The Science Of Boost

By design, reciprocating engines are air pumps. They compress the aspirated air-fuel charge, ignite it, convert this expansion of hot gases into mechanical energy, and then expel the cooler, lower pressure gases. The amount of energy converted is determined by the pressure exerted on its pistons by combustion and the length of its expansion cycle. By increasing how aggressively a given mass of air-fuel charge is compressed, higher combustion pressures are achieved, allowing more energy to be extracted and thus creating more mechanical power output.
ROOTS SUPERCHARGER
In 1859 two brothers Philander Higley Roots and Francis Marion Roots founded The Roots Blower Company in Connersville, Indiana.
Roots superchargers operate by pumping air with a pair of meshing lobes resembling a set of stretched gears. The incoming air is trapped in pockets surrounding the lobes and carried from the intake side to the exhaust of the blower.
TWIN-SCREW SUPERCHARGERS
In 1935, Swedish engineer Alf Lysholm patented a new air pump design as well as a method for its manufacture that improved upon the limitations of Roots blowers. Lysholm had replaced the lobes with screws, creating the rotary-screw compressor.
CENTRIFUGAL SUPERCHARGERS...
INTERCOOLERS
Forcing more air into a cylinder with boost easily creates more power in an engine by increasing the air mass of the intake charge beyond what is possible with natural aspiration. This also inherently pushes volumetric efficiency well beyond 100%
Because forced induction occurs outside of the engine the properties of the air mass can be further enhanced by cooling, by passing the compressed air through a heat-exchange device known as an intercooler.
TURBOCHARGERS
In some extreme cases, it can take as much as ⅓ of the base engine's power to drive the supercharger to produce a net gain in power.
The first turbocharger design was patented in 1905 by Swiss Engineer Alfred Büchi. He had conceptualized a compound radial engine with an exhaust-driven axial flow turbine and compressor mounted on a common shaft.
Turbochargers work by converting the heat and kinetic energy contained within engine exhaust gases, as they leave a cylinder. Radial inflow turbines work on a perpendicular gas flow stream, similar to a water wheel.
This shaft is housed within the center section of a turbocharger known as the center hub rotating assembly. Not only must it contain a bearing system to suspend the shaft spinning at 100,000s of RPMs, but it must also contend with the high temperatures created by exhaust gases.
In automotive applications, the bearing system found in most turbochargers are typically journal bearings or ball bearings. Of the two, journal bearings are more common due to its lower costs and effectiveness. It consists of two types of plain bearings; cylindrical bearings to contain radial loads and a flat thrust bearing to manage thrust loads.
Turbine aspect ratio - This is the ratio of the area of the turbine inlet relative to the distance between the centroid of the inlet and the center of the turbine wheel.
Compressors Trim -This is the relationship between the compressor wheels’ inducer and exducer diameter.
WASTEGATES
In order to prevent safe pressures and speeds from being exceeded, a mechanism called a wastegate is employed. Wastgates work by opening a valve at a predetermined compressor pressure that diverts exhaust gases away from the turbine, limiting its rpm. In its most common form, wastegates are integrated directly into the turbine housing, employing a poppet type valve. The valve is opened by boost pressure pushing a diaphragm against a spring of a predetermined force rating, diverting exhaust gases away from the turbine.
BLOW OFF VALVES
On engines with throttles, such as gasoline engines, a sudden closing of the throttle plate with the turbine spinning at high speed causes a rapid reduction in airflow beyond the surge line of the compressor. A blow-off valve is used to prevent this.
MULTI-CHARGING
Twincharging started to appear in commercial automotive use during the 1980s, with Volkswagen being a major adopter of the technology. In its most common configuration, a supercharger would feed directly into a larger turbocharger.
TWIN-SCROLL TURBOCHARGER
Twin-scroll turbochargers have two exhaust gas inlets that feed two gas nozzles. One directs exhaust gases to the outer edge of the turbine blades, helping the turbocharger to spin faster, reducing lag, while the other directs gases to the inner surfaces of the turbine blades, improving the response of the turbocharger during higher flow conditions.
VARIABLE GEOMETRY
Variable-geometry turbochargers are another example of turbocharger development. They generally work by allowing the effective aspect ratio of the turbocharger’s turbine to be altered as conditions change.
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[@NewMind]

Check out this related video on how oxygen sensors work - kzbin.info/www/bejne/gXqpaYNof5Z2m6c

[@mihaiachim5299]

In your animation the air goes in the wrong direction :). Check the air direction at the same system in the animation made by MAN in the following video :) kzbin.info/www/bejne/rZjCY3iVpZuSjJo

[@ObservationofLimits]

One caveat. Turbochargers don’t generally use engine coolant for temperature stability, but the oil. Turbos get far too hot to use the coolant.

[@ObservationofLimits]

You could also technically setup a complicated twincharged system. With a supercharger that disengages at a certain rpm for low end boost as the turbo kicks in. I’ve seen a number of project builders accomplish this with too much time and money 🤣

[@ObservationofLimits]

Shit I commented too soon. I meant twin charging where the supercharger feeds the engine at low rpm, then a turbo at high rpm. Not *compound* charging where one device runs another.

[@ObservationofLimits]

Also, compound low/high sequential compressors is common in diesels too

[@jnrivers]

This is the most in-depth explanation of forced induction I've ever seen.

[@erik.hansen]

Over complicated is the word you were looking for...

[@linyenchin6773]

Jachin Rivers it is a respectably concise sequential expounding of the flow of cause and effect in relation to engin purpose~evolution. Although posessing an above average attention span(due to covid lockdown) I am average and ignorant person. As such; this meticulous and well polished breakdown is appreciated expounding. It is unfortunate that *Emotional Constipation* distracts most minds into fickle vanity~insecurity that makes them express mama like nonsens ie. Eric Hansen: "Over complicated is the word you are looking for..." He can't even count; over complicated = two word, nit "the word" aka "single word." Pure *Emotional Constipation.*

[@digital1518]

@@linyenchin6773 bruh

[@snookaisahtheotengahrepres5681]

@@linyenchin6773 damn you burned him good and proper.

[@John-pm5qi]

Seriously!!!!!

[@Mastervidcritic]

The animation of the roots supercharger at 5:25 has the air flowing the wrong way.

[@Pow3llMorgan]

Or, well, the rotors rotating in the wrong direction.

[@Mastervidcritic]

The animation of the twin screw compressor is also completely wrong 7:14

[@roboterson]

The impeller in the super charger at 9:10 has its blades facing the wrong way, you can't really tell what way its turning because its animated so quickly but I would assume its also wrong.

[@Trebseig]

Yep: turning in the wrong direction. And the air doesn't go through straight.

[@adamvalt6609]

oh i was so confused... how would the air compress so much to fit in between the rotors

[@steventhehistorian]

25:07 the WRX ejected its foglight cover. That's a +5hp net gain.

[@YISP7]

Minimum^^

[@BruceCarbonLakeriver]

speed holes :D

[@stagehits]

Everyone's nitpicking about the air flowing the wrong way at 5:25, I'm more interested in the guy at 14:34 who is queueing for petrol with his lawnmower.

[@stagehits]

Also, this is a great video! Keep it up!

[@dazaspc]

Fuel Crisis in the 70's. A limited supply of imported oil caused an inadequate supply of petrol for the public. The cars line is so long due to only a limited amount available for each customer, say 3~5 gallons. He is queuing with his mower because you were not allowed to fill a can at all. You were not allowed to fill a mower if it was in your car as that would be your entire entitlement for that car on that day.

[@stagehits]

@@dazaspc Thanks! Makes sense now! I would have just let my lawn grow, but I'm just lazy!

[@danielgeorgianni1687]

How about the lady in the beginning who pulled the nozzle out while it was still pumping.... 🤣

[@PatRiot-]

@@stagehits this was the generation of “both ways through the snow and jungle to get to school” They wanted it more than we do lmao

[@james4wd236]

I've been a mechanic for over 12 years so I know most of the information provided in this video, but I enjoy watching videos like these just to broaden my understanding of the automotive world and you never know you might learn something. This is by far the best visual and in depth accurate video (excluding the one part) I've seen made about a subject surrounding automobiles. Fantastic video 👍

[@2000freefuel]

I'd REALLY like to see a setup using three turbochargers in a series compounding configuration, with the largest performing the role of "Altitude Compensation"

[@UncleWermus]

All I've ever known about FI was contained in this presentation, combined with twice as much stuff I didn't know ALONG with the history... I wish I could like this twice

[@tensevo]

Basically nothing on F1 MGUH though. Those hybrid systems are stunning. Zero lag.

[@MultiPleaser]

The video contained info I picked up over the years one bit at a time. Plus a new bit, where they cut the ignition so unburned fuel goes into the exhaust and ignites there and spins the turbo. We used to do a trick on our bikes where we went full throttle, cut the ignition (thumb switch), filled the exhaust with air/fuel mixture, then thumbed the ignition back on. This ignited all the fuel in the exhaust at once and exploded like a quiet gunshot. Doesn't work on EFI. '(

[@bkdexter79]

I enjoy these videos because: A) No distracting music, B) Pure facts and figures, C) No flowery "chic" terms or phrasing, D) Interesting subject matter that is relevant to modern life. Thank you for keeping it "simple"...so to speak.

[@niklasxl]

yeah as others have also said the blower is turning the wrong way, the air goes around the outside

[@paulbyerlee2529]

Was about to say the same thing 🤣

[@denniswalsh8476]

Yeah... noticed that too... and The turbo is turning the wrong way also. The rotor turns from the larger cross section of the volute to the smaller cross section. It's the opposite for the hot turbine section.

[@AliHSyed]

Srsly dude. Kudos to you. This is some HIGH QUALITY content.

[@trentdawg2832]

Dis sum good chit

[@yngfljm2277]

pretty animations =/= high quality *content*

[@robson6285]

The pumped airflow is the Opposite way in the animation of the rootsblowerpump. The lobes move the air on their outsides up, not down between them as drawn

[@rpkamins]

I love the longer format and the amount of detail you went into. You make great videos, keep it up!

[@ThePlaystationgames1]

Hey @New Mind. I know you might not see this but if you do, thank you for the hard work you do with these videos. I am currently getting ready to go to University for Mechanical engineering and your videos gave me even more confirmation that I am making the right decision. You are an inspiration and you should keep up the hard work!!!

[@BrownMInc]

How's it coming along? I'm in my 3rd year ;)

[@ThePlaystationgames1]

I'm two semesters in banging out my core classes. Any advice for me?

[@BrownMInc]

@@ThePlaystationgames1 awesome! In all honesty there will be rough patches but anything worth having we gotta work for. Just keep in mind that those down times are temporary even if you can't immediately see your way out. It'll pass. In terms of practical things though, it's all about time management. Grades are important but so(and possibly even more) is the network you build. Get involved but not at the expense of your education likewise don't shun extracurriculars chasing decimal points. You won't always be on the ball, I regularly fall off track but for as cheesy as it sounds, it's really those of us who can consistently get back on our feet that move forward. Second year is generally the toughest year not just because of course difficulty but because it forces us to find that balance. Depending on where you are it's designed to weed out the less resilient of us. I don't doubt you Internet stranger so best of luck in your journey!

[@FLUFFSQUEAKER]

Even though i already knew this, this was still super interesting and so well explained! Best explaination of forced induction i have ever seen

[@NassersGarage]

What a wonderful presentation and information- since the beginning of your channel I knew you’re a car guy , now I’m sure 👍🏼 keep em coming

[@Root3264]

0:15 wtf??? What the hell is she doing, how is someone able to spill that much gas??

[@jmac1099]

haha! Diesel.. But yeah, give her some slack, doesn't know how to shake it like a guy!

[@daleolson3506]

She's on her phone

[@saintchuck9857]

I hauled fuel for 25 years. Idiots at fuel pumps isn't limited to 1 gender. People have zero respect for fuel until overflows and ignites under their vehicle with the spouse and kids in it.

[@ohioplayer-bl9em]

Seems like ever pump that has a diesel nozzle on it is covered in fuel. The pump and the ground around it is covered in fuel. I know diesel doesn't evaporate away like gasoline but how does it get their in the first place. I'm convinced that diesel users are absolutely animals when they refill the tank. They can't take 10 seconds to allow the fuel to finish draining out of the nozzle before pulling it out and getting it everyplace. I try to avoid the split pumps when getting gas as it never fails to get diesel all on the bottom of my shoes which I get to smell for the next hour or two. Maybe the pumps ALL suck and drip like an old man? Not sure..

[@kens97sto171]

@@ohioplayer-bl9em It's a combination of both of those things. sometimes the valve does not close completely when you let the handle loose. I've had diesel pumps sit there and just continuously dribble no matter how long you waited. I've had a few where you grab the pump handle and as you're trying to put it into the gas filler a whole bunch of fuel dumps out because it's been filling up that nozzle the whole time. I've had it happen at gas pumps also. But as you mentioned sometimes it's just impatience and people don't wait the 5 seconds or so it takes for the fuel to drain out

[@julzsep90]

This channel has been exactly what I've been missing due to seeking more understanding in the field which I'm most passionate about. Most automotive pages brief upon many subjects but go on to say this is a basic understanding. This information is digestible and in depth , thank you

[@scottharvey7730]

The illustrations show the air taking the wrong path through the rotors. It actually goes around the outside and the meshing rotors seal the air down. There is no room for displacement between the rotos it therefore has to use the volume of the shape of the mating parts. Great video. Thank you.

[@jamiejackson492]

How does this channel not have more than a million subscribers? New Mind has some of the best content on KZbin!

[@L33tSkE3t]

This is impeccably well researched and brilliantly articulated.

[@anchorbait6662]

Thank you soo much for making this wonderful video. One of the best examples I have seen.

[@yashpawarelitepawar]

I wish i knew this channel when I actually studied these things in engineering. this is the most detailed yet lucidly explained video I have seen till date. kudos!!

[@bombo139]

The animation at 5:10 is wrong, the rotors spin backwards compared too the airflow

[@super8mmo]

that's not true

[@joshuahodge1181]

Maybe you need to hold your phone upside down

[@jhbonarius]

Indeed! This is a better animation kzbin.info/www/bejne/qGXZY3SuirV_qbs

[@sergiourquijo4000]

i was about to comment on it. The air pases throught the outside (close to the wall) so in that animation it goes up

[@RandornCanis]

Also 6:55. I swear, even later with centrifugal superchargers and turbochargers; the impellers illustrate correct vane geometry, but appears the same backwards rotation. It's all a clever ploy to drive comments.

[@PRH123]

Thanks very much, I have searched all over for an overview of what makes modern small turbos in automobiles different from their predecessors. This is the only overview I’ve ever found. Thanks! Would be very interesting to see an overview of one particular engine, such as a budget compact car like the Chevy Aveo for example.

[@cyrilio]

I’m super impressed by the animations. Looks so goood.

[@creverett9]

oh my god these videos are so good. one of the most under rated content on yt.

[@JB-zn1kx]

I have too spracharged cars and one turboed. I learned a lot and will tell all my other friend in 6 October to watched and learned!!

[@M0N33R]

Sincere thanks for this amazing material

[@curtisjackson9145]

That was awesome! What a great learning experience this was for me!!!

[@CdotPoppy]

Love the videos! Always great for a long watch!!

[@skoalsoldier]

The Roots system is also used in metering natural gas at higher flow rates. For normal domestic metering, from 250 cfh to 1000 cfh, we usually use positive displacement diaphragm meters that use internal diaphragms to inflate and deflate, measuring the gas volume and turning a counter to show usage. This is then billed to a customer at a known pressure, adjusted for temperature. At higher volumes, 2m cfh to 56m cfh, we will use Roots style meters. They still work off of the positive displacement principle, yet the rotating assembly has a higher volume permission than a diaphragm design and do well at measuring large volumes of gas. They also aren’t restricted to the lower pressures of diaphragm meters, and some are used at upwards of 200 psig. This allows high pressure/volume through the meter, which a customer can then regulate down for their specific applications.

[@AustinPerdue]

Easily the best video I've seen on this topic.

[@BigDawwwg101]

Brilliant complete video. So much info.

[@nekomakhea9440]

the chad jet turbine engine: when your entire engine is one giant turbocharger because you want ALL the boost

[@jadesmith6823]

For once an utterly brilliant lesson 🙏🙌

[@mikesutton2765]

That was brilliant! Thanks man. Love your videos🤙🤙🤙🤙

[@DerKeyCee]

It's a shame this channel has not more subs/views. I just cannot get enough of this

[@Zpajro]

Realy nice animations you have, the quality is really good.

[@zachsteiner]

It’s a damn shame this video didn’t perform better. This video is amazing. I’ve always been fascinated by forced induction and I’ve never seen such an in depth, well put together video. I throughly enjoyed it.

[@CheaddakerT.Snodgrass]

Problem solved: The animation crisis portion was filmed on a mirror.

[@w0ttheh3ll]

that doesn't solve anything

[@bryankirk3567]

@@w0ttheh3ll Check the rotation of the rotors and you will figure out why this vid is nonsensical.

[@bryankirk3567]

Bejeez! I only had two beers! I thought I was totally drunk! Everything was working opposite to an apple falling off a tree.

[@w0ttheh3ll]

@@bryankirk3567 I know that the video is wrong. My statement was that mirroring wouldn't make it right.

[@garretarmijo1592]

3:59 OMG THAT WAS JUST THE INTRO!!! HOLY CRAP THAT'S AMAZING!!!!!!!! I GIVE YOU MAD PROPS

[@quietcool4884]

The narrator and producer of this vid have likely never turned a wrench or had grease on their hands. Go see Richard Holdener's channel if you want to learn about forced induction from someone with years of actual experience, he has a multitude of hands on video's and tests along with years of dyno tests and numbers for every engine and combination imaginable.

[@blubb7711]

5:05 the air is actually going in oppostie direction than in this model.

[@operator8014]

Haha, I didn't catch that at first. Nice.

[@travian821]

now makes sense

[@dmeemd7787]

Yeah I don't know why so many supercharger animations are backwards, the rotors go away from each other from the perspective of the intake 🤷‍♂️. worked and all types of drag racing, literally and never saw one spin backwards- the weird part is I have heard people did that are running or working on a screw blown / roots blown applications and say they spent towards each other when they clearly don't on the engine they are running.. not too many but too many LOL

[@TRPGpilot]

Very well explained. Thank you!

[@mx5_enigma308]

Extreamly well done!!!

[@bovanshi6564]

Exceptional quality as always

[@cellokid5104]

Wow, great explanation and history

[@kashmirha]

This is a superb content. Before this I was a noob not even knowing what turbo means in engines.

[@someoneelse4492]

Great video! I"m glad I found your channel.

[@zoobie2000]

Great video thanks for posting

[@adamraddatz1820]

Excellent video! Thank you

[@AmirRosenzweig]

Thanks for the great Video!

[@turboclub.comcarclubfortur3199]

Excellent factual and entertaining explanations of all facets of ICE induction utilising mechanical compression of air. Economy can be extracted ( so Ford believes with EcoBoost ) but is rarely the reason for the added expense or complexity! The Pleasure of Power is!!

[@craig221]

This is single-handedly the best video that explains boost supercharging turbocharging hyper charging whatever charging you like Great vid champ! 🍻

[@jesseshort8]

Awesome work, very informative.

[@SpaceCakeism]

Well, to me, this explained a lot of the technical terms used in Initial D; thanks mate.

[@mrrobertwolfiii1079]

Appreciate you kindly allow this review.

[@lorq3370]

Dude, kudos for this quality video.

[@LooseNut099]

High quality video, exhaustively researched and well thought through. The graphics alone must have taken a considerable effort. Well done.

[@gueuledange06]

Nice video, thanks for the explanation.

[@crazy8sdrums]

Very good video with a solid cross-section of engine boost tech and narrated succinctly! Great job!

[@steveskouson9620]

Except almost every example is running backwards, in some way. steve

[@peterherrington3300]

As a rider with a charge cooled aftermarket belt driven centrifugal supercharger (hayabusa/rotrex) I found your video extremely informative. Many thanks for detailed explanation. Add 1 sub from England 🇬🇧

[@GarageSupra]

Great video, easily the best on youtube covering all bases except the new electronic wastegates

[@mr.c5217]

Excellent training video to show students 👏

[@richardanderson4161]

Nicely done, thanks.

[@bongosock]

superb presentation! thanks :)

[@MatthewTaylor3]

This was very well done.

[@roberttrisca8210]

the way you present it,,, man, u're absolutly briliant.

[@roberttrisca8210]

i really admire you, a lot.

[@JurisKankalis]

This was actually interesting. Good work!

[@baronvonlimbourgh1716]

Love the whine of a roots blower!! BOOST = LIFE

[@manthos.y]

Wastegates, externals, and blow-off valves explained in a scientific level not seen before. Outstanding!

[@Malibuthe6th]

big car nerd here, glad to see New Mind cover this. i think the worksmanship of this video can be summed up by the almost 4 minute intro. excellent stuff

[@HardHatPat]

Powerband explained in the first minute. Thank you.

[@G5Hohn]

Engineer for a major engine company here- best presentation on forced induction I’ve seen.

[@lorriecarrel9962]

Best I've ever seen,good job.

[@stevenmitchell7830]

Very well done.

[@onkcuf]

Wow! More Air + Fuel? Science! Brilliant.

[@JupiterCamelz]

Awesome, beautiful!!! Not a better explanation of this out there!

[@nunyabusiness8538]

one of the best channels on youtube

[@ricepony33]

Great overview!

[@TurboWorld]

Great video full of informationional nuggets!

[@thetezz0001]

Exceptionally documentary very well presented top work and quality

[@SuperDrivetrainSolutions]

Great explanation thanks. There is even more to describe twin charged setups please. I have done it and its awsome! Complex yes, but zero lag!

[@caseyedds2032]

What an incredible video

[@alangreen_za]

Amazing video. Thank you. That petrol pour though...

[@stevepoythress4678]

Great presentation

[@midship_nc]

fantastic video!

[@gacherumburu9958]

Thanks for the info..👍

[@user-rd5nc1nb9f]

Excellent video

[@debudebu1324]

I am addicted to your videos

[@chidon7465]

That was nice, well done! :)

[@ahobimo732]

This is damn near encyclopedic! Very impressive.

[@c-moneycantrell7681]

This guy did his homework for sure!!!! Just wish my brain could absorb half of this information lol,,,,, great video!!!!!!

[@waterishdrake8693]

Great video!

[@shagirani5518]

Very well explained video.. 👍👍

[@buzzyinurface]

This is literally the gold standard for educational videos on FI

[@sindhengineering5197]

Great service

[@SpecialEDy]

Obvously a turbo guy, I have a Twin Screw sitting a few feet away from me and am a little sad it got the least attention. Im glad you mentioned volumetric efficiency.

[@jbflores01]

excellent video!

[@turbo_brian]

23:45 that's backwards. The large turbo feeds the small turbo. The compressed inlet charge increases the flow capacity of the small unit. Also a small nuance, you said that lowering the compression ratio decreases the thermodynamic efficiency of the engine. While it's true that high boost levels require lower static compression ratios, the dynamic compression ratio is much higher so the thermodynamic efficiency of the engine is higher. Think of it as the air gets compressed, then cooled, then compressed again, meaning you can have a much higher compression level before detonation temperatures are reached. Otherwise this is a surprisingly accurate video. You've clearly done your research.

[@jeffhurckes190]

Agreed Brian. One could also think of it like a gas turbine like a twin or triple spool turbofan. N1 is larger than N2, and N2 is larger than N3 (if a triple spool engine).

[@debudebu1324]

Very nice explaination