The biggest reason to go ITB is to get rid of the effect a plenum has on the positive pressure waves that pulse back into the plenum when the intake valve shuts. These waves can affect adjacent cylinders because they share that plenum. If the plenum is eliminated, the pulse waves go into ambient pressure and cannot affect the adjacent runners. Tuning the stack length helps when you tune for high, medium, or low RPM power gains because you can actually "time" the pulse to be exiting or nearing the exit of the stack when the valves open on the next cycle. Doing this can create a positive pulse wave INTO the engine. I am measuring 0.05psi of positive pressure, not vaccum, above 5500 RPM on my 2.0 Zetec with ITBs because of this phenomenon. I've been told this is the biggest reason ITBs can be beneficial. I did notice big gains up top when I built mine. And the car doesn't run out of breath up top, it just keeps pulling, which is great when I want to leave it in 2nd due to an upcoming turn at the track and don't want to waste time shifting up then down again. Before, I would kind of run out of steam and it was a draw whether I upshifted to 3rd or rode it out. Now, it's definitely better to leave it at WOT from 7200 to 7700 where it would fall on its face before.
As a Honda fanatic (particularly a F series fanatic,) I have seen f and h series motors with itbs, and they are so freaking aggressive. The VTEC just roars away.
Great Video, great explanation. I will tell you from experience, I've worked on some of the old Weber Carbs that had separate throttle, as well as some aftermarket Fuel Injection systems built to replicate those old carburetors, and have a separate throttle bodies at each cylinder. The worst part about them is they are SUPER sensitive to the throttle plates being adjusted perfectly to have identical airflow through each of the throttle plates when the linkage is adjusted to have all the slack taken out of every point. If you have them out of balance, or the linkage is off and opens some before others, you'll end up with running problems or issues on acceleration as you have different amounts of air flowing into each cylinder. It's a great system in theory, I just have not seen where we have the details worked out well enough for widespread implementation.
@@iRyan876 how to get good throttle response on a drive by wire system? I ask because it seems like no production car made today has drive by metal cable anymore
@@treerexaudi I think it's ECU tuning that does it. A lot of the time, pedal position is not mapped linearly to throttle position. Since the ECU pretty much does everything, then... Also consider that leaner fuel mixtures make it harder for the motor to rev quickly. It's why most small engines with turbos end up not being that much better, they have to inject a lot more fuel when you floor it to get it to spool quickly and _then_ lean out.
That could actually be a really great technology to implement on forklifts and other propane engines because they have a massive amount of lag associated with throttle responses.
@@TucsonDude it is actually very important. Some of them have auto bleep systems when you ask for pressure to tilt the forks for example and Lagg can stall the engine.
Once again a great, to the point, informative video. I'm installing individual throttle bodies on my Toyota RXI today, I just needed YOUR reassurance that I'm not wasting money, and the technicians aren't setting a unreasonable expectation, just to make a quick buck
I love you! I am a trainee auto mechanic and I recently got an engine with ITBs and was asking my teacher about them only Monday and you made this video today! I always watch your videos but this was cosmic! Thank you!
Your explanation is great , and each system has its advantages , The IR system is great for road racing where crisp throttle response is needed and great midrange power , but it will never make the top end power if a plenum system . This is because of how restrictive it is . When you have say a single 4bbl on a plenum each cylinder has access to all 4 throttle bores , not just 1 as in the IR system , so hi RPM power is always better . An example , I have done a lot of dyno development on a 4 cylinder Olds Q4 engine . From running the stock factory fuel injection w single throttle body w plenum to hand built intake w 2 throttle bodies on a plenum , and then 2 Weber 48mm carbs on a hand built IR intake and then to a single Holley 780 cfm 4bbl on a plenum intake . Each had its own power curve and different driving feel , The Webers have instant throttle response , but are down on peak TQ and HP to the plenum system , not much different in drive ability but very crisp off idle . On the Dyno the weber carbs were down 10 lb ft of Tq and 13 Hp over the Holley carb set up , which made 289 Lb Ft Tq @ 5200 rpm and 305 Hp @ 7200 rpm .
That is true however it's a pity with how Nissan designed them. I don't understand why they went to so much trouble to make an ITB setup and then to compromise the design that badly.
@engineeringexplained just watched an old video from 2011 about horsepower vs torque, such a difference in your confidence! You have come a long way.. great stuff and keep up the very interesting and informative videos :)
Nice use of the whiteboard! Much easier to follow than lots of CGI stuff! Would it be possible for you to do a vid on turbochargers vs superchargers (if you haven't already!)? The differences, advantages and disadvantages. Are they better suited to certain types of engines (no. of cylinders, capacity etc). Would be cool to hear your thoughts.
The reason why I am here is I am building a 1/25th scale car model of the 66 Buick Wildcat. It has options for motor. One being dual quad carbs. vs 8- Velocity stacks. I didn't know anything about which has the advantages. Now I do. Thanks !
My AE92 Corolla is fitted with a 4AGE 20v silvertop with ITB's from factory. It's super fun to drive and sounds amazing even though I'm using a single cone filter.
Can you please do a video on velocity stacks? Explain exactly what they do and how to maximize the benefits. Also various applications. I am currently experimenting with them hahaha
what they do i can help with, rather than trying to feed air into a straight ended tube the velocity stack creates a larger and smoother surface area to pull air into the tb, resulting in a smoother flow of air. think of it like a funnel if you will. hardly a scientific answer but hey it might help you understand them a little better - cheers
Not quite correct. It makes the air transition into a smaller area. This reduces the pressure of the air but increases the velocity as it comes into the engine. You want somewhat turbulent air in your engine for some reason that was explained to me but I forgot.
thegarage.jalopnik.com/what-are-velocity-stacks-and-why-you-want-them-on-your-1792235442 create one with carbon fiber, then put a servomotor for each to modify the legnht then put the engine on tuning and vary the lenght for different charge and rpm and you get the most power from them for each point of the map. you should tune them for each cylinder
To feel the difference, do like this: Make a pipe in paper, 100mm long and 40mm in diameter for example Blow air through it with your mouth and put your hand in the other end to feel the air flow. (remember the flow) Then insert a "velocity stack" in the pipe, make the stack of something harder(cardboard, plastic etc) Blow through and feel the flow again and you should feel that the air hits your hand faster/harder than it made without the stack! The velocity/speed of the air has increased because of the smaller area in the pipe.
Several of you guys are mixing velocity stacks with air horns. Its certainly true that this shape is beneficial to flow compared to an abrubtly cut off pipe. However there is more to true velocity stacks than this. When the intake valve closes in your engine, it creates a small pressure wave travelling outwards through your velocity stack. Now from this point on, my knowledge is a bit sketchy but ill try to explain the basic concept. Anyway, when the pressure wave reaches the end of the stack, the pressure drops dramatically because of the increase in volume, and this in turn creates another pressure wave in the opposite direction. The idea is to tune the length and shape of the stack to harvest this pressure wave as the next intake cycle starts to help with initial cylinder filling, sort of like an opposite scavenging effect created by a properly tuned exhaust. In this way, it is in theory possible to create an engine with a volumetric efficiency greater than 1, or in other words, an engine which passes in one revolution more air through itself than its actual engine displacement. Now i am no fluid dynamicist or expert, just an interested layman. I'm not sure how or if the horn shape affects the pressure wave itself, but i would think a straight tube would create a stronger pressure wave, but naturally the intake needs to flow well. possibly in a straight cut off intake pipe, incoming air would cancel out the pressure wave due to turbulence from having to change directions sharply.
Idk if your channel is still up and running and you will see this but If so I appreciate how detailed and well explained your videos are....They have been very helpful as I am kind of new to the tuning world and without alot of mechanical background..But I'm learning thanks to your videos and again they are much appreciated...😎
On carburetored cars and bike it allows for per cylinder adjustment of the air fuel ratio. This allows for higher cylinder pressures, because you do not have to provide margin for fuel mixture variation from cylinder to cylinder.
Hey EE, performance oriented ITB cars are tuned Alpha-N or TPS vs. rpm. N/A cars can be tuned without a intake manifold in this case. Turbo cars still need a manifold for fueling adjustments while in boost.
Was hoping someone would mention Alpha-N. Vacuum signals from ITBs are very "noisy" and not very strong at partial throttle for reasons outlined in the vid. I built ITBs for a car I turbocharged some years ago. To map the engine, I ran Alpha-N and applied corrections to fuel and ignition based on positive manifold pressure. Worked like a charm and had fantastic throttle response.
The true benefit of independent throttle bodies is the stereo warble you get from open velocity stacks when they're installed on a V8, flat 6, or flat 4, and the engine bay is behind you. There is nothing like that sound. It's glorious.
You still have the same pumping losses at partial throttle. Torque output is all about MASS flow. Mass flow for a given torque output is the same regardless if you have individual runners or a manifold. He’s talking about pumping losses in a transient environment, IE manifold filling, which matters not at wide open throttle or steady state cruise. Reduced pumping loss from ITB is so tiny that it doesn’t matter. IF you could control each throttle individually, and completely close off some of the runners so NO air flows, you could drastically reduce pumping work, but you would essentially have created a variable displacement engine. Throttle response is the only real advantage. You can gain some width in the power band by running slightly different runner lengths, and ITB’s would make it easier to match if you had a carb, but that’s about it.
Back in the day I owned an '93 Alfa Romeo 33 with 1.7L 16v boxer engine. This engine had ITB and was super enthusiastic on the throttle input. Loved that. I hate to say, but the NC Miata is driven by a ship diesel in comparison in this particular respect. BUT; The Alfa Romeo 33 with the 1.7L 8v boxer engine had even quicker throttle response then the 16v variant. Well, at least from idle. This 8v had a single throttle body. Never fully understood this. Perhaps due to having two camshafts an 8 valves less it had lower inertia?
The sibilance is a bit harsh / distracting in this video (more so than usual). Even still, I learned something new, so keep em' coming. Thanks Engineering Explained!
I used to own an Alfa Romeo Giulietta 1.8 with the "Alfanord" twincam engine that used to power Alfas a few decades ago with displacement from 1.3 to 2 liters (also, Alfetta, Alfetta GT/GTV, and, before, Giulia & Giulia GT). Those Alfa engines were all ITB and actually very reactive, although it was difficult to sync the 4 TBs, to avoid some disappointing power gaps. Not so many mechanics were able to do the job properly and was also expensive. The 2 liter engine was the first to switch from two 2-barrel carburetors to electronic injection, unfortunately losing the ITB feature
It's because there's allmost nothing to muffle the sound of engine sucking air. Especially when you have vvt like vtec or vanos, you can really hear it kickin' in
Great explanation! I've Always wonder why my Yamaha XJ6 Bike haves 4 throttle bodies instead of simple and small, specially when talking about bikes where space is reduced. Another downside that I can notice on my bike is that is heavier to pump the throttle when we are talking about 4 butterflies instead of 1. The spring to hold the butterflies is much stronger.
they're amazing! personally, I cant wait to get to tune and mess with stuff like that! and i think it can increase power and efficiency as well. if he hasn't already done a video on freevalve tech he totally should!
All of the car systems that feed off a constant vacuum would have to be rerouted - two off the top of my head are the PCV valve and the brake booster. But I can definitely see this setup being better for performance cars.
ITBs add serious cool points to any vehicle lucky enough to have em. Even if they didn't have any performance benefits, they looks and sound incredible. I'd love to find some clear resin intake plenums to show off the ITBs on my M5, but I just don't see that happening.
Usually if you're running ITB you'd move to a speed density / alpha-N model rather than a vacuum tree. Also the engine response is important with a dog engagement gearbox, where you need a blip to unload the flanks and the more reactive the engine the faster the shift.
Engineered explained you should make a video in the future of what the causes may be for a exploding engine or nitrous , I've seen many videos of them exploding but I don't know how exactly or what may have caused it to explode
Can you please explain how ITBs would reduce pumping loss? I understand how they help combat manifold filling times to improve throttle response, however in the steady-state part-load conditions, how would pumping work change? Pumping loss is a function only of the gas flow rate and the pressure loss across the restriction (W = m(p1v1 - p2v2)). Therefore, for the same engine load (MAP) and volumetric efficiency + engine speed (flow rate), I would expect the throttle loss to be independent of the size and shape of any manifold volume in the system, before or after the throttle(s).
lol that might be it. I've been trying to figure out why they are hatchbacks and the requirement for mass produced cars did pop up. But if that's the case, why don't we see Toyota Corollas, Nissan Altimas, Ford Taureses and Honda Civics in Rallys? Those cars are roughly around the same dimensions as some of the Rally Hatchbacks I've seen minus the hatchback.
Its mostly the mass production thing. Also the heritage of the sport is people who like to be outside, drive cars on dirt roads, and camping. Hatchback is obvious choice for those reasons. Don't forget all wheel drive. Very Important.
removing the inlet manifold as suggested would lead to massive induction roar and pulling hot air in from around the engine would decrease power. Also the long run of the 1st example can offers a mild supercharge effect as each inlet valves open at different times.
Very few cars have individual throttle bodies but it's the norm on motorcycles. The only bikes I'm aware of that don't have ITBs are some old v-twins where they share a carb between the cylinders and some 6 cylinder engines where someone decided it'd be cheaper to use 3 carbs instead of 6.
It's funny I was just watching a 2 yr old RCR video of the 96 Ford F150 which curiously did have 2 throttle bodies i always wondered about. Then I watch this one clearing up the reasons (allowing me at least to contemplate).
Just started watching this video, but beforehand I'd like to tell you that your videos are always awesome. I hope you continue using your excellent brain to produce this awesome content and never leave the internet to go caveman mode and instead work on a TV show like some of your friends. Just sayin'
Can you show me using the whiteboard which gets more chicks? I swear up & down that the ladies love ITBs, but I have a friend, let's call him Sherman Klump, who is adamant that a single TB is what really drives the ladies wild. Hahahaha. JK. Great video as always!!!
really good info, didnt really cover the torque benefits that bodies. they have a much wider torque curve. obviously this is relative to velocity stacks or plenum being correctly matched for the set up, but that instant throttle response is relative the the torque increase much lower down in the revs
Have you ever measured PMEP using ITB versus STB on the same engine? I just think that saying that ITBs have any benefit on PMEP is a big simplification. Nice video btw.
Question,,, on 04:23 --- the power / RPM relation and the shorter and longer runners issue, is there a video talking about this in details ??? I kinda lost you there :)
You missed maybe the most important argument for ITB's. Resonant pulses have a significant effect on cylinder to cylinder air/fuel mixtures in common plenum intakes, to the tune of 10% or more lambda.
Toyota used 4 throttle since late 90's from 4AGE Silver Top & Black Top engine 1.6cc 20 valve 5 valve per cylinder 3 intake 2 for exh valve.Make horse power from 160-165 hp/162 Nm at 5200-5400 rpm and redline 7800-8600 rpm without valve lift system.The most early torque compare to others 1.6 engine...
Done a couple ITB and the make much more torque in usually a 1000 to 1500 rpm range, heard some do a good bit better. I'd rather have one motor with a broad torque curve that will win most of the time over one that wins at one track.
pls make a video on brake oil temperature change when using brakes.....I have searched online and there is no video on this topic..pls make one...thanks
The intake plenum is not at atmospheric pressure. There's an inherent pressure loss associated with the intake filter. Also the throttle body is a choking device. You can always make up for itb with larger single throttle body. but good points.
Individual throttle bodies can help Traction control as any individual o multiple cylinder power can be reduced equals more smoother control. Twin cylinders motorbikes can utilise this well.
So if my car comes with a variable intake runner length system, upgrading to an ITB basically means that i can only pick a specific RPM range and enhance that range. Right ?
Not positive, but I believe so. I _think_ you'll sacrifice at one end of the rev range to enhance the other end. It makes sense...but I'm no engineer. :-P
+Alex Haws my car comes with the variable intake runner length system to eliminate a torque dip at 3k RPM. If i were to theoretically upgrade to a ITB, i will sacrifice daily drivability cause the ITB doesn't solve the torque dip issue. Right ?
Davin Yap i think it depends on what else you do to the motor and how powerful it is to begin with. how much tq dip is being prevented with a variable runner length? if its low then you probably will not notice a dip... unless your using a dynamometer. i should note that i am not saying change or stay. just stating my opinnion
what if you upgrade to larger runners and throttle bodies that way it’s not as restrictive and then boost it? that way it gets air faster. would the ITB then be better???
off topic: could you look into and make a video about start stop systems? Maybe some calculations to compare a car with and without it, with same chassis but with weight differences and also try to include a purchase price. So to give a answer: is it worth it?
I noticed that the f80 m3 (or m4) doesn't have IBTs like the e90/92, do forced induction engines benefit less from IBTs than NA engines? The r34 Nissan Skyline, despite being twin turbo charged, does have IBTs.
everyone in the comments is talking about how sophisticated this system is...well its much simpler than what many, possibly most cars use today use direct injection which runs at pressures up to 3000 psi and some use both direct injection and port injection...im just glad this is all going away soon. my next motorcycle will be the zero electric powered bike
Advantages to ITB's: they look awesome, sound awesome, are awesome
100%
Also the only reason I'm keeping my CAI. Sounds cool even though it does absolutely nothing for performance
awesomeness is a must !!
No complaints. The intake sound though!
Awesomeness does increase HP!(Happiness Power)😆
The biggest reason to go ITB is to get rid of the effect a plenum has on the positive pressure waves that pulse back into the plenum when the intake valve shuts. These waves can affect adjacent cylinders because they share that plenum. If the plenum is eliminated, the pulse waves go into ambient pressure and cannot affect the adjacent runners. Tuning the stack length helps when you tune for high, medium, or low RPM power gains because you can actually "time" the pulse to be exiting or nearing the exit of the stack when the valves open on the next cycle. Doing this can create a positive pulse wave INTO the engine. I am measuring 0.05psi of positive pressure, not vaccum, above 5500 RPM on my 2.0 Zetec with ITBs because of this phenomenon.
I've been told this is the biggest reason ITBs can be beneficial. I did notice big gains up top when I built mine. And the car doesn't run out of breath up top, it just keeps pulling, which is great when I want to leave it in 2nd due to an upcoming turn at the track and don't want to waste time shifting up then down again. Before, I would kind of run out of steam and it was a draw whether I upshifted to 3rd or rode it out. Now, it's definitely better to leave it at WOT from 7200 to 7700 where it would fall on its face before.
Tim Oyer excellent insight. Thank you.
+Tim Oyer
Great, informative answer. Thumbs up!
You missed just one important thing... Engine sounds so much better with ITB's :)
Saved me a comment, thanks.
laferrari uses this thing
@MDS your comments started off topic. You missed the point of not only the class but the OP gains. You are on the wrong side of the equation!
As a Honda fanatic (particularly a F series fanatic,) I have seen f and h series motors with itbs, and they are so freaking aggressive. The VTEC just roars away.
F23 r nice
Great Video, great explanation. I will tell you from experience, I've worked on some of the old Weber Carbs that had separate throttle, as well as some aftermarket Fuel Injection systems built to replicate those old carburetors, and have a separate throttle bodies at each cylinder. The worst part about them is they are SUPER sensitive to the throttle plates being adjusted perfectly to have identical airflow through each of the throttle plates when the linkage is adjusted to have all the slack taken out of every point. If you have them out of balance, or the linkage is off and opens some before others, you'll end up with running problems or issues on acceleration as you have different amounts of air flowing into each cylinder. It's a great system in theory, I just have not seen where we have the details worked out well enough for widespread implementation.
And it seems that weatherproof cold air intake is easier to do on non-ITB setups.
Throttle response for me! I need my car to react when I say so!
Sacha-yves jean-louis thank you! Drive by wire sucks!
@@iRyan876 how to get good throttle response on a drive by wire system? I ask because it seems like no production car made today has drive by metal cable anymore
@@treerexaudi I think it's ECU tuning that does it. A lot of the time, pedal position is not mapped linearly to throttle position. Since the ECU pretty much does everything, then... Also consider that leaner fuel mixtures make it harder for the motor to rev quickly. It's why most small engines with turbos end up not being that much better, they have to inject a lot more fuel when you floor it to get it to spool quickly and _then_ lean out.
@@lfox02 2020 honda civics have extremely bad throttle response
That could actually be a really great technology to implement on forklifts and other propane engines because they have a massive amount of lag associated with throttle responses.
Lag is probably not important on forklifts unless you're racing them.
@@TucsonDude it helps with precise manipulation though
@@TucsonDude who says he isn't 🤣
@@its_only_karma7440 all the forklift drivers drive them flat out.
@@TucsonDude it is actually very important. Some of them have auto bleep systems when you ask for pressure to tilt the forks for example and Lagg can stall the engine.
Once again a great, to the point, informative video. I'm installing individual throttle bodies on my Toyota RXI today, I just needed YOUR reassurance that I'm not wasting money, and the technicians aren't setting a unreasonable expectation, just to make a quick buck
nice one! you might expand this to turbo itb setups as well. those are even more complicated and interesting!
I love you!
I am a trainee auto mechanic and I recently got an engine with ITBs and was asking my teacher about them only Monday and you made this video today!
I always watch your videos but this was cosmic! Thank you!
You, my dear sir, are so lucky it's not even funny. I could trade for that position in a heartbeat if I had the option to.
@@saumabhobagchi5547 I am a lady but teehee, thanks so much!!
May one day the Universe give you ITBs!!
@@BabyxBandit Thanks. Appreciate it 😊
@@saumabhobagchi5547 You are so welcome!😊😊
Have a good day and happy new year!
@@BabyxBandit A very happy new year to you too 😊😊
Your explanation is great , and each system has its advantages , The IR system is great for road racing where crisp throttle response is needed and great midrange power , but it will never make the top end power if a plenum system . This is because of how restrictive it is . When you have say a single 4bbl on a plenum each cylinder has access to all 4 throttle bores , not just 1 as in the IR system , so hi RPM power is always better .
An example , I have done a lot of dyno development on a 4 cylinder Olds Q4 engine . From running the stock factory fuel injection w single throttle body w plenum to hand built intake w 2 throttle bodies on a plenum , and then 2 Weber 48mm carbs on a hand built IR intake and then to a single Holley 780 cfm 4bbl on a plenum intake . Each had its own power curve and different driving feel , The Webers have instant throttle response , but are down on peak TQ and HP to the plenum system , not much different in drive ability but very crisp off idle .
On the Dyno the weber carbs were down 10 lb ft of Tq and 13 Hp over the Holley carb set up , which made 289 Lb Ft Tq @ 5200 rpm and 305 Hp @ 7200 rpm .
I have ITB's in my E30, and now i'm a very happy guy!
How is the consumption
Just like older 4cylinders Motorcycles having 4 carburators insted of one giant carburator.
i think even newer motorcycle use ITB bcs u need a sharp engine response in a performance bike
@@st.christophorus I wouldn't say my motorcycle is new being a 2005 FZ6, but it's got ITBs in an airbox.
Love my GTiR, came standard with quad throttle bodies
Pulsar gtir had the only sr20 which had itb
Nika Tskhovrebadze was also the most powerful
That is true however it's a pity with how Nissan designed them. I don't understand why they went to so much trouble to make an ITB setup and then to compromise the design that badly.
@engineeringexplained just watched an old video from 2011 about horsepower vs torque, such a difference in your confidence! You have come a long way.. great stuff and keep up the very interesting and informative videos :)
Nice use of the whiteboard! Much easier to follow than lots of CGI stuff! Would it be possible for you to do a vid on turbochargers vs superchargers (if you haven't already!)? The differences, advantages and disadvantages. Are they better suited to certain types of engines (no. of cylinders, capacity etc). Would be cool to hear your thoughts.
The reason why I am here is I am building a 1/25th scale car model of the 66 Buick Wildcat. It has options for motor. One being dual quad carbs. vs
8- Velocity stacks. I didn't know anything about which has the advantages. Now I do. Thanks !
ITB's are often tuned using throttle position vs RPM, with corrections for intake air temperature and barometric pressure
My AE92 Corolla is fitted with a 4AGE 20v silvertop with ITB's from factory. It's super fun to drive and sounds amazing even though I'm using a single cone filter.
Can you please do a video on velocity stacks? Explain exactly what they do and how to maximize the benefits. Also various applications. I am currently experimenting with them hahaha
what they do i can help with, rather than trying to feed air into a straight ended tube the velocity stack creates a larger and smoother surface area to pull air into the tb, resulting in a smoother flow of air.
think of it like a funnel if you will.
hardly a scientific answer but hey it might help you understand them a little better - cheers
Not quite correct. It makes the air transition into a smaller area. This reduces the pressure of the air but increases the velocity as it comes into the engine. You want somewhat turbulent air in your engine for some reason that was explained to me but I forgot.
thegarage.jalopnik.com/what-are-velocity-stacks-and-why-you-want-them-on-your-1792235442
create one with carbon fiber, then put a servomotor for each to modify the legnht then put the engine on tuning and vary the lenght for different charge and rpm and you get the most power from them for each point of the map. you should tune them for each cylinder
To feel the difference, do like this:
Make a pipe in paper, 100mm long and 40mm in diameter for example
Blow air through it with your mouth and put your hand in the other end to feel the air flow. (remember the flow)
Then insert a "velocity stack" in the pipe, make the stack of something harder(cardboard, plastic etc)
Blow through and feel the flow again and you should feel that the air hits your hand faster/harder than it made without the stack!
The velocity/speed of the air has increased because of the smaller area in the pipe.
Several of you guys are mixing velocity stacks with air horns. Its certainly true that this shape is beneficial to flow compared to an abrubtly cut off pipe. However there is more to true velocity stacks than this. When the intake valve closes in your engine, it creates a small pressure wave travelling outwards through your velocity stack. Now from this point on, my knowledge is a bit sketchy but ill try to explain the basic concept. Anyway, when the pressure wave reaches the end of the stack, the pressure drops dramatically because of the increase in volume, and this in turn creates another pressure wave in the opposite direction. The idea is to tune the length and shape of the stack to harvest this pressure wave as the next intake cycle starts to help with initial cylinder filling, sort of like an opposite scavenging effect created by a properly tuned exhaust.
In this way, it is in theory possible to create an engine with a volumetric efficiency greater than 1, or in other words, an engine which passes in one revolution more air through itself than its actual engine displacement.
Now i am no fluid dynamicist or expert, just an interested layman. I'm not sure how or if the horn shape affects the pressure wave itself, but i would think a straight tube would create a stronger pressure wave, but naturally the intake needs to flow well. possibly in a straight cut off intake pipe, incoming air would cancel out the pressure wave due to turbulence from having to change directions sharply.
do a video abaut stright pipes, like the difrences , and diesel vs gas
It never matters what the subject is. The way this guy explains everything makes me enjoy watching it.
Idk if your channel is still up and running and you will see this but If so I appreciate how detailed and well explained your videos are....They have been very helpful as I am kind of new to the tuning world and without alot of mechanical background..But I'm learning thanks to your videos and again they are much appreciated...😎
NO MORE POWER , ... I THOUGHT SO YES !!! ! !!! Just a better response in the mid revs . Thanks for the video .
On carburetored cars and bike it allows for per cylinder adjustment of the air fuel ratio. This allows for higher cylinder pressures, because you do not have to provide margin for fuel mixture variation from cylinder to cylinder.
You got the best videos for a guy like me who has to know how everything works, at least when it comes to cars :D
Hey EE, performance oriented ITB cars are tuned Alpha-N or TPS vs. rpm. N/A cars can be tuned without a intake manifold in this case. Turbo cars still need a manifold for fueling adjustments while in boost.
Was hoping someone would mention Alpha-N. Vacuum signals from ITBs are very "noisy" and not very strong at partial throttle for reasons outlined in the vid.
I built ITBs for a car I turbocharged some years ago.
To map the engine, I ran Alpha-N and applied corrections to fuel and ignition based on positive manifold pressure.
Worked like a charm and had fantastic throttle response.
The true benefit of independent throttle bodies is the stereo warble you get from open velocity stacks when they're installed on a V8, flat 6, or flat 4, and the engine bay is behind you. There is nothing like that sound. It's glorious.
The 1st drawing reminds me of an ABF intake :)
You still have the same pumping losses at partial throttle. Torque output is all about MASS flow. Mass flow for a given torque output is the same regardless if you have individual runners or a manifold.
He’s talking about pumping losses in a transient environment, IE manifold filling, which matters not at wide open throttle or steady state cruise. Reduced pumping loss from ITB is so tiny that it doesn’t matter.
IF you could control each throttle individually, and completely close off some of the runners so NO air flows, you could drastically reduce pumping work, but you would essentially have created a variable displacement engine.
Throttle response is the only real advantage. You can gain some width in the power band by running slightly different runner lengths, and ITB’s would make it easier to match if you had a carb, but that’s about it.
Back in the day I owned an '93 Alfa Romeo 33 with 1.7L 16v boxer engine. This engine had ITB and was super enthusiastic on the throttle input. Loved that. I hate to say, but the NC Miata is driven by a ship diesel in comparison in this particular respect. BUT; The Alfa Romeo 33 with the 1.7L 8v boxer engine had even quicker throttle response then the 16v variant. Well, at least from idle. This 8v had a single throttle body. Never fully understood this. Perhaps due to having two camshafts an 8 valves less it had lower inertia?
The sibilance is a bit harsh / distracting in this video (more so than usual). Even still, I learned something new, so keep em' coming. Thanks Engineering Explained!
your videos are by far the most useful. keep it up 👍
I used to own an Alfa Romeo Giulietta 1.8 with the "Alfanord" twincam engine that used to power Alfas a few decades ago with displacement from 1.3 to 2 liters (also, Alfetta, Alfetta GT/GTV, and, before, Giulia & Giulia GT). Those Alfa engines were all ITB and actually very reactive, although it was difficult to sync the 4 TBs, to avoid some disappointing power gaps. Not so many mechanics were able to do the job properly and was also expensive. The 2 liter engine was the first to switch from two 2-barrel carburetors to electronic injection, unfortunately losing the ITB feature
This is nice. I hate it when I step on the gas and there isn't immediate acceleration.
Question:
Why do ITBs sound so good? Can a „normal“ intake manifold sound similar?
It's because there's allmost nothing to muffle the sound of engine sucking air. Especially when you have vvt like vtec or vanos, you can really hear it kickin' in
EE rockin' the smedium t-shirt today.
Makes his guns look bigger
you are awesome , presence of you alone and how you explain it makes videos very good and helpful , thanks my friend
Finally did it. Liked and subscribed. Thank you!
Great explanation! I've Always wonder why my Yamaha XJ6 Bike haves 4 throttle bodies instead of simple and small, specially when talking about bikes where space is reduced.
Another downside that I can notice on my bike is that is heavier to pump the throttle when we are talking about 4 butterflies instead of 1. The spring to hold the butterflies is much stronger.
I didn’t realize how cool these were! XD
I want one, I need one!!
Doing this on my BMW M52tuB28 engine, can’t wait to hear it roar😮💨
what are your thoughts about using actuators instead of the camshaft to run valves and using them as throttle bodies at the same time?
asaikaly2 Like how BMW engines work?
they're amazing! personally, I cant wait to get to tune and mess with stuff like that! and i think it can increase power and efficiency as well. if he hasn't already done a video on freevalve tech he totally should!
He has done one on it, showing that the valves can open faster than with a cam shaft and have a longer duration
Preproto i thought so, just wasnt sure if i saw it somewhere else. im pretty excited for it.. i feel like its the next big change like EFI was!
Here are my thoughts! th-cam.com/video/FJXgKY2O4po/w-d-xo.html
Single handedly keeping the whiteboard industry alive 🤘
Great video! This is the best explanation I have ever heard. Thanks!
Miss my 70 Honda 750-4 itb’s and single baffle 2-1 pipes oh my the pull and the sound.
I'm now planning on Harrop Hurricane ITB on my LS7 'style' build for my for Chevy SS. So much for my Plazmaman Race intake with a 102mm TB.
Im seriously considering making an itb v12 toyota 1gz build in the near future. They sound so visceral at full throttle!
great video jack keep it up
Nice, very informative, I realize this morning seeing the tittle of the your video that I didn't really knew the pro and cons of these, so thanks.
Video idea: take a look back at some of the most legendary engines and what makes them so great
i run itbs with alpha n. i loved it to bits for the throttle response
All of the car systems that feed off a constant vacuum would have to be rerouted - two off the top of my head are the PCV valve and the brake booster. But I can definitely see this setup being better for performance cars.
From what I have seen already from the ITB , this is the different length of the trumpet resulting to more power or more torque !
ITBs add serious cool points to any vehicle lucky enough to have em. Even if they didn't have any performance benefits, they looks and sound incredible. I'd love to find some clear resin intake plenums to show off the ITBs on my M5, but I just don't see that happening.
Can you reduce engine vibrations by giving each cylinder a different amount of air?
ast5515 whoa tony stark
Could start with an inline 6 engine.
Usually if you're running ITB you'd move to a speed density / alpha-N model rather than a vacuum tree. Also the engine response is important with a dog engagement gearbox, where you need a blip to unload the flanks and the more reactive the engine the faster the shift.
He also didn't mention that going to ITBs lessens the negative effect of aggressive cams on idle quality.
That is the best explanation I have seen for ITBs. Thank you.
Engineered explained you should make a video in the future of what the causes may be for a exploding engine or nitrous , I've seen many videos of them exploding but I don't know how exactly or what may have caused it to explode
Yup ITB’s are going on the 1UZ
Thank you
The best thing about ITBs is the noise. Forget any power gains, a good noise will put a smile on any petrol heads face.
Nice vid! But ditch the MAP and go for tps and wideband on ITB's
The itb's also allow for equal distribution of the air/fuel ratio and each cylinder can be tuned individually
Can you please explain how ITBs would reduce pumping loss? I understand how they help combat manifold filling times to improve throttle response, however in the steady-state part-load conditions, how would pumping work change? Pumping loss is a function only of the gas flow rate and the pressure loss across the restriction (W = m(p1v1 - p2v2)). Therefore, for the same engine load (MAP) and volumetric efficiency + engine speed (flow rate), I would expect the throttle loss to be independent of the size and shape of any manifold volume in the system, before or after the throttle(s).
I've Learnt Alot From Engineering explained..😎
Don’t forget the sound of itb’s 😍😍😍 and they’re generally a lot more expensive
Can you do a video on why most rally cars are hatchbacks? What are the advantages?
lol that might be it. I've been trying to figure out why they are hatchbacks and the requirement for mass produced cars did pop up. But if that's the case, why don't we see Toyota Corollas, Nissan Altimas, Ford Taureses and Honda Civics in Rallys? Those cars are roughly around the same dimensions as some of the Rally Hatchbacks I've seen minus the hatchback.
It gives the poor buggers another exit choice when they are upside down!
Weight and mobility
Its mostly the mass production thing. Also the heritage of the sport is people who like to be outside, drive cars on dirt roads, and camping. Hatchback is obvious choice for those reasons. Don't forget all wheel drive. Very Important.
sharpemang well, Toyota was competing with the old corolla years ago
Great Video!
Awesome video!
removing the inlet manifold as suggested would lead to massive induction roar and pulling hot air in from around the engine would decrease power. Also the long run of the 1st example can offers a mild supercharge effect as each inlet valves open at different times.
only suggestion is to give us a few examples of cars that have each- job well done- really enjoy your channel.
Very few cars have individual throttle bodies but it's the norm on motorcycles. The only bikes I'm aware of that don't have ITBs are some old v-twins where they share a carb between the cylinders and some 6 cylinder engines where someone decided it'd be cheaper to use 3 carbs instead of 6.
Scott Moore any car with an RB26 swap or a 1989-2002 GTR has ITBs unless changed.
It's funny I was just watching a 2 yr old RCR video of the 96 Ford F150 which curiously did have 2 throttle bodies i always wondered about. Then I watch this one clearing up the reasons (allowing me at least to contemplate).
Just started watching this video, but beforehand I'd like to tell you that your videos are always awesome. I hope you continue using your excellent brain to produce this awesome content and never leave the internet to go caveman mode and instead work on a TV show like some of your friends. Just sayin'
Can you show me using the whiteboard which gets more chicks? I swear up & down that the ladies love ITBs, but I have a friend, let's call him Sherman Klump, who is adamant that a single TB is what really drives the ladies wild. Hahahaha. JK. Great video as always!!!
Always wondered about this. Thanks!
Can you do a video on why there are some many restrictions and regulations on racing. Wheel size, engine ect.
That's quite simple. Racing is a competition, a competition needs to be fair to be intresting. To be fair, you need a set of guidlines aka rules.
really good info, didnt really cover the torque benefits that bodies. they have a much wider torque curve. obviously this is relative to velocity stacks or plenum being correctly matched for the set up, but that instant throttle response is relative the the torque increase much lower down in the revs
Have you ever measured PMEP using ITB versus STB on the same engine? I just think that saying that ITBs have any benefit on PMEP is a big simplification. Nice video btw.
Question,,, on 04:23 --- the power / RPM relation and the shorter and longer runners issue, is there a video talking about this in details ??? I kinda lost you there :)
Please I need an explanation about the runners length regarding ITB, how it effects low rpm to high rpm
*_Since tuning is illegal in that US. I don't think we can even have these installed because we would have to tune the A/F ratios?_*
Can you do a video on dos, don'ts, and benefits on vehicles with an electronic shifter. Thanks
Great video! Now I understand why so many AE86's look like they have trumpets on their engine head haha
You missed maybe the most important argument for ITB's. Resonant pulses have a significant effect on cylinder to cylinder air/fuel mixtures in common plenum intakes, to the tune of 10% or more lambda.
Toyota used 4 throttle since late 90's from 4AGE Silver Top & Black Top engine 1.6cc 20 valve 5 valve per cylinder 3 intake 2 for exh valve.Make horse power from 160-165 hp/162 Nm at 5200-5400 rpm and redline 7800-8600 rpm without valve lift system.The most early torque compare to others 1.6 engine...
Done a couple ITB and the make much more torque in usually a 1000 to 1500 rpm range, heard some do a good bit better. I'd rather have one motor with a broad torque curve that will win most of the time over one that wins at one track.
pls make a video on brake oil temperature change when using brakes.....I have searched online and there is no video on this topic..pls make one...thanks
The intake plenum is not at atmospheric pressure. There's an inherent pressure loss associated with the intake filter.
Also the throttle body is a choking device. You can always make up for itb with larger single throttle body. but good points.
I think anything added to the intake adds some restriction. ITB usually max out stock injectors unlike the stock intake manifold.
Hi, You should make video about ITB and turbo vs single throlle and turbo. Lots of opinions is abouts those 2 systems...
Individual throttle bodies can help Traction control as any individual o multiple cylinder power can be reduced equals more smoother control. Twin cylinders motorbikes can utilise this well.
So if my car comes with a variable intake runner length system, upgrading to an ITB basically means that i can only pick a specific RPM range and enhance that range. Right ?
Not positive, but I believe so. I _think_ you'll sacrifice at one end of the rev range to enhance the other end. It makes sense...but I'm no engineer. :-P
Davin Yap if you remove the intake manifold, yes. As Jason said, you can remove not you should
+Alex Haws my car comes with the variable intake runner length system to eliminate a torque dip at 3k RPM. If i were to theoretically upgrade to a ITB, i will sacrifice daily drivability cause the ITB doesn't solve the torque dip issue. Right ?
Davin Yap i think it depends on what else you do to the motor and how powerful it is to begin with. how much tq dip is being prevented with a variable runner length? if its low then you probably will not notice a dip... unless your using a dynamometer.
i should note that i am not saying change or stay. just stating my opinnion
just turbo it
my single cylinder motorcycle has one carburetor. now i know why it has such great throttle response
what if you upgrade to larger runners and throttle bodies that way it’s not as restrictive and then boost it? that way it gets air faster. would the ITB then be better???
if you haven't done a video on it yet, you should do a video on why running an engine without an air filter causes the engine oil to get dirty faster.
ITB's
would love to see a video on the advantages/disadvantages of a "hot V engine"
Travis Wiebe pros reduce lag, cons engine temp increases
off topic: could you look into and make a video about start stop systems? Maybe some calculations to compare a car with and without it, with same chassis but with weight differences and also try to include a purchase price. So to give a answer: is it worth it?
I noticed that the f80 m3 (or m4) doesn't have IBTs like the e90/92, do forced induction engines benefit less from IBTs than NA engines? The r34 Nissan Skyline, despite being twin turbo charged, does have IBTs.
great vid but dont forget about the more moving parts on itb's => more potential failures than just one bog ole throttlebody
everyone in the comments is talking about how sophisticated this system is...well its much simpler than what many, possibly most cars use today use direct injection which runs at pressures up to 3000 psi and some use both direct injection and port injection...im just glad this is all going away soon. my next motorcycle will be the zero electric powered bike