The Truth About Compressor Surge

[@alip6366]

Finally someone who actually understands how this works. Thank you CT.

[@mrmidnight32]

ali p how does he understand it? He just explained it’s ok. He showed no examples or reasoning as to why. Having 20+ years in machine and car shops and understanding tolerances and bearings back pressure under load or not is still pressure. Which is going to put force on the bearings which will wear one direction more than another. This wearing the bearings to premature failure. The whole it wears under WOT but not when it’s no makes no sense. Either way it’s back pressure on the turbine and bearings. So either it does or doesn’t at all.

[@DanSlotea]

Manufacturers understand better. And they put valves to protect from surge. Thank you manufacturers.

[@renners9636]

Dan Slotea not true, they are mainly in place to prevent the noise and due to they fact that many standard hot wire/thin film air flow meters could not measure the direction of air flow, and as surge when surge occurred the air flow meter incorrectly measured more air than was being consumed by the engine, causing a temporarily rich tune and emissions problems. The Anti surge was just a happy coincidence, many early turbo cars of the 80s had no bov.

[@NoGrip]

@@renners9636 Many 80s cars also had Brown interiors, solid rear axles and were absolutely terrible. It doesn't make them correct. Also that was like 37 years ago, technology changes. Look at Borg Warner.

[@renners9636]

No Grip can you be more specific in your argument against me? My statement was very simple and only covered one aspect, that the main reason cars were initially fitted with blow off valves was not to protect against *damage* from compressor surge itself but to stop incorrect fuel readings under surge conditions and to stop annoying noises that most drivers would not expect from a normal car. I made absolutely no claim of anything being better, the implication of me mentioning some 80s gasoline cars not having blow off valves was to validate the 100s of thousands of turbochargers that have lived and live without being destroyed by compressor surge, I never advocated it as correct, but simply noted in the case of many oem cars that it is was a design that did not doom the turbocharger to early mechanical failure. Manufacturers are more worried about possible emissions and noise issues than a few turbos failing sometime after warranty is up. Maybe turbos running 30+psi are more susceptible to wear I couldn’t say.

[@BenFlipsCars]

So without a blow out valve, the car will laugh. With the blowout valve, the car will sneeze??

[@koko61336]

fuck this comment i love it

[@moodyf2966]

I like it when it laughs

[@starkz3965]

I wil remember this comment for a long time

[@MahilalPeiris]

Hahaha dude

[@gasperbucinel]

Yes.

[@moeezahmedshahaab]

Thank you so much for this, please do keep making these types of videos where you explain common misconceptions. Superb guys

[@JamesRussoMillas]

Wow! So like half of us thought flutter was just a fancy sounding blow-off valve haha.

[@nate1491]

James Russo that’s what has made me so pissed! All these “tuner” 600whp subies talking bout “it’s a BOV”

[@e34boat88]

maybe 10% its clearly not bov. BUT some of the turbo cars that makes flutter noises does have bov but it only realeases part of the boost so the sound is kinda mixed

[@midniteclub1654]

some people wind there blow off valves up tightly so it surges on low boost and opens the blow off valve on high boost

[@GlassTopRX7]

Yep my car flutters when I roll off in normal driving and chirps when I'm getting into it. Just depend on much boost there is before lifting.

[@TheCarBro]

GlassTopRX7 how tight is your bov set?

[@jrbuch]

Been running no BOV on my single turbo 1JZ for near on 3 years now. Makes 20+psi on e85 reliably all day every day without issue. Why fix something if it isn't broken?!

[@jarhead1145]

You'll be fixing it a lot sooner than someone with a BOV.

[@e34boat88]

Archer old turbo buicks with blow thru system didnt have bovs and you can still find perfectly working ones with the same old turbo. so after 25+ years and thousands of miles and still no broken turbo...

[@jarrusjenkins]

Also to note, WRC cars don't use BOVs either because (believe it or not) they slow the impeller speed down more than without one causing more lag ;)

[@assi2assi]

as far as i know the bmw m6 GT3 don´t use a bov either and you can hear the flutter when they let off the gas ^^

[@I-didnt-ask-you]

andrenegwer says the guy parroting what he saw in a video from a very respectable, but less experienced member of the community. They are much more experienced experts who will tell you the opposite. What he covers is is mostly true but you still cause premature wear without a valve regardless.

[@ErwinSchrodinger64]

Thanks! I was so worried with my quad turbo charged & dual supercharged Civic Si, with stock internals, would break all my turbos.

[@e34boat88]

ErwinSchrodinger64 i wish this was trye and you had mad vids about it bruh

[@ErwinSchrodinger64]

This is an automatic message to notify anyone that ErwinSchrodinger's quad turbo charged & dual supercharged Civic Si, with stock internals, had so much horsepower and so fast, it became a time machine and he went back in time.

[@e34boat88]

ErwinSchrodinger64 all that was possible due not using bov

[@DhirC35]

🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣

[@DoktrDub]

A civic can handle 1000 hp on stock internals easily, fax

[@waifuracer6516]

I actually like the flutter sound much more than the blow off one. It just sounds more epic :)

[@Kj16V]

Car Throttle THANK YOU!! At fucking last somebody got it right!! Seriously: Utmost respect to you for actually RESEARCHING this subject and not just repeating what every forum / back of BOV box said.

[@TheK18]

I get the best of both worlds with the Tial Q on my ms3. Spring in it is a -12 psi spring, and the vacuum in the intake manifold takes about a quarter to a half second to go from positive boost to -12 vacuum, and therefore it takes that long before the valve opens after boost. I get this lovely "stutu-schhhhh" noise from it and I absolutely cannot wait until I have a Garrett GTX2867R gen II on it and can hear the noise a 9 blade compressor makes vs the k04 6 blade.

[@quinnjohn1]

If you're running the correct sized turbo, intercooler and piping for your setup, a BoV isn't necessary, the only thing a BoV MIGHT, and I stress the might, help with is eliminating lag (if you even have any) between gear changes as the turbine of the turbo won't slow down as much with the surge of pressure when the throttle blade is closed. As for the increased wear on the turbo when not using a BoV, for every study I've seen saying that it wears the turbo quicker, there's another that says it won't! :/ From my own experience, the only benefit I've noticed from a BoV has been reducing lag between gear changes. I put something like 15000 miles on a mk3 Supra 2.8 single turbo I built back in 1999 without a BoV then after some advice from a mk4 Supra owner, I fitted a BoV and it did help to eliminate the lag I was getting between gear changes. I ran the car for 2 years after that (must've been at least another 20000 miles) without any noticable signs of wear on the turbo, I sold the car to a friend who ran it just over a year before smashing it and one of the few things that was ok to salvage was the turbo!

[@DoktrDub]

Yeah, hear changes and when you close the throttle before reopening, I have noticed slight differences in lag reduction with a well placed BOV, as for longevity... I don’t think it’s that dramatic of a difference with our without as long as your system in balanced like you said

[@turbopanda7012]

yes

[@BigTurboLos]

good fix for this is flat foot shifting 😂

[@theposerhoser]

I'm under the impression you're mistaking the purpose of a blowoff valve and a wastegate. The boost control solenoid in conjunction with the wastegate and recirculation valve is what should maintain boost pressure between shifts, a blow off valve in theory is only there to blow off air pressure when you come off throttle

[@amorag59]

@@theposerhoser No he's correct. A wastegate is only there to prevent overspeeding of the turbo. A recirculation valve has a very similar job as a bov, a bov vents to atmosphere and a recirculation valve vents back to the inlet of the turbo. Not sure why you added the wastegate to the mix.

[@mikey_gc8]

That R33 at the end was purely demonic

[@KiNG-fr5ib]

agreed

[@stoteliusiaubas9653]

Wait so thath means we can have sututututu ?

[@Villyum]

Stoteliu Siaubas that’s what I’m hearing.. throwing out BOV now..

[@sbr7018]

BRAABABABA STUTUTUTUTU

[@TennesseeBass849]

Been saying this for years and no one would believe me

[@randiey95]

only low boost

[@TheShamRockii]

@@randiey95 define low boost because im thinking if 15 psi qualifies🤔

[@ozzy1280]

Hands down the clearest explanation for this. Thanks guys.

[@pablosanty509]

Thanks for making this video because people that never owned a turbo car comment and try to act li,e they know their shit.

[@garren3498]

my first turbo car was a -99 saab 93 2.0t and i tuned it from 150 to 270 without a bov, and its still fine and it has 320000 km on the clock!

[@raivis923]

@@garren3498 hows ur saab holding lol

[@Brennonicolini]

Could you do a video about blower idle surge? I never fully understood the concept behind it. Thanks!

[@g__wizz]

same concept. to much air is being pumpd, vs what is being used.

[@captainzoll3303]

of course there's a VL commodore...

[@fazzer3519]

why wouldn't there be?

[@Kj16V]

aka. Dose Mobile :D

[@7X1..]

Up the Vl and Rb30.

[@Deluxe556]

haha love my vl and I was surprised it made it into what I assume is an american made video but almost all turbo vls are bound to be flutter machines. Mines soon to join the turbo charged crew ;)

[@noahv1916]

VL most over rated car in Australia pisses me off but I love the rb but just so over rated compared to batta

[@troy_rx7939]

Had my own turbo spin the nut off the compressor due to closed throttle surge and seen others do it too. It is all good if your turbo runs a left hand threaded shaft but the ones i have seen undo are right hand threaded. The turbines inertia due to weight is greater than the compressor wheel so it tends to back off the nut on the compressor wheel when there is a differential of forces applied. Cheers.

[@S.ASmith]

knock off garrett and BW moment

[@strider5119]

Got proof that it was specifically compressor surge that caused that? Cause I have never heard of that happening, ever lol

[@Boaters_hub]

Pushing 24psi no bov/dv for atleast 6 months daily driven. No issues yet. It makes sense that the free spinning turbo can chop the air with reverse pressure with minimal wear to the bearings/shaft because of its free spinning state.( whatever exhaust flow from the engine while shifting wouldnt be nearly the pressure returning through the intercooler) I don’t understand why so many others preach its pre detonation of the turbo?

[@markoz673bajen8]

UK:CarThrottle = USA: DonutMedia Bitvh who do you love?

[@faisal3398]

Who you calling a bitch?! bitch

[@benjaminofuasia9236]

LMFAO the yg reference is great

[@bonk1049]

Both

[@SirVr6rio]

it's obvious that anyone who says that hasn't driven or even heard a turbo car IRL.. good vid man.

[@brianhoefer7148]

As a Machinist/Welder/Fabricator/Mechanical Engineer, in 2004 or there about's, I got to work on a diesel semi-tractor that was attempting a Bonneville world speed record for that class. The diesel engine was turbocharged and producing 75+ psi. The turbo stall was discovered with a high-speed camera aimed at the fan. This wheel was coming to near complete stop and re-spooling. The solution was to add a Roots Blower to the mix to positively insure that the flow from the turbo was moving forward. This semi was geared so tall that it needed another tractor to push it to 75 mph just to get going in first gear.

[@wallcouldtalk]

Well, this is the coolest thing I've read all day. Funny enough a day that someone was trying to tell me how bad compressor surge is, which is why KZbin suggested this video to me. Do you happen to remember who or what company that was? It wasn't Cat with the race C10, was it?

[@brianhoefer7148]

@@wallcouldtalk Search KZbin for "Ye Old Dragon".

[@DriftNick]

How was the turbo coming to a near complete stop?

[@strider5119]

Got a link to a video of that? cause it sounds bullshit to me. Turbos spins at tens of thousands of rpms, it's not going to stall and come anywhere near a complete stop in between gears. That's an outrageous claim

[@conradsealy9603]

I could be wrong but having a bov does make for much quicker boost response if you are going to be on and off the throttle frequently as in road racing,time attack,off road rallying and auto cross.

[@getbent876]

I had seen some comments about that and I never did understand how it could spin the compressor backwards, turbochargers are essentially non-postive displacement pumps and a fluid pushed backwards through one would be extremely inefficient at causing any movement of the compressor wheel.

[@atranas6018]

Does it means if no blow off valve in the system there will be more turbo lag because the turbine had slowed down so much when throttle valve closed?

[@jockobo]

Anas Takiyudin it's really not that bad at all

[@arekb5951]

I'd say it depends. If you're letting off the throttle for a brief moment (like changing gear) residual pressure that haven't gotten out through the turbo yet will help to build the target pressure faster, but if you let off and leave it for a longer time (so the pressure can completely escape), then yes, rotor will take more time to spool up. Nevertheless, in both cases, the differences are barely noticeable.

[@MV60]

Surge is better for response as the intercooler still has a charge in it that it otherwise has not dumped all out through a bov.

[@MV60]

Lag is actually the time it takes for the pressurised air from the turbo to make it to the manifold. A top mount will have less lag than a front mount typically.

[@MV60]

Ok, the hot side is the turbine, the cold side is the compressor. They spin at the same time being linked with a solid shaft. Ok moving on, what you're probably trying to describe is boost threshold where there is enough exhaust gas to spin the turbo to the point it produces positive pressure. Turbo lag as I said above is what happens above that boost threshold.

[@henrysage1838]

You’ve just convinced me to put a cover plate on my blow off valve. Congrats.

[@v8trauma]

Already knew, but it's nice to see someone else who doesn't believe the forum ninjas. For everyone who isn't sure ; Blow off and recirc valves only help stop compressor stall on over run/closed throttle. Usually vacuum operated, though I did see a rather complex electric set up that was supposed to keep it spooling longer. The best way to do that is antilag, but that's the easiest way to shorten the life of any turbo, but so much fun.

[@streeatbeat]

Its scary to me that people don't actually get this as it's the most BASIC understanding of how a turbo works. Think about that for a while. these are the same people that yell ''RICER'' if you made a modification they don't approve of.

[@grantts7]

StreatBeatsAudio Subwoofers basically people who call themselves car guys but have no clue at all

[@bestleesinna7702]

It sounds to me like you're just band-wagoning, because you aren't really providing reasoning behind your argument. You're simply persecuting. Compressor surge fundamentals are not the most basic understanding of how a turbo works. That's usually stage 2 or stage 3 in understanding a turbine's mechanics. An inexperienced person who has just finished their build wouldn't likely be aware that their blow-off valve serves purpose outside of alleviating pressure in charge pipes and intercooler piping/intercooler. If they heard open throttle compressor surge for the first time, they might just assume it's cool turbo noises and functioning as normal. Once they've blown the seals and bearings out of the turbo, then it might be something they learn. Also, some of your statements don't even correlate. You're a bit all over the place, which is what leads me to the conclusion that you're simply here to make others feel bad to make yourself feel better about your own ignorance. I'm not attacking you, but I would ask that you not attack others. If you think you have such a complete grasp on turbo-charging, perhaps you should do some research into intake harmonics and then come back and comment. You still have a lot to learn as well. Everyone starts somewhere. Learning is a process. I've spent years of my life building turbo'd cars and still learn things every day through trial and error, other people providing me information and tips, and research and equations. If you assume compressor surge is a fundamental pillar in understanding turbo-chargers, you've never seen a 16 year old driving a boosted Civic with no blow-off valve, no intercooler, no waste-gate, and no BCM or piggy-back. Turbo-charging is more complex than you are for probably prepared.

[@NoGrip]

@@bestleesinna7702 lol

[@the_modfied_car4903]

@@bestleesinna7702 turbo flutter does not wear the turbo out due to simple fluid dynamic laws

[@bestleesinna7702]

@@the_modfied_car4903 do you understand how bearings, friction, impact and directional force work? Cause what you said makes me think you don't. Turbo flutter is puts force on the fins in one direction, abruptly ceases that energy, which causes secondary forces to commence. This is a back and forth motion that wears down bearings and shafts. A smoother change in pressure results in less violent motion and reduced wear. You don't know what you're talking about. Fluid dynamics are all fine and dandy in theory but mechanical elements are your point of wear. Anything that moves, wears. You combine the immense heat and rpm a turbo operates at and you get accelerated wear. Not to mention the difference between double-sleeve, sleeve-bearing, and dual-ball-bearing turbos. Turbo flutter causes wear. Arguing against that isn't ignorance now, because you should know better. Arguing against it is stupidity because you're arguing against physics. This kind of wear is demonstrated by the price-hike of dual-ball-bearing turbos despite them being cheaper to manufacture than other varieties. It's because those forces don't wear them AS much, but still do. I just...I can't even talk to you right now. If you don't know something, ask. But don't try to teach people incorrectly.

[@crazyworld6832]

Great explanation. So now if I take off my stock bov on my stock 1.4 tsi I will not have any problems? I love the stututu sound

[@ngt84]

There can be surge with wide open throttle as well.... If you mismatch the compressor wheel with the engine flow demand. Its not the air that is trapped. Its the compressors wing stall that makes the fluttering noise. You can also have surge in airplane engines as well and it vibrates in similar fashion.

[@AimUser13]

Honestly, thank you so much CarThrottle.

[@aimless-drifter]

Ran no BOV on 240sx KA-T it felt like a better turbo response not to have a BOV, because when I'm off throttle the would turbo flutter for around 2 second. So I guess for those 2 sec, it's like I have reservoir of boost ready to use. So If I opened the throttle within 2 seconds after closing the throttle the boost would just shoot back up to the boost limit almost instantly.

[@xFlow777]

so basically it will not damage your turbo but it will reduce performance since every time you slow down turbo on gear shift it will have to build up boost again when you open the throttle

[@DaytonaRoadster]

thats why WRX recycle the air, so they dont have to wait again

[@billymanilli]

@@DaytonaRoadster That's not the reason why... The length of the intake pipe is so absolutely negligible compared to the mass of air coming into that engine, not even superman would notice a difference between a BPV or BOV "response time" ... Two main reason that I can think of atm is that, most people who buy a new vehicle want it to be quiet. Believe it or not, not everyone with a turbocharged vehicle (there are TONS of them out there if you think about it ), wants to hear "PSSSSSHHHHHH!!!" every time they let off the gas. However, an even more important reason is this: If the vehicle has a MAF sensor setup (which most newer cars do), and you install a BOV, it's going to cause a huge unmetered air leak every time the valve is open, which can make the engine sputter, stall, throw a CEL, etc...

[@strider5119]

If you take ages to shift gear, maybe. Otherwise, no. The difference between bov and not having one is minimal. Flutter happens because there is compressed air between the turbo and throttlebody and it escapes. BOV's vent when the air between those same points reaches the amount its set to and will flutter for the rest anyway. You just don't really hear it at that point.

[@acundiff21]

This finally answerd my questions. Thanks guys. Subscribed.

[@OliverFetter]

So how do you correct open throttle surge (ie turbo is too spooled for motor at a lower rpm)?? It's not to fix the turbo lol you definitely need a valve somewhere to correct it 🤔

[@andrewtaylor2237]

thank you so much, now my question is, does the bigger the turbo mean more flutter or does it matter?

[@johnmar1622]

thanks CT that cleared my confusion. Now I can have highest settings during acceleration with no flutter , but only after you lift the throttle-closed.

[@guigui70051]

2:37 the subtitles say "Music" when there is the BOV sound 😂

[@olivergodfrey2159]

Guten Tschüss my favorite genre of music😂😂

[@yuki_is3007]

They are not wrong

[@JoeOnMarz]

So the flutter isn’t bad for the turbo as long as it only happens off throttle??

[@produKtNZ]

The first problem I see with this video is while yes, you're right in your explanation dispelling this myth - but "Oh you're wrong because 'Car Throttle Extra' said so" is most likely not going to cut it. Maybe you could cite your sources behind the logic explained in this video?

[@tieganklock9672]

So my 2014 Audi A4 2.0T Quattro does what sounds like an open throttle surge. I do have a cold air intake so it can be heard very clearly under heavy load. What do I have to do to fix this?

[@skerlone]

Surge is a limitation of any centrifugal compressor in that it can't raise the pressure without a minimum flow. When you put a big compressor on a small turbine that runs on a small engine it's likely to get surge when starting to make boost at low rpms

[@strider5119]

Old comment, but that's open throttle compressor surge.

[@skerlone]

@@strider5119 Any centrifugal compressor has a surge line on the compressor map. That is an area of the map that shows the lower limit of air flow and higher limit of pressure at that low air flow. Any modern turbo engine doesn't get in that area of the map because the right turbo choice.

[@zachogdahl210]

Yessss finally. I argued with people all the time about this, glad someone finally makes a detailed video explaining the differences.

[@stuartsheppard321]

so without a BOV is okay like on a 2JZ-GTE like on a supra without it okay if I throttle and I don't hear it when I throttle and when I do it bad is that correct

[@strider5119]

if you hear it while accelerating it's bad. If you hear it when you lift your foot off, its fine

[@alan350z8]

So if it’s installed correctly, do you still need a blow off valve? Because if you have a blow off valve you won’t get the closed throttle flutter, correct?

[@codycall6513]

So how do you stop a turbo from open throttle turbo surge? Why do people use BOV’s? Does the waste gate have anything to do with it?

[@strider5119]

Make sure the turbo is sized correctly for the engine and don't run more boost than it can make use of. Bov's just help vent air when you let off throttle, I assume it's mostly to do with noise pollution. Wastegate has nothing to do with it

[@LondonsFinest09]

Wait.. so if it flutters straight after you take your foot off the accelerator it doesn’t harm your turbo? I’ve been searching for a video and this is the closest that’s made any sense

[@BradlehDadleh]

So the take-away from this video then, is that turbo flutter is ok, and doesn't hurt the lifespan or longevity of the turbo? Cuz if thats the case, I'm buying a BPV for my WRX haha

[@breakingdecks1899]

EGC_Warlock im also looking for that answer

[@drrrrockzo]

Can you not setup a blow off valve so that it opens at a set boost pressure much like a waste gate? Then you could have the blow off valve venting excess air volume at WOT, which should stop the surge. I'm not familiar enough with turbos to have encountered this issue, so please enlighten me.

[@STINKYPOOPOO42069]

Not sure if you are still curious, but if you install a flow control valve you can adjust it to where it becomes a delayed blow off, gives you the turbo flutter we love and then relieves pressure. It's cool to play around with and you can adjust it as you would an aftermarket bov, AND you are able to do it on a stock BOV

[@cibuliux]

I got question. Like most diesel cars atleast one i own (VW golf mk4) doesnt have Blow off valve from factory. But it does not damage the turbo?

[@Nebbia_affaraccimiei]

Lukas Juozaitis. Let me know when you see the throttle closing on a diesel

[@cibuliux]

Nebbia affaraccimiei ohhh really ;D sorry 😂 my bad

[@lazarjanjusevic3]

Nebbia affaraccimiei but is it somehow possible to get this "compression surge" sound from a turbo diesel?

[@cibuliux]

Lazar Janjusevic well i never heard it and i highly doubt that it possible

[@lazarjanjusevic3]

Lukas Juozaitis. It's possible but i don't know how... Search on yt for 1.9tdi surge or turbo diesel surge and it sounds exactly like this

[@gannonb99]

Open throttle compresser surge, couldn't that also be called boost creep, or is that only related to not having a big enough BOV

[@sparkhype1652]

Thnx for the clarity, but what about diesels w/o a throttlebody?

[@EscoBoosted]

So prevent open throttle compressor stututu you put on a big wastegate right ?

[@shenlongthetiger9524]

So i got a question, sorry about my bad english. I installed a closed air BOV that means the air is going back to system/turbo. My car does that stutututu and it's really really good! The question is im destroying my turbo like that?

[@strider5119]

no

[@MrTorchboss]

I’d assume since diesels have no throttle plate and run via metered fuel injection. Cutting the fuel would be of similar effect for it since there’s no combustion for drive pressure to drive the turbo?

[@billymanilli]

yep, pretty much!

[@connorsault3178]

can someone pls explain to me surge on turbo diesels, since there's no throttle plate usually, what would cause the surge? letting off throttle, less fuel going into engine, engine doesn't need as much air, air being thrown back towards compressor = surge? Someone enlighten me i'm confused lol, looking online has only made me much more confused.

[@kiel7302]

I have a recirculating valve. do i need to replace them with bov?

[@lloydy___8720]

2:13 - 2:19 Surely if the BOV is set to 20 psi and the turbo is making 21psi at wide open Throttle, surely the BOV will open unless it’s computer run and the BOV opens at close throttle Help!

[@Sean_Cockrell]

You are thinking about the waste gate, now that is on the exhaust side not the intake side. The BOV has a vacuum line that connects to the intake manifold somewhere after the throttle body, this is how it opens to dump excess air when you back off the throttle. As the throttle body closes a vacuum (Between the engine and throttle body) causes the valve to pull open and dump excess pressure or recirculate it (Between the Turbo and throttle body). The BOV should not be opening under boost. The waste gate will bypass the turbo (exhaust manifold to downpipe) and this will drop boost pressure, can be set statically or computer controlled

[@lloydy___8720]

Sean Cockrell Thanks, I knew about the wastegate exhaust side but I thought that the BOV was set to a certain psi too but now I know it’s the intake manifold vacuum. Cheers bud

[@mezzosplash]

Lloydy___ I have a mk4 golf 1.8t which makes fluttering noises under full throttle, it has been chipped a few years ago and now that i have watched this vid I'm becoming a bit worried. Should I undo the chipping or make the bov open later? Please help ;_;

[@danr8194]

@@mezzosplash change your diverter valve, diaphragm splits internally.RS6 710P or 710N version are the best.

[@hassanmirza395]

so If i install a DV+ blow off on my focus st and make the bov spring tighter I can have turbo flutter sound and have no issues with the turbo what so ever?

[@madar9467]

My GTI with K04 started to make this close throttle flutter after stage 1 (300hp 440Nm) , first thought that it's DV, changed but still same sound..

[@tamer27antepli]

If ur having open throttle surge can’t you just install a valve that opens when this happens in order to keep the pressure from getting to high?

[@grantts7]

tamer ursavas it’s called a waste gate

[@tamer27antepli]

Grant i tought the waste gate was only for closed throttle surge

[@grantts7]

tamer ursavas a waste gate basically limits how much the turbo spools by dumping excessive exhaust gas. If you have open throttle surge this is because the turbo is spinning too fast / producing more air than the engine can use. To stop this you get a correctly sized waste gate that can dump the excessive exhaust gas and keep the turbo spinning at its correct speed. I hope this makes sense

[@tamer27antepli]

Grant isn’t it better to dump the compressed air instead of the exhaust?

[@NoName-oj5km]

so the surge actually (very slightly) lenghtens the lifespan of the turbo by slowing the turbine down?

[@terrellwilson4508]

Hey! I have a question. I’m new to the car scene, like brand new and I need help knowing the difference between a radiator, and a intercooler and what the pros and cons of each are.

[@DoktrDub]

I’m guessing you figured it out since this comment is 2 years old? As in that a radiator and intercooler are for two different systems, intercooler cools air from the turbo for the engine, radiator cools coolant/water, for general engine cooling, I said cooling so many times just now lol

[@strider5119]

LOL. please tell me you figured this one out?

[@fulano787]

Compressor surge is compressor surge. It doesn’t make it any less damaging that the throttle is open or not. It’s still trying to push air freely that it can’t. This causes faster bearing wear because the off centering torque and vibrations.

[@strider5119]

LOL. One is definitely more damaging than the other. Closed throttle is simply air between the turbo and throttlebody escaping back out the turbo. Open throttle compressor surge is doing the same thing, but while the throttle body is open. Meaning you're trying to force more air into an engine that can't make use of it, likely because the turbo size is mismatched. Open throttle compressor surge is definitely an issue.

[@fulano787]

@@strider5119 you’re saying “open throttle is an issue” like closed throttle is not an issue lmao. It has nothing to do with mismatched turbo size and everything to do with wastegate settings and control on open throttle while closed throttle has nothing to do with wastegates and everything to do with the use and settings of dump/ blow off valves. Remember, we’re talking about compressor surge here. The max turbo spool is controlled by the wastegate while the release of pressure after the compressor is released by a BOV, Recirc, Diverter or Dump Valve (different names and routing but solving the same issue) during throttle closure. What I believe you’re talking about and getting confused about is over boosting. Compressor surge is from the speed of the blades being too high for the amount of airflow at the time which in turn makes the blades lose “grip” on the air. This causes damaging vibrations and faster bearing wear by off centering… well, I already explained that.

[@Mr.Wongburger]

​@@fulano787 there is a difference. Open throttle the turbo is actively trying to make more boost. High boost pressure hitting high boost pressure trying to escape through the compressor puts massive strain on the thrust bearing. Closed throttle the turbo is idling, there is a pressure difference from the compressor that is lower than the pressure coming back at it.

[@fulano787]

@@Mr.Wongburger yes, compressor surge is different. No, it does not happen at idle.

[@Mr.Wongburger]

@@fulano787 As long as you understand that during open throttle compressor surge, you are trying to stuff more air into the engine than it can take. That is bad compressor surge and is what damages the turbo. High boost trying to push against a wall. Closed throttle means the engine is no longer making boost, so the turbo is no longer pushing, the boost it was making can not be higher. This means that the air escaping is lower than what the turbo makes which is okay because turbos are designed to handle specific boost pressures. Normal boost pushing against vacuum.

[@StatusQuo209]

Ive been running my Big turbo A4 for a few years without a BOV. zero shaft play.

[@travisburgemeister313]

A blow of valve will work at WOT they open at whatever PSI they are calibrated for regardless of throttle position

[@NicsCarChannel]

then how come I lost all my chu chu noises when upgrading to a larger turbo? recirculate blow off valve is also installed before and after the upgrade.

[@Mr.Wongburger]

Heads up for those that run a Maf sensor on the turbo inlet, subaru guys I'm talking to you. Doing this mod will cause problems with your tune. The air moving out of the turbos inlet on closed throttle is being metered and telling the computer it needs more fuel to go into the cylinders on closed throttle.

[@emtrenadordragon595]

So it does not damage your turbo at all?

[@jongordon5048]

Wait but I thought flutter is better the a bov bc it can retain some of the compressed air creating less turbo lag where as the bov removes all of the air leaving with more turbo lag.

[@Shreddylife]

No bov will slow the speed of the turbine between shifting. A bov will cause the turbo to spin higher rpm between shifts helping with lag but you wont really notice a difference enough to feel it imo

[@jl5177]

Soooooo is it as simple as me ordering a bov blanking plate and thats it? Or does one require a tune?

[@ethanpickett8618]

ive heard on smaller and older turbos compressor surge can cause more damage, if i blocked off my recirc valve on my 98 wrx with the stock td04 turbo would it do much damage?

[@matthewlock5833]

Older turbo's are actually less susceptible to damage due to not using ceramics or ball bearings.

[@MidnightMechanic]

Just one question, if the throttle valve is the main culprit for reverse air surge, why do Diesels have blow off valves since they have no throttle body?

[@billymanilli]

While they don't need them, they still help on a diesel to keep the intake air flowing smoothly through the compressor. Although, as you said, there are no TBs on them, the thing that drives the turbocharger is the exhaust volume/heat... so when you stop "pouring on the coals" the turbo doesn't have as much exhaust roaring through it anymore, and that causes the entire engine's flow (VE) to slow down VERY dramatically (which will in turn "fight" against the compressor's high rpm), so they open up a "BOV"/solenoid to allow the turbo to continue freely pumping the air through.

[@rickybobby8224]

How do oem boost control solenoids eleminate the closed throttle surge?

[@TzouPhotography]

Is deleting my Electronic bov will b a problem? Audi a3 tfsi 1.8

[@TrumpsaTerroristChangeMyMind]

Mine doesn’t make a flutter noise but it does sound like it’s clogged cuz when accelerating if the turbo works at 100% it whistles a little sounds clean tho Other time it makes sort of choke noise like chckk and the turbo lands flat on its face usually occurs after 4000 rpm but occasionally at 3100rpm as well the turbos only 98k miles old I do have a P0299 code that goes away after using degreaser for a few days even up to a week! And there’ll be no problems until it clogs back up Could this be an oil intake issue? I really hope so cuz it’s only $25 for the part haha while the turbo could range from 250-700

[@TunerNerd]

There are some BOV with an internal max pressure bypass. Stock Subaru STI BOV does this, at least the older ones opens at about 23 psi. For those wishing to run higher boost on stock BPV, they modify this safety check and boost higher. Not sure how it helps with surge though,

[@Bennyjet89]

Learn something new everyday when you’re willing

[@SMBBM92]

I've had a ghetto blanking plate on my WRX Wagon's stock recirculation valve for over 5 years and 40,000 miles with no issues. If you want flutter then I highly recommend it. Every genuine expert I've spoken to had said it's not going to cause any harm. Especially in a stock turbo that doesn't run particularity high boost. 👍

[@Georgealfa21]

I think it depends on the tuning set up if a blow off valve is necessary. In my car i had the recirculation factory valve . It makes a chousss sound. Lately there's a problem that causes loss of boost and i have to go to my mechanic to solve it. By the way what is ghetto blanking plate?

[@michavanderlinden9764]

What’s the point of a bov then ? If it isn’t harmful

[@kalibnolan]

So I see a lot of Subaru’s that flutter during boost, does that mean it’s bad for them as well?

[@BIGGELATO]

so my intake tube came off my 2015 sonata and the turbo now makes a flutter sound but its not stu tu tu like we hear on supras and shit, its more of a mechanical chop sound :l anyways its on waranty but i wanted to know how to make it stututu not chopchopchop lmao.. :P so any answers help, some say add a adjustable BOV and have the spring tention tight.. any suggestions?

[@curvs4me]

Closed throttle surge still hammers thrust load back and forth. I've never heard Anyone say the wheel can turn backwards, that's crazy. Closed throttle surge is that last exhaust clearing the turbine with the compressor having nowhere to compress. The thrust load of the compressor is applying force towards the center, the turbine is also applying force towards the center. They cancel each other out in normal operation. When the pressure builds high enough in the charge pipe that it has to escape past the compressor it JAMS the whole cartridge towards the compressor side. Jam is the absolute best way to describe it. As soon as the pressure is low enough in the charge pipe it jams back to the center, also immediately exceeding the threshold and jamming the cartridge again. So yes, closed throttle surge shortens the life of the cartridge. Yes, it can also break blades on the compressor wheel although it is not likely in a hot street setup. When the charge pipe hits max pressure in a 3 BAR + system, the load on the wheel is incredible. If you think about the Hellephant 426 with the 3 liter putting it 1000hp to the wheels. It is using a modern high efficiency positive displacement supercharger. It is using somewhere in the neighborhood of 350-400hp to drive the supercharger at peak. Turbos on the same motor at the same boost will make 1370hp give or take. That's how much force is on those little tiny compressor wheels. To be able to heat air up 150-200 degrees flowing 1000cfm is extreme kilowatts of power compressing. As you said, blow off valves aren't designed for open throttle compressor surge. They are specifically designed for pressure discharge in closed throttle. Why make them if it is not necessary? Rhetorical, because smashing thrust load and taking it away 6 or 7 times on a 13mm bearing with 180 kilowatts of force on it is not good for anything. Especially in a manual gearbox car where you are constantly letting off the throttle.

[@Shreddylife]

Been running a closed bov for 6 years now with the same journal bearing turbo and it still has no shaft play what so ever. 😄 Closed throttle turbo flutter is not bad unless its on open throttle and surging like the uploader said

[@Mr.Wongburger]

His explanation is correct. Though it matters how much boost and what the turbo journal bearing setup was designed for. If you are boosting 30 psi on a setup designed for for 15-20 psi, you will definitely shorten the thrust bearings life span. But a bov isn't the perfect solution either. There will always be thrust bearing strain, bov or not. The bov isn't releasing all the pressure fast enough for closed throttle pressures to not affect the thrust bearing. It does minimize it though. Modern turbos are built different. Better materials, billet wheels, better oiling and cooling. I think the people who are giving their own anecdotal experience should give others a better idea on how turbos are handling flutter these days. Only downside I've come across is lag.

[@freddiegarcia3430]

But what if you have a bpv? Wouldn’t be the same if you don’t need any valve on the turbo?

[@strider5119]

bpv is basically the same thing

[@maddog5814]

BRB going to install a heavy ass spring on my N54 Blow-off Valve because I love that flutter sound.

[@Salvnyc_]

What bov you using on your n54?

[@rogamingxd5602]

A guide how to produce that sound from your turbo would be the best !

[@strider5119]

I could explain it to you, it's very easy

[@benjaminkrasznai2282]

@@strider5119 can you explain it to me? Would be helpful!!

[@strider5119]

​@@benjaminkrasznai2282 sorry, only just saw this. You just need to either block or delete your factory bov (or equivalent). Also blocking the vacuum line that goes to the bov. Sometimes you can get away with just blocking the vacuum line, but some bov's will still open with enough pressure. From turbo to filter, you want as much aluminium/stainless as possible, no plastic/factory stuff. You also want as free-flowing of a filter as you can get. Eg an aftermarket upgrade or just a pod filter. The sound will vary depending on the intake and also the volume of the intercooler/piping. Some cars sound shit when they flutter, some sound fantastic.

[@full-send-engineering]

hx on my rb for years now no bov com surge can be elevated with either flat shift enabled on aftermarket eco and or supercharger bypass valve this also bypasses surge at wot :)

[@Mainroad.Manjis101]

I know I’m very late, but does anybody have know where to find the original of the Sliver R33 dosing at the end?

[@rxnova]

so genuinely, BPV and BOV. neither will make sututut, i have a BPV on my 06 wrx and i want the SUTUTU i thought i could only get that with throwing out my BPV for a BOV so am i right in saying that if i take off my BPV (and get a proper tune) it'll not hurt reliability or proformance?

[@strider5119]

You won't really notice the performance difference between having a bov or not. I'd like to see any kind of valid proof that there is a difference.

[@MrHugaKuga]

Great video thanks ... might be worth doing one to explain why BOVs are pointless on turbo diesels ;-)

[@drummonkeystuffuk1875]

Well going on my car engine - it has no throttle plate. and is a deisel turbo, still get some nice flutters though when off thy gas!

[@christianingerson8784]

So as long as it's not fluttering during boost you wont add extra wear to your turbo?

[@strider5119]

Yep. Anyone who tells you otherwise is a lying clown. I have not once heard of a turbo being destroyed by flutter, and I have many friends with 500-600hp turbo cars that have no blow off valve.

[@Dripppz]

Because Bovs are illegal in Australia (mostly) it is unnecessary to run one and the turbo flutter does not mean the turbo is being damaged

[@strider5119]

Atmospheric venting bov's are illegal in Australia. You can have them if they're plumbed in.

[@kenanmaccormack1524]

If you’re getting flutter while driving and not releasing the pedal, you have other issues lol, only time you should have flutter is when you take your foot off the pedal

[@zaneelliott7538]

Ok so we have done this to my sisters 2020 veloster n performance package and I seen that bov block off plates arnt safe for journal bearing turbos but are safe for bearing turbos so Is it safe to do a bov block off plate on journal bearing turbos?

[@xXCODkingProductions]

With some newer cars they have a recirculating blow off valve which the car is tuned for. So id be careful for your application. But no matter the bearing it doesnt matter but a ball bearing turbo will always be better simply because its not relying on oil pressure to stay affloat. Ive been stututing on my journal bearings for 2 years fine

[@Scytha86]

It will not damage the turbo but wear a little bit more over the years im sure. In the end the spool get opposite force, with blow off valve it will spinning only one way for it entire life.

[@driftliketokyo34ftw35]

I like the flutter of the close throttle compressor surge rather than a blow off valve because the search goes STUTUTUTUTUTUTU while the blowoff valve just goes tshhhhhhh.

[@GoldenTurboMedia]

Aren't wastegates installed to prevent open throttle compressor surge?

[@Moore91]

Wastegates only divert exhaust around the turbine to try to maintain a desired amount of boost. If you set that boost too high it will still surge. It's something most of us wont experience. You really only see it on highly modified car running tons of boost.

[@AcheLone]

you need to make sure the intake pipe was secured cause mine does come off after the flutter.....yeah the air seek the weakest way out

[@MotorHeadTech]

My a4 sounds like stustustu when i installed a dv, so is thr sound bad every time i let go of the throttle o ly?

[@jonathangallardo6458]

I have a stock WRX does that mean I can do this?

[@jamiewalker8772]

Ahh praise be to this video. I shall share it far and wide so I don’t have a group of 17 year olds telling me my turbo is about to blow... (yes double entendres intended)