@@1loumellor51 the wise man would simply share this knowledge,with clear and concise references to guide us to light. Use your knowledge for good and not impertinence👑
so the thing is, all turbo brands, reputable ones atleast, have a efficiency chart for their turbos, its not concrete but it puts you in the ballpark. the tools are out there to pick the right turbo for a civic but everybody just looks at what someone else has that is making the power they want, slap it on and think its fine. ive been telling people for years that 10lbs on a small/oem turbo is not the same as lets say a 6266, alot of good information in the vid, alot of the street hondas are going backwards with their builds because they dont do the research but with turbos being more efficient, most dont know the difference and end up buying 3 or 4 turbos for no reason. the biggest issue with compound setups besides the cost, is trying to fit it all within an engine bay. put the turbos too close and one cant perform as best as it could, get the manifold design wrong and youve negated the benefits etc. it adds complexity that most are not willing to do aside from a sema car
Good stuff! I've built a couple compound and twin charged setups in the past. Love the braud power band. Another way you could convey the small turbo is a displacement multiplier (big turbo too). 2.4L x 2bar is 4.8L 4.8Liter will spool the Big turbo easier. Can't wait to see this setup. Hopefully on your awd car.
Great video, compound turbo setups are so rare in the aftermarket for non diesel engines but as you alluded have so many benefits. Group b cars like the Lancia Delta Integrale S4 used a supercharger turbocharger compound setup, it was a lot more complicated and probably a lot less efficient and reliable than a compound turbo. For a street or roadcourse driven car this setup would make a lot of sense to try out. In the coming years we'll see hybrid electric turbos make their way into the aftermarket since the OEMs are already using them in a bunch of Porsches, Audis and whatever else. Once that happens spooling big turbos will have a whole new dimension available, and the most interesting part is how the electromotor portion of the hybrid turbos doesn't only allow for near instant turbine response, but also can be used for fine boost control by acting like an alternator (electric regen), and can also recover a bunch of power to charge its own power supply. Hmm, i wonder what would happen if we combine the two lol.
Just randomly saw this and subbed. You took real world knowledge and experience and converted it into an easily understandable, and clearly explained lesson thank you subbed.
No there differently is but I don't think it will work as good as we think it will remember there not trying to go 200 plus down a track it's more for low end pull is why they do it
It's already been proven to work. I'm not re-inventing the wheel. On the drag racing side, you run much larger turbos with a target of efficiency over spool time and up with more power per psi of boost.
It works so good I diesel because the diesel uses heat to make it's combustion thats why it doesn't use a sparkplug it doesn't need it because the compound turbo setup makes heaps of it thats why it work so dag good on them.... but hey like I said I'm building something that hopefully come out on some next level sh@$ and wanted to build the first k series awd compound turbo setup so if they really do make it happen the way he says on the video that they already have it done and it's going to be dyno tuned soon i can not wait for it like you don't understand i can't wait not only dyno it but have the car running like it should something you can drive everyday anywhere I'm in sh#$ if it works out as good as it sounds I'll give you my word I'll have the boys at humble do my engine/turbo setup my word!!!
It honestly makes a lot of sense... I've been thinking about super charging and twin turboing my charger to get a similar effect. I'm definitely gonna save this video for when I start my build.
You seem to forget you have to split the exhaust drive pressure between the two turbos. From all the math I have done trying to compound a gas engine (BMW). You need over 40 psi to have the drive pressure , to spin bolth turbos and be more efficient than a single set up. It's like the opposite of multiplication on the exhaust. You have to divide the exhaust drive pressure. Turbo spins based on the pressure difference on the turbine ... You just took a bunch of pressure to spin the first turbo , now hope you have enough to spin the big one.
You’re incorrect and dramatically overthinking it. The small turbo raises the displacement of the engine. Giving the bigger turbo more exhaust gasses. The small turbo operates as a standard turbo setup powered by the engine. The big turbo operates as a standard turbo setup powered by the big engine and the turbo. The air temperature multiplication is significantly less. Running 1 turbo at 40+psi generates more heat than the net of 2 at 14.5
@@humbleperformance how is it a standard set up when the first turbo does not breath exhaust to atmosphere? Its turbine is exhausting into a pipe , that has back pressure , created by the energy required to spin the second turbo. The bigger question? At what power does a compound become more efficient than a single ..... Math says 41 psi on a 2.8 BMW that redlines very close to 9000 rpm. Look up alien engineering . The only BMW I know running this set up. He will tell you the same thing I am. It's physics
You can say a turbo makes less heat at 14.5 Guess what ? That compressor map has a island .... That's the coldest air charge .... If you underspin a turbo , it makes MORE HEAT than it would in its efficiency island. 14.5 of psi on a big turbo is less efficient than a higher boost number.
@@humbleperformance”raised the displacement of the engine” Check it guys he bumped his engine displacement up with a second turbo he’s running a K30 now
Fun video and informative. I's hilarious that you used an example of trying to spool 1000hp on your way to work, as if that's entirely useful on the street. Even 500hp is practically unusable on the street.
I have have had a pleasure of driving a same car (2.5 s60) with similar power on both set ups, high 500s on single, mid 600s on comp. Not my car, but I can tell you it was like drivig completely different, faster car, absolute pleasure to drive everywhere : twisties, city, motorway/highway. Never took it to a track as it wasnt my car but owner did let me drive it 300km to next city and back the next day, that is the road I know well been on it since childhood and drove it many times in all sorts of cars, sometimes even both directions in the same day. Two mountains to cross, a lot of fast bends, big sweeping corners, but also a decent amount of tight slow twisties. It also has long fsst stretches with some slight curves which aren't a problem till you are doing over 200kmh ... what a joy in a compound car that was I loved every bit of it slow or fast, its like driving a high comp big liter n/a engine, it kind of reminded me of my old k24 euro accord, on steroids. I would absolutely love to compound a 10g civic with 2.4 in it ... but for now my 10G 1.6 i-dtec is getting a compound from crv till I figure how to swap with 2.2 idtec and compound that.
I really enjoy the banter in fb! The only real downside is complexity and space. Sounds like you figured it out. Jarvis had his figure out really well too. Anti lag and nitrous are really hard on the engine, another win for compounds
ive wondered for years why smaller engines haven't taken advantage of this. compound turbos are really popular in the diesel world and has been for years. I absolutely love this idea for hondas and other small engines
the work it takes just makes me want to make the boring power of an LS. granted I'm a poor, but it takes hella effort to get drivability out of different platforms. mad respect to the build and should the difference in torque curves
love this video and other things you could add when talking about spool times is turbo converters and transbrakes and how these can also close the gap in spool times just like ani lag.
could also talk in terms of air mass instead of air volume, much more intuitive since cramming more air mass = more power. cold air = more mass, hot air = less mass
Hot air big Cold air small Sticks more in someone's head than air mass. The purpose of the video is simplify these concepts and be extremely digestible.
@@humbleperformance understandable, love the videos man. Can't wait to see the results and I'm also curious on exhaust backpressure if the small turbo causes a bottleneck when targetting for that big horsepower of the big turbo or it doesn't cause any bottleneck at all
The wastegates are used to bypass the backpressure in the small turbo housing. You then re route it into the big turbo so all back pressure is standard for the large turbo.
Diesel world has been playing this game for a long time. BMW had a factory compound also didn’t they? Seeing some compound 4 cylinder builds excites me.
I think the term he was trying to think of was CFM. That would have simplified much of his discussion. The other missing part of the discussion is how it works in practice, compounding has been done since the 70s-ish. The Problem at the time was two fold, 1) basic turbocharger technology, metals used flow rates etc. 2) controls them. Today we have come light years in computing power, turbine speed sensors wastegates etc. all they really had back then was vacuum lines some check valves and a couple of solenoids. The biggest problem then and now is still packaging all these parts have to fit somewhere managing the heat is another problem. Looking forward to the next vid in the series.
@ true, I only say that because it seemed like the host was searching for words. Air speed, density, pressure, temperature humidity, volume, etc affect the equation. Not trying to be a jerk just saying that while trying to make a casual video is great a script would help with some of the pauses in speech.
One thing to consider is that the PR run on each turbo is the square root of the total PR. So you end up running high flow at low PR. Most turbos today have aero for high PR and you will be “off the map” to the bottom right. Unless you go Giant turbo if you want to stay on the map (especially for the atmosphere turbo),,, OR talk to someone like TiAL/Xona who have three specific aero packages and are coming out now with a low PR optimized aero package. Perfect for compounding. There are some out there already
@@humbleperformanceit’s not just about size, it’s the aero design. Most modern turbos are designed for single turbo, high PR aero. Which is the opposite of what you need for compounding. You need high flow at low PR. Most turbos would end up very inefficient with compounding. Yes, spool fast and make tq faster, but all create TON of heat.
Which once again, is why turbo sizing is critical. Aero is obviously an important factor, but ultimately, sizing is the major contributor factor. In the same way a 5 star safety rated compact sedan is less safe than a 1 star rated SUV in a collision. Or a world champion featherweight boxer gets destroyed by an average heavyweight. There’s a hierarchy that cascades down.
@@humbleperformance you keep saying sizing when I am saying design. It’s not just the size. It’s the design/aero as well. Two turbos of the same size of 68mm could have dramatically different results in compounding. But they are the same “size”. One optimized for 1000hp (100lb/min) on a 2.0l as a single turbo would be optimized for ~5 PR. Run that as a compound and it would need to flow 100lb/min at 2.25 PR. It will be way off the compressor map. Probably less than 50% efficient. Sure, yes, you could size up to something like a giant GT55 to get on the map. “Sizing”. Or you could use aero optimized for low PR and keep a smaller turbo and achieve the same results, less weight, less space etc. So I disagree that sizing is the most important. It’s the package. Aero first since options exist that are suited for compounding; then size. Isn’t the stated goal of compounding to optimize the setup (power, efficiency, IAT etc?). So I say, why be barbaric with unsuited aero, and have to pick inappropriate sizes 🫶🏼 If you’d like, I can email you compressor maps to demonstrate my assertion.
A turbo optimized for 100lb/min at x PR is always going to fall within a certain size range because of the cascading effect. You’re speaking at the low, nitty gritty level, when ultimately it’s influenced by the size of the turbo. Your target pressure and flow rate will always be limited by size. Both turbos can be 68 compressor inducers, but the exducer is also important, the turbine inducer and exducer is also important. You’re not going to find major variances in turbos when the numbers are the same.
In theory it is good,but making it work is a real pain in the as. You need a lot of calculations on what turbos you need to run,boost control is pain it is raised so fast.You don't mention when using compound setup always make less power on the same boost than single turbo. You say efficiency-if you want good efficiency,you need to put an intercooler after every turbo, that's what intercoolers do -increase efficiency. So imagine 2 turbos 2 intercoolers so much piping,you will run out of space.
You’re dramatically over complicating it. It’s not difficult at all nor does it require what you think it does/it doesn’t operate the way you think it does. Compound setups make more power at same boost than singles. Yes, ideally you would intercooler between stages, but it't not required. I didn't run out of space, I already did it.
Actually, one large intercooler is far better, because you're starting with very hot air, and the delta T is high, therefore the the one intercooler is very efficient.@humbleperformance
Conversely, you lose available volume if you aren't taking steps to increase density. The point of I/Cing between the stages is to raise the density (increasing the available volume for air to occupy allowing for more air) that the high pressure turbo is multiplying to increase the final flow-rate of the turbo. If the IC ONLY comes after the high pressure, youre sending less dense air into the small turbo to compress, whereas intercooled before and after the small turbo you're giving the small turbo more mass to send to the engine and therefore more power. So while you might have a larger temperature delta with a single heat exchanger before the intake, you end up with less mass by the time it reaches it.
Really good description of the setup and how it works. One thing that would have been nice to touch on is why the turbos are sized differently. Since it sounds like with 2 same-sized sequential turbos, neither would be 'breaking a sweat'. I think the real answer has to do with the size of the larger turbo's outlet matching the smaller turbo's inlet?
What? This point was directly addressed and the entire point of the video lol. You can run 2 of the same sized turbos or closely matched turbos and have benefits in a compound setup as well. Ie. Running 2 turbos of the same size to reduce the load is more efficient than running one strung out.
@humbleperformance I mean why make the bigger turbo the low pressure turbo and the small turbo the high pressure turbo. How do you size the turbos, etc. I did get the compound turbo setup in general being the point of the video, I just think the sizing aspect was glossed over. If you use a too small turbo for either compound turbo, what will happen, etc.
awesome video cool idea diesel trucks have used this for a long time but if you want the same spool as a small turbo and the flow of a big single but without the added weight and complexity of of a compound system look into twinscroll turbos same idea but inside one turbo and what makes that amazing is dual variable valve timing as you can adjust your intake and exhaust timing to get more exhaust velocity with the same flow rate very very helpful at low rpm and this is exactly why i love my jdm subaru as they come with this from the factory also when your doing compound you can spread the boost thresholds too far apart otherwise the small turbo becomes a restriction if you are trying to make massive power with the big turbo, when done right than can make insane power with quite a low boost threshold essentially all wrc cars use this now as it helps alot with mid corner power, my goal with an ej is to use a stock block with aftermarket forged pistons ring gapped correctly with a twinscroll small frame garret turbo and be able to make full boost 3k or under and peak power around 500whp, not as outright fast as some high boost 2l cars but the low rpm power should be night and day and should make for an incredible car to drive
Agree they are different. Each exhaust pulse leaves low pressure behind as it flows down the runner until ex valve closes and it settles out. If the next cylinder’s ex pulse enters that low pressure it’s potential force to be applied to the turbine is slightly reduced. Twin scroll manifolds and turbine housings divide those pulses all the way through the housing volutes based on firing order so they never overlap and effect each other. Generally each volute/scroll are the same size/AR. There are variable AR twin scrolls with different sized volutes controlled by a valve at the turbine inlet altering volute usage based on demand/conditions, but that’s more comparable to variable geometry and doesn’t offer the compounding aspect he was describing, just different turbine AR with still one fixed compressor geometry. Not 2 separate sized turbos. As far as I know subaru doesn’t offer such a setup and it might annoy you to hear mitsubishi does. If you want high power mid corner from an ej, make sure it keeps oil pressure. Often overlooked killer of those engines.
WRC antilag tech uses bypassed boost directly into the collector with added fuel. Anyone can do this but people don’t understand that you can turn your exhaust manifold pre turbo into a a combustion stage like a turbine engine.
My small T3/T04E turbo won't even spool fast, I think I have a boost leak because it used to spool way better, or it's just dying because it's 20 years old. It has hardly any shaft play though so who knows
Is because is and old turbo the technology is garbage. I have a smaller pulsar turbo than the t04 I used to have before. It spool quicker and makes more power.
@@delatuned Yeah it's an old journal bearing turbonetics turbo. It used to spool quick just a couple years ago though so I'm thinking boost leak, it sounds weird around the bov when spooling so I think it might be faulty
So one thing I've always wondered when I see these compound setups is why don't the outlet on the compressor side of the small turbo blow into the intake side of the big turbo why is it the the big turbo outlet on the compressor side blow into the small turbo ??
Teknotoys 240sx runs a compound setup and held the 4cyl world record for a while… only dethroned because it’s been inactive for a few years. Info is hella valid.
Garrett has a turbo sizer to get you in the ballpark of the turbo you need. Let me address the difference in some setups: the large laggy turbo that has massive power near redline will help reduce the massive torque down low in the launch rpm range. 3-4K depending on your tires which will lead to snapped axles and broken transmissions. So you launch, don’t break and now all your power is on the top end. Where your rpm’s will drop 1.5-2k rpm. So now you’re staying in that big power portion for the rest of the run. If you want big torque down low get ready to have replacement parts online. Big torque is cool in a street car but not full blown comp drag racing
Been theory crafting this for 15+ years sadly haven't been able to execute it due to financial reasons. You have to be very careful the way it's plumbed for this to work on these high revving Hondas. You need to run the exhaust primaries into a low angle merge collector directly into a large e-gate that feeds the big turbo. If you get it, you get it.
Not at all over complicated. You will work one turbo way hard and the other not at all if you can't control the drive pressure. You will be less efficient than a single without control. Unless you get stupid lucky and the system and turbo sizes balance out .... Good luck unless you copy exactly someones working example they took the time to develop correctly. ( It will probably be just like the o.l. description... Big e gates.)
Volvo created a engine that injects air into the exauat side of the turbine to reduce lag. I wonder that is something you may want to exprieunce? Could be a solution? Equipped with a powerful compressor that efficiently charges up, this product stands out as a remarkable piece of technology. Accompanying it is an exceptional educational video that enhances the user experience by providing invaluable insights and guidance.
For racing categories that require a turbo inlet restrictor (think rally) to limit power, would there be any advantage of a compound turbo setup? I feel as though you’re still limited by the airflow and any benefits from compounding boost would be lost? Perhaps I’m thinking about this wrong?
One of the big key points is to pick two turbos that meet the goals but also keeping them operating at the same PR at there optimal efficiency island in there respective maps. Welcome to the performance diesel world! Lol
In a compound setup you are going to need a much bigger turbo for the top end. The single turbo that you brought up in your example there is making 1000hp at a significant pressure. The question then becomes, will your engine be able to handle that pressure multiplied by the small turbo? What you have to do is size the turbos by flow. A single running 56+psi to make a 1000hp is not going to make that in a compound setup unless your engine is capable of withstanding 100+psi. You will be limited on pressure so you will need a turbo capable of flowing enough air to make 1000hp at around 20psi or so. You also won't be able to run the smaller turbo at 30-40psi without sending your head to space as well. It's a matter of finding the balance of sizing a small turbo that will minimize lag, yet have decent power under the curve of the large turbo within the pressure limit. Then sizing the large turbo to meet your power goal within the pressure limit.
Gale banks has said "psi does not equal volume. Just because it says 20lbs on both turbos doesn't mean the same amount of air is being moved. It's why I can have less boost on one setup and make more power than the other spinning it to the moon"
Just a clarification Twin turbo refers to twin turbos of the exact same design The ford 3.5L v6 ecoboost is the perfect example here Compound also known as sequential turbos is the one your talking about here Many semi trucks use compound turbos An example of a small displacement diesel that runs compounds is the nissan titan xd with the cummins diesel v8
No it doesn’t. See twin turbo FD RX7. (Two different turbos) Sequential and compound is not the same thing. Compound is not ‘also known’ as sequential, it’s completely different. Parallel, Sequential, and Compound are the three types of multi-turbo setups. Twin denotes 2 turbos, it does not mean identical.
This people always doing some crazy stuff but bringing data this is just next level technically now educating everyone else to be builders not "just fast"
you should look into the variable geometry turbo chargers holset and i believe ihi and garret make them. it can eliminate a twin turbo setup just like the diesel industry did years ago.
Exactly what I was thinking when looking at diesel compound turbo setups making more psi at a lower rpm too bad I’m stuck on more amperage and voltage at a lower rpm with my k series ⚡️😅
Question: if the smaller turbo is further compressing air from the large turbo, would the air exiting the small turbo be super heated? Specifically, once the large turbo reaches optimal range for it's size.
Many people do compound on small diesels in EU its just not much documented on it so is should somewhat work with a Honda engine also for a street use.
When does the small turbos back pressure become an issue, if and when can the waste gate be used in between turbo manifold and big turbo bypassing excess back pressure from small turbo?
As the boost ramps up and the back pressure builds up, are you able to "exhaust" or dump enough of the exhaust gases and quickly enough through a single (say 45mm) wastegate on the high pressure turbo? I ask because I also assume the intention is to keep the hot side small enough to still see the benefits of a much quicker spool. Interesting to see this work on an internally gated T4 Twinscroll B2 EFR Turbine housing as the primary turbo using a bigger turbo to raise the pressure in a 700HP streetable setup.
@@humbleperformance I want to see the art perfected compounds are very common in diesel but gas is a different beast. I was planning on doing a compound set up and even have most of the parts to do it now but a lot of smart people have tried compound and it hasn't worked out. There's alot of science that needs to be figured out on the gas side especially for something that's not just for a drag application. I think alot of the principles hold true small turbo first after engine to spool faster and draw through the larger turbo for intake. But boost and exhaust control I think is still an unknown. That's why I'm eager to see specific testing and solutions for street/race application. Would also be interested in someone testing inter-cooling after both turbos as this should theatrically be the most efficient/best use of compound charging especially for a gas engine.
Good explanation, but explaining with pictures or drawings would make it 10x better. I'd say a lot of people just go for the number, I understand if you are drag racing the car, but I'd prefer a small twin scroll manifold with a decent size turbo to avoid overcomplicating things
I dont think id want to daily a 1000hp race car. For just strictly race purposes id assume the nitrous/turbo setup would run faster than the compound turbo setup youre referring to? Just trying to get an idea of where a car with this setup would sit. Definitely unique though.
This has been common in the diesel world since WW2 and the old Detroit engines blowing turbos through a blower. I'm honestly surprised the Honda guys don't seem to use it all the time
But like i said i love yall channel alot and if you make it happen ill be going that way myself trust me on that one its Just like the supercharge/ turbo setup up the super down low and the turb up top
Good stuff Kenny! No doubt compounding works, but going a step beyond the basics shown, where do you reach limitations, as in, when does the smaller turbo start to become a limitation? My understanding is (although you're draining HP from the crank), compounding isn't limited to turbo's, and so you can have a turbo, preferably a larger flowing one, to compound incoming charge for a blower (ideally a more efficient design like a Whipple), often referred as twin-charged. Same can occur though, where at a given point, the compressor closest to the intake valves can become a restriction. Edit* I guess, what I'm curious to know, is what ratios between the big vs small are optimal before you see the small becomes a restriction within mid-high rpm ranges?
If we asum your engine is breading the same amount per revolution a cross rpm range, you can simply calculate briefly like if the 1000hp turbo makes full boost @8k you get one bar of boost with the small turbo, you should get the big one spooled @ 4k Now if you have inter cooling between the turbos, you should be able to rice the boost of the whole system and make the 1000hp @4k if the engine can handle it. Ewen better, if you have a small turbo that gives 2.5 bars of boost @ 2k you might get the big turbo spuled @ 2.3k rpm The big turbo sees a 2l engine @8k rpm and when you put one bar of boost with the small turbo @4k rpm your big turbo sees a 4l engine @4k rpm and soools like that. Be honest on what your power goal, or your torque goal is, what can the engine and gearbox handle, don't go to big with the small turbo, the big one will make the power anyway,
You either disable VTEC and change Cams so it's always running on DOHC, Or Adjust VTEC to 2500rpm so the ECU is not running on single cam before VTEC so Both Cams overlap at peak torque so no power loss, this is where you map in boost for instant torque no turbo lag.
I'm with it, so Kenny tell me, if I'm shooting for 600 hp and I want all that lower down low too, up to peak hp and I wanna do this twin turbo compound set up, what two size turbos would be appropriate for 600hp?
The best piece of information to know about turbos, is that they're not as good as superchargers. Put a blower on your car. Centrifugal, roots, twin screw... whatever. You will like it more.
Have you figured out the backpressure limits of these systems? The smaller turbo exhaust housing will always be the limiting factor. First turbo hold 1:1 pressure to backpressure ratio when its in its efficiency range but as soon as the second turbo is active the flow is greater than the small turbo housing can flow therefore doubling backpressure resulting in a much lower overall system efficiency. Now at what point does this become a system limiting factor? So far nitrous oxide is still the best way to inflate engine power in order to spool larger turbochargers. I see that max power is not your end goal so yes maybe compounds can be a great thing here.
@@humbleperformance I didn't see anything in the video describing your wastegate control strategy. Have you measured backpressure at all?Enlighten me because it doesn't work the way i think it does.
Explaining how to make it work is beyond the scope of the video. There’s also many different types of control strategies people employ. If you want to find out how it works, try it yourself.
Its not about psi. Everyone focuses on that number when you should be focusing on the cfm that the turbo is capable at flowing and where you will be on the compressor map efficiency. As for the solution to faster spools there are a few ways to solve this today and has been for a number of years. People just don't impliment them like they should. Compounds are used often in the diesel trucks to reach 4, 5 or 6 bar much much faster compared to a single setup.
With compound you get the acces to a bigger turbo and get it spooled with the small one. Its a beast setup, I did a couple, complex, but unbeatable for the amount of boost you can make with low backpressure and from low rpm too
Small turbo=less efficiency is not good statement. There are small turbos with really high efficiency, same as big one. But it's efficient in particularly low mass flow. Big turbos are efficient at bigger flow numbers. Design of compressor wheel and compressor housing is what determines compressor stage efficiency
@ well not directly, but most people usually get them to setup shift cuts and no lift shift to carry boost into the next gear. Do you think this setup would be quick spooling to keep boost levels high between gears on syncho transmissions where letting off between gears is needed
Once again, the dogbox is not relevant in this conversation. You don’t have the full understanding of the benefits of a dogbox. You can do exactly what you’re talking about with a big turbo synchro car minus the no lift part.
I feel sequential turbos would be more suited for awd civics due to much more torque but I guess the only way to find out for sure is to try and I dont think ive ever seen a sequential turbo k series
still one of the best intros on youtube
By far my favorite
It's crazy I get emotional it's so good
But by the end of the video I wondered what rock this dude has been hiding under to not know about compound turbo setups
Now we need a video of the conpound turbo setup in action, so we can all try and copy
it's coming. theres ~2 hours of footage of building the setup lol
@@humbleperformanceWE CANNOT WAIT🤤🤤🤤🤤🤤
It's been done sooo many times
@@1loumellor51 the wise man would simply share this knowledge,with clear and concise references to guide us to light. Use your knowledge for good and not impertinence👑
There's actually a genesis coupe running this setup and mustang that both just set records for each chassis
so the thing is, all turbo brands, reputable ones atleast, have a efficiency chart for their turbos, its not concrete but it puts you in the ballpark. the tools are out there to pick the right turbo for a civic but everybody just looks at what someone else has that is making the power they want, slap it on and think its fine. ive been telling people for years that 10lbs on a small/oem turbo is not the same as lets say a 6266, alot of good information in the vid, alot of the street hondas are going backwards with their builds because they dont do the research but with turbos being more efficient, most dont know the difference and end up buying 3 or 4 turbos for no reason. the biggest issue with compound setups besides the cost, is trying to fit it all within an engine bay. put the turbos too close and one cant perform as best as it could, get the manifold design wrong and youve negated the benefits etc. it adds complexity that most are not willing to do aside from a sema car
Good stuff! I've built a couple compound and twin charged setups in the past. Love the braud power band.
Another way you could convey the small turbo is a displacement multiplier (big turbo too).
2.4L x 2bar is 4.8L
4.8Liter will spool the Big turbo easier.
Can't wait to see this setup. Hopefully on your awd car.
100%.
Wow I'd love to share some beers with ya and hear about your twin charged setups
Can't wait to see your dyno results with a compound setup on a k series 👍👍👍
I perfer a twin charge k😮
I wanna see one on a j series
Great video, compound turbo setups are so rare in the aftermarket for non diesel engines but as you alluded have so many benefits. Group b cars like the Lancia Delta Integrale S4 used a supercharger turbocharger compound setup, it was a lot more complicated and probably a lot less efficient and reliable than a compound turbo. For a street or roadcourse driven car this setup would make a lot of sense to try out.
In the coming years we'll see hybrid electric turbos make their way into the aftermarket since the OEMs are already using them in a bunch of Porsches, Audis and whatever else. Once that happens spooling big turbos will have a whole new dimension available, and the most interesting part is how the electromotor portion of the hybrid turbos doesn't only allow for near instant turbine response, but also can be used for fine boost control by acting like an alternator (electric regen), and can also recover a bunch of power to charge its own power supply.
Hmm, i wonder what would happen if we combine the two lol.
Been following this on FB. This man is a genius lol
Eh. He didn’t figure anything out 😂
Just randomly saw this and subbed. You took real world knowledge and experience and converted it into an easily understandable, and clearly explained lesson thank you subbed.
And it's so crazy that this been around for years people just got to do research
Diesel people have been doing it forever and car people are still saying there's no benefit.
No there differently is but I don't think it will work as good as we think it will remember there not trying to go 200 plus down a track it's more for low end pull is why they do it
It's already been proven to work. I'm not re-inventing the wheel. On the drag racing side, you run much larger turbos with a target of efficiency over spool time and up with more power per psi of boost.
It works fantastic on diesels so I can only imagine using it on as efficient of a motor as something like the k series
It works so good I diesel because the diesel uses heat to make it's combustion thats why it doesn't use a sparkplug it doesn't need it because the compound turbo setup makes heaps of it thats why it work so dag good on them.... but hey like I said I'm building something that hopefully come out on some next level sh@$ and wanted to build the first k series awd compound turbo setup so if they really do make it happen the way he says on the video that they already have it done and it's going to be dyno tuned soon i can not wait for it like you don't understand i can't wait not only dyno it but have the car running like it should something you can drive everyday anywhere I'm in sh#$ if it works out as good as it sounds I'll give you my word I'll have the boys at humble do my engine/turbo setup my word!!!
Great info and thank you for breaking it down. Turbo spooning is the way to go.
It honestly makes a lot of sense... I've been thinking about super charging and twin turboing my charger to get a similar effect. I'm definitely gonna save this video for when I start my build.
Great breakdown for the community, Keep doing your thang ! Much love from Jersey!
The more you teach me, the more I decide to stay N/A on my kswap and and supercharge my s2k
You seem to forget you have to split the exhaust drive pressure between the two turbos. From all the math I have done trying to compound a gas engine (BMW). You need over 40 psi to have the drive pressure , to spin bolth turbos and be more efficient than a single set up. It's like the opposite of multiplication on the exhaust. You have to divide the exhaust drive pressure. Turbo spins based on the pressure difference on the turbine ... You just took a bunch of pressure to spin the first turbo , now hope you have enough to spin the big one.
Other issue, you boost stage one, now you have hotter air going into turbo 2. The heat is compounded as welll.
You’re incorrect and dramatically overthinking it.
The small turbo raises the displacement of the engine. Giving the bigger turbo more exhaust gasses. The small turbo operates as a standard turbo setup powered by the engine. The big turbo operates as a standard turbo setup powered by the big engine and the turbo.
The air temperature multiplication is significantly less. Running 1 turbo at 40+psi generates more heat than the net of 2 at 14.5
@@humbleperformance how is it a standard set up when the first turbo does not breath exhaust to atmosphere? Its turbine is exhausting into a pipe , that has back pressure , created by the energy required to spin the second turbo. The bigger question? At what power does a compound become more efficient than a single ..... Math says 41 psi on a 2.8 BMW that redlines very close to 9000 rpm. Look up alien engineering . The only BMW I know running this set up. He will tell you the same thing I am. It's physics
You can say a turbo makes less heat at 14.5 Guess what ? That compressor map has a island .... That's the coldest air charge .... If you underspin a turbo , it makes MORE HEAT than it would in its efficiency island. 14.5 of psi on a big turbo is less efficient than a higher boost number.
@@humbleperformance”raised the displacement of the engine”
Check it guys he bumped his engine displacement up with a second turbo he’s running a K30 now
Fun video and informative. I's hilarious that you used an example of trying to spool 1000hp on your way to work, as if that's entirely useful on the street. Even 500hp is practically unusable on the street.
My last one for today just cannot wait your idea come to life
Still hands down thr best intro on youtube!!! 🔥
I have have had a pleasure of driving a same car (2.5 s60) with similar power on both set ups, high 500s on single, mid 600s on comp. Not my car, but I can tell you it was like drivig completely different, faster car, absolute pleasure to drive everywhere : twisties, city, motorway/highway. Never took it to a track as it wasnt my car but owner did let me drive it 300km to next city and back the next day, that is the road I know well been on it since childhood and drove it many times in all sorts of cars, sometimes even both directions in the same day. Two mountains to cross, a lot of fast bends, big sweeping corners, but also a decent amount of tight slow twisties. It also has long fsst stretches with some slight curves which aren't a problem till you are doing over 200kmh ... what a joy in a compound car that was I loved every bit of it slow or fast, its like driving a high comp big liter n/a engine, it kind of reminded me of my old k24 euro accord, on steroids. I would absolutely love to compound a 10g civic with 2.4 in it ... but for now my 10G 1.6 i-dtec is getting a compound from crv till I figure how to swap with 2.2 idtec and compound that.
As long as gale banks doesnt watch this, you're good.
This is 100% correct right here
I really enjoy the banter in fb! The only real downside is complexity and space. Sounds like you figured it out. Jarvis had his figure out really well too.
Anti lag and nitrous are really hard on the engine, another win for compounds
I agree 100% the biggest downside is the packaging. The complexity it's really high, people just heavily overcomplicate it.
ive wondered for years why smaller engines haven't taken advantage of this. compound turbos are really popular in the diesel world and has been for years. I absolutely love this idea for hondas and other small engines
i learn so much from your videos and comment responses. thank you
the work it takes just makes me want to make the boring power of an LS. granted I'm a poor, but it takes hella effort to get drivability out of different platforms.
mad respect to the build and should the difference in torque curves
love this video and other things you could add when talking about spool times is turbo converters and transbrakes and how these can also close the gap in spool times just like ani lag.
could also talk in terms of air mass instead of air volume, much more intuitive since cramming more air mass = more power. cold air = more mass, hot air = less mass
Hot air big
Cold air small
Sticks more in someone's head than air mass. The purpose of the video is simplify these concepts and be extremely digestible.
@@humbleperformance understandable, love the videos man. Can't wait to see the results and I'm also curious on exhaust backpressure if the small turbo causes a bottleneck when targetting for that big horsepower of the big turbo or it doesn't cause any bottleneck at all
The wastegates are used to bypass the backpressure in the small turbo housing. You then re route it into the big turbo so all back pressure is standard for the large turbo.
Amazing video. Finally explains how boost works to people.
Thanks for the compliment!
Diesel world has been playing this game for a long time. BMW had a factory compound also didn’t they? Seeing some compound 4 cylinder builds excites me.
That’s how guys are able to tow with awesome egts and still have top end 👌🏽
I think the term he was trying to think of was CFM. That would have simplified much of his discussion.
The other missing part of the discussion is how it works in practice, compounding has been done since the 70s-ish. The Problem at the time was two fold, 1) basic turbocharger technology, metals used flow rates etc. 2) controls them. Today we have come light years in computing power, turbine speed sensors wastegates etc. all they really had back then was vacuum lines some check valves and a couple of solenoids. The biggest problem then and now is still packaging all these parts have to fit somewhere managing the heat is another problem.
Looking forward to the next vid in the series.
Flow rate is barely a portion of the conversation. Understanding pressure ratios is the single most important aspect.
@ true, I only say that because it seemed like the host was searching for words. Air speed, density, pressure, temperature humidity, volume, etc affect the equation. Not trying to be a jerk just saying that while trying to make a casual video is great a script would help with some of the pauses in speech.
One thing to consider is that the PR run on each turbo is the square root of the total PR. So you end up running high flow at low PR. Most turbos today have aero for high PR and you will be “off the map” to the bottom right. Unless you go Giant turbo if you want to stay on the map (especially for the atmosphere turbo),,, OR talk to someone like TiAL/Xona who have three specific aero packages and are coming out now with a low PR optimized aero package. Perfect for compounding. There are some out there already
Correct. This is where turbo sizing is critical!
@@humbleperformanceit’s not just about size, it’s the aero design. Most modern turbos are designed for single turbo, high PR aero. Which is the opposite of what you need for compounding. You need high flow at low PR. Most turbos would end up very inefficient with compounding. Yes, spool fast and make tq faster, but all create TON of heat.
Which once again, is why turbo sizing is critical. Aero is obviously an important factor, but ultimately, sizing is the major contributor factor.
In the same way a 5 star safety rated compact sedan is less safe than a 1 star rated SUV in a collision. Or a world champion featherweight boxer gets destroyed by an average heavyweight.
There’s a hierarchy that cascades down.
@@humbleperformance you keep saying sizing when I am saying design. It’s not just the size. It’s the design/aero as well. Two turbos of the same size of 68mm could have dramatically different results in compounding. But they are the same “size”.
One optimized for 1000hp (100lb/min) on a 2.0l as a single turbo would be optimized for ~5 PR. Run that as a compound and it would need to flow 100lb/min at 2.25 PR. It will be way off the compressor map. Probably less than 50% efficient.
Sure, yes, you could size up to something like a giant GT55 to get on the map. “Sizing”. Or you could use aero optimized for low PR and keep a smaller turbo and achieve the same results, less weight, less space etc.
So I disagree that sizing is the most important. It’s the package. Aero first since options exist that are suited for compounding; then size.
Isn’t the stated goal of compounding to optimize the setup (power, efficiency, IAT etc?). So I say, why be barbaric with unsuited aero, and have to pick inappropriate sizes 🫶🏼
If you’d like, I can email you compressor maps to demonstrate my assertion.
A turbo optimized for 100lb/min at x PR is always going to fall within a certain size range because of the cascading effect.
You’re speaking at the low, nitty gritty level, when ultimately it’s influenced by the size of the turbo. Your target pressure and flow rate will always be limited by size.
Both turbos can be 68 compressor inducers, but the exducer is also important, the turbine inducer and exducer is also important.
You’re not going to find major variances in turbos when the numbers are the same.
In theory it is good,but making it work is a real pain in the as. You need a lot of calculations on what turbos you need to run,boost control is pain it is raised so fast.You don't mention when using compound setup always make less power on the same boost than single turbo. You say efficiency-if you want good efficiency,you need to put an intercooler after every turbo, that's what intercoolers do -increase efficiency. So imagine 2 turbos 2 intercoolers so much piping,you will run out of space.
You’re dramatically over complicating it. It’s not difficult at all nor does it require what you think it does/it doesn’t operate the way you think it does.
Compound setups make more power at same boost than singles. Yes, ideally you would intercooler between stages, but it't not required.
I didn't run out of space, I already did it.
Actually, one large intercooler is far better, because you're starting with very hot air, and the delta T is high, therefore the the one intercooler is very efficient.@humbleperformance
Conversely, you lose available volume if you aren't taking steps to increase density. The point of I/Cing between the stages is to raise the density (increasing the available volume for air to occupy allowing for more air) that the high pressure turbo is multiplying to increase the final flow-rate of the turbo. If the IC ONLY comes after the high pressure, youre sending less dense air into the small turbo to compress, whereas intercooled before and after the small turbo you're giving the small turbo more mass to send to the engine and therefore more power.
So while you might have a larger temperature delta with a single heat exchanger before the intake, you end up with less mass by the time it reaches it.
@@humbleperformance Ok show us how much boost you need to make 1000hp with compound and single turbo setup.
On this particular setup, ~40 on the compound setup, 45 on the single.
Really good description of the setup and how it works. One thing that would have been nice to touch on is why the turbos are sized differently. Since it sounds like with 2 same-sized sequential turbos, neither would be 'breaking a sweat'. I think the real answer has to do with the size of the larger turbo's outlet matching the smaller turbo's inlet?
What? This point was directly addressed and the entire point of the video lol.
You can run 2 of the same sized turbos or closely matched turbos and have benefits in a compound setup as well.
Ie. Running 2 turbos of the same size to reduce the load is more efficient than running one strung out.
@humbleperformance I mean why make the bigger turbo the low pressure turbo and the small turbo the high pressure turbo. How do you size the turbos, etc. I did get the compound turbo setup in general being the point of the video, I just think the sizing aspect was glossed over. If you use a too small turbo for either compound turbo, what will happen, etc.
Once again, this was directly addressed, and the sizing was also directly addressed.
nice summary without getting too technical.
awesome video cool idea diesel trucks have used this for a long time but if you want the same spool as a small turbo and the flow of a big single but without the added weight and complexity of of a compound system look into twinscroll turbos same idea but inside one turbo and what makes that amazing is dual variable valve timing as you can adjust your intake and exhaust timing to get more exhaust velocity with the same flow rate very very helpful at low rpm and this is exactly why i love my jdm subaru as they come with this from the factory also when your doing compound you can spread the boost thresholds too far apart otherwise the small turbo becomes a restriction if you are trying to make massive power with the big turbo, when done right than can make insane power with quite a low boost threshold essentially all wrc cars use this now as it helps alot with mid corner power, my goal with an ej is to use a stock block with aftermarket forged pistons ring gapped correctly with a twinscroll small frame garret turbo and be able to make full boost 3k or under and peak power around 500whp, not as outright fast as some high boost 2l cars but the low rpm power should be night and day and should make for an incredible car to drive
Twin scroll turbos are not remotely the same in terms of performance nor in concept.
Agree they are different. Each exhaust pulse leaves low pressure behind as it flows down the runner until ex valve closes and it settles out. If the next cylinder’s ex pulse enters that low pressure it’s potential force to be applied to the turbine is slightly reduced. Twin scroll manifolds and turbine housings divide those pulses all the way through the housing volutes based on firing order so they never overlap and effect each other. Generally each volute/scroll are the same size/AR. There are variable AR twin scrolls with different sized volutes controlled by a valve at the turbine inlet altering volute usage based on demand/conditions, but that’s more comparable to variable geometry and doesn’t offer the compounding aspect he was describing, just different turbine AR with still one fixed compressor geometry. Not 2 separate sized turbos. As far as I know subaru doesn’t offer such a setup and it might annoy you to hear mitsubishi does. If you want high power mid corner from an ej, make sure it keeps oil pressure. Often overlooked killer of those engines.
WRC antilag tech uses bypassed boost directly into the collector with added fuel. Anyone can do this but people don’t understand that you can turn your exhaust manifold pre turbo into a a combustion stage like a turbine engine.
My small T3/T04E turbo won't even spool fast, I think I have a boost leak because it used to spool way better, or it's just dying because it's 20 years old. It has hardly any shaft play though so who knows
Is because is and old turbo the technology is garbage. I have a smaller pulsar turbo than the t04 I used to have before. It spool quicker and makes more power.
@@delatuned Yeah it's an old journal bearing turbonetics turbo. It used to spool quick just a couple years ago though so I'm thinking boost leak, it sounds weird around the bov when spooling so I think it might be faulty
@95TurboSol I changed my garret t04 60 trim for a disco potatoe gen 3 pulsar turbo and it spools better and made more hp on 3psi of boost less
Sounds great. Can’t wait to see it!
So one thing I've always wondered when I see these compound setups is why don't the outlet on the compressor side of the small turbo blow into the intake side of the big turbo why is it the the big turbo outlet on the compressor side blow into the small turbo ??
Teknotoys 240sx runs a compound setup and held the 4cyl world record for a while… only dethroned because it’s been inactive for a few years. Info is hella valid.
People refuse to hear this logic. Jett Racing eclipse with the 4g63 record. Or Eric Jarvis with the stock chassis s2000 record.
im curious if u could do a break down on twin turbo vs compound turbo just how u did with single vs compound very informative great video!
Can't wait to see the results
Garrett has a turbo sizer to get you in the ballpark of the turbo you need. Let me address the difference in some setups: the large laggy turbo that has massive power near redline will help reduce the massive torque down low in the launch rpm range. 3-4K depending on your tires which will lead to snapped axles and broken transmissions. So you launch, don’t break and now all your power is on the top end. Where your rpm’s will drop 1.5-2k rpm. So now you’re staying in that big power portion for the rest of the run. If you want big torque down low get ready to have replacement parts online. Big torque is cool in a street car but not full blown comp drag racing
Fundamentally incorrect in nearly every way.
@ so when you race you let your rpm’s drop from 8k to 2500-3000? You know that doesn’t happen in a race so why you bs
Been theory crafting this for 15+ years sadly haven't been able to execute it due to financial reasons. You have to be very careful the way it's plumbed for this to work on these high revving Hondas. You need to run the exhaust primaries into a low angle merge collector directly into a large e-gate that feeds the big turbo. If you get it, you get it.
Way over complicating how it works
Not at all over complicated. You will work one turbo way hard and the other not at all if you can't control the drive pressure. You will be less efficient than a single without control. Unless you get stupid lucky and the system and turbo sizes balance out .... Good luck unless you copy exactly someones working example they took the time to develop correctly. ( It will probably be just like the o.l. description... Big e gates.)
Volvo created a engine that injects air into the exauat side of the turbine to reduce lag. I wonder that is something you may want to exprieunce? Could be a solution? Equipped with a powerful compressor that efficiently charges up, this product stands out as a remarkable piece of technology. Accompanying it is an exceptional educational video that enhances the user experience by providing invaluable insights and guidance.
I made 650hp on my compound turbo cummins. It made 2,086 foot pounds of torque. 72psi down low with a tapered fuel trim up top.
For racing categories that require a turbo inlet restrictor (think rally) to limit power, would there be any advantage of a compound turbo setup? I feel as though you’re still limited by the airflow and any benefits from compounding boost would be lost? Perhaps I’m thinking about this wrong?
Good job Kenny
Thats why i picked up Borg warner EFR 8374 turbo on a stock k20 type r motor and it spools up quick and hard in the midrange
Seems to be a lot of resistance to this. But, data is data; whether you like what it is or not. I’m Excited to see how it went.
Been thinking about compounds for the last month for my build.
knew where this was going from the thumbnail. the only way to have your cake and eat it too... is to have two cakes. two snaily boosty cakes.
One of the big key points is to pick two turbos that meet the goals but also keeping them operating at the same PR at there optimal efficiency island in there respective maps. Welcome to the performance diesel world! Lol
Absolutely 100% correct.
In a compound setup you are going to need a much bigger turbo for the top end. The single turbo that you brought up in your example there is making 1000hp at a significant pressure. The question then becomes, will your engine be able to handle that pressure multiplied by the small turbo? What you have to do is size the turbos by flow. A single running 56+psi to make a 1000hp is not going to make that in a compound setup unless your engine is capable of withstanding 100+psi. You will be limited on pressure so you will need a turbo capable of flowing enough air to make 1000hp at around 20psi or so. You also won't be able to run the smaller turbo at 30-40psi without sending your head to space as well. It's a matter of finding the balance of sizing a small turbo that will minimize lag, yet have decent power under the curve of the large turbo within the pressure limit. Then sizing the large turbo to meet your power goal within the pressure limit.
Gale banks has said "psi does not equal volume. Just because it says 20lbs on both turbos doesn't mean the same amount of air is being moved. It's why I can have less boost on one setup and make more power than the other spinning it to the moon"
Just a clarification
Twin turbo refers to twin turbos of the exact same design
The ford 3.5L v6 ecoboost is the perfect example here
Compound also known as sequential turbos is the one your talking about here
Many semi trucks use compound turbos
An example of a small displacement diesel that runs compounds is the nissan titan xd with the cummins diesel v8
No it doesn’t.
See twin turbo FD RX7. (Two different turbos)
Sequential and compound is not the same thing. Compound is not ‘also known’ as sequential, it’s completely different.
Parallel, Sequential, and Compound are the three types of multi-turbo setups. Twin denotes 2 turbos, it does not mean identical.
This people always doing some crazy stuff but bringing data this is just next level technically now educating everyone else to be builders not "just fast"
It would be nice to have an animation of this conpound turbo setup.
you should look into the variable geometry turbo chargers holset and i believe ihi and garret make them. it can eliminate a twin turbo setup just like the diesel industry did years ago.
It does not.
Exactly what I was thinking when looking at diesel compound turbo setups making more psi at a lower rpm too bad I’m stuck on more amperage and voltage at a lower rpm with my k series ⚡️😅
Question: if the smaller turbo is further compressing air from the large turbo, would the air exiting the small turbo be super heated? Specifically, once the large turbo reaches optimal range for it's size.
Temperature of the two turbos nets less than a single turbo running the same boost.
Many people do compound on small diesels in EU its just not much documented on it so is should somewhat work with a Honda engine also for a street use.
I have a supercharger rn can i do the same thing compounding a supercharger and turbo?
It's very similar but not the exact same effect. It's a compound twincharged setup which comes with a few different downsides.
When does the small turbos back pressure become an issue, if and when can the waste gate be used in between turbo manifold and big turbo bypassing excess back pressure from small turbo?
It doesn’t
As the boost ramps up and the back pressure builds up, are you able to "exhaust" or dump enough of the exhaust gases and quickly enough through a single (say 45mm) wastegate on the high pressure turbo? I ask because I also assume the intention is to keep the hot side small enough to still see the benefits of a much quicker spool. Interesting to see this work on an internally gated T4 Twinscroll B2 EFR Turbine housing as the primary turbo using a bigger turbo to raise the pressure in a 700HP streetable setup.
You’ll have to salt to taste there. Typically want more gate than normal.
I would love to see you pull it off. Right now I don't know if the benefits outweigh the cons though.
It’s already done
@@humbleperformance I want to see the art perfected compounds are very common in diesel but gas is a different beast. I was planning on doing a compound set up and even have most of the parts to do it now but a lot of smart people have tried compound and it hasn't worked out. There's alot of science that needs to be figured out on the gas side especially for something that's not just for a drag application. I think alot of the principles hold true small turbo first after engine to spool faster and draw through the larger turbo for intake. But boost and exhaust control I think is still an unknown. That's why I'm eager to see specific testing and solutions for street/race application. Would also be interested in someone testing inter-cooling after both turbos as this should theatrically be the most efficient/best use of compound charging especially for a gas engine.
Good explanation, but explaining with pictures or drawings would make it 10x better. I'd say a lot of people just go for the number, I understand if you are drag racing the car, but I'd prefer a small twin scroll manifold with a decent size turbo to avoid overcomplicating things
What do you think about turbo charging the new civic hybrid? It's pretty quick stock.
The engine is weak
@humbleperformance thanks for the feedback. Keeping it stock for the mpg. 💯
Interresting video, thanks for the info. Only your talking speed was also on boost 😂, great job !
I dont think id want to daily a 1000hp race car. For just strictly race purposes id assume the nitrous/turbo setup would run faster than the compound turbo setup youre referring to? Just trying to get an idea of where a car with this setup would sit. Definitely unique though.
This has been common in the diesel world since WW2 and the old Detroit engines blowing turbos through a blower. I'm honestly surprised the Honda guys don't seem to use it all the time
Will you ever do it with a B series
But like i said i love yall channel alot and if you make it happen ill be going that way myself trust me on that one its Just like the supercharge/ turbo setup up the super down low and the turb up top
Could k24 take a compound on stock internals ?
I wouldn’t
Do you have to worry about overspeeding the smaller turbo once the larger one is spooled up?
No. That's not a concern. The small turbo doesn't speed up as power goes up, it actually slows down.
@ interesting that’s pretty cool. Looking forward to dyno results!
Sounds amazing run 2 cheap turbos as a test. Thing is won't the big turbo over spool/spin the little turbo? Possibly cause damage, can you test that?
No. That’s what the wastegate is for.
👀 Hifiman Sundara in the back, someone has good taste in audio 👏🏽
💯
Great information! How would this apply to the SFWD or XFWD classes? By that, I mean the rules.
Illegal
Variable geometry turbos solved this problem a long time ago. Yet no one uses or manufactures them for the aftermarket.
Good stuff Kenny! No doubt compounding works, but going a step beyond the basics shown, where do you reach limitations, as in, when does the smaller turbo start to become a limitation?
My understanding is (although you're draining HP from the crank), compounding isn't limited to turbo's, and so you can have a turbo, preferably a larger flowing one, to compound incoming charge for a blower (ideally a more efficient design like a Whipple), often referred as twin-charged.
Same can occur though, where at a given point, the compressor closest to the intake valves can become a restriction.
Edit* I guess, what I'm curious to know, is what ratios between the big vs small are optimal before you see the small becomes a restriction within mid-high rpm ranges?
same setup of orange supra?
If we asum your engine is breading the same amount per revolution a cross rpm range, you can simply calculate briefly like if the 1000hp turbo makes full boost @8k you get one bar of boost with the small turbo, you should get the big one spooled @ 4k
Now if you have inter cooling between the turbos, you should be able to rice the boost of the whole system and make the 1000hp @4k if the engine can handle it.
Ewen better, if you have a small turbo that gives 2.5 bars of boost @ 2k you might get the big turbo spuled @ 2.3k rpm
The big turbo sees a 2l engine @8k rpm and when you put one bar of boost with the small turbo @4k rpm your big turbo sees a 4l engine @4k rpm and soools like that.
Be honest on what your power goal, or your torque goal is, what can the engine and gearbox handle, don't go to big with the small turbo, the big one will make the power anyway,
You either disable VTEC and change Cams so it's always running on DOHC,
Or Adjust VTEC to 2500rpm so the ECU is not running on single cam before VTEC so Both Cams overlap at peak torque so no power loss, this is where you map in boost for instant torque no turbo lag.
That’s not how it works at all.
Can the stock motor rods handle from low rpm turbo pressure build?
I wouldn’t
I'm with it, so Kenny tell me, if I'm shooting for 600 hp and I want all that lower down low too, up to peak hp and I wanna do this twin turbo compound set up, what two size turbos would be appropriate for 600hp?
I wouldnt compound at 600. Plent of options that work fine at that power level.
@ gotcha, would be a cool set up still forsure though
So the small turbo windmills the bigger turbo in a sort of fluid coupling.
The best piece of information to know about turbos, is that they're not as good as superchargers.
Put a blower on your car. Centrifugal, roots, twin screw... whatever. You will like it more.
Have you figured out the backpressure limits of these systems? The smaller turbo exhaust housing will always be the limiting factor. First turbo hold 1:1 pressure to backpressure ratio when its in its efficiency range but as soon as the second turbo is active the flow is greater than the small turbo housing can flow therefore doubling backpressure resulting in a much lower overall system efficiency. Now at what point does this become a system limiting factor?
So far nitrous oxide is still the best way to inflate engine power in order to spool larger turbochargers. I see that max power is not your end goal so yes maybe compounds can be a great thing here.
Turbo housing isn’t the limiting factor/ it doesn’t work the way you think it does.
@@humbleperformance I didn't see anything in the video describing your wastegate control strategy. Have you measured backpressure at all?Enlighten me because it doesn't work the way i think it does.
Explaining how to make it work is beyond the scope of the video. There’s also many different types of control strategies people employ.
If you want to find out how it works, try it yourself.
How does this differ from twin scroll?
Will the 2nd turbo not be more laggy because the small turbo uses most of exhaust energy?
No
Its not about psi. Everyone focuses on that number when you should be focusing on the cfm that the turbo is capable at flowing and where you will be on the compressor map efficiency.
As for the solution to faster spools there are a few ways to solve this today and has been for a number of years. People just don't impliment them like they should. Compounds are used often in the diesel trucks to reach 4, 5 or 6 bar much much faster compared to a single setup.
Good stuff Kenny!
Great video 💪🏼
How about twin scroll with quick spool valve?
Not remotely close
@humbleperformance but not even close to the complexity too
And not even close to the same power.
@@humbleperformance the max power is still limited by the big turbo to the exact number
With compound you get the acces to a bigger turbo and get it spooled with the small one. Its a beast setup, I did a couple, complex, but unbeatable for the amount of boost you can make with low backpressure and from low rpm too
Small turbo=less efficiency is not good statement. There are small turbos with really high efficiency, same as big one. But it's efficient in particularly low mass flow.
Big turbos are efficient at bigger flow numbers. Design of compressor wheel and compressor housing is what determines compressor stage efficiency
No there are not. There is no small turbo in existence that is 1000+HP capable.
Interesting and informative
Can u run a supercharger to a turbocharger
Wouldn't the turbine housing size on the small turbo be a bottleneck?
Do you think your compound setup would work just as good at the track? Do you think this kind of setup could eliminate the need for a dog box?
That has nothing to do with the purpose of a dogbox
@ well not directly, but most people usually get them to setup shift cuts and no lift shift to carry boost into the next gear. Do you think this setup would be quick spooling to keep boost levels high between gears on syncho transmissions where letting off between gears is needed
Once again, the dogbox is not relevant in this conversation. You don’t have the full understanding of the benefits of a dogbox.
You can do exactly what you’re talking about with a big turbo synchro car minus the no lift part.
little typo but might make a few confused, 14.5 of boost would be 29psi absolute
I feel sequential turbos would be more suited for awd civics due to much more torque but I guess the only way to find out for sure is to try and I dont think ive ever seen a sequential turbo k series
Compound turbos make more torque than sequential turbos.