My intention is for my videos to be more of casual conversations, so that it's easy to learn. That said, my intentions are not to use improper vocabulary to confuse the listener. Thanks for points this out!
Innovation and improvement is always happening, there are a lot of ways to reduce lag that companies have been pretty successful in implementing. Not looking into racing careers much, though I do plan on getting involved in autocross soon! :)
You're a boss man I love cars but sometimes it's hard to understand systems like these properly. Thank you so much for these videos! Love your STI by the way I'm looking for a WRX only cause of my budget but I hope you're enjoying your subbie, take care!
@Nayr747 In the video (although I did not state) I was taking an example from idle. The point that I was trying to come across (but was reasonably misunderstood) is that with a turbo (unlike a supercharger) you won't have quick response from idle up.
Just bought a VW Polo 1.2 TSI. I don't know a LOT about engines. I know some, but certainly nothing about turbochargers. Actually.. I didn't even know my car had one.. ^_^ I experienced that sudden "kick" a lot, and was wondering what it was. I feared it was some kind of defect. After watching this video, not only am I confident that it's completely normal, but I also learned something. You explain it VERY well. Subbed & thumbs up. Thanks!! ;-)
I seen in Malaysia they use a 1.2 tsi in the beetle I wonder why they don't bring that engine to the US. You just control that sudden boost of power with throttle response.
Great! If you want a bit more structure to learning (since you're new) you can check out my website. howdoesacarwork(dot)com. I break it up into lessons to make everything clear.
Right, depending on how quickly you shift and what rev you are at. Higher revs mean more exhaust, as the engine cylinders are pushing out their contents more frequently than at lower revs. If you shift quickly, the losses will be minimal. If you take your time, allow the engine speed to drop to idle, then reapply the throttle, you could lose your boost.
Once you have enough exhaust, you will no longer have lag, regardless of what rpm you are at, but at high rpms you will already have revved up the engine, spooling the turbo, meaning you already have boost.
No, compressor surge is when you let off the throttle and the added pressure has no where to go (no BOV, or not a large enough BOV) so the pressurized air goes back through the turbo.
Correct: different geometries, variable geometries, decreasing friction, twin-turbos, twin-scroll turbos, and of course the obvious anti-lag systems are all ways of reducing lag. I'm sure I left out some others.
Yes, higher rpm means more exhaust, and yes, smaller turbos (as well as all turbos) have limitations. At higher rpms the smaller turbo can start to lose pressure, and it is obviously operating less efficiently if it is spinning faster, and only forcing in the same (or less) amount of air. Higher speeds means more friction, and higher temperatures.
@Nayr747 No I'm glad you helped explain it. I want people on here to answer each others questions, so I'm glad you responded. And I meant to include that my example was from idle but totally failed to do so once I pressed the record button.
hello engineering explaned, i would like too give my imput on this video if you do not mind... there are several steps too decrease turbo lag, 1 use a lesser mass turbine and compressor as you explaned 2, have a ball bearing turbocharger, 3 reduce back pressure with turbo back exhaust or straight pipe allowing exhaust too flow more freely through turbine, 4 reduce intake restriction on the compressor side too reduce the resistance of airflow allowing the turbo too spool up faster because it is easier for it too draw in air. 5 increase the engines compression which will often require higher octane fuels but increasing compression increases pressures in combustion chamber over all increased exhaust pressures which allow turbo to spool faster... 6 combocharging, the supercharger should increase pressure in the combustion chamber at low revs as well as supplying boost at low revs, increasing exhaust pressure decreasing the time it takes for the turbine too spool up.... then when the turbo spools up you get even more boost, however fuel and ignition timing will have too be adjusted for increased boost at the higher revs...
@@johnjester254 Likely, the lag would be reduced, but also would performance. Smaller turbine means higher pressure in the exhaust pipes (upstream of turbine), which also means that residual gas will increase, and so will knock probability and exhaust temperature. Whoever made your car, has no reason to use a smaller turbine, actually, they try to use the smallest that still works fine enough at peak power. A smaller one will cause a lot of problems! Anyway, do not do that!
This would likely be achieved by altering the wastegate. You could reduce maximum boost by setting the wastegate to open sooner. Turbo kicking in a certain RPM is a result of the turbo design - larger turbos take more exhaust and thus will only produce adequate boost at higher RPM.
It works just like the intake except in reverse. The intake does not pull in air, and then cycle it continuously around the turbine, it feeds it to the engine instead. The exhaust gas feeds the exhaust turbine, and is then fed out (to the left in the image I've drawn) to the exhaust, and will pass through the catalytic converter, piping, muffler, etc..
@HiShBL2 Yes, but using a smaller turbine would mean reducing the amount of air you could pull in, so you'd be limiting your power gain from the turbo.
Rotating mass has very little to do with turbo lag. Lighter and better designed turbines do gain response slightly due to weight reduction, but most of it is in the ability of the turbine to utilize the exhaust gas (blade size and design) to make the compressor overcome the vacuum that the engine is creating. Lower RPMs mean less air and fuel is being used, so the exhaust valves open less frequently and release less heat. Since heat causes gases to expand, the linear rise in RPMs creates a relatively linear rise in exhaust temps (increasing the surface area of the particles that make up the exhaust gas). The bigger the temperature difference between the intake air and exhaust gas, the more boost is created. The exhaust turbine is already spinning plenty fast the second you punch it from idle, but the lack of exhaust pressure pushing against the turbo's exhaust turbine blades is what creates lag. If it was solely or mostly the weight and mass of the turbine/compressor that created lag, then I doubt that you would be able to see the compressor spinning at idle.
You're probably one of the best youtubers in this field alright a turbo isn't the most technical thing you explain but everything you post gets all the fudemental knowledge in without making it pointlessly hard to understand!Thanks dude, you keep making vids and I'll keep watching them, hope you make lots of cash you deserve it!!
These older videos always have an awkward moment and I love it. Great information! I've learned more about my car from this channel than I've learned driving it over the last year. Subbed!
You left out a major contributor to the turbo lag, which is the total volume of the forced induction system. If you have large intake pipes and intercoolers, the compressor turbine must work harder/longer to fill the system with the compressed air as opposed to system with a lesser volume.
+HardestofStyles Correct! Thank you for actually knowing your shit. These guys don't know anything about cars so they just eat this shit up. The main contributor to turbo lag is the time it takes to the system from the turbo to the engine with the volume of air it needs to reach the desired air pressure.
The volume of the intake system has a negligible impact on lag relative to the inertia if the rotating assembly. Let's take an average modern diesel truck. If we assume a 3"x36"x24" intercooler and 10' of 4" pipe between turbo and manifold that equates to approximately .6cf for the intercooler with caps and .1 cf for the piping. To account for an absolute pressure of 45psi this system contains about 2acf of air. If the compressor is pumping 1200acfm at full boost it would take about 1/600 of a second to pressurize the intake. This is insignificant compared to the .5-1.5 seconds it takes to spin the turbo up on the same diesel.
@BeatniKkers When the engine is unloaded, it doesn't take much throttle to rev it up. This means you're not using much gas. Without using much gas, you're not creating enough exhaust to properly spool up the turbo. However, it is possible to create boost if you hold it long enough, it just might not be as much as you'd like. Wouldn't recommend revving high in neutral frequently though. But who hasn't heard a ricer at stoplight showing off some BOV noises? It's obviously possible.
That's the thing though, everyone's like "I don't like forced induction because of the turbo lag" When you DON'T have the turbo working (IE, it's still spooling), you're effectively driving the vehicle as if it was Naturally Aspirated. It's just that you're so used to the power that comes when the turbo kicks in (the boost), that you think it's less than what it should be. There's really NO downside to forced induction, of course, besides the wait time for the extra power, and the extra cost involved. I highly recommend, especially for people who live at higher elevations, the turbocharger helps maintain a smooth powerband that is lost when N/A engines can't breathe enough.
But the air is still being blown in, as with N/A, it just hasn't reached a high spool, doesn't mean there is "less" air... at least, not with the setup I have, I don't have a very large turbo so maybe that's why.
Mihaly Lukacs , ah -- sounds reasonable. Actually I think I figured out why my turbo-diesel smokes at first on acceleration - even though the turbo is not yet producing pressure, the engine is still injecting the extra amount of fuel. This results in a too rich mix and thus the smoke. My first assumption was that there was just a problem with the air availability.
+Jaanus Piip , We just had the Pikes Peak Hill Climb a few weekends ago and I heard one of the racers say that his car can make 18lbs of boost at sea level but only 12lbs here.
+Nick Joslin It all goes through the turbo, until you let go of the gas and/or pressure gets too high. Then the wastegate opens, and bypasses the turbo.
panzerveps thought it was just so dust and debris won’t go in the turbo and mess it up and the intake prevents that and filters the air be for going in
christian gonzalez the wastegate is on the exhaust side. When you let off the gas, the throttle closes. The turbine/compressor keeps spinning adding pressure to the intake side until a pressure actuator opens up the wastegate. The exhaust then bypasses the turbine and the turbo is no longer adding pressure, protecting your throttle body and intake piping.
@anish4 Say you have a V6 twin turbo, the exhaust manifold from each set of 3 cylinders is routed to a separate turbo. So you would then have two air intakes, though it's possible to connect the piping if you wanted to.
I do not believe you actually explained turbo lag. You explained turbo spool time, such as accelerating from idle. Turbo lag is actually when the throttle plate is completely open, the turbo is compressing the intake at the desired pressure, THEN the throttle plate is closed, and THEN back to wide open very quickly. The delay time from the turbo being at full operational pressure, coming out of boost, and how quickly it returns back into boost......that is turbo lag. So, if you were racing, in full boost for a second or so, had to lift off the throttle for a split second and mash the throttle back down again......that delay back to go back into full boost is turbo lag. It may seem like a nit picking thing, but time to spool and turbo lag are two very different things. From Garret's website: Turbo lag is the time delay of boost response after the throttle is opened when operating above the boost threshold engine speed. Turbo lag is determined by many factors, including turbo size relative to engine size, the state of tuning of the engine, the inertia of the turbo's rotating group, turbine efficiency, intake plumbing losses, exhaust backpressure, etc.
You are correct, I've actually got a video explaining this technique that I'll be releasing in a few weeks. There are several forms of ALS, but this is one of them for sure.
not 100% true, the time it takes for a a turbo to get into boost is the boost threshold, lag is how long it takes to make full boost after its passed the threshold
Exactly Leon, This "engineer" is explaining "Boost Threshold", Turbo lag can be explained by saying: To measure turbo lag the engine needs to be above the boost threshold, which is what this guy is explaining, when the engine is in the threshold apply full throttle and if it does not respond straight away that is lag.
What do you think thermal expansion causes (some call this combustion)? High pressure gas that turns into high velocity gas when the exhaust valve opens...
Man, I remember sharing your channel on my Facebook yeears ago, like 5+ years. Still the only channel I've shared like that and said your channel simply deserves a share. Glad to see its doing well cause nobody explains it like you brotha!
What is the basis of your argument? When you add components, you add losses. If you were to analyze a pump with pipe flow, it becomes clear that to minimize the head loss, you want as few bends as possible, and a uniform diameter pipe. Integrating in an intercooler means more bends, more pipe, and various flow rate changes.
Wow. So I bought F150 Ecoboost about a year ago and was losing my mind trying to figure out what was happening when when I would ask for a lot of acceleration and didn't get it. I was also wondering why all of a sudden my driving style was causing slight spin outs. Great stuff, bro and thank you!
To add, if you translate amount of gas pedal to amount of exhaust gas your feeding the turbo, when there is no resistance that EngineeringExplained spoke of, you can only press the pedal slightly down for a brief period before the rpm is too high and you have to let off. So it makes sense that your not really effecting the turbo by reving in neutral. Compare that to when you start driving, you give the engine the resistance of moving your vehicle and it allows you to press the pedal and hold.
Instead of just feeding air directly to the engine (like in naturally aspirated engines), first the exhaust has to spool a turbine. It takes energy to spool up this turbine, causing a delay for the intake turbine to rotate. Once the intake turbine is rotating, it's forcing in extra air, hence the engine has boost. Some air obviously gets through even if the turbine is not spooling, but it's not enough for the extra power that a turbo provides.
Allows for excess pressure to escape from the intake (before the throttle body) once the throttle is closed. This is so that the air doesn't have to force its way back through the turbocharger (compressor surge).
1. The size of the turbine affects the maximum amount of air that can flow through it effectively. At high rpms the smaller turbos can't pull in as much as air something larger (bigger piping means greater maximum airflow). Also, there are speeds where turbines are most efficient, meaning the pull in the greatest amount of air versus the energy used to pull in the air. Smaller turbines are more efficient at lower speeds than larger ones. 2. 1 bar of boost is 1 bar of boost, regardless of turbo.
Thanks for the response! And all your videos! Yeah, I'm having big time turbo acceleration loss in my car (noticeable from when I purchased it a year ago). Dealership is giving me a hard time saying that it's normal turbo lag, but it's gotten noticeable worse over time. Appreciate the info!
Not sure where you get these numbers. 20 psi is high for just about anything. I don't know of any imports that stock run close to 30 psi. And the reason is it's too much pressure! 30 psi means your adding another 2 atmospheres of air pressure into each cylinder, that's pretty extreme. Yes, it can be done, but not without replacing all the components with higher strength ones. Also, diesels will run 20+ psi usually no problem (stock) because they are built with stronger materials.
Don't forget to mention the anti-lag systems some rally cars employ - I think it works by having an extraneous combustion right before the turbine while the engine isn't revving up like during gear shifts to keep the spool up. Makes for some awesome afterburn coming out of the exhaust pipe
on some small engines there is a vane called a governer that is like an accelerator petal. the flywheel has fins that act like a fan and the fan blows air over the governer and keeps the motor running at the same rpm. if there is load on the engine the rpm drops and the governer sends more fuel to the motor to speed it up and vice versa when it spins to fast (when the load is sudenly dropped)
@bobanppvc Better technology now. Lower mass turbines, less friction, twin-scroll, proper sizing, better materials. Lots of things make for improved spool time compared with older turbos.
@anish4 It would be possible, yes, but if they are geared differently one will spin slower, so this may cause undesirable results. If the exhaust spins faster than the intake, you'll be restricted of the amount of air you can pull in. If the exhaust spins slower, it would probably be more difficult to spool. Find a happy medium and it's probably good though!
Mustangs have larger engines than Evos, so not as much boost is needed to create the same amount of power. A mustang engine is twice as big or larger, so it creates a huge amount of power with lower boost levels, even though the actual amount of fuel/air burned will be similar.
Pod filters are not illegal in Australia, they just have to be encased in a box like factory filters. If they are not in a box you will be given a fine and be asked to fix it.
@EngineeringExplained Finally, your statement about turbo size and boost is slightly inaccurate. Boost is added pressure, which comes from the amount of air the turbo can pull in. Since larger turbos can pull in more air than smaller turbos (using the same engine) they can create more boost.
You forgot something: Lower mass turbine= less power. A very interesting configuration is BMW's (which is used in the Cooper S, JCW) twin-scroll turbine which allows a wide powerband and high output. Also the twin turbo configuration (in some cases) with 2 distinctive turbo's which when the smaller turbo to spools up, the transition is made to the bigger one.
If I understand correctly, yes. Naturally aspirated engines won't really lag since the second the throttle plate is open, more air will enter the cylinders.
Could you elaborate? What's going to power this electrical system? It would have to be belt driven if it were to be powerful enough, or a powerful motor with a separate supply of energy. Either way, it would be parasitic or add mass.
Yes, but without a load it won't be able to produce much boost. It doesn't require much fuel to rev up an engine by itself; having the car in gear gives it resistance and will thus allow using more fuel and creating more exhaust gases, spooling the turbo.
First question: Turbo lag doesn't affect power, just how long it takes to get the power. The answer to your question is no, because the turbo will be forcing in more air, and therefore more fuel will be burned. The more fuel you burn, the more heat is created. More heat = more pressure = more power. Second question. I should make one on this eventually. It's a good topic for sure.
VGT(or VTG or whatever, they all do the same thing in the same way;it's the same principle maybe some minor mechanical differences) tends to overcome the turbo lag issue(and many other aspects) by increasing the pressure of existing gasses therefore lowering the spin up time of the turbo. Almost all the new cars build today have variable geometry. You can google VGT vs regular or something like that.
It makes the psshh sound because it's a valve releasing pressurized air. As far as compressor surge I could have mentioned it but also could be another video. Great sound though.
To add to what EngineeringExplained said, the amount of turbo lag depends on a lot of factors. The main factor is the size of the turbo. So if the turbo is bigger, the turbine itself is bigger, which means its more massive, which means it takes more to get it moving. The amount of exhaust gas that your engine is capable of producing determines how fast it can get the turbo spinning. A smaller turbo in this case would mean less lag because its easier to rotate.
usually it is not the twin scroll design that reduces the lag. it is the fact that twin scroll turbos are usually smaller than normal, so they spool up faster. the twin scroll design basically channels the exhaust gases through 2 separate pipes, one for cylinders 1-4 and one for 2-3 (on a 4 cylinder engine) so each stroke gases always goes on a different line than the previous stroke, since the stroke sequence is 1-3-4-2 (or 1-2-3-4)...that results in better gas flow into the turbine
Well I wouldn't say that big turbos require high rpms, they just require a lot of exhaust. Big engines that are low revving can easily do the trick as well. Big turbos are found on both, and honestly they're probably a lot more reliable on large displacement engines.
I'm not certain but I feel like I experience turbo lag a lot with my Veloster Turbo (it's my first car and first turbocharged car I've ever driven so very little experience). I'm about to go look into it but this video gave me a very good idea of what exactly turbo lag is. Great job EE
A mate once told me something about modified hot side housings with a slightly different intake angle on them so the exhaust hits the fins better for better low rpm efficiency, that could also be considered a factor. Also some turbines have shaped fins for that particular reason so a combination of the 3 should provide a high degree of efficiency
If you reduce the amount or diameter of piping or intercooler volume you will have less volume to pressurise, resulting in less turbo lag. The spool speed of the turbo is typically not called turbo lag and ussually means the AR rating of your turbo is too high for your engine size or rpm application (wanting more boost at lower rpm vs higher rpm)
in repsonse to many, how to prevent turbo lag? or toreduce the ammount of turbo lag. One thing you can do is make the hot side piping smaller. say your using 2.5 inch piping to get the air to the turbo, make it smaller and it will take the same amount of exhaust gases and make them move with more force therefore creating a lower ammount of turbo lag
depends, small turbos are more efficient or practical under certain circumstances. My 335i has relatively small twin turbos but it means it takes less exhaust pressure to create boost, thus resulting in a car that has low turbo lag and turbos that work at lower revs. BMW went with smaller twin turbos instead of a larger turbo to avoid turbo lag and still push some decent psi.
Not a whole lot, the engine needs some form of resistance, and friction alone doesn't provide that much. With an engine revving and the car in neutral it won't produce enough exhaust to really spool up the turbo.
@EngineeringExplained I wasn't trying to say larger turbos *can't* create more boost, just that they don't always. It sounded to me like sheennick12345 was saying a smaller turbo just necessarily means smaller boost. You can make a smaller turbo produce a lot of boost but it will still produce less air mass than a larger turbo at the same psi, resulting in less power.
@EngineeringExplained and also the turbolag in the twin-config is smaller because it it easier to spin two small turbines rather than one larger one. I have such config in my RS6. The lag is barely noticeable
I would love to see you make a video explaining twincharging. The polo gti 6r uses twincharging to create roughly 180PS from a 1.4 litre block. Stock. Stage 1 tunes have seen 210PS and I think a stage 3 one (Hurdy on UK polos.Net) I think was creating almost 400ps from the same 1.4 litre block. That astounds me and I'd live to hear your take on that, Engineering Explained.
@sheennick12345 My point was that turbo lag isn't really an issue in racing, and the parts that were problems have been mostly overcome with anti-lag, nitrous, etc to spool the turbo off the line. For the everyday driver it might be a small issue in some situations. For instance, when I'm accelerating up a steep hill and I upshift too early my RPM drops to around 2,000 where I'm out of the compressor map for my turbo.
Im a big fan of engineering explained and yes im subscribed. I don't mean to sound like a bad back seat driver but....i dont feel that you have covered the entire question of turbo-lag. Turbo lag is caused by the exhaust housing being big. For eg...A GT35R turbo with an A/R 0.64 rear vs A/R 1.06 rear. 0.64 will come on boost much earlier making a lot of low to mid range power but may run out of puff earlier in the top end. But with the 1.06 will make power from mid to top end.
Man, you are explaining things to me that I've always wanted to know. I really appreciate all the information that you're giving.
You're welcome!
My intention is for my videos to be more of casual conversations, so that it's easy to learn. That said, my intentions are not to use improper vocabulary to confuse the listener. Thanks for points this out!
Innovation and improvement is always happening, there are a lot of ways to reduce lag that companies have been pretty successful in implementing. Not looking into racing careers much, though I do plan on getting involved in autocross soon! :)
I have a very detailed answer to that question on my website. The link is in the video description, then go to "FAQs -> Future Plans"
You're a boss man I love cars but sometimes it's hard to understand systems like these properly. Thank you so much for these videos! Love your STI by the way I'm looking for a WRX only cause of my budget but I hope you're enjoying your subbie, take care!
Pablo Contreras Both are great cars, good luck in your search!
Pablo Contreras did u end up getting that wrx?
@Nayr747 In the video (although I did not state) I was taking an example from idle. The point that I was trying to come across (but was reasonably misunderstood) is that with a turbo (unlike a supercharger) you won't have quick response from idle up.
Just bought a VW Polo 1.2 TSI. I don't know a LOT about engines. I know some, but certainly nothing about turbochargers. Actually.. I didn't even know my car had one.. ^_^ I experienced that sudden "kick" a lot, and was wondering what it was. I feared it was some kind of defect. After watching this video, not only am I confident that it's completely normal, but I also learned something. You explain it VERY well. Subbed & thumbs up. Thanks!! ;-)
Thanks for subscribing, congrats on your new car!
I seen in Malaysia they use a 1.2 tsi in the beetle I wonder why they don't bring that engine to the US. You just control that sudden boost of power with throttle response.
I'm getting used to it. It helps a lot, knowing what actually happens. I'm getting better, and it's pretty much seamless now. ;)
with throttle control you mean...
is why you go for dual turbos so you can help prevent turbo lag
Great! If you want a bit more structure to learning (since you're new) you can check out my website. howdoesacarwork(dot)com. I break it up into lessons to make everything clear.
Right, depending on how quickly you shift and what rev you are at. Higher revs mean more exhaust, as the engine cylinders are pushing out their contents more frequently than at lower revs. If you shift quickly, the losses will be minimal. If you take your time, allow the engine speed to drop to idle, then reapply the throttle, you could lose your boost.
Check out the main video on my channel page, or search my channel for "engines - explained."
Once you have enough exhaust, you will no longer have lag, regardless of what rpm you are at, but at high rpms you will already have revved up the engine, spooling the turbo, meaning you already have boost.
No, compressor surge is when you let off the throttle and the added pressure has no where to go (no BOV, or not a large enough BOV) so the pressurized air goes back through the turbo.
I love your channel man, you do an awesome job of explaining things. Keep it up!
few years late
Correct: different geometries, variable geometries, decreasing friction, twin-turbos, twin-scroll turbos, and of course the obvious anti-lag systems are all ways of reducing lag. I'm sure I left out some others.
Great video
Yeah
Yes, higher rpm means more exhaust, and yes, smaller turbos (as well as all turbos) have limitations. At higher rpms the smaller turbo can start to lose pressure, and it is obviously operating less efficiently if it is spinning faster, and only forcing in the same (or less) amount of air. Higher speeds means more friction, and higher temperatures.
Oh god.............all the "experts" are gonna come out of the wood work to correct this guy on any minor detail hes got wrong.
What does God has to do with that little mortal man
@@fbekker1838 I guess the answer to that question is.... that little mortal man is real!
@Nayr747 No I'm glad you helped explain it. I want people on here to answer each others questions, so I'm glad you responded. And I meant to include that my example was from idle but totally failed to do so once I pressed the record button.
hello engineering explaned, i would like too give my imput on this video if you do not mind... there are several steps too decrease turbo lag, 1 use a lesser mass turbine and compressor as you explaned 2, have a ball bearing turbocharger, 3 reduce back pressure with turbo back exhaust or straight pipe allowing exhaust too flow more freely through turbine, 4 reduce intake restriction on the compressor side too reduce the resistance of airflow allowing the turbo too spool up faster because it is easier for it too draw in air. 5 increase the engines compression which will often require higher octane fuels but increasing compression increases pressures in combustion chamber over all increased exhaust pressures which allow turbo to spool faster... 6 combocharging, the supercharger should increase pressure in the combustion chamber at low revs as well as supplying boost at low revs, increasing exhaust pressure decreasing the time it takes for the turbine too spool up.... then when the turbo spools up you get even more boost, however fuel and ignition timing will have too be adjusted for increased boost at the higher revs...
Thanks for this...can u still reduce lag by swapping the turbine with a smaller turbine and not changing the compressor wheel?
@@johnjester254 Likely, the lag would be reduced, but also would performance. Smaller turbine means higher pressure in the exhaust pipes (upstream of turbine), which also means that residual gas will increase, and so will knock probability and exhaust temperature. Whoever made your car, has no reason to use a smaller turbine, actually, they try to use the smallest that still works fine enough at peak power. A smaller one will cause a lot of problems!
Anyway, do not do that!
@@DC-rn1fc thank you
This would likely be achieved by altering the wastegate. You could reduce maximum boost by setting the wastegate to open sooner. Turbo kicking in a certain RPM is a result of the turbo design - larger turbos take more exhaust and thus will only produce adequate boost at higher RPM.
Just for reference, the wheel on the intake side of a turbo is called a compressor, not a turbine.
Adam Brackney true other wise it wouldnt suck the air
It is a turbine with high static air pressure
shut up nerds
This channel has gone a long way. Great video!!!
1:56 his finger lol
It's aerodynamic
It works just like the intake except in reverse. The intake does not pull in air, and then cycle it continuously around the turbine, it feeds it to the engine instead. The exhaust gas feeds the exhaust turbine, and is then fed out (to the left in the image I've drawn) to the exhaust, and will pass through the catalytic converter, piping, muffler, etc..
love all the videos. could u do one that explains twin scroll turbos?
12yrs and still educating. Thanks for this my guy!
very nice explanations,even for non engineering guy like me could understand that. keep up the good work. sub'd :)
@HiShBL2 Yes, but using a smaller turbine would mean reducing the amount of air you could pull in, so you'd be limiting your power gain from the turbo.
Rotating mass has very little to do with turbo lag. Lighter and better designed turbines do gain response slightly due to weight reduction, but most of it is in the ability of the turbine to utilize the exhaust gas (blade size and design) to make the compressor overcome the vacuum that the engine is creating. Lower RPMs mean less air and fuel is being used, so the exhaust valves open less frequently and release less heat. Since heat causes gases to expand, the linear rise in RPMs creates a relatively linear rise in exhaust temps (increasing the surface area of the particles that make up the exhaust gas). The bigger the temperature difference between the intake air and exhaust gas, the more boost is created. The exhaust turbine is already spinning plenty fast the second you punch it from idle, but the lack of exhaust pressure pushing against the turbo's exhaust turbine blades is what creates lag. If it was solely or mostly the weight and mass of the turbine/compressor that created lag, then I doubt that you would be able to see the compressor spinning at idle.
+GioGuitarDude ur explanation definitely makes more sense.
You're probably one of the best youtubers in this field alright a turbo isn't the most technical thing you explain but everything you post gets all the fudemental knowledge in without making it pointlessly hard to understand!Thanks dude, you keep making vids and I'll keep watching them, hope you make lots of cash you deserve it!!
Even after 10 years why are we still talking of turbo lag ? All R & D engineers were on holiday?
These older videos always have an awkward moment and I love it. Great information! I've learned more about my car from this channel than I've learned driving it over the last year. Subbed!
You left out a major contributor to the turbo lag, which is the total volume of the forced induction system. If you have large intake pipes and intercoolers, the compressor turbine must work harder/longer to fill the system with the compressed air as opposed to system with a lesser volume.
+HardestofStyles Correct! Thank you for actually knowing your shit. These guys don't know anything about cars so they just eat this shit up. The main contributor to turbo lag is the time it takes to the system from the turbo to the engine with the volume of air it needs to reach the desired air pressure.
The volume of the intake system has a negligible impact on lag relative to the inertia if the rotating assembly. Let's take an average modern diesel truck. If we assume a 3"x36"x24" intercooler and 10' of 4" pipe between turbo and manifold that equates to approximately .6cf for the intercooler with caps and .1 cf for the piping. To account for an absolute pressure of 45psi this system contains about 2acf of air. If the compressor is pumping 1200acfm at full boost it would take about 1/600 of a second to pressurize the intake.
This is insignificant compared to the .5-1.5 seconds it takes to spin the turbo up on the same diesel.
So how do u minimize turbo lag. N by doing such mods will it damage the car ?
@BeatniKkers When the engine is unloaded, it doesn't take much throttle to rev it up. This means you're not using much gas. Without using much gas, you're not creating enough exhaust to properly spool up the turbo. However, it is possible to create boost if you hold it long enough, it just might not be as much as you'd like. Wouldn't recommend revving high in neutral frequently though.
But who hasn't heard a ricer at stoplight showing off some BOV noises? It's obviously possible.
That's the thing though, everyone's like "I don't like forced induction because of the turbo lag"
When you DON'T have the turbo working (IE, it's still spooling), you're effectively driving the vehicle as if it was Naturally Aspirated. It's just that you're so used to the power that comes when the turbo kicks in (the boost), that you think it's less than what it should be. There's really NO downside to forced induction, of course, besides the wait time for the extra power, and the extra cost involved.
I highly recommend, especially for people who live at higher elevations, the turbocharger helps maintain a smooth powerband that is lost when N/A engines can't breathe enough.
I'm not so sure about that, wouldn't the engine be a little air-deprived due to the turbo not feeding air into the throttle body?
But the air is still being blown in, as with N/A, it just hasn't reached a high spool, doesn't mean there is "less" air... at least, not with the setup I have, I don't have a very large turbo so maybe that's why.
Mihaly Lukacs , ah -- sounds reasonable. Actually I think I figured out why my turbo-diesel smokes at first on acceleration - even though the turbo is not yet producing pressure, the engine is still injecting the extra amount of fuel. This results in a too rich mix and thus the smoke. My first assumption was that there was just a problem with the air availability.
+Jaanus Piip , We just had the Pikes Peak Hill Climb a few weekends ago and I heard one of the racers say that his car can make 18lbs of boost at sea level but only 12lbs here.
But getting hit by that turbo boost in a corner can easily make you lose control. So there is a disadvantage.
Amazing to see how far you've come in the last 11 years. I love your videos, you've taught me a ton. Please keep it up!
Does the turbo have a separate intake from the engine, or does all of the intake first pass through the turbo before making it's way to the engine.
Nick Joslin all must pass through the turbo. The engine and turbo intakes are connected to each other.
+Nick Joslin It all goes through the turbo, until you let go of the gas and/or pressure gets too high.
Then the wastegate opens, and bypasses the turbo.
panzerveps thought it was just so dust and debris won’t go in the turbo and mess it up and the intake prevents that and filters the air be for going in
christian gonzalez the wastegate is on the exhaust side. When you let off the gas, the throttle closes. The turbine/compressor keeps spinning adding pressure to the intake side until a pressure actuator opens up the wastegate. The exhaust then bypasses the turbine and the turbo is no longer adding pressure, protecting your throttle body and intake piping.
@anish4 Say you have a V6 twin turbo, the exhaust manifold from each set of 3 cylinders is routed to a separate turbo. So you would then have two air intakes, though it's possible to connect the piping if you wanted to.
I do not believe you actually explained turbo lag. You explained turbo spool time, such as accelerating from idle. Turbo lag is actually when the throttle plate is completely open, the turbo is compressing the intake at the desired pressure, THEN the throttle plate is closed, and THEN back to wide open very quickly. The delay time from the turbo being at full operational pressure, coming out of boost, and how quickly it returns back into boost......that is turbo lag. So, if you were racing, in full boost for a second or so, had to lift off the throttle for a split second and mash the throttle back down again......that delay back to go back into full boost is turbo lag. It may seem like a nit picking thing, but time to spool and turbo lag are two very different things.
From Garret's website:
Turbo lag is the time delay of boost response after the throttle is opened when operating above the boost threshold engine speed. Turbo lag is determined by many factors, including turbo size relative to engine size, the state of tuning of the engine, the inertia of the turbo's rotating group, turbine efficiency, intake plumbing losses, exhaust backpressure, etc.
+1. Turbo lag is exactly how Garret explains it on their website.
So, turbo lag is how long it takes for the turbo to get back on action after the throttle's been closed for a second.
You are correct, I've actually got a video explaining this technique that I'll be releasing in a few weeks. There are several forms of ALS, but this is one of them for sure.
not 100% true, the time it takes for a a turbo to get into boost is the boost threshold, lag is how long it takes to make full boost after its passed the threshold
lol, learned this the other day.
Exactly Leon, This "engineer" is explaining "Boost Threshold", Turbo lag can be explained by saying: To measure turbo lag the engine needs to be above the boost threshold, which is what this guy is explaining, when the engine is in the threshold apply full throttle and if it does not respond straight away that is lag.
greebuh Mmm exactly.
What do you think thermal expansion causes (some call this combustion)? High pressure gas that turns into high velocity gas when the exhaust valve opens...
2019 gang
I do hope to eventually get into VGT's and the like. I'm sure there are aftermarket turbos of the sort.
Ricer academy
Man, I remember sharing your channel on my Facebook yeears ago, like 5+ years. Still the only channel I've shared like that and said your channel simply deserves a share. Glad to see its doing well cause nobody explains it like you brotha!
Not sure what you're asking. I majored in mechanical engineering, and these topics fall within the category of mechanical/automotive engineering, yes.
What is the basis of your argument? When you add components, you add losses. If you were to analyze a pump with pipe flow, it becomes clear that to minimize the head loss, you want as few bends as possible, and a uniform diameter pipe. Integrating in an intercooler means more bends, more pipe, and various flow rate changes.
Wow. So I bought F150 Ecoboost about a year ago and was losing my mind trying to figure out what was happening when when I would ask for a lot of acceleration and didn't get it. I was also wondering why all of a sudden my driving style was causing slight spin outs. Great stuff, bro and thank you!
To add, if you translate amount of gas pedal to amount of exhaust gas your feeding the turbo, when there is no resistance that EngineeringExplained spoke of, you can only press the pedal slightly down for a brief period before the rpm is too high and you have to let off. So it makes sense that your not really effecting the turbo by reving in neutral. Compare that to when you start driving, you give the engine the resistance of moving your vehicle and it allows you to press the pedal and hold.
Instead of just feeding air directly to the engine (like in naturally aspirated engines), first the exhaust has to spool a turbine. It takes energy to spool up this turbine, causing a delay for the intake turbine to rotate. Once the intake turbine is rotating, it's forcing in extra air, hence the engine has boost.
Some air obviously gets through even if the turbine is not spooling, but it's not enough for the extra power that a turbo provides.
Allows for excess pressure to escape from the intake (before the throttle body) once the throttle is closed. This is so that the air doesn't have to force its way back through the turbocharger (compressor surge).
1. The size of the turbine affects the maximum amount of air that can flow through it effectively. At high rpms the smaller turbos can't pull in as much as air something larger (bigger piping means greater maximum airflow). Also, there are speeds where turbines are most efficient, meaning the pull in the greatest amount of air versus the energy used to pull in the air. Smaller turbines are more efficient at lower speeds than larger ones.
2. 1 bar of boost is 1 bar of boost, regardless of turbo.
Thanks for the response! And all your videos! Yeah, I'm having big time turbo acceleration loss in my car (noticeable from when I purchased it a year ago). Dealership is giving me a hard time saying that it's normal turbo lag, but it's gotten noticeable worse over time. Appreciate the info!
If the previous bearing was crap, yeah. Surge comes from pressure coming back through the turbo when you close the throttle valve.
Yep, it's been requested quite a bit so it's definitely on the to-do list.
Perhaps, aside from any losses associated with bringing the air through the turbo/intercooler.
I was looking for exactly what you explained. Thank you for the concise no BS tutorial, keep it up, and i wish you the best.
I just came across this video.... I understand how turbo lag works. I just want to say, you did a really good presentation!! good job.
Not sure where you get these numbers. 20 psi is high for just about anything. I don't know of any imports that stock run close to 30 psi. And the reason is it's too much pressure! 30 psi means your adding another 2 atmospheres of air pressure into each cylinder, that's pretty extreme. Yes, it can be done, but not without replacing all the components with higher strength ones. Also, diesels will run 20+ psi usually no problem (stock) because they are built with stronger materials.
Don't forget to mention the anti-lag systems some rally cars employ - I think it works by having an extraneous combustion right before the turbine while the engine isn't revving up like during gear shifts to keep the spool up. Makes for some awesome afterburn coming out of the exhaust pipe
on some small engines there is a vane called a governer that is like an accelerator petal. the flywheel has fins that act like a fan and the fan blows air over the governer and keeps the motor running at the same rpm. if there is load on the engine the rpm drops and the governer sends more fuel to the motor to speed it up and vice versa when it spins to fast (when the load is sudenly dropped)
@bobanppvc Better technology now. Lower mass turbines, less friction, twin-scroll, proper sizing, better materials. Lots of things make for improved spool time compared with older turbos.
Tightening up your BOV also can improve ON/OFF/ON throttle response, as it doesnt blow out the positive pressure as easily
Don't have a video on ECU's, except for tuning. I do have a video on traction control though.
Yep, I've got two videos on this if you're interested. "Anti-lag System - Explained"
@anish4 It would be possible, yes, but if they are geared differently one will spin slower, so this may cause undesirable results. If the exhaust spins faster than the intake, you'll be restricted of the amount of air you can pull in. If the exhaust spins slower, it would probably be more difficult to spool. Find a happy medium and it's probably good though!
Mustangs have larger engines than Evos, so not as much boost is needed to create the same amount of power. A mustang engine is twice as big or larger, so it creates a huge amount of power with lower boost levels, even though the actual amount of fuel/air burned will be similar.
You are just like my physics teacher who does not use big or extra diagrams yet explains the concept excellently
Pod filters are not illegal in Australia, they just have to be encased in a box like factory filters. If they are not in a box you will be given a fine and be asked to fix it.
@EngineeringExplained Finally, your statement about turbo size and boost is slightly inaccurate. Boost is added pressure, which comes from the amount of air the turbo can pull in. Since larger turbos can pull in more air than smaller turbos (using the same engine) they can create more boost.
Yes, if you're going to be creating a lot more power you may need to upgrade the cooling system.
You forgot something: Lower mass turbine= less power. A very interesting configuration is BMW's (which is used in the Cooper S, JCW) twin-scroll turbine which allows a wide powerband and high output. Also the twin turbo configuration (in some cases) with 2 distinctive turbo's which when the smaller turbo to spools up, the transition is made to the bigger one.
@hamdanae12 Correct, but at the expense of warmer air entering the cylinders. Less efficient, less powerful.
If I understand correctly, yes. Naturally aspirated engines won't really lag since the second the throttle plate is open, more air will enter the cylinders.
Could you elaborate? What's going to power this electrical system? It would have to be belt driven if it were to be powerful enough, or a powerful motor with a separate supply of energy. Either way, it would be parasitic or add mass.
Yes, but without a load it won't be able to produce much boost. It doesn't require much fuel to rev up an engine by itself; having the car in gear gives it resistance and will thus allow using more fuel and creating more exhaust gases, spooling the turbo.
First question: Turbo lag doesn't affect power, just how long it takes to get the power. The answer to your question is no, because the turbo will be forcing in more air, and therefore more fuel will be burned. The more fuel you burn, the more heat is created. More heat = more pressure = more power.
Second question. I should make one on this eventually. It's a good topic for sure.
VGT(or VTG or whatever, they all do the same thing in the same way;it's the same principle maybe some minor mechanical differences) tends to overcome the turbo lag issue(and many other aspects) by increasing the pressure of existing gasses therefore lowering the spin up time of the turbo. Almost all the new cars build today have variable geometry. You can google VGT vs regular or something like that.
Glad it helped you out, thanks!
It makes the psshh sound because it's a valve releasing pressurized air. As far as compressor surge I could have mentioned it but also could be another video. Great sound though.
To add to what EngineeringExplained said, the amount of turbo lag depends on a lot of factors. The main factor is the size of the turbo. So if the turbo is bigger, the turbine itself is bigger, which means its more massive, which means it takes more to get it moving. The amount of exhaust gas that your engine is capable of producing determines how fast it can get the turbo spinning. A smaller turbo in this case would mean less lag because its easier to rotate.
usually it is not the twin scroll design that reduces the lag. it is the fact that twin scroll turbos are usually smaller than normal, so they spool up faster.
the twin scroll design basically channels the exhaust gases through 2 separate pipes, one for cylinders 1-4 and one for 2-3 (on a 4 cylinder engine) so each stroke gases always goes on a different line than the previous stroke, since the stroke sequence is 1-3-4-2 (or 1-2-3-4)...that results in better gas flow into the turbine
Well I wouldn't say that big turbos require high rpms, they just require a lot of exhaust. Big engines that are low revving can easily do the trick as well. Big turbos are found on both, and honestly they're probably a lot more reliable on large displacement engines.
I'm not certain but I feel like I experience turbo lag a lot with my Veloster Turbo (it's my first car and first turbocharged car I've ever driven so very little experience). I'm about to go look into it but this video gave me a very good idea of what exactly turbo lag is. Great job EE
A mate once told me something about modified hot side housings with a slightly different intake angle on them so the exhaust hits the fins better for better low rpm efficiency, that could also be considered a factor. Also some turbines have shaped fins for that particular reason so a combination of the 3 should provide a high degree of efficiency
The only dude on UA-cam who can make a whiteboard interesting. Never miss an EE video.
If you reduce the amount or diameter of piping or intercooler volume you will have less volume to pressurise, resulting in less turbo lag. The spool speed of the turbo is typically not called turbo lag and ussually means the AR rating of your turbo is too high for your engine size or rpm application (wanting more boost at lower rpm vs higher rpm)
It's probably just switching gears, as you said, which causes the delay. It's an economy car so you can't expect incredibly quick shifting.
in repsonse to many, how to prevent turbo lag? or toreduce the ammount of turbo lag. One thing you can do is make the hot side piping smaller. say your using 2.5 inch piping to get the air to the turbo, make it smaller and it will take the same amount of exhaust gases and make them move with more force therefore creating a lower ammount of turbo lag
depends, small turbos are more efficient or practical under certain circumstances. My 335i has relatively small twin turbos but it means it takes less exhaust pressure to create boost, thus resulting in a car that has low turbo lag and turbos that work at lower revs. BMW went with smaller twin turbos instead of a larger turbo to avoid turbo lag and still push some decent psi.
Good video, keep it up. Nice camera by the way, definitely looks much better haha.
Not a whole lot, the engine needs some form of resistance, and friction alone doesn't provide that much. With an engine revving and the car in neutral it won't produce enough exhaust to really spool up the turbo.
@EngineeringExplained I wasn't trying to say larger turbos *can't* create more boost, just that they don't always. It sounded to me like sheennick12345 was saying a smaller turbo just necessarily means smaller boost. You can make a smaller turbo produce a lot of boost but it will still produce less air mass than a larger turbo at the same psi, resulting in less power.
EGR Explained please, I really like the way you explain things and the diagrams are awsome. EGR!
@EngineeringExplained and also the turbolag in the twin-config is smaller because it it easier to spin two small turbines rather than one larger one. I have such config in my RS6. The lag is barely noticeable
I'm onboard with your turbine/compressor terminology, but why are you bringing up submarines?
I would love to see you make a video explaining twincharging. The polo gti 6r uses twincharging to create roughly 180PS from a 1.4 litre block. Stock. Stage 1 tunes have seen 210PS and I think a stage 3 one (Hurdy on UK polos.Net) I think was creating almost 400ps from the same 1.4 litre block. That astounds me and I'd live to hear your take on that, Engineering Explained.
@sheennick12345 My point was that turbo lag isn't really an issue in racing, and the parts that were problems have been mostly overcome with anti-lag, nitrous, etc to spool the turbo off the line. For the everyday driver it might be a small issue in some situations. For instance, when I'm accelerating up a steep hill and I upshift too early my RPM drops to around 2,000 where I'm out of the compressor map for my turbo.
Im a big fan of engineering explained and yes im subscribed.
I don't mean to sound like a bad back seat driver but....i dont feel that you have covered the entire question of turbo-lag.
Turbo lag is caused by the exhaust housing being big.
For eg...A GT35R turbo with an A/R 0.64 rear vs A/R 1.06 rear.
0.64 will come on boost much earlier making a lot of low to mid range power but may run out of puff earlier in the top end.
But with the 1.06 will make power from mid to top end.