@@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👑
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.
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
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!!!
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
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
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
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.
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.
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
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"
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.
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
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.
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.
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
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.
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.
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.
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?
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.)
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?
@ 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.
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
I can't deny the advantages of a compound setup but I've always been curious of the drawbacks. What effect does pushing that much exhaust through the smaller turbine housing have? Do you route your wastegating from the large turbo into the inlet of the small turbine, or behind the outlet. How do you manage wastewater priority between the two? I'm excited for the follow up with some real world testing
The wastegate before the small turbo serves as a backpressure dump. You see normal pressure at the small turbo, it can be dumped to atmosphere or (ideally) into the turbine of the big turbo letting you retain all that exhaust energy and increased drive pressure for faster spool. If you run a wastegate before the big turbo (most people dont gate the big turbo and rely on the small turbo's output presure alone to regulate boost), it dumps to atmosphere. You cant reroute it before the small turbo otherwise we'd be re-routing normal single turbo stuff back into the manifold lol.
I believe you are close to accurate, but I believe you are wrong about the pressure, I believe they individual add together as pressure measured is outlet minus inlet. So a 14 pound small and a 5 big turbo would truly give you about 14+14+5=33 pounds. This pressure is measured at the manifold and has the flow of a big turbo at that pressure, giving the bigger power number and of course the efficiency means you have significantly more air mass at that pressure. In essence the multiplication is in efficiency but pressure is always a differential and thus additive. 99% of your logic is sound and this truly should work and you're proving it too :)
No, what I stated is indeed correct. Turbos are air multipliers, it is not additive, if it were, it would be called additive and not compound. You’re compounding the pressure, not the flow.
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
It's not a secret, the problem is that you think you've discovered some secret, and no one has thought of it) But not a word was said here about the turbine, the wheel size and AR, about back pressure and how it affects power. Many people make the mistake of thinking only about the compressor, completely forgetting about the turbine. The turbine can eat up power and cause detonation
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
compound is very hard to do you have to match the turbos really wel one smaller and one bigger but just the right size and the right size for the engine
@humbleperformance I've heard compound puts alot of wear and tear on the turbo blades since it needs to compress compressed air and also you need inter cooler in between turbo to turbo and turbo to intake manifold and then boost control is sketchy as hell. I really think from a reliability/ simplicity standpoint and everyday use a sequential turbo setup like the 2jz would be better in the long run
Wouldn’t a twincharged setup work ? , I’d just assume it’ll be more logical to have a supercharger for low end power until the big turbo comes in the high rev range . But please I’m intrigued on your opinion.
It can work under the same principle but you get additional parasitic loss and you don’t get as much of the benefit of faster spool time of the small turbo nor the added exhaust temperate that increases spool time. Does it work? Yes. Does it work as well? No. Are they both cool? Absolutely.
This might work for street cars but theres not much space in the bay for compounds but if it works it works. For drag cars specifically this is irrelevant, they already use two step anti lag on the line so it already is building boost. So it would just add unnecessary complexity and weight
You mention turbo charger efficiency but don’t touch on the subject of the smaller turbo running out of its efficiency range at higher rpm levels. You should add that a bypass (normally a wastegate) is installed before small turbo inlet so that it can divert air that would cause it to get out of its efficiency range. Example: Small turbo feeds big turbo. Small turbo reaches limit of turbo efficiency range. Bypass or wastegate opens to divert additional exhaust air to big turbo. Small turbo is still at efficient limit but the bypass is diverting additional air to big turbo since it still hasn’t reached the limit of its “turbo efficiency range.” No?
Crazy to see the number of keyboard warriors ready to go to war to prove that this cant or wont work when its been done many years now. Proof that the internet made most people dumber.
Presumably you need a massive wastegate on the smaller turbo, feeding back into the big turbos turbine, otherwise it'd choke up (pressure too high on exhaust) and overheat.
I’ll save my comments on usefulness for the dyno chart. That being said compound has been around sport compact since the nopi days. It’s stupid complex by comparison to a small shot of nitrous which, I get it. You don’t want to run spray on the street. But why not just go real ALS The harder and less complex move would have been a real ALS strategy with the turbo smart ALS valve. You pull that off and you’d have the same result without an extra turbo and enough piping to plumb a hot tub. And, more importantly you would have been original. Where
::read in Xibits voice:: Yo dawg, we heard you like turbos, so we put a turbo, on your turbo! You’ve officially been Pimped! In all seriousness, does the small turbo ever become a “choke” point? This is really cool stuff. Big thing in Diesel world, but I don’t know much about it from experience.
This was a question I had on my side personally. The wastegate before the small turbo works as a backpressure dump and all the pressure is sent to the 2nd turbo.
@ got it. Very cool. So let the small turbo do the work then vent it when it becomes a restriction. Seems like really cool idea. Excited to watch this unfold. Love your guys content.
What about the exhaust side restriction that comes along with the small turbo that will kill the pressure ratio and rise the combustion chamber temperature both will kill power and worsen efficiency. Further more this setup will as far as I'm aware not only compound the pressure but also the temperature. I get that the compressor sides are operating in a window of optimal efficiency but even there has to be an increase in temperature and then once again at the second compressor side. BTW the way you made it look that the spool of a turbo is determined by the size and therefore the inertia is not the whole story... generally bigger turbos come with bigger turbine housings that alow more exhaust flow and therefore waste exhaust energy in the lower revs. This is a even bigger contributor to turbo lag than just inertia. So in my opinion there is no take away from this video at last.
Wastegate controls exhaust side. Temperature is multiplied at a lower factor than a single due to efficiency of the turbos dropping the overall net temperature. If a single turbo makes 40psi and is at 60% efficiency and 2 turbos are at 14psi at 78% efficiency, the two turbos run colder. “You made it look like the spool of the turbo is caused by the size. Bigger turbos come with bigger wheels” Do I never need to elaborate on this… lol
The wastegate is a valid point. A point that was missing in the video. The numbers you've stated with 60% and 78% make barley a difference. Eg at 30°C the difference is just 0.7°C and there is no reason a single turbo has to be less efficient if it is sized correctly. It could also be at 78% and then it would be 11°C cooler. The last point you have made is not understandable to me. But I'm not a native speaker. Maybe you can explain it to me. Cheers
The waste gate point wasn’t missed it was in fact in the video nor needed to be explained. Once again 2x turbos running in their efficiency run cooler and denser than 1 turbo running on the edge of its efficiency. To explain the last point, the turbine sizing is a part of turbo sizing.
I don't think this is an apt comparison for tracking a car based on the power band here when gearing comes into play a lot on the track, suspension, wheel hop etc. You also aren't typically runing north of 600hp on a track setup with a honda. There's also something to be said for having a mid range turbo and being aware of your powerband when racing, and dropping out of boost. The problem you're proposing is mostly related to a skill issue. You can have a compound turbo and still not be able to drive a 1000hp honda on a track, which most people tracking wouldn't be doing anyways because of the amount of wheel hop etc that would occur, oversteer etc. The gearing on a 1k hp Honda is typically for drag, and you're never going to see the top end of that powerband anyways on the track meaning you're still in the 600hp range anyways. Then it comes down to turbo efficiency of the compound setup versus a single turbo, you need more cooling on the compound setup, you need adequate cooling on a single turbo setup. The major problem with a lot of single turbo hondas is not the spool, it's the heat soak. Here are some more drawbacks from a compound turbo setup: 1. Cost, 2 turbos is more expensive then 1 2. Cost and space: plumbing and dual intercoolers, where do they go? You're talking about a completely gutted track rat or drag monster. 4. Tuning wasteagates and blow off complexity throughout the powerband and your antilag. 5. The ven diagram of weight to power ratio 6. It's more about the bragging rights than it is about the functionality at the end of the day unless you're building this for a very specific use case. You'd be better off putting in jet engine turbo lag system from the 90s and a big turbo, single unit and less moving parts. 7. The turbine material is just as important as the center shaft construction etc. 1 very efficeint turbo is better than 2 pieces of shit.
While your comments aren’t completely off, you do have a fundamental misunderstanding. Compound turbos run cooler than singles at the same power level and do not require more than 1 intercooler. There are definitely benefits to running more than one, but even with one it’s still more optimal. Running a small turbo with mid range might work on a course that isn’t power sensitive, but if it is, you’ll lose a lot of time on the straights compared to a setup that makes power to redline. You also fundamentally have faster power response on throttle due to the steeper manifold pressure increase. Tuning gates is WAY simpler than people are leading it to be, you tune the car like it’s a single turbo. It’s ALL about functionality. Bragging rights is having a high horsepower car that’s laggy. Functionality is having a high horsepower car that works. For a road course car, you can run a dramatically “undersized” turbo for insane response and a bigger turbo for power while being more efficient than a single turbo.
@humbleperformance if you can't make power to redline on a honda, seems like a tune issue or a gear setup issue. Or maybe your fuel is leaning out. A lot can be going wrong there. It's true you don't need 2 intercoolers. You could run a single normal or a smaller one with meth. I disagree that this setup on a track will beat a single turbo every time. I know many lap record k series holders that have single turbos in their classes versus other platforms that have more. I will watch out for the build though I think it's cool.
What you’re saying isn’t remotely based in reality. Small displacement engines can’t make high power without a large turbo. They can’t make responsive power without a small turbo. With a single turbo you have to balance the two downsides to find optimal. Compound removes both cons. This isn’t a tuning issue, it’s physics.
@humbleperformance I haven't said anything in contrast to what you're saying except that the general track application for what you're talking about isn't utilized for a reason. It's used in rally for a reason. Let me know how hitting the end of the straight away at 1000hp goes at the end of your power band. Lol. You're better off tuning down for track so that you're within an optimal power band. It's also very easy to hit 8k RPM in a k series and does not take a lot of time, as you suggest. Street tuning >>>> dyno also
Not knowing about it being used =/= it’s not being used. You outright said if a Honda isn’t making power to redline, it’s a tuning issue or another issue. That was in direct conflict to what I said and explains where compound is superior. You can scale this concept up and down with different power levels. But if you want a car that you can drive around on the street at 600-800, then go a road course at 400-500 and then be able to go to the drag strip with 1000, and be able to do all 3 of these things, compound is the only way it’s possible.
This is a great video but I think it would have been a bit more clear if you had a big turbo and a little turbo and pointed to the two while explaining it!
I agree. I didn’t want to show the car and spoil the setup though. Under my feet is actually a turbo I was going to use for the visual but I never used it lol
I think the question then becomes what are the cost implications of this setup compared to Twincharging (supercharger in the low end) and does this mean our 1000hp civics can become dailies 😂
Your rite about everything your saying but it's just to much money everything not only the money but to get them running rite is a mess jdm cars from back then like the skylines and a few more cars came like that from the factory but again the money the space you need to run a setup like that then to get it running rite not only that the turbos have to be sized perfect for it to even work look up the TH-cam channel driving 4 answer he made a video on it thats crazy the kid knows what he's talking about a really really good channel to learn from but I do want to say I love this video I'm building a 93 si hatch and I planned on being one of the first to run the compound setup your talking about till I seen his video and did more and more research on my own.... but keep it coming can't wait to see what you have going might just change my mind 💯..!!! I think it did and the toyota super differently came that why
Skylines were not Compound setups, they were Parrallel setups. The setup is not difficult mechanically, and is FAR FAR simpler than 90s JDM Twin Turbo setups. Packaging and the fact it's not something that you can just buy like everyone now a days has to do to build a car are why no one does this. People are too afraid to step outside of what 'everyone else' says.
I'm pretty sure there was a 87 to 92 super that came like that but anyways your going to have knock before you ever make real power the trucks can do that because that's what they do conpress hot air
@@humbleperformance civic eg coupe twincharged D16 (roots Supercharger and turbo ) Rx7 fc (compound turbos) 13b , 3000gt (twin turbo to twin screw ) 6g72 but might be changing project to k24, evo x working on (smaller turbo to centrugal supercharger)
At the end of the day it will work but your Going to put way more into then it worth your not Goin to be able to push the car to its peak before you get massive knock from 2 times the heat that 2 turbos are going to make at big boost levels its bad enough with just 1
@humbleperformance Kenny i love what you do for all of use so for me you better make it work because I really want that to be my setup and my word if you make it happen I'll have yous do my build I called the shop to see what it would run me for yous to build my motor she told me a gran plus what ever the mechanic shop will come out to so she told me about 1500 you make it happen and I'll send you everything I have for my engine for yous to build
I have a better opinion! VGT turbos! I am running A s300v in my e320 cdi which usually comes with a smaller turbo thats maxed out at 290 hp. With the Vgt turbo s300v I can Make 550 hp while being able to spook around 3300 rpm where as before a similar turbo would spool 1000 rpm higher.
We run vgts on street hondas in pnw. Works much like he's planning. I actually have a video on Instagram showing a f22 on a vgt and showing the instant powerband and it keeps going. 1 turbo 1 manifold usual setup.
@HondaPoweredAustin VGTs aren’t currently capabale of supporting 1000+HP nor are they as quick spooling for that high power application. Can only do so much there.
@humbleperformance then that is what the performance world is missing 😉 I cant wait to see what your talking about though. And you are correct on the vgts not supporting 1000hp.
@@humbleperformance no it is different. turbo lag is the delay from the time you apply throttle until you get boost while the engine is within an operating range where the turbo will make requested boost. Boost threshold is the rpm that the engine is at when it is first able to make requested boost.
I like the analogies but these are NOT twins (that is two OF THE SAME turbos), nor is it sequential. It has it's own term for a reason. It compounds two DISSIMILAR turbos. Great video but some inaccurate verbiage.
incorrect. Twins only refers to 2, it does not mean identical. Everyone typically understands when you talk about a twin turbo setup, you mean a parallel turbo setup. There are 3 types of twin turbo setups though. The JDM twin turbo cars (Supra, RX7 for example) from the 90s were sequential twin turbo cars with dissimilar turbos. Parallel, Sequential, and Compound. To reiterate again, the word 'twin' only means two. It does not mean identical. Think of mismatched turbo sizing as fraternal twins. Parallell = 2 divorced turbos (they do not have to be the same size) Sequential = 2 turbos in sequence. Compound = 2 turbos in sequence with linked inlets. Compound is a sequential setup with linked intake side. The term compound comes from how it handles the intake side, thats the differentiator between sequential and compound.
Make a 4 cylinder awd car with almost no lag and reliable horsepower like 400-600 range. Not sure what engine will be best yet or how much boost to run. The drivetrain will be from a 2009 sti though so there's that.
still one of the best intros on youtube
By far my favorite
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
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%.
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
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!!!
Can't wait to see your dyno results with a compound setup on a k series 👍👍👍
I perfer a twin charge k😮
Been following this on FB. This man is a genius lol
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
Still hands down thr best intro on youtube!!! 🔥
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
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
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.
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.
This is 100% correct right here
Amazing video. Finally explains how boost works to people.
Thanks for the compliment!
My last one for today just cannot wait your idea come to life
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 👌🏽
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.
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"
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.
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
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
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.
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.
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.
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
i learn so much from your videos and comment responses. thank you
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.
Great information! How would this apply to the SFWD or XFWD classes? By that, I mean the rules.
Illegal
I don't have time to correct all of the things wrong on this. Ugh.
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.
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.
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.
👀 Hifiman Sundara in the back, someone has good taste in audio 👏🏽
💯
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?
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.)
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
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
Can't wait to see the results
So the small turbo windmills the bigger turbo in a sort of fluid coupling.
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 !
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.
Good job Kenny
Wouldn't the turbine housing size on the small turbo be a bottleneck?
Sounds great. Can’t wait to see it!
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
I can't deny the advantages of a compound setup but I've always been curious of the drawbacks. What effect does pushing that much exhaust through the smaller turbine housing have? Do you route your wastegating from the large turbo into the inlet of the small turbine, or behind the outlet. How do you manage wastewater priority between the two? I'm excited for the follow up with some real world testing
The wastegate before the small turbo serves as a backpressure dump. You see normal pressure at the small turbo, it can be dumped to atmosphere or (ideally) into the turbine of the big turbo letting you retain all that exhaust energy and increased drive pressure for faster spool.
If you run a wastegate before the big turbo (most people dont gate the big turbo and rely on the small turbo's output presure alone to regulate boost), it dumps to atmosphere. You cant reroute it before the small turbo otherwise we'd be re-routing normal single turbo stuff back into the manifold lol.
Great video 💪🏼
Will the 2nd turbo not be more laggy because the small turbo uses most of exhaust energy?
No
I believe you are close to accurate, but I believe you are wrong about the pressure, I believe they individual add together as pressure measured is outlet minus inlet. So a 14 pound small and a 5 big turbo would truly give you about 14+14+5=33 pounds. This pressure is measured at the manifold and has the flow of a big turbo at that pressure, giving the bigger power number and of course the efficiency means you have significantly more air mass at that pressure. In essence the multiplication is in efficiency but pressure is always a differential and thus additive. 99% of your logic is sound and this truly should work and you're proving it too :)
No, what I stated is indeed correct.
Turbos are air multipliers, it is not additive, if it were, it would be called additive and not compound. You’re compounding the pressure, not the flow.
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.
Hondas at World Cup are powered by engine assisted turbos. No diss at all to them. That boost by gear teleports them in 3rd gear
Nobody uses boost by gear anymore.
The lag kinda makes it more fun tho because the boost hits hard af
Imagine you get that feeling but it's right when you hit the pedal.
It's not a secret, the problem is that you think you've discovered some secret, and no one has thought of it) But not a word was said here about the turbine, the wheel size and AR, about back pressure and how it affects power. Many people make the mistake of thinking only about the compressor, completely forgetting about the turbine. The turbine can eat up power and cause detonation
Without going into the weeds...
'not a word was said about the turbine'
You clearly didn't watch the video.
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!
compound is very hard to do you have to match the turbos really wel one smaller and one bigger but just the right size and the right size for the engine
It’s really not difficult. Just take a turbo you know works for the small turbo and 1.5-2x the flow rate and you’re in the ballpark.
Reminds me of the 2jz all the exhaust goes into one turbo at first then it goes to both turbos once it hits 5-6psi boost
It’s not the same. Reference the video again. You’re talking about a sequential setup. Compound is another step.
@humbleperformance I've heard compound puts alot of wear and tear on the turbo blades since it needs to compress compressed air and also you need inter cooler in between turbo to turbo and turbo to intake manifold and then boost control is sketchy as hell. I really think from a reliability/ simplicity standpoint and everyday use a sequential turbo setup like the 2jz would be better in the long run
I been preaching this to my customers it’s not psi it’s cfm why compressor maps are important
Wouldn’t a twincharged setup work ? , I’d just assume it’ll be more logical to have a supercharger for low end power until the big turbo comes in the high rev range . But please I’m intrigued on your opinion.
It can work under the same principle but you get additional parasitic loss and you don’t get as much of the benefit of faster spool time of the small turbo nor the added exhaust temperate that increases spool time.
Does it work? Yes. Does it work as well? No. Are they both cool? Absolutely.
Its not logical
> parasitic loss
> additional torsion stress to the crank
How does this differ from twin scroll?
This might work for street cars but theres not much space in the bay for compounds but if it works it works. For drag cars specifically this is irrelevant, they already use two step anti lag on the line so it already is building boost. So it would just add unnecessary complexity and weight
Incorrect.
Makes perfect sense, wonder if I can add this to my 2025 Acura Integra Type S 🤔
The l15 would benefit heavily, that being said, there’s a lot more problems with that platform that you have to work around first
@ Copy
You mention turbo charger efficiency but don’t touch on the subject of the smaller turbo running out of its efficiency range at higher rpm levels. You should add that a bypass (normally a wastegate) is installed before small turbo inlet so that it can divert air that would cause it to get out of its efficiency range.
Example: Small turbo feeds big turbo. Small turbo reaches limit of turbo efficiency range. Bypass or wastegate opens to divert additional exhaust air to big turbo. Small turbo is still at efficient limit but the bypass is diverting additional air to big turbo since it still hasn’t reached the limit of its “turbo efficiency range.” No?
This should be obvious by way of how a turbocharger system works and would simply make a long video longer.
I never see any compound setups on the street or at the track
Crazy to see the number of keyboard warriors ready to go to war to prove that this cant or wont work when its been done many years now.
Proof that the internet made most people dumber.
Presumably you need a massive wastegate on the smaller turbo, feeding back into the big turbos turbine, otherwise it'd choke up (pressure too high on exhaust) and overheat.
Correct
How about vgt turbo on gasoline turbo. The way porsche do in 911 turbo
I’ll save my comments on usefulness for the dyno chart. That being said compound has been around sport compact since the nopi days. It’s stupid complex by comparison to a small shot of nitrous which, I get it. You don’t want to run spray on the street.
But why not just go real ALS
The harder and less complex move would have been a real ALS strategy with the turbo smart ALS valve. You pull that off and you’d have the same result without an extra turbo and enough piping to plumb a hot tub. And, more importantly you would have been original.
Where
Hell yea man thanks for sharing the knowlage
No problem! Glad you learned something.
::read in Xibits voice:: Yo dawg, we heard you like turbos, so we put a turbo, on your turbo! You’ve officially been Pimped!
In all seriousness, does the small turbo ever become a “choke” point? This is really cool stuff. Big thing in Diesel world, but I don’t know much about it from experience.
This was a question I had on my side personally. The wastegate before the small turbo works as a backpressure dump and all the pressure is sent to the 2nd turbo.
@ got it. Very cool. So let the small turbo do the work then vent it when it becomes a restriction. Seems like really cool idea. Excited to watch this unfold. Love your guys content.
You don’t just vent it, you recycle the energy to make more power.
Damn what an intro montage
What about the exhaust side restriction that comes along with the small turbo that will kill the pressure ratio and rise the combustion chamber temperature both will kill power and worsen efficiency. Further more this setup will as far as I'm aware not only compound the pressure but also the temperature. I get that the compressor sides are operating in a window of optimal efficiency but even there has to be an increase in temperature and then once again at the second compressor side. BTW the way you made it look that the spool of a turbo is determined by the size and therefore the inertia is not the whole story... generally bigger turbos come with bigger turbine housings that alow more exhaust flow and therefore waste exhaust energy in the lower revs. This is a even bigger contributor to turbo lag than just inertia. So in my opinion there is no take away from this video at last.
Wastegate controls exhaust side.
Temperature is multiplied at a lower factor than a single due to efficiency of the turbos dropping the overall net temperature.
If a single turbo makes 40psi and is at 60% efficiency and 2 turbos are at 14psi at 78% efficiency, the two turbos run colder.
“You made it look like the spool of the turbo is caused by the size. Bigger turbos come with bigger wheels”
Do I never need to elaborate on this… lol
The wastegate is a valid point. A point that was missing in the video.
The numbers you've stated with 60% and 78% make barley a difference. Eg at 30°C the difference is just 0.7°C and there is no reason a single turbo has to be less efficient if it is sized correctly. It could also be at 78% and then it would be 11°C cooler.
The last point you have made is not understandable to me. But I'm not a native speaker. Maybe you can explain it to me.
Cheers
The waste gate point wasn’t missed it was in fact in the video nor needed to be explained.
Once again 2x turbos running in their efficiency run cooler and denser than 1 turbo running on the edge of its efficiency.
To explain the last point, the turbine sizing is a part of turbo sizing.
I don't think this is an apt comparison for tracking a car based on the power band here when gearing comes into play a lot on the track, suspension, wheel hop etc. You also aren't typically runing north of 600hp on a track setup with a honda. There's also something to be said for having a mid range turbo and being aware of your powerband when racing, and dropping out of boost. The problem you're proposing is mostly related to a skill issue. You can have a compound turbo and still not be able to drive a 1000hp honda on a track, which most people tracking wouldn't be doing anyways because of the amount of wheel hop etc that would occur, oversteer etc. The gearing on a 1k hp Honda is typically for drag, and you're never going to see the top end of that powerband anyways on the track meaning you're still in the 600hp range anyways.
Then it comes down to turbo efficiency of the compound setup versus a single turbo, you need more cooling on the compound setup, you need adequate cooling on a single turbo setup. The major problem with a lot of single turbo hondas is not the spool, it's the heat soak.
Here are some more drawbacks from a compound turbo setup:
1. Cost, 2 turbos is more expensive then 1
2. Cost and space: plumbing and dual intercoolers, where do they go? You're talking about a completely gutted track rat or drag monster.
4. Tuning wasteagates and blow off complexity throughout the powerband and your antilag.
5. The ven diagram of weight to power ratio
6. It's more about the bragging rights than it is about the functionality at the end of the day unless you're building this for a very specific use case. You'd be better off putting in jet engine turbo lag system from the 90s and a big turbo, single unit and less moving parts.
7. The turbine material is just as important as the center shaft construction etc. 1 very efficeint turbo is better than 2 pieces of shit.
While your comments aren’t completely off, you do have a fundamental misunderstanding.
Compound turbos run cooler than singles at the same power level and do not require more than 1 intercooler. There are definitely benefits to running more than one, but even with one it’s still more optimal.
Running a small turbo with mid range might work on a course that isn’t power sensitive, but if it is, you’ll lose a lot of time on the straights compared to a setup that makes power to redline. You also fundamentally have faster power response on throttle due to the steeper manifold pressure increase.
Tuning gates is WAY simpler than people are leading it to be, you tune the car like it’s a single turbo.
It’s ALL about functionality. Bragging rights is having a high horsepower car that’s laggy. Functionality is having a high horsepower car that works.
For a road course car, you can run a dramatically “undersized” turbo for insane response and a bigger turbo for power while being more efficient than a single turbo.
@humbleperformance if you can't make power to redline on a honda, seems like a tune issue or a gear setup issue. Or maybe your fuel is leaning out. A lot can be going wrong there.
It's true you don't need 2 intercoolers. You could run a single normal or a smaller one with meth. I disagree that this setup on a track will beat a single turbo every time.
I know many lap record k series holders that have single turbos in their classes versus other platforms that have more.
I will watch out for the build though I think it's cool.
What you’re saying isn’t remotely based in reality.
Small displacement engines can’t make high power without a large turbo. They can’t make responsive power without a small turbo. With a single turbo you have to balance the two downsides to find optimal.
Compound removes both cons.
This isn’t a tuning issue, it’s physics.
@humbleperformance I haven't said anything in contrast to what you're saying except that the general track application for what you're talking about isn't utilized for a reason. It's used in rally for a reason.
Let me know how hitting the end of the straight away at 1000hp goes at the end of your power band. Lol.
You're better off tuning down for track so that you're within an optimal power band.
It's also very easy to hit 8k RPM in a k series and does not take a lot of time, as you suggest.
Street tuning >>>> dyno also
Not knowing about it being used =/= it’s not being used.
You outright said if a Honda isn’t making power to redline, it’s a tuning issue or another issue. That was in direct conflict to what I said and explains where compound is superior. You can scale this concept up and down with different power levels. But if you want a car that you can drive around on the street at 600-800, then go a road course at 400-500 and then be able to go to the drag strip with 1000, and be able to do all 3 of these things, compound is the only way it’s possible.
This is a great video but I think it would have been a bit more clear if you had a big turbo and a little turbo and pointed to the two while explaining it!
I agree. I didn’t want to show the car and spoil the setup though. Under my feet is actually a turbo I was going to use for the visual but I never used it lol
@@humbleperformance Can't wait to see more of it, this is such a great channel
Supra stock twin turbo has this setup been out for awhile
No it doesn’t.
Full spool at 5000 rpm helps the engine live longer .
How about superchargers
I think the question then becomes what are the cost implications of this setup compared to Twincharging (supercharger in the low end) and does this mean our 1000hp civics can become dailies 😂
You still have to use a 1000HP Capabale turbo to make 1000, but the smaller turbo can be a cheap unit.
Time to sell the house and live in a Honda
Your rite about everything your saying but it's just to much money everything not only the money but to get them running rite is a mess jdm cars from back then like the skylines and a few more cars came like that from the factory but again the money the space you need to run a setup like that then to get it running rite not only that the turbos have to be sized perfect for it to even work look up the TH-cam channel driving 4 answer he made a video on it thats crazy the kid knows what he's talking about a really really good channel to learn from but I do want to say I love this video I'm building a 93 si hatch and I planned on being one of the first to run the compound setup your talking about till I seen his video and did more and more research on my own.... but keep it coming can't wait to see what you have going might just change my mind 💯..!!! I think it did and the toyota super differently came that why
Skylines were not Compound setups, they were Parrallel setups. The setup is not difficult mechanically, and is FAR FAR simpler than 90s JDM Twin Turbo setups.
Packaging and the fact it's not something that you can just buy like everyone now a days has to do to build a car are why no one does this. People are too afraid to step outside of what 'everyone else' says.
I'm pretty sure there was a 87 to 92 super that came like that but anyways your going to have knock before you ever make real power the trucks can do that because that's what they do conpress hot air
There was not.
This similar setup is on 3 of my cars. For these reasons
What are your cars and setups? Sounds sick
@@humbleperformance civic eg coupe twincharged D16 (roots Supercharger and turbo ) Rx7 fc (compound turbos) 13b , 3000gt (twin turbo to twin screw ) 6g72 but might be changing project to k24, evo x working on (smaller turbo to centrugal supercharger)
@claudedottin1312 have any videos of them?
@ I will soon 👍🏽
@@claudedottin1312 Definitely interested in the Evo x setup lol
BANKS IS THE MASTER OF THIS .
What about anti-lag big turbo street car
Heat
Pictures and illustrations might help to get everything you're saying across
Still think to make this work better it need turbo speed sensor and e waste gates and a full stand alone ecu
Definitely tangible benefits for all of that yes but not required. Boost by compressor speed would be nice, egate? Not required at all.
It sounds really good but back pressure is a problem
You might be able to alleviate that with a waistgate between the turbos to bring the exhaust flow back up
Backpressure is not a problem
Where are the Rx7's?
i would just say if you want to know turbo charging check out banks power its not all abouth boost
At the end of the day it will work but your Going to put way more into then it worth your not Goin to be able to push the car to its peak before you get massive knock from 2 times the heat that 2 turbos are going to make at big boost levels its bad enough with just 1
Incorrect. On a fundamental level.
@humbleperformance Kenny i love what you do for all of use so for me you better make it work because I really want that to be my setup and my word if you make it happen I'll have yous do my build I called the shop to see what it would run me for yous to build my motor she told me a gran plus what ever the mechanic shop will come out to so she told me about 1500 you make it happen and I'll send you everything I have for my engine for yous to build
I have a better opinion! VGT turbos! I am running A s300v in my e320 cdi which usually comes with a smaller turbo thats maxed out at 290 hp. With the Vgt turbo s300v I can Make 550 hp while being able to spook around 3300 rpm where as before a similar turbo would spool 1000 rpm higher.
We run vgts on street hondas in pnw. Works much like he's planning. I actually have a video on Instagram showing a f22 on a vgt and showing the instant powerband and it keeps going. 1 turbo 1 manifold usual setup.
@HondaPoweredAustin VGTs aren’t currently capabale of supporting 1000+HP nor are they as quick spooling for that high power application. Can only do so much there.
@humbleperformance then that is what the performance world is missing 😉
I cant wait to see what your talking about though.
And you are correct on the vgts not supporting 1000hp.
You have not found anything, fix N/A power band first and then boost just adding another turbo is no fix. Or you combine a supercharger with a turbo
Incorrect.
Actually it's the opposite.......hot air is small, cold air is big, based on molecular density.
You are taking not about turbo lag but the boost threshold. 😐
Also known as… turbo lag.
@@humbleperformance no it is different. turbo lag is the delay from the time you apply throttle until you get boost while the engine is within an operating range where the turbo will make requested boost. Boost threshold is the rpm that the engine is at when it is first able to make requested boost.
Explain the difference and then I’ll explain to you how I was talking about turbo lag.
Legit 🦅
I like the analogies but these are NOT twins (that is two OF THE SAME turbos), nor is it sequential. It has it's own term for a reason. It compounds two DISSIMILAR turbos. Great video but some inaccurate verbiage.
incorrect. Twins only refers to 2, it does not mean identical.
Everyone typically understands when you talk about a twin turbo setup, you mean a parallel turbo setup. There are 3 types of twin turbo setups though.
The JDM twin turbo cars (Supra, RX7 for example) from the 90s were sequential twin turbo cars with dissimilar turbos.
Parallel, Sequential, and Compound.
To reiterate again, the word 'twin' only means two. It does not mean identical. Think of mismatched turbo sizing as fraternal twins.
Parallell = 2 divorced turbos (they do not have to be the same size)
Sequential = 2 turbos in sequence.
Compound = 2 turbos in sequence with linked inlets.
Compound is a sequential setup with linked intake side. The term compound comes from how it handles the intake side, thats the differentiator between sequential and compound.
Ok that answers like every question I've had about what I plan to do.
Make a 4 cylinder awd car with almost no lag and reliable horsepower like 400-600 range. Not sure what engine will be best yet or how much boost to run. The drivetrain will be from a 2009 sti though so there's that.
Basically turbo diesel technology on gas car