blowoff valve

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Originally posted by JohnBM01
The reason why people wouldn't want to have Overboost in a game is because real racers don't use such a thing. Overboost is kind of more like drag racing and illegal street racing (even though I don't endorse it). I don't think an overboost will sell for GT4 cars even though a Trial-tuned Toyota Celica SS-II will most likely be in GT4. I wouldn't even recommend it for racing in GT4. I wouldn't recommend it especially for passing. It would make GT4 more of an arcade game than a arcade/simulation.

Well, that's what I think. And I tried to tell my side without saying "ricer," "rice rocket," or anything like that, because that's not my style.
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Such misguided information... Over-boost and High-boost are two different things. Most "real racers" if they have a turbocharged vehicle, do infact have adjustable boost. Although in most professional racing series where turbocharging is allowed, the ammount of air the turbo can push is restricted. It doesn't make much sense to raise the boost when the turbo is still pushing it's air through a straw-sized restrictor now does it?

Overboost = boost spike = Bad

High-boost = user adjusted boost setting = Good or bad. Depending on if the a-f ratio is kept lean/stoich/rich. More boost and not enough fuel is bad news. More boost with adequate fuel is a damn good time.

I agree, I don't think "overboost" will sell for GT4 either. I also wouldn't "recommend it for racing in GT4". I too also wouldn't "recommend it especially for passing". Unless you were talking about a turbo-diesel, in that case I would disagree with you.

More often than not the people that go around saying "rice" and "ricer" are the very people that have no idea what the hell they're talking about.
 
The escudo in gt3 had a bit of turbo lag(fully tuned).
gtr.gif
 
Originally posted by cubits
Of course it has something to do with the turbine spinning... that's what produces the pressure to make the bov bo (teehee)!
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So much misinformation.:eek: The BOV is actuated by intake manifold vacuum, not by the pressurized air coming from the compressor. If that were the case, the BOV would be would be open whenever boost was present, which would be completely counterproductive.

BTW he was right when he said the BOV has nothing to do with the turbine spinning. The turbine does not provide boost, the compressor does.
 
Originally posted by DRIFT4EVA
You actually gain power with a blowoff valve. It lets the air out so the turbine will wind up again quicker, allowing you to get away quicker
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I think the sound you're thinking of is a waste-gate, most likely an internal one (the external's are hell loud and usually only used on drag/racing cars because they produce to muhc noise for a street legal car.)
The reason you have a waste-gate is to release excess pressure to prevent engine damage or knocking (This may be known as overboost). This would result form and oversupply of air when changing gear because the Turbo would still be at full boost and the engine would be revving slower (Therefore consuming less air).
 
Originally posted by Crayola
I think the sound you're thinking of is a waste-gate, most likely an internal one (the external's are hell loud and usually only used on drag/racing cars because they produce to muhc noise for a street legal car.)
The reason you have a waste-gate is to release excess pressure to prevent engine damage or knocking (This may be known as overboost). This would result form and oversupply of air when changing gear because the Turbo would still be at full boost and the engine would be revving slower (Therefore consuming less air).
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The purpose of a wastegate is to prevent overboost. That in turn prevents engine damage. The wastegate does not prevent engine damage and or knocking directly however. Proper tuning and acceptable boost ranges do.

One question for you. How in the hell would the turbo be at full boost if the throttle was closed while changing gears? We have some reading up to do...:)
 
See you'r revving high in the rev ranges before you change gear, therefore the turbo is at full-boost. Then when you change gear without some-sort of wastegate the compressor can't realease pressure. You forgot that even once you release the throttle the engine is still spinning, and therefore there is still pressure.

Yeh, the wastegate doesn't stop knocking-or engine damage directly but If you look in my first post that's what I said; it prevents overboost which in-turn results in damage.
 
Originally posted by Crayola
See you'r revving high in the rev ranges before you change gear, therefore the turbo is at full-boost. Then when you change gear without some-sort of wastegate the compressor can't realease pressure. You forgot that even once you release the throttle the engine is still spinning, and therefore there is still pressure.

Yeh, the wastegate doesn't stop knocking-or engine damage directly but If you look in my first post that's what I said; it prevents overboost which in-turn results in damage.
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WOW:confused:

Just because the engine is revving high doesn't necessarily mean the turbo is at full boost, or boosting at all for that matter. Turbo boost is does not depend on engine RPM directly. What matters more is throttle application and engine load. A turbocharged engine can be at redline and not be in boost depending on the throttle angle. You're forgetting something crucial. The blow-off valve releases boost whenever there is intake manifold vacuum, aka partial throttle.

Also, the wastegate has nothing to do with the compressor. The wastegate release excess exhaust pressure to keep the maximum boost value in check. It's the BOV's job to release the boost to prevent compressor surge. It's not there to save the engine at all. It's there to save the turbo.

Once again, if you take a turbocharged engine to redline and release the gas completely, there will be ZERO BOOST whether it's at redline or 2500 RPM. Guaranteed. How in the world can there be boost pressure present in the intake manifold if:

1. The throttle plate is shut
2. The BOV is releasing all the boost
3. There is no load on the engine

Once again, we have some reading up to do...:)
 
The way you've written it makes it sound like once you release the throttle the engine stops turning immediatly,it is still spinning and therefore still consuming oxygen.
 
Originally posted by Crayola
The way you've written it makes it sound like once you release the throttle the engine stops turning immediatly,it is still spinning and therefore still consuming oxygen.
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First let's get a couple definitions cleared up.

Boost pressure is the measure of any pressure in the intake manifold above atmospheric pressure (14.7 PSI @ standard temperature and pressure)

Vacuum is the negative pressure that exists in the intake manifold at any throttle opening less than Wide-Open Throttle (WOT). Another way of looking at this is anything below atmosperic pressure (14.7 @ STP) is considered vacuum.

When you let off the gas at high RPM even with a turbocharged engine, there is vacuum (negative manifold pressure) because the throttle plate is completely closed while the engine still wants to digest air. The whole point of the throttle plate is to restrict airflow to the engine to control the engine RPM. The BOV uses this negative manifold pressure to open up and release any boost before it gets to the engine. This is why even if you let off at high RPM there will be no boost but vacuum instead. Not only does it seem like you have limited knowledge of turbocharging, it also seems like you dont know the basics of how an engine works. I don't know it all, but I'm ready to learn if i dont know something. You should do the same.:)

I'm done whoring this thread up. If you want to learn any more, please PM me.:)
 
Originally posted by joatmon25
First let's get a couple definitions cleared up.

Boost pressure is the measure of any pressure in the intake manifold above atmospheric pressure (14.7 PSI @ standard temperature and pressure)

Vacuum is the negative pressure that exists in the intake manifold at any throttle opening less than Wide-Open Throttle (WOT). Another way of looking at this is anything below atmosperic pressure (14.7 @ STP) is considered vacuum.

When you let off the gas at high RPM even with a turbocharged engine, there is vacuum (negative manifold pressure) because the throttle plate is completely closed while the engine still wants to digest air. The whole point of the throttle plate is to restrict airflow to the engine to control the engine RPM. The BOV uses this negative manifold pressure to open up and release any boost before it gets to the engine. This is why even if you let off at high RPM there will be no boost but vacuum instead. Not only does it seem like you have limited knowledge of turbocharging, it also seems like you dont know the basics of how an engine works. I don't know it all, but I'm ready to learn if i dont know something. You should do the same.:)

I'm done whoring this thread up. If you want to learn any more, please PM me.:)
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You are so right, it's not even funny, actually yeah it is.:lol: :lol:
 
JohnBM01
I tell you, as much as I love racing, cars, and racing cars, overboost is turning out to be a hot topic to this Chat. The reason why people wouldn't want to have Overboost in a game is because real racers don't use such a thing. Overboost is kind of more like drag racing and illegal street racing (even though I don't endorse it). I don't think an overboost will sell for GT4 cars even though a Trial-tuned Toyota Celica SS-II will most likely be in GT4. I wouldn't even recommend it for racing in GT4. I wouldn't recommend it especially for passing. It would make GT4 more of an arcade game than a arcade/simulation.

Well, that's what I think. And I tried to tell my side without saying "ricer," "rice rocket," or anything like that, because that's not my style.[/QUOTE

Why would this car make it more of an arcade game? cause it has a really large spoiler, big chrome wheels and some stickers?,the trial celica is actually really fast and those are its "show" wheels, (it has some what looks like some white volk te37s for its "track" wheels) its not too far from top secret's Civic Type R and Integra Type R, I plan on getting gettin one of these myself in the game, I know its no Evo 8 or anything but it performs really well in real life (based on laptimes at tsukuba), and is very tunable suspension wise.
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a bov enhaces performance by letting back pressure relese from the system.... its helps!!!!! a bov actually helps the car stress less becuz when it lets the air escape then you will not have compressor surge! IE: turbo lag/detenation.. i know from experiance what the diffrence can make of a car... i work at a shop with SR20det's built for driftng/autocross. m not trying to sound like a dick but it helps! so get one! they don't just sound cool! they help! also if u have less backpressure u have less turbo lag! meaning quicker response! unless u are running a larger turbo then of course u will have lag even at 7 p.s.i hope i helped! :)
 
909drifter
a bov enhaces performance by letting back pressure relese from the system.... its helps!!!!! a bov actually helps the car stress less becuz when it lets the air escape then you will not have compressor surge! IE: turbo lag/detenation.. i know from experiance what the diffrence can make of a car... i work at a shop with SR20det's built for driftng/autocross. m not trying to sound like a dick but it helps! so get one! they don't just sound cool! they help! also if u have less backpressure u have less turbo lag! meaning quicker response! unless u are running a larger turbo then of course u will have lag even at 7 p.s.i hope i helped! :)
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Where do i begin? :boggled:

1. Please explain in technical terms how a BOV helps performance...
2. Please explain how a BOV "helps a car stress less"
3. Please explain what causes a BOV to open in the first place
4. Please explain how turbo lag is related to detonation- Im eager to hear this one :lol:
5. Please explain how compressor surge relates to turbo lag
6. Please explain how/why you working at a shop makes you credible...that's like saying everyone that's works at a car dealership know their shiet...

I'm curious to hear your responses. Have a nice day.

Mike
 
gmartin
Most cars these days that come with a turbo from the factory don't have a blowoff valve. And actually, there isn't really a need for it.
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wrong

gmartin
Most cars these days that come with a turbo from the factory don't have a blowoff valve. And actually, there isn't really a need for it.
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wrong

gmartin
if the air is released from the turbo, then it has to spin the turbine again, thus taking longer to give the engine more power. If the air is still in the turbo (with no blowoff valve) then the turbine doesn't stop spinning giving you more turbo responsiveness at a lower RPM and power when you need it.
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wrong

RedGsxEclipse
May I add the turbo does not recieve any air from the side the blow off valve is on. The throttle body piping which the BOV is connected turns into exhuast which enters the exhaust housing.
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you may want to take a look under your own hood, if you do infact own a GSX, because you are wrong

RedGsxEclipse
The only side which deals with air is through the turbine housing from the intake and Fount mount intercooler....
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wrong

RedGsxEclipse
replying to "qmartin" therefor you "Do Not" lose power from the bov you lose gasmilage from the Mass air flow sensor readings being bouced all over.
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again, take a look under your hood at where the MAF sensor is, and you will discover that you are wrong


909drifter
a bov actually helps the car stress less becuz when it lets the air escape then you will not have compressor surge! IE: turbo lag/detenation...
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riiiiighhht.... on wait no - wrong

909drifter
also if u have less backpressure u have less turbo lag! meaning quicker response! unless u are running a larger turbo then of course u will have lag even at 7 p.s.i hope i helped! :)
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are we still talking about BOV's? Because if so, you are wrong

I love this board. weeeee!
 
well, the only thing i've got to say is: MAKE THE NOIZE LOUDER!!!

you can't barely hear the sound of the BOV's in the other GT's, or i must have forgotten it........:dunce:
 
Way to go dragging up old threads.
 
how can you say you dont need a BOV, if youre turboed, and you have no BOV your engine will explode, during shifts the pressure build up is so high that some has to be released. besides if they werent necessary why the hell would every turbo car have a BOV
 
yaoming3000
how can you say you dont need a BOV, if youre turboed, and you have no BOV your engine will explode, during shifts the pressure build up is so high that some has to be released. besides if they werent necessary why the hell would every turbo car have a BOV
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*sigh*....

Once and for all:


The BOV is there to protect the compressor, not the engine!!!!!!
 
Monster7
Every factory turbocharged vehicle that I can think of, and that I have seen, has a compressor bypass valve. A cbv is plumbed back into the intake and is almost impossible to hear from outside or even inside the vehicle.

A blow off valve or relief valve is typically vented to the atmosphere. No matter what valve design you have, they all serve one purpose: Prevent compressor surge

Exhaust spins the turbine - The turbine is connected via a shaft to the compressor - The compressor brings in the air. When you let off the gas pedal the throttle plate closes and that extra air that didn't make it into the manifold slams into the plate causing it to go backwards and attack the compressor, forcing it to spin in the opposite direction = bad news. A bov-cbv prevent that air from ever reaching the compressor, and in turn keep it spinning in the right direction.
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They're all BOVs, whether they're atmospheric or plumbed back to the manifold. I can think of one factory turbo car that did not come with a BOV: 1986 Dodge GLHS (IIRC). It didn't have a BOV because the throttle plate was actually before the turbo, so off-thottle the compressor inlet went to vacuum, hence no need for a BOV. They changed it the following year and moved the throttle plate after the compressor and added a BOV, as probably every other factory turbo car is.

Compressor surge as you mentioned is particularly bad on the thrust bearing because of the change in load going from on- to off-boost.
I also think that the rally cars should have the waste gate blow off valve sound like the real WRC cars.
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WRC cars don't have BOVs. They have ball-bearing turbos which reduce the impact of compressor surge and they have deep pockets so they don't care if they have to put a new turbo on every rally. What you hear in rallying is actually compressor surge, and it's a high-pitched HEEE HEEE HEEE sound. It sorta sounds like loud brakes, but it's not.
 
It seems like kids come in this thread, read what the intelligent people say about turbocharging, and throw together random/unrelated crap to try to make themselves look knowledgeable about cars. Very good read.
 
Bahbo
It seems like kids come in this thread, read what the intelligent people say about turbocharging, and throw together random/unrelated crap to try to make themselves look knowledgeable about cars. Very good read.
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QFT
But seriously there are alot of stupid people out there that jumped on the "Car/StreetRacing" bandwagon ever since F&F. They pretend so much to know about cars and spread useless and FALSE crap about cars. If i could give an Award for the Most Useless thing Made ever in the history of mankind i would give it to everyone who was directly/indirectly involoved with F&F:tdown:
 
I dont even bother explaining how bovs, wastegates, turbos etc work anymore, I have done it so many time im sick of it.

BTW there is always chance of broken pieces of compressor blades and metal pieces that enter and damage the engine once the turbo blows.

BTW2 The 1GGTE Supras (GZ70) also hasnt got a bov
 
I think the Lancia Delta Rally car from gt3 has a good blow off sound. But it is still way cooler with the air-filter whisteling in NFSU2
 
it is quite funny reading what so called experts have to say about turbos and bovs. you can tell who knows there stuff and who is full of **** and watch's to much fast and the furious.
 
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