw, ive done fluid at uni too ;)

[aimre]

seriously reading this has made me more confused then wen i started LOL

OK, ill try and clear things up.

It does wear your turbo (so does normal use) BUT how much, no one seems to really know.

Some people say a lot while some people say its so little its not even worth considering (and i dont mean bob off the internet, i mean large companies that have the money to invest in R&D)

The only evidence we really have, is through trial. Now people on calaisturbo have been dosing for years, and many say that they havent rebuilt their turbos in years.

BUT, there is also people on calaisturbo who attribute their turbos failure to dosing. Only problem is, is that these failure can also be attributed to other causes.

SO, what u can do

- Fit a cheap bov $50. But these often leak, causing power loss and more headaches

- Fit a decent bov $400. Shouldnt leak, and should last a few years. Evantually do wear and start to leak.

- Dont fit anything. $0. BUT may cause premature failure. So it might cost a rebuild. ($400-700). Remember turbos do wear and all will eventually need a rebuild. Think of it as an excuse to hiflow ;)

[gReY-oNe]

^^^ lmao
thanks for clearing that up

plus i brought one already anyway LOL

[Lukezen27]

^^^ lmao
thanks for clearing that up

plus i brought one already anyway LOL

lol yeah

what model did you buy?

Cheap or ....

[gReY-oNe]

i picked it up from my friends friend
an apexi twin chamber one
i wouldnt say its the best but it dus its job

[Muzz]

Im not saying it doesnt do any damage, im just saying its so little, its not worth worrying.

That is a totally perfect and legit opinion, and I can see what your saying 200%.
I think you guys have totally taken what ive said so far, completely in the wrong context.

See this is exactly what I was saying in my very 1st post, it really all just comes down to your own personal opinions, and values.


Run one if you like the noise or you want your turbo to be working in the best possible conditions, and the extra cost dosnt bother you.

Dont run one, if you dont like the "psssshhhh", you like the dose sound, or your happy to risk maby reducing your turbos working life, to save some cash.
(Please note the above word “maby”)

I’m the kind of person that wants every thing working exactly as intended, I would like to know that my turbo is working in the best conditions I can give it. If I can eliminate it from having to deal with it regularly seeing surge conditions for a reasonable price, I will.
I guess you could say, I value long service life mostly, and I do. I want my setup to run like an oem designed system, with everything working exactly as intended.

You seem to be the kind of person that isn’t going to spend his money on a product that he will never really see much of a benefit from. And when it really comes down to it, you aren’t, the downside being that your turbo will be exposed to harsher conditions, which may, or may not effect turbo life. And as I’ve stated, NONE of us have the knowledge to say how much it will.



It does wear your turbo (so does normal use) BUT how much, no one seems to really know.

Exactly.

Add to that the fact that every system is different, each turbo is different, everyone’s running different psi levels, power levels, airflow rates, the compressor graphs are different, different turbos will be more vulnerable to damage from surge, times spent in surge between systems will be different, etc, etc, etc.

On some systems, a bov may be completely and utterly pointless, while on others it may be very necessary to prevent excessive wear. Weather or not a bov is useful depends greatly on the setup.

We don’t know how much surge will effect the turbo, only that turbos don’t like surge conditions.
Again, I’ve never stated that a bov will greatly effect the turbo’s lifespan, all ive been stating is that it’s a solid fact, that surge conditions are bad for the turbo.

I’m not saying my setup will be better than yours or anything at all like that, there’s no such thing, its all a matter of view.
For me, my setups better because I can drive around, knowing than my turbochargers as happy as it can possibly be under the bonnet. Its not being exposed to detrimental conditions so theres no worries of any negative effects that may be caused from the repetative surging.

For you, your setups better because you havnt wasted money on a part that really isn’t going to effect much at all, especially performance wise. And why not, as you’ve stated you know plenty of people running without one successfully. On top of that you also enjoy the sound of not running one. Not to mention not running one saves cash for other mods.

As I stated in my 1st post, it’s ALL a matter of values, and opinions. We all have different values, my values call for me to get a bov, yours call for you to pass, spend that money elsewhere.


Nizpro doesnt use them, responsible for the 1153hp xr6t, and you would think at those heat levels, premature wearing should be exaggerated.

True, but then again, maybe they feel it’s not worth the trade off between the extra weight, and the longevity of the turbo, there could be plenty of reasons why they feel better off without one.
I cant imagine a car of this level will be using the same turbo all they way to the end of its lifespan due to wear, bov or not.
Plus I’m sure they have a decent budget, so slightly accelerated wear would probably be less of an issue.

Again, the question of weather or not to run a bov comes down to what you value, and your objectives for the car.


Prodrive, the guys that run the subaru WRC car, and various other race cars, seem to think its unnecessary in the road going concept.

The guys responible for the Aqua subaru dont seem to think that its needed.

Fair enough, obviously every turbo system not running one is doing so for a reason. Weather it be for cost reasons, no measurable benefits in performance at a cost in weight, no measurable benefits in turbo life, or whatever, we cant say.

Just because various different cars have chosen to leave a bov out of the system, doesn’t automatically mean their doing so because there’s no effect at all on the turbochargers lifespan.:thumbsup:

[Muzz]

The only evidence we really have, is through trial. Now people on calaisturbo have been dosing for years, and many say that they havent rebuilt their turbos in years.


True, and while it does give an ok indication, that a turbo can deal ok with slight surge conditions, its not enough to say with a bov on X engine, the turbo lasted 180,000kms before needing a rebuild, and on the same engine, in simular driving conditions, without a bov the turbo only lasted 155,000kms.

[aimre]

Here, ill add to mre confusion.

http://www.youtube.com/watch?v=OtMmze0KM6Q

At about 20 sec in, youll hear the Audi drive past, and u can hear it dose. But then at 50 sec, when the lancia drives past, it sound like its got a BOV.

Although audi won both constructors and drivers championship ;)

BTW, there a bad accident in that, which marked an end to Group B rallying.... its safe to watch the first 1.20 min

[aimre]

http://www.youtube.com/watch?v=quDX36WJM7k

some more dosing rally cars

5 min in and its all about the lancia... lots of BOV noises

http://www.youtube.com/watch?v=tdgkmirNPf8

O btw, these cars were 4 sec slower than f1 cars of the time, which were making over 1000hp from theit 1.5L engines

[Muzz]

Sorry for the slow reply to your post sting, i havnt had much time latly.

Garrett says it themselves, CAN cause damage when in CONTINUOUS or LONG PERIODS of time in the surge region.

No, what Garrett says is exactly this:

Continued operation within this region can lead to premature turbo failure due to heavy thrust loading.


Not "continuous operation in this region", but "continued operation in this region", there’s a big difference.

This could very easily mean - if the turbo continues to see surge conditions throughout its life, this may lead to early failure. NOWHERE in that statement does it imply that the surge needs to be continual for the effects to be damaging, so don’t try and pretend it does, ok.

Infact if you read on slightly, you’ll also come to this statement:

This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve.
^^If they were actually saying that damage may occur, only if the turbo was continually running in surge, they wouldn’t go stating that the problem is usually addressed by running a bov, now would they.


Generalized FAQ answers is not SOLID PROOF of anything.

Exactly what are you trying to say with this statement?

Are you trying to say Garrett doesn’t actually have proof that operating in surge conditions is bad for their turbos? Did they go and put false info into there FAQ and turbo tech sections yeah? There making misleading statements like the one below are they?

In cases of extreme surge, the thrust bearings of the turbo can be destroyed

Maybe your trying to say they’ve never really bothered to work out if surge conditions are detrimental??
Dude, do you seriously think that the engineers who have determined that operating in surge is bad for the turbos they are designing, have done so without any proof? Stop kidding yourself, ok.


Consider the forces involved between continuous operating in the surge region versus a little bit of chatter from your charge pipes filled with some boost.

Ok, I will.


Got negligible?
No, I get equal.

Consider a turbo experiencing a surge condition for half a second, consider the same turbo experiencing the same surge but for a period of 10-15 seconds.

There’s going to be NO differences in the forces involved, the only difference is the TIME that the forces are being applied....

A continuous period of surge compared to the same amount of surge in short bursts of time, would probably only cause more heat energy release, due to the extended periods of friction. Heat that probably won’t even effect the temp of the metal receiving the extra friction, much, as it would already be damn hot.


A little bit of chatter from your charge pipes.

Where did you learn that the chatter is actually coming from the piping?
Is this solid info you’re sharing here, or are you stating what you think?

Garrett seems to think it’s from the compressor.

This region is characterized by mild flutter to wildly fluctuating boost and “barking” from the compressor.

Maybe you’re just doing your best to make it seem like surge from suddenly blocking the airflow is somehow less damaging than surge for other reasons.
Is this something you actually know, or is it something you feel, or is it just a misleading statement to try and help convince people of your opinion?

[Muzz]

Also please get off your high horse about everyone's knowledge. You've done one fluid mechanics course and you think you know it all?

Hahahahhahahhaha you’re funny.
High horse? Wouldn’t that imply that I think I know more than you guys?


unless you’ve studied fluid dynamics to a very high level which none of us have.


Infact, id even go as far as to say that, im the one who understands how very extremely little I actually know.


none of us here can even BEGIN to understand


as I’ve stated, NONE of us have the knowledge


We don’t know how much surge will effect the turbo


I’m not saying my setup will be better than yours or anything at all like that

^^Yes clearly I’m under the impression I know more than everyone else, everything ive said screams it out hey.
BTW, I haven’t done a fluid dynamics course, never implied I did????


Please... Leave your comments on education at the door and concentrate on the discussion not those discussing it.


do you understand how the surging air effects the turbines mechanicals? Im guessing not, which really dosnt make what your saying any more than an uneducated opinion

I never said anything about Aimre's Education. I was stating that he dosnt know exactly how operating in surge is going to effect the parts of the turbo, like the rest of us, so cant really go saying its not going to effect the turbo, as he dosnt have that knowledge. And neither do i which i though was made clear by this statement:

unless you’ve studied fluid dynamics to a very high level which none of us have.

[Muzz]

Just read the 1st 6 pages of this thread. Quite a few people have stated that there is zero effect on turbo life from running in an unstable surge condition at every gear change for a split second, like its a fact.

I was just wondering if anyone who has stated this has any actual info to support their claims??
Turbo manurfactures all seem to state that the thrust loads on the shaft when the throttle is snapped shut, can cause accelerated wear of the thrust bearing. I havnt seen anything to prove or disprove this yet. Untill somone can show it dosn't, ill be listening to the people designing these products who say it does.

[aimre]

I never said anything about Aimre's Education.


Im guessing not, which really dosnt make what your saying any more than an uneducated opinion, the worst kind there is.

i'll reply further when i get back from uni

[DLO01]

I was just wondering if anyone who has stated this has any actual info to support their claims??
Turbo manurfactures all seem to state that the thrust loads on the shaft when the throttle is snapped shut, can cause accelerated wear of the thrust bearing. I havnt seen anything to prove or disprove this yet. Untill somone can show it dosn't, ill be listening to the people designing these products who say it does.


I asked a turbo manufaturer/repairs workshop some questions in regard to Bov's and thier effect on Turbos. Hope this clears up any misconceptions or myths that we may have. This is their response:

I asked **** here the same questions as you've asked me, and although he has seen no 100% positive sign of damage due to no BOV, he still recommends using one for over 10psi of boost pressure when using a Ball Bearing turbocharger.

As for the BOV helping keep the turbocharger spooling, I can definately say this works, as turbocharger reversion would definately cause the turbocharger to reduce spool speed quite rapidly. There may only be a small difference in response time, but there is definately a difference.

This is the best sort of answer your gonna get i think. They way I see it, your gonna have more load on the shaft with more boost you have, so therefore you will get more wear. Simple.

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Quote: String
"A little bit of chatter from your charge pipes. "

Where did you learn that the chatter is actually coming from the piping?
Is this solid info you’re sharing here, or are you stating what you think?

Garrett seems to think it’s from the compressor.

Oh dear. I completely meant and said that the charge pipes cause "chatter". I can take partial quotes out of context too.



Garrett doesn’t actually have proof that operating in surge conditions is bad for their turbos.


You're shooting down my interpretation of garrett's FAQ only to try to bend it in your direction. Please...

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When turbochargers operate in surge for long periods of time, bearing failures may occur

Please explain to me your interpretations of continuous and continued, and how they relate to Garrett's own words: "long periods of time" (which you so beautifully claimed they did not say).

[string]

10-15 seconds of surge = x ammount of boost pushing back for 10-15 seconds of mayhem.
Off throttle surge = x ammount of boost in a given volume leaking back through the compressor, obviously diminishing pressure quickly over time, thus also force. You thought you were being smart with your pedanticism over the term "force", you have failed.

Also, explain to my why metal which is already hot "probably" won't have it's temperature affected by friction. I thought you did mechanical engineering???

[Bludger]

just dose and replace when failure occurs

[Lukezen27]

just dose and replace when failure occurs

Yeah I've decided to dose and that's it :thumbsup:

aimre makes a good point, the cost seems about that same in the end anyway...

[Muzz]

Exactly, not running one youd never know worse off anyways.

[Muzz]

Sting, i dont have time to bicker with you on somthing as petty as this, this is the last time im going to reply.


A little bit of chatter from your charge pipes.


Where did you learn that the chatter is actually coming from the piping?
Is this solid info you’re sharing here, or are you stating what you think?

Garrett seems to think it’s from the compressor.


Oh dear. I completely meant and said that the charge pipes cause "chatter". I can take partial quotes out of context too.

Sorry man, here ill use your whole quote for ya.


Consider the forces involved between continuous operating in the surge region versus a little bit of chatter from your charge pipes filled with some boost.

You’re implying that surge from the throttle snapping shut, is less harmful then surge for other reasons. Are you not?
Do you know this for sure?

Your saying straight out “a little bit of chatter from the charge pipes filled with some boost”. If you infact know its not from the charge pipes, then why the hell say it? :thumbdwn:

Why not say it exactly how it is?
"Consider the forces involved between continuous operating in the surge region, versus seeing the surge region for a split second every gear change."

Oh yes, that’s right, it dosnt help support your views, better to say it in a way that gives the impression that surge from closing the throttle is less damaging.

Just a little bit of chatter from the pipes filled with some boost? Couldn’t think of a better way to make it sound harmless, great job!

Im not taking ANYTHING out of context, im using your quote in the exact context you said it bud.
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Generalized FAQ answers is not SOLID PROOF of anything.


Exactly what are you trying to say with this statement?

Are you trying to say Garrett doesn’t actually have proof that operating in surge conditions is bad for their turbos? Did they go and put false info into there FAQ and turbo tech sections yeah? There making misleading statements like the one below are they?


You're shooting down my interpretation of garrett's FAQ only to try to bend it in your direction. Please...

Bend it my direction? Are you ****ing kidding? This is a joke correct?
Please, god please, tell me how what I said helps support my views, go on, Ill paypal you $10 for trying.

No im “shooting down” your quote because it shows absolutely nothing, and adds zero to either side discussion. For us, no, we cant take it as “proof”, but im not using it as “proof”, I posted it to show that garrett believes turbos don’t like operating in surge. Simple.

Because this info is in their FAQ (and also turbo tech section), doesn’t mean crap.
Its not like they go “Oh well, its only a FAQ section, we’re not sure if surge is bad, but it’s a FAQ, so lets just say it is anyways”.
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When turbochargers operate in surge for long periods of time, bearing failures may occur
Please explain to me your interpretations of continuous and continued, and how they relate to Garrett's own words: "long periods of time" (which you so beautifully claimed they did not say).

Ok, my bad. I was reading from garrets turbo tech section, not from the FAQs. There are 2 sections that apply.





Surge is the left hand boundary of the compressor map. Operation to the left of this line represents a region of flow instability. This region is characterized by mild flutter to wildly fluctuating boost and “barking” from the compressor. Continued operation within this region can lead to premature turbo failure due to heavy thrust loading.


When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side.


Either way, what I said still stands:

This could very easily mean - if the turbo continues to see surge conditions throughout its life, this may lead to early failure. NOWHERE in that statement does it imply that the surge needs to be continual for the effects to be damaging, so don’t try and pretend it does, ok.


Garrett says it themselves, CAN cause damage when in CONTINUOUS or LONG PERIODS of time in the surge region.

Infact if you read on slightly, you’ll also come to this statement:


This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve.


Please explain to me your interpretations of continuous and continued, and how they relate to Garrett's own words: "long periods of time" (which you so beautifully claimed they did not say).


I was relating it to the words:

Continued operation within this region can lead to premature turbo failure due to heavy thrust loading.

Continuous – Doesn’t stop.
Continued – Can mean continuous ASWELL as "repeating into the future", Can easily mean either one.

Eitherway, the quote below shows that they are implying continued, short surges, not only a single continuous surge.


This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve.

[Muzz]

10-15 seconds of surge = x ammount of boost pushing back for 10-15 seconds of mayhem.
Off throttle surge = x ammount of boost in a given volume leaking back through the compressor, obviously diminishing pressure quickly over time, thus also force.
I really cant imagine that for the 0.3-0.5 seconds that your foots off the accelerator that that’s enough time for the boost to go below what it is set at.
Think about it, when the throttle snaps shut, there is a massive spike of boost, the turbos still spinning like crazy, but decelerating quickly.
In that .5 seconds max, I really cant see it slowing to the point that boost is actually going to drop back down and below the regular boost setting, with the turbo still spinning at a great rate of knots.

Infact, id put every cent of my money on the AVERAGE boost level for the .5 seconds that the throttle is snapped shut, being well above the stock boost level. I very strongly doubt that the average level of boost for that time to be less then where the boost is set.


You thought you were being smart with your pedanticism over the term "force", you have failed.

You thought you were being smart with your term pedanticism, you have failed. <-god that sounds gay, huh.



Also, explain to my why metal which is already hot "probably" won't have it's temperature affected by friction. I thought you did mechanical engineering???

Im basing that on the fact that a piece of metal at 300 degrease isn’t going to get hotter if 250 degrees of heat is applied, infact the 250 degrease of heat will actually cool the metal at 300 degrease. I’m not to sure what happens with heat energy from friction hence the word “Probably”.
Either way, id say the heat change will be nothing compared to if we were talking about the same friction on cold metal.

I don’t do mechanical engineering, im studying it, big difference. Im only 1.5 years into it, got a hell of a lot to learn yet.

Anyways, arguing about this shit is completly pointless, if you reply, i agree with everything you have to say.
Im over this crap.

[BAMBANG PAMUNGKAS]

bov = great if ur a ricer

[kazam]

wow, after 10 pages of replies you say sumthing as stupid as BOV = great if ur a ricer?....

[krogoth]

bov = great if ur a ricer

orly? dont all skylines come with stock bovs?

[BAMBANG PAMUNGKAS]

serious man. bov are good if they are plumback.

otherwise, wtf they do. nothing but make noise and reduce compressor surge / dose. thats right.

so its a ricer mod.

[Lukezen27]

Clearly this subject was something a lot of people were thinking about :wave:

[string]

Whoa burn; you 'study' mechanical engineering not 'do' it... For a second there I was completely confused! Please, be a bit more pedantic, it makes you sound oh so smart...

Stop trying to pretend that your interpretation of their FAQ is any more correct than mine. Nowhere in the FAQ does it provide any conclusive evidence for either case, so either dig deeper or keep your "proof" to yourself.

Can't wait to get a hold of some Muzz Thrust Bearings. They cool down with friction, but only when they get to operating temperature! Genius!

[Muzz]

Dude, you are to funny, i had to reply.


Whoa burn; you 'study' mechanical engineering not 'do' it... For a second there I was completely confused! Please, be a bit more pedantic, it makes you sound oh so smart...

Dude WTF is wrong with you? Seriously, you state:


Also, explain to my why metal which is already hot "probably" won't have it's temperature affected by friction. I thought you did mechanical engineering???

I took this as "i thought you would know, cus your an engineer"

My reply "i dont know everything, im not an engineer, only a student"

And you come back with this gay shit?


Whoa burn; you 'study' mechanical engineering not 'do' it... For a second there I was completely confused! Please, be a bit more pedantic, it makes you sound oh so smart...

ABSOLUTLY ***ING PATHETIC:thumbdwn:
Dude i was simply replying to what you said to me.
Shits getting real low when your comeback is at me, for defending my lack of knowledge, against you.:thumbdwn:


Stop trying to pretend that your interpretation of their FAQ is any more correct than mine. Nowhere in the FAQ does it provide any conclusive evidence for either case, so either dig deeper or keep your "proof" to yourself.

Dude, do you even read what i write?


For us, no, we cant take it as “proof”, but im not using it as “proof”, I posted it to show that garrett believes turbos don’t like operating in surge. Simple.

You sir, are a complete and utter dumbass:thumbsup:

My interpretation of garrets FAQ, dumbass, is simply that garrett are stating that surge is bad for the turbo, nothing more.

Well what do you know, in the FAQ garrett is stating that surge is bad.
Im not INTERPRETING shit, im looking at garretts site, and looking at where there stating its bad.

Did i ever say it was proof? NO
Did i say to us, its not proof? YES
Did i say, i cant imagine them stating that without their own proof? YES
Do you keep making more of an ass of yourself? YES
Are you an idiot? DOUBLE YES


Can't wait to get a hold of some Muzz Thrust Bearings. They cool down with friction, but only when they get to operating temperature! Genius!

Dude, go back, READ.
Im not even talking about bearings, im stating fact about heat transfer.
If somthing at 300 deg is in contact with somthing at 250 deg, it will cool down.

OBVIOUSLY this isnt gunna happen, because what the hell is going to cool the bearings down? The point, which obviously flew straight over your head, is that somthings thats hot, isnt going to suffer a massive rise in heat, as its already chocka block full of heat energy already, and is going to absorb heat at a much much slower rate than somthing which is cool.

[Muzz]

Sting, open your eyes, your wasting your time arguing with somone whos not on either side.

Im not for or against BOVs, its all a matter of what you value, both sides of the argument are perfectly valid, and your still here bitching at me for being wrong? Good on ya!

Your doing such a great job as a soldier for the "no bov's" crew, you should be very proud.

How can i be wrong when my opinion is:

To run one, or not to run one, simple question.

Run one if you like the noise or you want your turbo to be working in the best possible conditions, and the extra cost dosnt bother you.

Dont run one, if you dont like the noise, your focoused on weight reduction, are scared of adding somthing else which can malfunction, you like the dose sound, or your happy to risk maby reducing your turbos working life, to save some cash.

Its ALL about what you value in your system


I’m the kind of person that wants every thing working exactly as intended, I would like to know that my turbo is working in the best conditions I can give it. If I can eliminate it from having to deal with it regularly seeing surge conditions for a reasonable price, I will.
I guess you could say, I value long service life mostly, and I do. I want my setup to run like an oem designed system, with everything working exactly as intended.

You seem to be the kind of person that isn’t going to spend his money on a product that he will never really see much of a benefit from. And when it really comes down to it, you aren’t, the downside being that your turbo will be exposed to harsher conditions, which may, or may not effect turbo life. And as I’ve stated, NONE of us have the knowledge to say how much it will.


Your wasting your time, and mine.

[kazam]

muzz 1
sting -100

[string]

Wow for someone who's time is so important you sure do write a lot.

And for the record if I ever bought a new turbo i'd get a bypass valve for sure. Oops there you go assuming things again!

[Muzz]

Wow for someone who's time is so important you sure do write a lot.

And for the record if I ever bought a new turbo i'd get a bypass valve for sure. Oops there you go assuming things again!

Great, its all good then...

[bennjamin]

this is bs.
Infractions dealt out.
Closed. Pm a mod if u require this reopened