turbo stall.. pahlease!
and the guy who said something about re-spooling if NOT having a BOV.. lol nice logic.. *shakes head*.
when will people stop going on hearsay and rather engineering fact.
Air intake - how do I get turbo flutter?
- Thread starter sexspecvr4
- Start date
turbo stall.. pahlease!
and the guy who said something about re-spooling if NOT having a BOV.. lol nice logic.. *shakes head*.
when will people stop going on hearsay and rather engineering fact.
You are quick to say im incorrect yet dont have an "engineering fact" in your post?
Didnt need to refer to me as a retard, could have simply stated your opinion. Im waiting for it?
Pop up your bonnet, put on a pod instead of an airbox, shorter piping to the inlets if needed, give it a high enough rev and listen to the sound ... what does it sound like? OH! thats right! a blade chopping sound? hmmmm what blades are there in the pipework...
If all the compressed air in the piping is not going into your manifold, and not going out a blow off valve (due to spring tension or just no BOV) where does it have to go? BACK through the compressor and out the other side... hence the sound. Chopping as it goes past the blades slowing them down..
You sir, are the retard. It doesnt take engineering to be able to realise what is happening and causing a simple sound.
In the red corner, driving the S13 is Steve...
In the blue corner, driving the galant VR-4 is Josh...
Honestly there is really no need whatsoever to use abusive language towards someone if you disagree with them....
In the blue corner, driving the galant VR-4 is Josh...
Honestly there is really no need whatsoever to use abusive language towards someone if you disagree with them....
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i have one of thes ssqv i bought it as i was told it would make a similar noise to a flutter but it actually sounds more like someone is shooting a bird with a nailgun
bradc
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Come on Steve, no need to be like that. At least try and explain yourself and what you beleive regarding the issue, and try to do it as eloquently as possible. Posts edited.
haha now it looks like im saying he said something it appears he didnt, and makes my post look like an overreaction
donest come up with "Edited by Bradc"? 
Because our turbo's make lots of boost from nowhere its hard to make them do it.... It will do it if you have very tiny amounts of boost, but that is nearly an impossible task haha
It only does it with a little bit of boost. When you get more boost its opens the big valve
godzilla
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My 2.2 cents, i have a non genuine copy version of an HKS SSQ ( on it when purchased ) and i am running only stock boost ( 7psi ) with a hks poo filter, now i also have an auto so dont hear it very often except when i want to scare cyclists etc and when released at full boost it is a high pitched squeak / whistle of sorts. Now to weigh in on the " flutter ", even at low boost like maybe just over neutral, it opens like a "normal" bov and makes a quiet psssshh. So no flutter at all for me. Maybe it is just because it isn't the $500 version But i am with Josh, i dont have any hard facts about the effects on a turbo's compressor from back pressure but to me its like what happens to a pedal on a pushie when you spray the hose at it and then stop it when you spray the hose at it in the oppisite direction.
and when released at full boost it is a high pitched squeak / whistle of sorts. Now to weigh in on the " flutter ", even at low boost like maybe just over neutral, it opens like a "normal" bov and makes a quiet psssshh. So no flutter at all for me. Maybe it is just because it isn't the $500 version But i am with Josh, i dont have any hard facts about the effects on a turbo's compressor from back pressure but to me its like what happens to a pedal on a pushie when you spray the hose at it and then stop it when you spray the hose at it in the oppisite direction.sorry didnt mean to have a go at u, i explain to people how 'flutter' works all the time, and no matter how many times people are corrected. some noob always has the 'my mates cuz said it kills ur turbos' line.
first of all turbos dont 'chop' air. the blades are spinning at ~30,000 rpm. its physically impossible to hear the air being chopped. the sound is cause of air escaping at different pressure levels. at certain rpm's, the turbos hold certain boost. as the rpm slows, the pressure will drop gradually in relation to the turbo spool speed. and the turbo never 'stalls' or goes backwards or any other BS. even on idel its spins relatively fast.
running no bov will actually help turbo repsonse time, this is why heavily modified cars dont run bov's. once the bov opens, the pressure is lost and the turbo has to spool up again. but with no bov, like i stated, the pressure will gradually drop. so when u get on the gas again, theres already boost remaining in the intake system.
the major contributing factor for factroy bovs is noise pollution. manufacturers dont want weird noises from their cars. they want the car to run nice and smooth and have the driver oblivious to whats going on under the bonnet. this is why a lot of older cars dont have bov's. it was before all emissions rules got strict.
as for reducing the life span of the turbos. turbos can handle EXTREME heat and pressure. way more than ur engine can handle. the average life of a turbo (based on experience) is around 100,000kms. now turbos are constantly under load for a lot of kms. a 'gradule' decrease in pressure opposed to a quick release is going to do sweet **** all to something eningeered to handle much much more extreme conditions.
please dont buy into the hype of bov manfuctures. they just wana sell products and will pedal any type of uncertainties to get ur money. if running no bov really kills ur turbo. me amoung other people would have replaced our turbos many times over. there is no proof it does any damage at all.
btw i got a vr4 now, silvia was my last project
and no i never ran a bov on it
first of all turbos dont 'chop' air. the blades are spinning at ~30,000 rpm. its physically impossible to hear the air being chopped. the sound is cause of air escaping at different pressure levels. at certain rpm's, the turbos hold certain boost. as the rpm slows, the pressure will drop gradually in relation to the turbo spool speed. and the turbo never 'stalls' or goes backwards or any other BS. even on idel its spins relatively fast.
running no bov will actually help turbo repsonse time, this is why heavily modified cars dont run bov's. once the bov opens, the pressure is lost and the turbo has to spool up again. but with no bov, like i stated, the pressure will gradually drop. so when u get on the gas again, theres already boost remaining in the intake system.
the major contributing factor for factroy bovs is noise pollution. manufacturers dont want weird noises from their cars. they want the car to run nice and smooth and have the driver oblivious to whats going on under the bonnet. this is why a lot of older cars dont have bov's. it was before all emissions rules got strict.
as for reducing the life span of the turbos. turbos can handle EXTREME heat and pressure. way more than ur engine can handle. the average life of a turbo (based on experience) is around 100,000kms. now turbos are constantly under load for a lot of kms. a 'gradule' decrease in pressure opposed to a quick release is going to do sweet **** all to something eningeered to handle much much more extreme conditions.
please dont buy into the hype of bov manfuctures. they just wana sell products and will pedal any type of uncertainties to get ur money. if running no bov really kills ur turbo. me amoung other people would have replaced our turbos many times over. there is no proof it does any damage at all.
btw i got a vr4 now, silvia was my last project
and no i never ran a bov on it
VR4Rocket
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I have heard that before as well, people not running a BOV, a number of printed text I have seen call them "wank factor sevens" and stated that they have no real use at all. From what I understand having a plumb back would be similar to having none at all as it is just recircing the air...
I do have 1 question though......if BOV are not needed how come they put them on as factory on turboed cars?
I do have 1 question though......if BOV are not needed how come they put them on as factory on turboed cars?
godzilla
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Thats what i thought, without knowing the exact figure i would reckon nearly all new turbo charged cars run a bov. And they pretty much are all recirc . If they had no effect at all then why would they have them? The thing with the recirc type is they are putting allready heated air back into the intake 
I know its not much but enough to give the engine a shot of heated air when you open the throttle back up.
I know its not much but enough to give the engine a shot of heated air when you open the throttle back up.
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1998 FL Legnum VR-4
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hahaha, take the front off it and remove the three legged thingy. That will solve the bird/nailgun sound...lol
I have found not running a BOV to be very detrimental to the life of turbos that i had fitted to my FJ20et over time. My understanding of the damage caused it that when boosting, a turbo is fine as it is being spun by the exhaust wheel and only putting force on the bearings in a rotational manner, and in a very linear way. When the compressor starts to stall, as the air starts to rush out back through the compressor housing, the force of the air hitting the fins causes the wheel to vibrate in a very violent manner, as the compressor wheel is trying to spin the way of the air rushing out, but the exhaust wheel is trying to spin in its normal manner. The counteracting forces harmonise the shaft, which is what causes the vibration. Like SteveP said, the air does not all come out at once, and rather does so in stages related to the differential in pressure. This means that it vibrates the fins quite erratically. The damage occurs to the bearings as they are only designed for dealing with rotational forces, and not anything which tries to move the shaft in a directional movement.
I found this to be the exact case on my engine. With a custom turbo i was running around 28psi with no BOV and it was bearings that kept wearing out. When i installed a BOV, this stopped happening. Vibration is a killer in any componant in an engine. Ask any engine builder how much trouble a tiny vibration in a crankshaft can cause, let alone in something that is spinning at sometimes nearly 10 times that speed. Its why turbos are balanced to the nth degree, even using tiny blobs of white paint on brand new aftermarket turbos to make sure the compressor wheels are all exactly the right weight.
Bit of an essay and i hope i got it right. Its been a while since i studied this stuff during my motorsport engineering course.
On a side note, in reference to SteveP commenting on the heavily modified cars not running bovs, i think he is reffering to seeing turbo drag cars without them. These days it is quite rare not to see them running a BOV, but some dont just for the fact that it is a big dollar race car that gets fully stipped and rebuilt between meetings, and the damage that occurs to turbos really happens over a long period, so runs down the strip are not going to make a whole lot of difference. You dont generally see a lot of big money street cars not running a bov.
I do really like the discussions on this topic. It is quite interesting with a lot of science backing up both camps. Plus then you have the BOV manufacturers that would love for you to buy one of their aftermarket jobs as well, with all their marketing and spin which goes along with that.
I found this to be the exact case on my engine. With a custom turbo i was running around 28psi with no BOV and it was bearings that kept wearing out. When i installed a BOV, this stopped happening. Vibration is a killer in any componant in an engine. Ask any engine builder how much trouble a tiny vibration in a crankshaft can cause, let alone in something that is spinning at sometimes nearly 10 times that speed. Its why turbos are balanced to the nth degree, even using tiny blobs of white paint on brand new aftermarket turbos to make sure the compressor wheels are all exactly the right weight.
Bit of an essay and i hope i got it right. Its been a while since i studied this stuff during my motorsport engineering course.
On a side note, in reference to SteveP commenting on the heavily modified cars not running bovs, i think he is reffering to seeing turbo drag cars without them. These days it is quite rare not to see them running a BOV, but some dont just for the fact that it is a big dollar race car that gets fully stipped and rebuilt between meetings, and the damage that occurs to turbos really happens over a long period, so runs down the strip are not going to make a whole lot of difference. You dont generally see a lot of big money street cars not running a bov.
I do really like the discussions on this topic. It is quite interesting with a lot of science backing up both camps. Plus then you have the BOV manufacturers that would love for you to buy one of their aftermarket jobs as well, with all their marketing and spin which goes along with that.
^^ that make sense.
if ur compressor wheel was vibrating, u would have had existing shaft play. turbos shouldnt have any play at all to allow vibration. if u do, u have a much bigger prob than 'flutter'. was ur turbo stock? kms? my stock turbo had a similar prob. when taken apart i found out it was starved of oil (blocked line) and lack of maintenance. also it had done 130,000 kms.
you are somewhat right with the exhaust gasses driving the turbo compressor. but at no point is the compressor air fighting this momentum and forcing the turbo to spin (or try to) the incorrect way. theres always gona be exhaust gasses (unless u quickly shut off ur car, even then the turbo will slowly spool down), so the turbo can never stall. the compressed air simply reverberates out via the turbo when the pressure level drops based on the rpm of the turbo.
to the guys asking why manufactures fit them. emmisions and noise pollution. the general public dont like their cars sounding like a pigeon purring.
i would love to see a 100,000 km test case with a car fitted with a bov vs a car without. run them on the dyno under similar conditions and check the turbos general condition, shaft play and ability to hold boost. but ive never seen any such testing, even by bov manfacturers. hence, no proof of their claims.
you are somewhat right with the exhaust gasses driving the turbo compressor. but at no point is the compressor air fighting this momentum and forcing the turbo to spin (or try to) the incorrect way. theres always gona be exhaust gasses (unless u quickly shut off ur car, even then the turbo will slowly spool down), so the turbo can never stall. the compressed air simply reverberates out via the turbo when the pressure level drops based on the rpm of the turbo.
to the guys asking why manufactures fit them. emmisions and noise pollution. the general public dont like their cars sounding like a pigeon purring.
i would love to see a 100,000 km test case with a car fitted with a bov vs a car without. run them on the dyno under similar conditions and check the turbos general condition, shaft play and ability to hold boost. but ive never seen any such testing, even by bov manfacturers. hence, no proof of their claims.
godzilla
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to the guys asking why manufactures fit them. emmisions and noise pollution
Steve, how would emmisions & noise pollution come into it if there is next to zero venting air?
Steve, how would emmisions & noise pollution come into it if there is next to zero venting air?
if u didnt have a bov u would certainly hear flutter (noise).. and current regulations dislike air coming out of ur intake, which is why atmo bovs are illegal. once it goes in, it should only exist via exhaust with a catalytic converter.
there is actually of lot of air in ur intake system at any one time, and increases depending on boost/compression. ask anyone with a atmo bov.
there is actually of lot of air in ur intake system at any one time, and increases depending on boost/compression. ask anyone with a atmo bov.
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I remember watching veilside being interviewed in japan about their gtr drag car. They said they dont run blow off valves and they said they do have to rebuild turbos damaged by compressor surge because of this
Heres a quote form somewhere ------- """A Blitz blow-off valve is on call to deter compressor surge. Compressor surge is a potentially damaging effect that occurs when the throttle plate is suddenly closed and boost that was on its way into the engine backtracks back into the compressor housing where it impacts the compressor wheel, substantially slowing it or reversing its direction altogether. This wheel reversal can be hard on shafts and bearings. The blow-off valve relieves the pressure by either venting it back to the atmosphere or re-circulating it in the intake tract before it can backtrack.""
Heres a quote form somewhere ------- """A Blitz blow-off valve is on call to deter compressor surge. Compressor surge is a potentially damaging effect that occurs when the throttle plate is suddenly closed and boost that was on its way into the engine backtracks back into the compressor housing where it impacts the compressor wheel, substantially slowing it or reversing its direction altogether. This wheel reversal can be hard on shafts and bearings. The blow-off valve relieves the pressure by either venting it back to the atmosphere or re-circulating it in the intake tract before it can backtrack.""
godzilla
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i thought we had already gotten past this point
oh and if they had to rebuild their turbos.. purely due to compression surge, i mean running 42psi and other factors on a drag car has no impact on the life span of a turbo whatsoever, why dont they run one.
all drag cars get stripped down and rebuilt after a few runs
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