TURBO FLUTTER and BLOW OFF VALVES explained in DETAIL - BOOST SCHOOL #8

[@d4a]

Become a Tuning Pro: hpcdmy.co/dr4a Support the channel by shopping through this link: amzn.to/3RIqU0u Go Fast Bits: gfb.com.au/ GFB TMS Respons: gfb.com.au/products/blow-off-and-diverter-valves/respons-tms/ The BOV from this video: gfb.com.au/products/blow-off-and-diverter-valves/respons-tms/respons-tms-t9033-adjustable-bias-venting-diverter-valve-bov-detail/

[@fastinradfordable]

I would like to know about my Stu tu tu tu is with a diesel with no throttle, and variable turbo

[@callumhaig1624]

@@fastinradfordable same here, have a vw twin seq. turbo with a air snorkel aimed at the driver ;)

[@Stank-b8w]

Listen besides boost school, I say you call it the “School of Spool”

[@d4a]

@@Stank-b8w Good one! Might use that some day. Thanks!

[@Stank-b8w]

@@d4a definitely do!

[@somerandoonline5852]

the man literally got his shirt wet as hell trying to explain throttle position, i tip my hat to u sir, ur commitment to educating others has no limit

[@uwot9021]

it's literally just water on his shirt

[@princesssolace4337]

I thought it was coolant😅

[@stephendent178]

But what or how do I fix it

[@UnnamedThe]

@@princesssolace4337 Water is just human coolant tbh

[@Jax2777]

Honestly, that's what made me sub

[@PRgabo]

I can't believe he actually made a graph of the stututu sound. This guy is a legend!

[@complexeddrummer]

That's a turbo efficiency chart. It's based on rpm, displacement, and boost volume. You use these to properly match a turbo setup with your engine setup to ensure the amount of exhaust pressure your engine will produce, your engine's expected air requirements, and the turbo's ability to push air line up effectively. Most people think "bigger turbo, faster car," but this isn't the case. If you're too far out of the turbo's efficiency curve, you'll starve or overload the block. Watch Donut media's video on boosting the Miata for a good breakdown of using that chart

[@wscap4576]

He's a beast rite

[@frazierl7898]

@@complexeddrummer I didn't know that's how that works but it makes sense

[@jahraizer250]

U don't graph your stu-tu-tu noises? .... novice

[@fuckyougoogleupthearse5725]

@@complexeddrummer he's talking about the chart after that one. The one that had disco stu in it

[@micsub]

It takes a very smart person to explain complex subjects in a simple way for non-familiarized people to understand easily. Thanks once again for such an educative video. I enjoy absolutely each and every one of them !

[@DavisPham-k9l]

Need advice, replaced my stock turbos ( cus they were leaking oil) on my 2015 m4, installed CTS stage 2+ turbos. Runs great with my stage 2 tune that I've been using. I hear the spool loud and clear, pulls hard, but I get this flutter sound especially when going hard in Sports+ mode, almost like in the end of this video. Would a custom tune fix this flutter? Ive seen smoke come out for like 15 seconds..twice in the last 2 months. A quote for custom tune by RK Tunes is going to cost about $1400 minimum.

[@JaketheB3AST]

The amount of information in the video is INSANE. Mad props to you sir. This video needs to go viral so people actually understand what’s going on to clear up the many misconceptions we have in the car community. You’ve gained a subscriber.

[@caffeinatedbean8281]

Your water example was priceless 😂

[@TheMcstevester]

He did it for science 🥲

[@truckingjamaicans5045]

I laughed hard ..

[@peekaboo1575]

All this BOV talk reminds me of a system Ford came up with for their Focus WRC car in the late 90s/early 00s. World Rally Cars have intake restrictors to keep the power down. Ford created a 'tank' at the back of the car which would capture all the air that would otherwise be vented off by the BOV. When the driver was off throttle this tank would be filled up with compressed air, which would be available for the engine once the driver floored it again. Once the FIA found out about it (it took them a few rallys IIRC) they were quick to ban it because in their eyes it negated the purpose of the intake restrictor by allowing more air than what should be available for the engine, even if only for a brief period of time.

[@ihxE.]

Very interesting, thank you for sharing this.

[@dimitriskefalouros1628]

Interesting

[@wscap4576]

O wow ive never herd of that. Thats really cool i might give it a try

[@d4a]

I remember this! It was really cool. Should I make a video about it?

[@frazierl7898]

@@d4a that would be sick. You've earned my sub.

[@jkvdv4447]

Twist the knob until it blows off... Interesting advice.

[@lbarkyl1807]

Pfffx x ddddd

[@crackedemerald4930]

"turning this knob is pure pleasure"

[@Official_Dee5iveTV]

Are we still talking about turbos 🤔👀😂😂

[@lalocura1828]

This comment was the best thing ever. Basically huh?

[@danilo86petrovic]

If every teacher had your approach of explaining things, 1 by 1 chronologically, where would be our limit...?!? Thank you for your effort!!! 🙏🏻🙏🏻🙏🏻

[@waverider5751]

He certainly has a gift for getting complex ideas through to most everyone.

[@markthomas36]

As a longtime mechanic, I would have to say that this is the best presented explanation as to why a bov is needed in a turbo circuit! Well done

[@DriftNick]

But you don't need one.

[@moiseslopez7831]

Well I have a 2013 Mercedes-Benz c250 and it has a turbo and I have a bov, but my mechanic toll me that it caused turbo lag and that was the reason that every time I accelerate it took a few seconds for the car to go.

[@markthomas36]

@@moiseslopez7831 Hi Moises, the problem isn’t the box, it’s the turbo. When you accelerate hard, it takes a few seconds for the turbo to spool up to a high enough speed to provide the boost required for the engine to have the power needed to accelerate. That is the reason for twin turbo engines. They have a very small turbo that speeds up very quickly to eliminate lag, but as they are small they can’t provide high boost pressure needed for high engine revs, do a second much larger turbo is I Also in the system, which provides the boost from the mid to high engine revs. I hope this explains what is happening in your Mercedes.😃

[@moiseslopez7831]

Danm, thanks 🙏 , now I'm sure that I don't need to take out my bov.

[@DriftNick]

@@markthomas36 If you have two turbos and one is bigger than the other it's not a twin turbo...

[@jakebatty530]

Just wanted to say thank you for your videos, I'm a trainee mechanic and have worked at a few different garages and it seems rare to find people who know what they're on about so I haven't learned as much as id liked about cars, and this channel has really helped me understand more about different parts of a car how they work what they do etc Fantastic content thank you

[@ahnafzahid9450]

another informative and entertaining episode of BOOST SCHOOL!!!!....Thanks again bro Saving it to my playlist on Turbos for future use!!!

[@Slaktrax]

These videos of yours are an important reference library for any gear-head. Thank you for your patience and good simple and sober approach to any of the subjects you cover. The humour in your diagrams is appreciated 🙂

[@soukoukou4730]

Stuututuuuu is priceless, that's why I wanted a turbo in the first place 😁

[@relax9086]

I actually have this sound everywhere in go and in my house, my phone ring tone, and in my life! 😂😂😂😂

[@soukoukou4730]

Help me sleep better at night

[@whiskey_icarus]

I noticed my turbo flutters after i installed a larger intake. Brings me endless happiness.

[@bryce1334]

This has got to be my most favorite automotive KZbin Channel. The videos are perfect for someone who is a visual learner. Also this channel goes to show that a video doesn’t need to be flashy and have a huge budget to be an amazing KZbin channel. Perfect Channel keep doing what you do best!

[@JKFab]

While I normally agree with the information you provide, I have to disagree here. “Off throttle” surge or turbo flutter does not cause additional strain on the turbocharger. Since the turbocharger is under its maximum thrust load during use (for example at 20psi) shutting the throttle does NOT increase this, and therefore doesn’t load the thrust components any more than they would be during normal use. This is very different to on throttle surge (when you are actually in the surge zone) which causes huge strain on the thrust components due to being at the working thrust load @ 20psi. This will often snap the turbine shaft clean in half. Having worked in the turbo industry for a few years, I’ve never seen a failure from the lack of a BOV. If you are experiencing on throttle surge, things such as anti-surge housings will allow you to push the surge line further away. I’ve also never noticed a difference between response between bov/no bov on a vehicle, but I run my car without one. Logically, without a bov, less air will need to be re-compressed and thus speeds up response. Although this is just a guess at best :)

[@d4a]

I had another commenter mention this too. I did cover on throttle flutter at the end of the video. What damages the turbo in off throttle surge isn't the thrust load itself. It's the shock loads of the pulsation as the excess pressure exists past the wheel.. It's rapid on-off loading or in-out of the surge zone that's the problem. I had another person say how they never saw damage due to no BOV. I'm pretty sure there are no bov failures out there but the attribution of their source becomes subjective because bearing damage is bearing damage and the same damage can be attributed to multiple different sources. It's true that off throttle flutter is harmless, but that's only when boost is low. This is why some early turbo cars didn't have bovs or recirc valves. But they ran like 7-8psi (0.5bar) of boost. I believe the thinking that bovs are useless may come from this era.Today you have cars that run 1.2-1.5 bar from the factory, and they all have recirc valves. In fact all factory boosted cars today have recirc valves. Looking at it simplistically, if off throttle flutter was really harmless and bovs useless than factory cars would never have them and would happily flutter along. Anti surge housings definitely help but they can't get rid of flutter on high boost applications.

[@JKFab]

@@d4a While I would agree with your assumption, that’s not how it works in the practical world. In all turbos (both JB and BB), theres actually no contact between bearings & shaft during operation, same with the thrust washer & bearing. The so called “shock loading” your talking about would only see an effect if you had a drop on oil pressure or oil contamination, allowing for contact. When exposed to on throttle surge, it doesn’t actually harm the bearings. It can, at most, overwhelm the thrust bearing and cause a failure there. But that’s only the case if the thrust collar & bearings surface area isn’t big enough to cope. The shaft will 99% of times snap before the thrust bearing is overloaded in a surge scenario I run 1.4 bar through my turbo, and have experienced no issue. I have customers who run 1.8-2 bar through their turbos with no bov either. Just because modern manufacturers use recirc valves, doesn’t mean it’s to prevent damage. They were implemented due to noise & emission reduction, not for turbo longetivity. I’m talking from personal experience working in the industry. Maybe I’ve just been extremely lucky with all my applications, but I don’t think that’s the case. Each to their own.

[@LollyLover54]

@@d4a Im not saying this is the definite case. But from factory they dont want loud noises that may concern the customer

[@mbaset]

I have to agree with JK_Fab here. Compressor surge under WOT will kill turbos. There is no need to for me to provide any detail as he explained it well. In saying that driving 4 answers, loving your videos, much love from Australia

[@TzouPhotography]

@@JKFab Hello mate, i wanna ask a question that lays in my head for 2 years now... I have a GOLF VI twincharged 1.4 around 235hp with 1.5 bar... I have a cold air intake installed AFTER the maf sensor.. and a stock bov.. i want that flutter sound so bad and I don't know how to achieve it.. nobody of my friends will help me because my car is the slowest.. I've seen many videos but not for my engine.. One thing i know is that it doesn't matter the size of the turbo because another friend of mine has the Vw up 1.0 stock, and it flutters like a supra. Thing is his car dosent come with a bov from the factory and also his intake filter is installed ON the turbo.. idk im too confused.. should i just unplug my bov? But then i get a funny noise... Or block the bov somehow ? I hope you see this.. and help me

[@mncobivictor4300]

Wonderful explanation, good illustrations. You explained better than most profs, well done

[@daltonrich7658]

I know next to nothing about turbos and this is probably the best video on KZbin for explaining it to a newbie like me! Superb job!

[@QuincyStick]

You're telling me I can't make dope stututu sounds without hurting my turbo? Day ruined.

[@Noahgore17....]

Agreed day ruined 😂

[@Pau11984]

facts I guess I'll be buying turbos for as long as I live and I'm breaking them on purpose oops😅

[@LiteBrite]

Well problem is that he’s wrong and you don’t need a Bov and it doesn’t hurt your turbo. He’s simply selling a part from a company who is sponsoring the video

[@QuincyStick]

@@LiteBrite They definitely increase wear. However, to what extent is highly debatable. I am of the opinion that the amount of additional wear is negligible. Either way, I'm going supercharger, so it doesn't really apply to me either way, haha.

[@MunchPremium]

​@@QuincyStickits worth the money...and I dont mean the blow off valve😉

[@gerardogonzalez3427]

This is literally my favorite video ever. I just started having turbo surge and this definitely helped me understand 100% how a turbo system works. Blessed. Thanks!!

[@Khang-wz2vl]

Thank you for very useful information. Very details. This video is exactly what I'm looking for as a Subaru WRX owner.

[@jdb47games]

I have seen several explanations of this, but yours is the clearest. Thanks.

[@AverageLlama]

But stututu is cool😔

[@matthewfudala7564]

Fr fr

[@AvectusExolir101]

: skull emoji:

[@silence9791]

Stutut if for kids like yourself

[@bolassnowman7429]

Yes but not when I have to buy a new turbo because mine is toast 😢

[@cibimbox9195]

Shorter name of the video would be HAPPINESS EXPLAINED IN DETAIL

[@Oper8or]

This is one of the best explanations of how BOV's work that i've seen. Excellent work!

[@jordonjames84]

When u explained Stututu as bad you blew my freaking mind. This particular video has been my favourite in the series so far

[@user-lj7sr6xg2t]

the way this guy explains such complicated stuff is incredible. 6 year olds could understand this. thank you!

[@mindandbodymuscle5345]

Yes, finally a channel getting to a subject I'm interested in. I will learn much and choose my kit wisely according to the bells and whistles.

[@maxcactus7]

Another outstanding video, D4A! You never fail to make difficult topics easy to understand and interesting and fun to learn about! I hope I can buy you a beer some day.

[@jeremywhittler8591]

On big turbofan engines you can actually see the blade bending under power. So it's flexing but you can't see it on a tiny turbo. All metals have a max bending cycle or fatigue, like bending a coke can tab back and forth until it breaks in half Less bending, extended life . I like these topics great explanations. I was an assistant teacher at NAS Pensicola Aeronautics school. Your explanations are great , good research.

[@AdityaKPutra]

Someone pls give this man a medal, i applaud you sir for making this hard subject easier for us to process 👏👏👏👏👏

[@Maxine97186]

Finally i found a bov that can be installed in a diverter valve car. I can now be happy without damaging my car. This helps so much!!! Thanks!

[@802Garage]

The Stutututu chart may be my favorite graphic yet from this channel, hahaha. Awesome video!

[@d4a]

I was thinking of you when I made it and wondered if you would notice 😂 I'm happy now

[@802Garage]

@@d4a That's awesome. Yes I love it. Post it on Insta so I can share it as a meme!

[@paulesmond793]

Awesome, Awesome video, with precise explanations of how the BOV and turbo system works. Certainly rated among the best I’ve seen and heard over my 25yrs as an automotive tech. Any novice should be very happy indeed😀, ..Saaalute, my friend! Real Talk💪🏾💯

[@driftingbrandonc.6480]

The surge noise is so good. Will never run a BOV. Excellent explanation video.

[@steverabbits]

Your vids are absolute genius. I learn more from 10 minutes watching you than days of study elsewhere. So, so well explained even a fool can understand it.

[@peekaboo1575]

The Group B quattros have the nicest turbo sounds out there, change my mind.

[@ethanrainsford4251]

That inline 5 helps too they sound phenominal

[@thestigv7216]

LANCIA GANG!

[@ethanrainsford4251]

@@thestigv7216 that was so uncontrolable but was so cool think it made somewhere in the realm of 600hp

[@peekaboo1575]

@@ethanrainsford4251 I thought the S4 made roughly 500 horses. It was fast because the twin-charged engine had no turbo-lag, not necessarily because of extra power. From what I know the most powerful Group B prototype was the Sport quattro E2 with somewhere between 550 and 600bhp. Then again I could be wrong.

[@ethanrainsford4251]

@@peekaboo1575 in all fairness they was all rediculous in power figures there most likely wasnt any dyno figures just speculations all we can gather though was they was fucking fast for what they was and they mustve took some massive balls to drive as hard as they were driven

[@MadGoose1440]

8:08 you are actually the best. Can't stop the learnin'! You make my mind into a super sponge that soaks up all this speed knowledge. Great works!

[@evensteven5735]

I'm not really a fan of blowoff valve noises or turbo flutter noises. But I do love Turbo whistle and most new cars you just can't hear much whistle at all. Back in the day, my 1st generation Eclipse had turbo whistle even when it was bone stock. Today's cars, you don't really hear any.

[@xXAsunaxKiritoXx]

You'll hear the High pressure fuel pump more than anything else lmao

[@ChunkyWaterisReal]

Man. I definitely hear mine in my s60 rdesign polestar. No intake work done yet either. Fucker can clean a driveway of leaves lol

[@thesillypig785]

I never understood why people like the flutter sound. A BOV like your showing at 9:35 sounds a million times cooler. I had one a Ford Escort RS Turbo and damn that thing was loud. Even when driving normal it was so loud enough to make people look. Good times!

[@AndrewB23]

That's subjective but I will argue a bov literally just sounds like you popped a tire or have a vacuum leak and flutter actually sounds cool

[@yohan1902]

flutter sounds badass, basic bov noise is boring

[@somerandomcapybara]

At the end of the day everything is subjective, but if you ask me give me whatever both sounds cool

[@haidenthomas6002]

This was genuinely interesting and very easy to understand. Thankyou for the education my good sir!

[@andilemhlongo9744]

from knowing nothing to knowing everything about blow off valves. you the BEST

[@jacopieterse138]

So this is the video that they show to the infants in day care .... No, seriously ... It really is so plain straight forwardly explained by yours truly, that even toddlers will be able to go out and spike dad's or mom's car with a t3 and a dump valve . 👌😎 Well done sir. Great explanation and excellent teaching. I enjoyed it immensely. 😎

[@doctorrusty6494]

THE best explanation of the BOV I have ever seen!!! I think even my dumb cat gets it now, as he was nodding while watching! Good job mate!!! Well done. And yeah, I love the "stu tu tu tu" graph too :D

[@rv6ejguy]

A counterpoint from the real world. I have been turbocharging engines professionally for over 40 years, including many for road racing. Never used a BOV, never had a compressor or bearing failure from surge. No engines from the golden turbo age of IMSA , Trans Am or F1 (mid '80s to mid '90s) used BOVs to my knowledge including ones used for 24 hour races. A lot of shifts in road racing at high boost...

[@inaNis_]

Of course I can’t be sure, but it might be because of the relatively short engine life those cars had compared to a tuner car, which is expected to last longer.

[@rv6ejguy]

@@inaNis_ I owned my 240SX turbo for 19 years, 150,000 miles. No BOV. Never touched the turbo. How long does it take to damage a turbo?

[@inaNis_]

@@rv6ejguy Of course I'm just theorizing here, but it could also have something to do with how much boost pressure you run on a regular basis. If you have a a car which you drive regularly, that runs 40 pounds, it could be beneficial to run a bov or a recirc. It seems like you were perfectly alright with no bov though, so that's great! You got to save money ( :

[@d4a]

The theory is sound. Boost pressure is key and this is why in the video I'm saying "if boost is high enough" a few times. Very early turbo cars didn't have recirc or bov but they ran like 7-8psi (0.5psi). Today every car has a recirc from the factory, because today we see 1-1.5 bar from the factory on some cars. I don't mean to offend anyone but bov or no bov it's hard to believe you did 150k miles with the same turbo on a car that was non-factory turbocharged and likely built to be driven hard. This has nothing to do with engine building skill but it's simply the expected life span of things. Also, a damaged bearing is a damaged bearing and will often look very similar regardless of damage source, which is why source attribution in the end becomes subjective.

[@rv6ejguy]

@@d4a I appreciate the response. I am saying Nissan, Toyota, Ford, Porsche, GM etc. in IMSA and Trans Am never used BOVs on any of their turbo engines including ones running at the Daytona 24 hour events. Many thousands of shifts at boost levels up to 40 psi in some cases. Ditto in F1 turbo engines running even higher boost. My 240SX was tracked and driven hard on the street for 19 years. I drove nothing but cars that I turboed for 30 years on the street and fielded 7 different turbocharged road racing cars winning 5 championships over 13 years. No BOVs and no turbo failures. I have over a million km driving turbo engines and fly a turbocharged aircraft I built now for 18 years. Zero turbocharger failures. This is real world, not theory and just another data point as I said. BOV or recirc valves are often used on OEM installations as you pointed out where they use MAF and would run like crap otherwise. Thank you for your fine videos. Really well done.

[@kashyaplondhe5844]

thank you sir for making video on this topic 99 %of doubt are clear thanks a lot ❤❤❤ love love

[@enpaul16]

Idk why i woke up from a dream and asked myself this question. Im not even a car guy 😂

[@DoesNotGiveAF]

I have tried to explain what WOT and compressor surge is and why theyre both bad in so many comments on youtube, the quality of a given turbo and their ability to handle the abuse, the potential risk to thrust bearings (even fins) and the general life span of the turbo especially with higher pressure applications. It really blows my mind how many people are making videos telling everyone it's not harmful at all and those of us trying to explain what it is and why it's bad are stupid and don't know what were talking about. Thanks for making a straight forward explanation for people, I hope this video gets more views than all the "remove your BOV vaccum line to sound cool like me" crap..

[@DriftNick]

People running 40+ psi with no blow off valve for years without issue vs random idiot on the internet that that probably doesn't own a turbo car and never has, I'm not sure who I should trust.

[@yohan1902]

Just cause yours blows up doesn't means others does. lol

[@strider5119]

Closed throttle compressor surge doesn't harm a turbo. Loads of famous, very high hp cars do not run one.

[@Braapd]

More like: “ How turbo flutter / bov works with Christoph Waltz “ Dig it bro haha

[@Dawid_Balcerzak]

I've installed that sort of BOV to my Audi 1.8 T engine about 2 years ago, happily using it till today, after x times of regulations lol

[@mc1996]

I wasn't expecting a "How to drink water tutorial" in the middle of the video :D

[@KFTunes1]

Best engine tech presentations on the internet - and anywhere else for that matter. Great stuff.

[@LPAtkins]

8:30 I agree in with the reasoning here but the turbo is going to be subjected to far more extreme moments when the exhaust is accelerating the turbine from a stand still, turbo flutter will likely have no measurable impact on life span. Real compressor surge, which is when the exhaust is actively driving the turbo definitely has the capacity to damage the turbo.

[@alientiger21]

was looking for a comment like this. The damage was far more prevalent in older turbos that had weaker components, but now, pretty much any relatively well built turbo is so robust that the thrust bearings and compressors have stress/strain limits much higher than anything flutter can cause (but not necessarily surge while accelerating).

[@bio-engineeredassaultturtl8929]

instantly subscribed to this dude. I went in expecting to have to skip a bunch of boring over explanation or extremely dumbed down stuff. Everytime i thought 'Oh, that makes sense, but what about X?' He went, 'Now, lets talk about X' this video is a masterpiece IMO

[@ltrs1212]

It's decided, I'm naming my son Stu.

[@horaciokanashiro-hv2zn]

Social pressure 😅

[@mlivshiz]

One of the best automotive channels out there. Awesome explanations of how things work. Love it.

[@scottmcqueen3964]

Shortened life span is worth it :D Although how much it actually shortens it is the interesting question, given anecdotally people have been running bovless systems for decades without issues, mainly in lower pressure setups of less than 20psi.

[@Lucas_Shaolin]

As turbo Yoda from the skid factory essentially said what you said, that he only uses BOV's on high boost applications for said engine and turbo combo.

[@09mantlek]

I am so glad I watched this video! Many folk owning H2 motorcycles install blow off valves and a few state the addicting chirping sound gets reduced or disappears. I can now assume this is because the stock return system on the bike doesn't flow as well as after market blow off valves which just vent it to atmosphere. Therefore the pressure is less in the aftermarket system therefore less chirping. The bike also runs no intercooler so I can assume Hot air gets recirculated in the stock system so boost temps rapidly increase from high RPM on and off throttle. Lots of thinking to do now. Hmmmm.

[@MGWilliams]

Great video's I've just been watching a few. A point worthy of note is when you hear compressor surge with closed throttle, the turbine is no longer under load from the exhaust as the flow to the engine has been halted so the turbo is only under load from the trapped air in the charging circuit. Its very unlikely to cause damage to a normal cars turbocharger. If you had a very large turbo like a Garrett T4 is more of a problem. If however you hear surging on acceleration it's going to be a problem, I had that on mid throttle on my subaru as it could not consume the flow rate of the turbo at mid rpm. It lucky can be fixed with mapping. In this scenario the turbo is under opposing forces from turbine to compressor, that will destroy the unit. In almost 20 years of experience I can honestly say regular turbos like T3 TD04 Vf30 etc won't mind flutter, I've never seen one fail solely because of it.

[@Lofi.z34]

Thanks. I was wondering why he was exaggerating how "damaging" the tsutututu surge was and my first thought was how miniscule (or non-existent) of an issue it really is

[@metalisalwaystheanswer8706]

Every scene in Initial D where Ryoske is sipping coffee by a computer...this channel is what should have been on the monitor. Sick video!!

[@d4a]

This is one of the most creative comments I got in a long time

[@josephf6785]

Excellent and concise explanations as always! This series is great!

[@smarterthanyou9090]

Many years ago there was a man who designed a turbo system for F1 race cars. Back then the cars Hal had blow off valves so that as explained in the video the lifespan of the turbo doesn’t get reduced, and also boost is not lost. He thought for a minute that all of that compressed air was getting wasted so he replaced the blow off valve with a chamber. The chamber would connect back to the air intake. When the throttle was closed, excess compressed air would be redirected into the chamber via a one-way check valve. While the throttle is closed, the engine loses power and the turbo charger will slow down. When the throttle is open again, the compressed air from the chamber would enter the intake again and feed the engine which also helped the turbo to spool back up more quickly. With nothing but a check valve, air chamber, and a little bit of pipe, he managed to increase the overall output of the cars. To give you an idea of how well it worked, He won every single race until everyone else started copying his method. It was so effective that they banned it after the first year.

[@jozsefizsak]

Very interesting, but is there any reason to vent any of the air to the atmosphere beyond liking the sound? After an initial interval of enjoyment, I tend to find many car noises annoying so I'd like to know if recirculating all the air is actually the best for performance.

[@TravisFabel]

So there's actual performance difference and theoretical performance difference. First let's go over what we're talking about. A recirculation valve is the same thing as a blow off valve except it recirculates back into the air box. This is what a lot of OEM turbo setups do. It's why you don't hear a big pfffft on stock vehicles. Also, If you're using a metered system where you can't just lose the air, it often recirculates back just past the meter so that it stays in the system. And a blow off valve is exactly like what he showed there. It just blows the excessive pressure to the atmosphere and often has a trumpet/horn shape that allows it to make that woosh noise louder. As to your performance question. Theoretically, you've compressed this air and it's hot and you are throwing it back into the air box. Now yes it's true that the air was compressed and now it's decompressing and therefore lowering and temperature but it's also picked up some heat from the whole system being heat soaked and everything and it will be a couple degrees warmer than it started. But that's it. The difference is extremely small. The only other difference is size. Most recirculation valves are fairly small compared to blow-off valves. If you are doing a large displacement engine, large turbo, etc You need to have a big valve. If you have a undersized recirculation valve you will hear the flutter, lose wheel speed, and still have to refill the pipes. If you're running a smaller engine, you can blow off the extra air, but if you blow too much of it away you have to refill your entire system and you get a slight delay. So sizing is important. Sizing is important for the whole system though so that should be expected... Now there's also the psychological part. It definitely sounds and feels faster when you hear it compared to it being silent. For that reason alone most people doing a build will have it make some noise. You can adjust how it blows off or where it blows off too so that it's not too loud. It doesn't have to be screaming... Although a lot of companies specialize in making it do that.

[@d4a]

I wanted to reply to the comment and explain but you already did that and beyond. Thank you.

[@TravisFabel]

@@d4a I actually started replying to this while watching your video. And you answered half of what I said later in the video so I probably didn't even need to type it. Lol

[@SemtexWarrior]

Turbo flutter that occurs when you lift off the throttle really isn't all that harmful to the turbo. I have driven my car every day for two years with turbo flutter and there has been no problems with it. The reason i felt safe doing so is that one of Swedens best and most experienced engine builders/tuners explained to me and others what is really going on when it flutters. Yes the turbine slows down but all of the forces involved are tapering off and there is no real load on the turbo after you let off on the throttle. The turbo killer is compressor surge at WOT where everything is under a lot of stress and this can actually snap the turbine axle in extreme cases and even if the axle is fine it will still put a lot of abnormal pressure on it's bearings so this should be avoided AT ALL TIMES! So: Foot off pedal -> flutter = OK. Foot on pedal (WOT) -> flutter = you will soon need a new turbo. Someone should really do a proper scientific test on how "ordinary" turbo flutter impacts turbo lifetime so we don't have to rely on he said/she said...

[@d4a]

As I said the in the video "if there's enough boost". The damage from closed throttle surge is strongly boost dependent. In low boost applications it usually won't do any harm, but when boost increases it will definitely shorten the life of the turbo and it's not "ok" 😊. It has been scientifically proven long ago and this is why all modern turbo cars run a recirc. I have discussed this with other commenters in more details below in case you're interested.

[@SemtexWarrior]

@@d4a I said that flutter that occurs after you let off the throttle is ok and it is unless your BOV is way too small or completely incorrectly adjusted. When everything works as intended you will get a hard blow off into atmosphere when you let off the throttle at high boost and it will only flutter at low boost when there is not enough pressure to hold the BOV open. Your turbo will not take any significant harm in this situation. If you get flutter when letting off the throttle at high boost then your BOV is either too small and can't physically handle the amount of air it needs to vent or it is adjusted incorrectly. In this situation something is not working or not setup correctly and damage could occur. So no, it is NOT boost dependent at all. It is dependent on whether the guy putting the engine build together is competent or not.

[@H4zZ4rDGaming1]

You already know my turbo S2000 build is getting the good old NO BOV treatment. I'll smile every time I let off the throttle while cowards hate on me in the distance

[@SteveIrwinsPetStingray]

Good lmao, turbo flutter is a gift sent from the gods and should not be shunned, in any practical application a BOV is not really necessary if your turbo has ball bearings (journal bearing turbos can experience some increased wear when not running a BOV depending on the application) and sure, the flutter may "slow down" the compressor wheel a bit, but the difference compared to using a BOV is negligible if you're looking for the fastest spool-up after throttle release. So in shorter terms, flutter away! Don't pay mind to those who look down on you for enjoying yourself, they don't know what they're talking about :)

[@seanrobinson4798]

Yes, finally someone said it! Flutter away my dudes! No bov for 6 years and zero issues!!!

[@notimportant8120]

Yes, actual compressor surge happens at WOT, not this compressor reversion he is describing in this video

[@gabriels.713]

I bought one of these for my turbo build. TOTALLY worth it. Especially since I can turn off the sound when I want to be extra sleepy

[@Haku-fc9eq]

Wow, this video is amazing. I always wondered how the stututu sound happens, and you explained it so clearly. Keep up the great work. Your videos help me a lot! ;) Thank you!

[@frankp8854]

Best video for learning about turbo problems...

[@hlbcarlito1]

great content keep going miss your long hair ;)

[@d4a]

I don't 🤣

[@henrycervantezzz5566]

I think is legit the best video on KZbin. Incredible dude. You are a genius. Thank you!

[@gazanever6291]

Mannnnnnnn, I appreciate this video coming from a long time car enthusiast "from afar" (always loved the curves, output, brands, prestige; never got into what's under the hood). Really easy to digest explanations/illustrations.

[@greenman7yyy]

Excellent, clear common language explanation. Unprovable!! PERFECT 🙂

[@davepartlow6430]

Very good explanation of what happens with a turbo. The only issue I have is at 11:25, where you incorporate the MAF into the system. Generally the MAF is located in the intake tube just prior to the throttle body, not before the turbo intake. And the BOV would be place on or after the intercooler, but not between the MAF and throttle body.

[@stoneee1234]

From my experience if your intake path isn't too muffled, bypass/recirc valves are quite audible albeit having a slightly different sound and less volume compared to pure blow off. So usually getting a less restrictive aftermarket intake is all it takes to get turbo noises, especially with plastic BPVs which OEMs tend to use, as they tend to be louder than metal ones.

[@peterjohn3180]

Yes pressure flow ratio. That's why they use duel stage blowers prevent compressor stall, this is also why tractor pullers gradually spool up or you get surge at sudden full throttle too. A lot of people think compound turbos are just to reduce lag. I have snapped a turbo shaft with over boost.

[@scipio5490]

That's just too much for words, the company that makes that couldn't say it better them self's . Hats off to you man 🎩

[@lethebuster]

I cant believe ive gone 3 years before i got to see a stutututu graph. Ty my friend.

[@MARthePaintballer]

Legit just installed a bov today and this vid helped with understanding how to 'tune' it. Thank you!

[@steverabbits]

Best explanation I've ever heard! Subbed! 👍🏻👍🏻

[@davekendall9749]

I can teach things very simply and well and don't like people who hide behind the fact they don't know, and try to over complicate things. you however are excellent and clear on your explanation to the smallest detail proof of your experience and passion. Thank you.

[@muntee33]

So glad to FINALLY hear someone state the obvious and important truth of this 'cool' stututu sound. Edit: Def, worth a sub. Now if you can explain 2 more things to these kids I'll be a fan for life. 1) About the importance of choosing the smallest diameter piping necessary for the inlet and the AFTERCOOLER with the lowest volume and pressure drop possible. 2) The importance of maintaining exhaust gas velocity throughout the entire exhaust. Where it slows down when entering a zone with a larger cross section (as a pulse remember) this pressure high pressure wave needs to be encouraged to accelerate again when again entering the following zone with a smaller cross section, it is important that the acceleration is aa soon as possible to resuce the high pressure wave reflecting back 'upstream' and interfering with the exhaust pulse entering the cavity. This is why resonators and baffles must be strategically placed. Anyway, point being.... Again, bigger is not better when you don't have the displacement to be wasteful with. You're exhaust diameter must be adequate for flowing the exhaust gas at a sufficient velocity that the boundary layer has minimal perpendicular pressure but is not too narrow to cause the boundary layer to become to compressed and cause turbulence in the gas flow. How this is done in a small displacement, high strung turbocharged engine is to incrementally decrease the exhaust diameter along its length to match the drop in gas temperature and maintain the gasses velocity, all with the sole aim of maintaining the lowest possible pressure at the turbine wheel by maintaining a optimally high exhaust velocity along its length and not transmit a high pressure wave/s back 'upstream' *The optimal consideration is dependent on the application of course, besides the gay excuse of a motorsport of driving in a straight line with WOT, most people will be more affected by throttle response, lag and spool time. Hence the spool up performance (and minimal lag) will be more important than loosing 3-5% of torque 200rpm earlier towards redline.

[@AkshayKrishnanR]

Regarding 11:54, why not just install that "MAF" stuff on intake manifold *AFTER* the intercooler rather than before the compressor?

[@BOOSTEDDUDE]

This was very helpful. I recently had a Diverter Valve fail on a recent road trip out of state. I was getting the turbo flutter when letting off the throttle on the highway. I continued on my trip because I still had good power and wanted to reach my vacation destination. I was able to drive home about 300 miles with the failed Diverter valve and didn't realize that compressor surge can potentially damage the turbo! I hope I didn't do much internal damage since I changed the Diverter valve as soon as I got home to fix this issue! Since my turbo is good for well over 70hp from where my HP is currently I'm hoping that helps. Either way, it seems fine now and I didn't loose any boost that I could tell when I had this issue on my recent trip.

[@neomustafi5744]

You and Engineering Explained deserve a nobel price for educating us👍👍👍

[@jackryan4313]

No idea how you don't have a mil yet, but I can now say that k was here before a million. You got yourself a new sub. This video was phenomenal

[@alexmarianclinch]

I love this guy, he knows how to explain, even for the dump people like me. I learn so much from his videos. Thank you!🙏

[@bryanebrahimmargolis4969]

Wow I did not even feel the 15min... you have mastered the art of teaching...

[@frankmicho5734]

This is the best explanation i've seen so far 👍

[@JeffReeves]

Amazingly detailed yet comprehensible video on turbo flutter and blow off valves. I'm really enjoying this series! Also thoroughly enjoyed the double entendres

[@neilstephen2282]

This guy is so knowledgeable and explains excellently in laymans terms. Well done on another brilliant video

[@Slantedvids]

This guy calmly made me a Bov/ turbo scholar.

[@madoba8717]

5:35 was actually waiting for this. Thank you!

[@TheOnly1Ever]

Thank you for explaining this properly. I am glad I have stayed with factory set up for now. It seems best to get a new engine management system if wanting to modify the turbo side of things.

[@dreadknot2238]

This video got be by far the best JDM tuner 101 out there for beginner's

[@brzk_]

this was honestly the best explanation i have ever seen

[@McBandit0]

ill just say it. the explantion of turbo flutter damaging the turbo due to compressor surge is only really applicable when your on wot (wide open throttle) when you let off the gas and close the throttle body your no longer increasing the exhaust gases and putting load on the turbo, so compressor surge due to closing the throttle body isnt as bad as people make it out to be as the load is already decreased on the compressor wheel. i know so many people who have ran nothing but block of plates for 10 + years and never damadged a turbo because of it. bpv's will allow you to get back on full boost sooner as it is recirculatig and not just sending to atmosphere like a bov or running a block off plate. just my 2 sense tho. really good video still!

[@d4a]

I responded to similar comments already. As I'm saying in the video "if boost is high enough". Low boost flutter isn't much of an issue, but when boost is higher it definitely strains the turbo.

[@jeremyhare9515]

Probabllyy the coolest sound ever. Basically

[@stefang1087]

I know exactly how those things work, but it makes me relax and catches my attention like I was a little child and you a very good story taller. And this is not just on this video, but on all of them. You are doing an amazing job! 😎👍

[@kristianmeijer929]

I honestly didn’t know jack sh*t about turbos before this. Thank you for helping me understand how they work 🙌🏻 You have my subscription 💪🏻

[@shawnwalsh5430]

You are a smart dude! I grew up working on Detroit engines that were supercharged and twin turbocharged.