Imagine compound turbo-ing with these... "Yo we heard ya like turbos so we put a turbo inside a turbo so you can double turbo the other turbo'ed turbo!"
No you don't. You just need to have common understanding of cars or engineering at all. You can be a mechanic and be able to explain the joke/understand it. you can be a basic petrolhead and be able to get that joke as long as you just understand and know what he's talking about. Just sayin'. I've met a lot of petrolheads in my line of work that just work on cars as a hobby and they know a lot more than i'd think they do. I mean yea sure they don't have the knowledge a specialist would, but hey that's why specialists are called specialists. :)
It seems that Honeywell has adapted the stators that feature in their turbine engines. In the twin-shaft turbocharger, Honeywell engineers have made the stators move and provide a second function. Very interesting. Thank you!
FYI, the Allison (now Rolls-Royce) 250 turboshaft engine was originally designed in the '60s with a multi-stage axial compressor feeding a single stage radial compressor. In the most recent design version of this turboshaft they have now eliminated all of the axial compressor stages and only use a single stage radial compressor to achieve all of the pressure ratio they require. Seems to indicate that radial compressors have been developed to the point that the added complexity of axial plus radial compressors is no longer required. The result of 50 years of engineering effort...
It isn't that they try to avoid the complexity of axial compressors, instead it is done for packaging reasons. Axial compressors are preferred almost universally, as they are much more efficient than radial, can work with higher flow rates, and (crucially) it is possible to implement multistage compression so that a much higher pressure ratio can be achieved. That is why every modern jet/turbine engine is using them exclusively, with the only exceptions of very small engines and engines that need to be packaged in a tight space (in helicopters typically). In very small applications axial don't work very well, since their aerodynamics don't scale well for small sizes. Also in helicopters there are usually tight packaging constraints for the length dimension, so usually a single radial stage is added following axial stages. The reason is that radials are much shorter (but wider) than axials, so replacing several axial stages with a single radial results in a much shorter engine (at the expense of performance and efficiency). Usually it is not enough to use just a radial compressor, since it limits the possible pressure ratio, so axial stages are added.
The Allison/RR 250 is a small turboshaft (250 - 400 HP) intended for use in light helicopters. The original design version used a multi-stage axial plus single stage radial compressor even though the application was light helicopters, and they have evolved the design over the years to now eliminate the axial compressor stages without any reduction in engine shaft power output. Seems to me that radial compressor performance has had to improve over the years to allow elimination of the axial stages, and that means simplification and mfg cost savings.
Yes advancements in technology allowed using just a radial compressor, but it's mostly done to reduce the length of the engine. With a modern axial-radial compressor design, the engine would be more efficient, potentially more powerful, but most importantly for this application - bigger. With a fully axial compressor it would be even more efficient and powerful, but much longer. In engines where the length is not a big issue radials are never used (you only find them in compact helicopter and turboprop engines). The best centrifugal compressors have a peak efficiency in the low 70%. For axial that is 85-93%. Also axial compressors allow much higher pressure ratios, which results in both more power and higher efficiency.
you should look into honeywells designs for turbo fan jet engines, the two shaft turbo seems very similar to a low bypass jet engine used on cargo aircraft -an aircraft mechanic
Basically a similar design to almost any modern turbine engine (split spool) -almost an airframe and powerplant mechanic, seriously just have to take As & Ps
Honeywell aka Garrett aka Airesearch patented its previous design used in TSCP 700, an auxiliary power unit (APU) used in McDonnell Douglas DC-10s and MD-11s. It is also eerily to the Air Cycle Machines (also by Honeywell) used in the old jets like DC-10s and Boeing 747s. The presence of many guide vanes could be its Achilles heel. I was an aircraft mechanic and I can vouch the numerous time these assembly fail. Nope, the turbochargers I see shall continue into the path of mechanical simplification, probably integrating many separate components into a single unit. IMHO that is just my view
Your videos just keep on being great and informative in some magical way; I mean who else can make a white board drawing awesome like you?! Thanks, Jason! Keep up the great work!
03-07 6.0 powerstroke has a variable vane turbo. 08-10 6.4 has sequential turbos and the larger is variable vane. 11-17 6.7 are twin scroll. Ford F series is the best selling truck so I’d say you pretty much hear variable vane turbos every single day. They’re everywhere.. check out the 6.7 scorpion powerstroke. The exhaust ports are inside the V. It could make an interesting video.
I get what your saying.Any diesel looking to maximize towing or make power is using a form of compounding turbos. I have a set of towing twins on my 01 ram. Night and day difference between towing with them and with out.
Sorry sir...but the GT32 SST they put in the early trucks of the 6.7 was a POS in terms of reliability and max power output and they replaced it with the more boring VGT variant of the GT37 in 2015 model year.
For those who may ask about the two shaft design, it must be due to have two different spindle speed on the two shaft, it does increase the efficiency of the compressor compared to a one shaft design ( this is used in the most recent airliner jet engine).
I loved your little humour insertions from time to time on this video. Whether intentional or not, you had me laughing sir. Good explanation as always.
You're ability to self-depricate sarcastically while noting engineering humor is amazing lol. Seriously, the fact that you can explain complicated systems so simply is a gift for us all, thank you. And more of that sarcastic humor, I love it.
they're already connected to the engine cooling system. so there isnt a whole lot more cooling you can really do there unless you could get the exhaust temp down significantly before it enters the turbo. the outer shaft can have holes in it to allow oil feed and drain to the inner shaft. not a huge deal i'd imagine.
"keeping that inner shaft cool and spinning freely would be one heck of a challenge." Not just spinning freely but handling the innate vibration problems of an automotive setup for that longer shaft along with gyroscopic reactions. I can't see something like a foil bearing lasting long in such an environment even though it'd probably be the best mechanical solution. You could counter the heat problems my moving to silicon carbide or other high temp+high strength ceramic materials but that's going to come with its own sets of problems - and costs. In any case if you do move to silicon carbide rotors, the fact that it's twice as strong as steel for 1/3 the mass means that if used in a conventional turbine you'd eliminate a large part of the lag issue and be able to spool to much higher velocities without requiring hideous mechanical complexity.
Great video. An idea for a future video would be to go through a taxonomy of forced induction system types including turbine (if used)/compressor style, and system configurations in use today with examples. It would be neat to see the range of commercially available systems today from supercharged Corvettes to sequential turbo diesels, quad turbo Veyron, and supercharged+turbocharged systems etc.
The two shaft model is similar to a standard jet aircraft turbofan engine like the CFM-56 engine on Boeing 737's. Those engines also have two shafts with the large front fan driven by a power turbine on the inner shaft with a second power turbine on the outer shaft that drives the compressor stages which feeds the burners of the jet engine. These jet engines use that big front fan along with multiple axial stages to reach very high pressure ratios in the range of 35:1. The single shaft turbo with both axial and centrifugal compressors is the more likely of the two to be put in service. It can provide tangible additional boost pressure with only a short extension of the shaft and perhaps a front support bearing. It could be created as an add on to existing turbos by screwing into the front of the compressor wheel and adding a short extension to the intake scroll shell. Building concentric shafts in automotive size turbos would be very difficult to create and maintain. This is because the longer inner shaft would have to be relatively thin to fit inside the centrifugal shaft. The larger hollow centrifugal shaft would have to be lubricated internally to ensure proper lubrication of the inner shaft. This makes the two concentric shafts very difficult and expensive to design, build and maintain. This is not a big deal in a multi-million dollar jet engine but a big obstacle in a production engine turbocharger.
i learned my HND in automotive engineering with half the information this guy shows. if only you were my lecturer back in the day then who knows what i would know now. your information is super clear and precise and the drawings are decent as well.
Locomotive turbos: gear driven until you reach a certain RPM, then exhaust driven after... it's a combination supercharger and turbocharger. That would be an interesting technology to adapt to automotive - twin charging in one compact package.
@@caleblarsen5490 oh, definitely. They typically only operate in low rpm high load states for a very short period of time - after that, it's either high rpm high load to get to track speed or idle/cruising once at track speed. The reason for being gear driven is that the turbo was optimized for high engine rpm operation - at low engine rpms, there's not enough exhaust gas volume to spin the turbo to the necessary turbo rpms; in a locomotive with a large engine, true twin charging or sequential turbo systems would be far too complex and large to be useful - hence the single unit that does both.
I like having a VGT on my truck (Detroit Diesel) because I can use light throttle to spool the turbocharger before a hill without using as much fuel. I can see how this Honeywell/Garrett design would be useful.
Frank Whittle is angry at you not remembering his jet design with what you call a “radial” he called centrifugal compressor. I know I’m geeking out on you, but you do make a great videos on great subjects. Thumbs up, to you as always.
During WW II many, many aircraft used multi-stage multi-speed superchargers and turbochargers. Some, such as the P-47 used a turbocharger feeding a supercharger. Because there is nothing a turbocharger or supercharger likes more than being fed by another turbocharger or supercharger. The German Bf-109 used a supercharger with a very advanced speed control that smoothly adjusted boost according to altitude.
A better descriptor is “Centrifugal” Flow rather than “Radial” Flow. This is the same technology as a jet engine. Since we are talking Honeywell turbochargers, look at the cutaway of the Honeywell (née Garrett) TFE-731 Turbofan engine. It has multiple axial flow stages in its compressor section followed by a centrifugal flow compressor before compressed air is sent to the burner section and then on to the exhaust turbines that drive the compressor and bypass fan sections of the engine.
That Honewell turbo could be called twin spool with variable stators. On another matter not unrelated, the 1st 'mans' jet engine was the J79. It was such a mechanically correct design that many are still in use today. It has variable stators and is of single spool design. There is a youtube video of a bloke with a cutaway j79 motor explaining the operation and gas flow. It is a short video and very informative.
I work at Honeywell and of the turbos that have had this design, the issue is with bore-through wheels. Mainly compressor wheels as our manufacturing process would cause minor imperfections within the bore which caused stress fractures at speed.
Twin spool is the right name of it in aviation. This is my long time prediction they will soon use the design of hybrid compressor of the jet engine...
You guys might get a kick out of some of the aircraft engines used in WW2, like the turbo compound Wright 3350, plus most others had either centrifugal superchargers, turbosuperchargers, or both, mostly to "normalize" the thin air at high altitude. But the TC 3350 had three turbos which had shafts that added the power right back to the crank for efficiency. The last dying throes of the large recips.
Thanks for the information. As I would like to use a dual turbo setup (one per bank) on a 5.2L based 383 Stroker (500HP-600HP NA) in a Chevy S-10. Although ideally a dual sequential setup would be outstanding if theres enough room in the engine bay. Small turbo blown into the Large turbo continuously (1000HP+). Unless I'm missing something obvious that would prevent this from working correctly.
Thanks for the insight to this new turbo design, I've seen bits and pieces of it but thought it was all about the extra set of blades but it actually has a second shaft as well. Seems like a really good idea in theory, but also its just another thing that can go wrong in some cases lol.
I was just watching a video a couple days ago showing a compound turbo setup on a diesel and thought “why has nobody come up with multistage turbochargers, like turbojet/turbofan engines?” I think it could eliminate lots of weight and complexity from an engine bay...
Minus the combustion chamber, yeah. It's very similar to a turbofan, except the second stage with a higher compression ratio compressor is radial rather than axial, obviously. I think this video would have been even better if he had noted the similarities between this and a turbofan engine. Additionally, you can make a turbojet engine out of a turbocharger, actually. The outlet of the compressor feeds a combustion chamber, and that feeds the inlet of the turbine. Can even make them with afterburners. Seeing one made with a turbo like this would be really freaking cool.
Reminds me of the input shaft on a dual clutch trans. A solid shaft riding inside another hollow shaft, both turning independently, but on the same axis.
I do enjoy your videos. I especially like how you supercharge your Honda S2000. A lot of what you say in your videos goes right over my head. I'm more of a Hands-On learner than a book learner. You reminds me of a lot of Kevin Cameron of Cycle World magazine he always would write engineering articles in Cycle World magazine. Now, he is getting older but still writing he has put out some CZcams videos. I would suggest giving some of his past articles I read if you can.
One reason we don't see two-shaft turbos in common automotive applications: it's apparently patented by Honeywell so no one else is able to use that design without paying for it (if they even license it). That said we also don't see sequential turbos done very often either, so their claim that sequential is more expensive probably holds up, else sequential turbos would be more commonly employed.
CZcams turbine mechanic AgentJayZ would disapprove of your description of the variable state vanes, unless they are actually supposed to be inlet guide vanes. His videos on turbo machinery operation and theory are well done.
Apparently the Honeywell turbocharger uses 2 concentric shafts. Lubricating the outer shaft should be no problem since it could be lubricated in the same manner as with a conventional turbocharger. However, lubricating the inner shaft would be an extreme challenge. I suppose that the outer shaft could have holes in it through which the oil could flow to lubricate and cool bearings between it and the inner shaft and simply let that oil be lost. Perhaps they could get a special dispensation from the EPA to ignore the resulting blue smoke. The EPA right now seems amenable to reducing many pollution restrictions.
What's the difference between twin scroll turbos and dual-volute turbos? I understand that fundamentally each type splits the exhaust flow to the turbo, but what do they differently and how does that affect boost response and overall flow? I've been seeing some recent patent documents from Borg Warner about dual-volute turbos.
I've never heard the term "radial" compressor. In aviation, we call this a centrifugal compressor. The turbine section of a turbocharger typically has what is known as "radial inflow", where the exhaust gas impinges on the turbine at the outer edge and then flows toward the shaft and then out the exhaust.
That sounds like a blow off valve now. -TCs is like this high pitch whistling bird is stuck in the engine bay. -Roots SCs sounds more like there's a banshee tied up in the trunk.
Turbos use free air superchargers mechanically have to bring in air . Supercharger are 4 x more expensive but they look cool and most can't be repaired.
Ford used a turbo similar to that design in the 2011-2014 ford powerstrokes. It proved to be somewhat problematic and they have since gone back to a more conventional vgt design. The turbo is a garret 851824.
deflecting the flow out to the highest torque radius of the radial is always going to increase the force. They're centripetal devices and the intent is to impart velocity to increase pressure so pushing the flow out and making it more laminar to the input will do a lot.
One of the flaws I can see in this sort of set up is going to be the cost of complexity and service. I would be interested in seeing price comparison of a similar flowing set of sequential turbo chargers.
Awesome upload as always. So I picked up the new 2019 VW Jetta with the 1.4l turbo and a MANUAL trans! Yup, VW is still making a base compact car with a manual option on the base S trim. It is actually pretty amazing so far but of course I still have about 800 miles to go on the break-in so I have not gone full send with her yet. This is the new 7th generation Jetta using the Audi MQB platform and it is nearly as large as a midsize car now. As an old dude I would say this is the perfect budget way for a youngster to get into a manual car that is still fun to drive while they get comfortable with the stick shift. Then they can trade up for BRZ or Mustang in a few years when ready for the rear wheel drive experience. Continued success for your channel and thank you for what you do. I use your uploads all the time to explain mechanical stuff to friends and family.
That's pretty cool. I just spent a few minutes on VW"s site looking at how one can spec that model. Manual trans, and 16" or 17" aluminum wheels would be nice. 17" may be a bit too heavy for that lower HP/torque though.
You are right about that and extremely smooth riding but yet with that manual at least still fun to jam around in. I dig the looks better than the competitors in this segment and again manual FTW.
Such a cool idea to extend the compressor map of a regular turbo. As you mentioned in the video, a lot less complex than a twin turbo set up. I have a Nissan Navara (Frontera) 2.3TT diesel and there is an awful lot going on just driving down the road. Yes it works, and makes a broad spread of torque from around 1200rpm up, but it's very complex.
Science and tech guys just can't ever seem to get enough of something that already works more than well enough as is without trying to turn it into something far more complicated than it has to be and by then,all the extra fancy cool new additional designs and components are no longer all that beneficial in the end when compared to the technology's original yet efficient form. The more additional parts and contraptions added would also reduce reliability as well by adding extra tight tolerances for having the shafts balanced along with extra bearings that can go bad. What the turbo industry should really be working on is how to actually make turbochargers last longer since they work in very harsh and high heat based conditions. For example,work on finding even more durable materials for components that could put an extended warrantee to where turbochargers could be guaranteed to remain in operational conditions for at least twice as long as what they currently are as a means to save the consumer more money without having to worry about dealing with so many rebuilds or replacements being so necessary.
Honeywell patent covers the Garrett original design which was an adaptation of the Garrett AirResearch Auxiliary Power Unit (APU) TSCP700 used in McDonnell Douglas DC-10 and MD-11 as well as Airbus A300B4. Yep, it's not new. But one of the critique of this design is that it is overly complex with its variable vanes. In aircraft use these vanes are powered hydraulically by fuel or servo air. In my experience, especially with the early ones, in which the vanes powered by servo air, I have to change the fuel control or its components as air leaks are difficult to trace. Other and later versions of APU especially single shaft design, are much more reliable.
Should do a video of the most efficient spinning turbos and which style turbo charges create the most power and maybe also adding which create the least amount of lag, adding if they were all about the same size or so. I’d like to see that in a video!!
"Swirl"? No. Just optimizing the angle at which the incoming airflow meets the axial compressor intake blades to improve flow (reduce turbulence and drag at the inlet blades). Likewise on the exhaust side, optimizing the flow outward to extract more energy from the flow (not lose energy to turbulence).
I Saw The First Example Of The Axial And Radial Wheel Turbo And I'm Thinking There Is No Way That Would Work. The Lag Would Be Horrendous Because The Weight Of The Rotating Assembly. Then I Saw An Actual Two Shaft Turbo And Boom! MIND BLOWN Hahahaha
How to hold the oil in? Something needs to hold the inner turbo shaft in place, so it does not move back and forth and it still needs to seal oil. The outer shaft needs to be ekstra large to allow the inner shaft, leading to lower efficiency then a regular turbo. The bearing part of the turbo is generally the smallest part of the turbo, if this part is made bigger to allow 2 shafts and a longer turbo shaft with ekstra fan, the packaging could be worse then 2 normal turboes. I have never seen this kind of turbo used anywhere, so the patent could just be a shotgun patent, shooting at something and patent all the idears hit by the shot.
A little more than halfway through the video I already learned that Honeywell also makes turbos. Here I thought they made HVAC thermostats, alarm system components, and other household stuff only.
Definitely need more collaborations with Car Throttle. Jason explains something really complicated, Alex then decides if it drifts and/or can be fisted.
Having worked on F-15's, our jet engine compressor is axially designed. I don't see how your drawing in the upper right will get any compression out of the axial compressor without a stator behind it (with vanes tilted in the opposite direction). Every compressor stage in a jet engine has a fixed stator between each compressor stage alternating the vane angle and building pressure by changing flow direction (or perhaps I should say flow deflection). The radial compressor uses the housing to develop pressure, plus the flow direction changing 90 degrees causes pressure, so doesn't need to have one. Are you sure there isn't a stator in there? The dual shaft has stators of a variable geometry variety, which jet engine compressors also employ on some stages. There are articulated arms which gang these together and tilt them in unison. I realize that you are describing automotive turbo or superchargers and not jet engines, but the compressors of both serve the same function. People have successfully hacked radial automotive turbochargers into simple jet engines by hooking the compressor and turbine stages together through a jet combustion chamber, so I believe the engineering similarities are a sound comparison.
Dual shaft? I feel like I got the shaft. I would rather you said dual compressor. I still only see one shaft. Love your videos sort of. I think everyone knows how I mean that. Keep up the work.
The extra mass of the axial turbine will represent a performance compromise/cost that, perhaps Honeywell don’t want to openly discuss. That compromise will manifest itself as lag and/or spool up delay. The only way to properly compare what the true benefits and/or downsides of the design are, is to plot boost pressure against exhaust turbine pressure and/or crankshaft rotational speed and/or time. The additional turbine is not a bad idea. But Garrett know (whether or not they openly admit it in their literature) the 2 shaft (or dual compressor turbine) turbocharger concept - compared to any other turbocharger with the same exhaust/compressor turbine geometry - *trades off additional boost for a delay in compressor/turbine shaft acceleration times; which means more lag and/or spool up delays. Essentially this is why most European car/engine manufacturers use a similar concept of another in-line (axial/other) pre-compressor, but power it with electrons, not exhaust gases. That way the *above-mentioned trade odds are almost completely removed. Good video.
This is very similar to modern jet and turbine engines. Most modern turbine engines use more than one shaft (called spools), with GE for instance using two spool engines and Rolls Royce preferring three spools. Also in many helicopter turboshaft engines and some turboprops a radial compressor stage is added to multiple axial stages in a very similar way to what is shown here. This is done when tight packaging is a prime concern (replacing several axial stages with a single radial results in a much shorter engine). As far as I know all engines that use that extra radial stage do it on a common shaft with the preceding axial stages.
I would guess that these turbochargers are not yet in use due to costs. Multiple spools turbomachinery are very expensive to design and manufacture. When Rolls Royce first developed their three spool engines they had underestimated the magnitude of the challenge they were facing, and the company nearly went bankrupt with the UK government having to bail them out. Also, while axial compressors are far superior to radials (they are far more efficient, and can use multiple stages for much higher pressure ratios), their aerodynamics don't scale well for the small sizes of turbochargers, so making that work would probably demand very tight manufacturing tolerances, also adding to high costs.
Neat, never heard of these. Closest to them I was aware of are compound turbo setups where you use a big turbo feeding a little turbo. Exhaust flow goes from cylinder head to the little turbo then the waste gas and waste gate bypassed exhaust feed the big one. So that way the big turbo can increase the PR to the little turbo. You get a very responsive setup with insane low end torque and power to redline. Maybe you could do a video on compounds like this, because most people don't seem to know about it.
I wonder if this enables the centrif to operate shock free compared to a single stage radial. If so, this would maintain a somewhat simpler design of the impeller and low manufacturing cost while also increasing it's thermal efficiency across the speed range. My guess is that the inlet experiences very good uniform flow circumferentially which helps.
I assume you mean sequential turbos in the traditional sense as used in the Supra and others? Because the comparison that comes to my mind is the use of compound turbos in diesel engines where the exhaust from the first turbo drives the turbine of a second turbo, which turns a compressor that sends boost into the compressor of the first turbo.
I assume you know, but if not, turbines (at least half) use axial/ radial compressors. Also use Ng (compressor) and separate Np (turbine, “power”) shafts. This is 60s tech
On a 2 spool axial flow compressor jet engine, its is understood that the compressor eats up 50% of the energy from burning fuel. Therefore, turbo-superchargers are not "free" power on piston engines.
in a jet engine it is more like 2/3 the power used to drive the compressor. In a piston it's not "free" power it is the option to burn more fuel and make power using "free" power that would otherwise be waste as heat and noise out the exhaust. piston engines and turbine engines have very little in common
Alxial compressors give smaller pressure ratios per stage. I would argue a compound turbo system would be more efficient , maybe heavier but simpler. Check out the design of jet engines.
This seems like a great idea for a 4 cylinder or even an inline 6cyl application. OEM turbos tend to be small. They are lag free but dont offer much high end power. Big turbos dont give you that lowend response. This dual shaft design looks to solve this without taking up the space that a sequential tt setup would. The axial compressor "preps" the radial one so it can get up to speed faster.....like accelerating from a rolling start vs standing still.
A turbo with two compressors on one shaft but has two compressor housing back to back inline for compound turbo applications would be something I would like to see devolved.
I'd like to see more on a mechanism for vanes in the turbo. I'm curious about failure modes of a vane breaking free after a few years and getting sucked into the turbo.
My understanding of guide vanes is that a spinning fan tends to spin air and the guide vanes redirect it back into the desired direction. It's basic jet engine science. More efficient might be to replace the vanes with a counter rotating fan blade. Theoretically double the air could be pushed at the same RPM that way. I always had a problem with jet engine stator vanes. Stator meaning stationary. Why would you want to carry stationary weight in something so dynamic. And why wouldn't you want to make it twice as hard to max out the bearings.
I can't wait to see how small the intercooler between the 2 compressor stages is, and how, at such a small size, it has any kind of efficiency or flow at all... It will have to be liquid to air though....
I think it’s pretty funny how you put out this video after your “how much faster is the S2000” video. It seems like the two different kind of vanes would improve the supercharger design on your S2000. The down low torque would be increased.
Reliablilty with two shafts/ sets of bearings is thier Achilles heel. Variable intake, with hybrid electric boost motor on same shaft is the turbo design of the future
We demand timelapse video as intro with you drawing before every video...
yes!
Plot Twist : He isn't the one drawing, in fact noone is. It is all CGI.
@Thomas B plot twist: even the comments, human!
In the immortal words of Pimp your ride, "we put a turbo IN YOUR TURBO!"
omar mendez yous hould market this idea before someone steals it from you.
yo dawg i heard you like turbos so we put a turbo in your turbo so you can boost while you boost
Imagine compound turbo-ing with these... "Yo we heard ya like turbos so we put a turbo inside a turbo so you can double turbo the other turbo'ed turbo!"
actually, the more correct metaphor would be "we put a turbo AROUND YOUR TURBO"
superdupergrover depends which one came first
Engineering Explained explains an engineering joke
lmfao
To be fair, you need an engineer to explain most engineering jokes.
No you don't. You just need to have common understanding of cars or engineering at all. You can be a mechanic and be able to explain the joke/understand it. you can be a basic petrolhead and be able to get that joke as long as you just understand and know what he's talking about. Just sayin'. I've met a lot of petrolheads in my line of work that just work on cars as a hobby and they know a lot more than i'd think they do. I mean yea sure they don't have the knowledge a specialist would, but hey that's why specialists are called specialists. :)
Found the engineer.
and i still dont get it
You should meet james may
I'd like to see both of them talking about torque & horsepower
and Jeremy doing donuts in the background
nazhif1 while the car on fire
nazhif1 "explain torque"
in front of the queen
It seems that Honeywell has adapted the stators that feature in their turbine engines. In the twin-shaft turbocharger, Honeywell engineers have made the stators move and provide a second function. Very interesting. Thank you!
What do you mean? Everyone enjoys reading SAE technical papers 😝
David Cheung ha ha!
FYI, the Allison (now Rolls-Royce) 250 turboshaft engine was originally designed in the '60s with a multi-stage axial compressor feeding a single stage radial compressor. In the most recent design version of this turboshaft they have now eliminated all of the axial compressor stages and only use a single stage radial compressor to achieve all of the pressure ratio they require. Seems to indicate that radial compressors have been developed to the point that the added complexity of axial plus radial compressors is no longer required. The result of 50 years of engineering effort...
It isn't that they try to avoid the complexity of axial compressors, instead it is done for packaging reasons. Axial compressors are preferred almost universally, as they are much more efficient than radial, can work with higher flow rates, and (crucially) it is possible to implement multistage compression so that a much higher pressure ratio can be achieved. That is why every modern jet/turbine engine is using them exclusively, with the only exceptions of very small engines and engines that need to be packaged in a tight space (in helicopters typically).
In very small applications axial don't work very well, since their aerodynamics don't scale well for small sizes. Also in helicopters there are usually tight packaging constraints for the length dimension, so usually a single radial stage is added following axial stages. The reason is that radials are much shorter (but wider) than axials, so replacing several axial stages with a single radial results in a much shorter engine (at the expense of performance and efficiency). Usually it is not enough to use just a radial compressor, since it limits the possible pressure ratio, so axial stages are added.
The Allison/RR 250 is a small turboshaft (250 - 400 HP) intended for use in light helicopters. The original design version used a multi-stage axial plus single stage radial compressor even though the application was light helicopters, and they have evolved the design over the years to now eliminate the axial compressor stages without any reduction in engine shaft power output. Seems to me that radial compressor performance has had to improve over the years to allow elimination of the axial stages, and that means simplification and mfg cost savings.
And I believe RRs new trident engines have three independent shafts. But it's axial of course
Axial= higher overall compression, centrifugal= highest compression ratio per stage
Yes advancements in technology allowed using just a radial compressor, but it's mostly done to reduce the length of the engine. With a modern axial-radial compressor design, the engine would be more efficient, potentially more powerful, but most importantly for this application - bigger. With a fully axial compressor it would be even more efficient and powerful, but much longer. In engines where the length is not a big issue radials are never used (you only find them in compact helicopter and turboprop engines).
The best centrifugal compressors have a peak efficiency in the low 70%. For axial that is 85-93%. Also axial compressors allow much higher pressure ratios, which results in both more power and higher efficiency.
you should look into honeywells designs for turbo fan jet engines, the two shaft turbo seems very similar to a low bypass jet engine used on cargo aircraft -an aircraft mechanic
Its also very similar to the re-badged Honeywell (Lycoming) turbo-shaft engines used on bigger helicopters. -another aircraft mech
I believe it's a very simple version of any two stage compressor -a third aircraft mechanic
Basically a similar design to almost any modern turbine engine (split spool) -almost an airframe and powerplant mechanic, seriously just have to take As & Ps
You mean Os & Ps?
Honeywell aka Garrett aka Airesearch patented its previous design used in TSCP 700, an auxiliary power unit (APU) used in McDonnell Douglas DC-10s and MD-11s. It is also eerily to the Air Cycle Machines (also by Honeywell) used in the old jets like DC-10s and Boeing 747s. The presence of many guide vanes could be its Achilles heel. I was an aircraft mechanic and I can vouch the numerous time these assembly fail. Nope, the turbochargers I see shall continue into the path of mechanical simplification, probably integrating many separate components into a single unit. IMHO that is just my view
Your videos just keep on being great and informative in some magical way; I mean who else can make a white board drawing awesome like you?! Thanks, Jason! Keep up the great work!
03-07 6.0 powerstroke has a variable vane turbo. 08-10 6.4 has sequential turbos and the larger is variable vane. 11-17 6.7 are twin scroll. Ford F series is the best selling truck so I’d say you pretty much hear variable vane turbos every single day. They’re everywhere.. check out the 6.7 scorpion powerstroke. The exhaust ports are inside the V. It could make an interesting video.
I get what your saying.Any diesel looking to maximize towing or make power is using a form of compounding turbos. I have a set of towing twins on my 01 ram. Night and day difference between towing with them and with out.
Sorry sir...but the GT32 SST they put in the early trucks of the 6.7 was a POS in terms of reliability and max power output and they replaced it with the more boring VGT variant of the GT37 in 2015 model year.
That two-shaft turbo design is absolute brilliance. I hope we get to see it in action soon.
Lubricanting the central rod will be a quite a challenge
@@justchillin3492these types of compressors have been used in jet engines for a while, im sure they already have design solutions that can be adapted
For those who may ask about the two shaft design, it must be due to have two different spindle speed on the two shaft, it does increase the efficiency of the compressor compared to a one shaft design ( this is used in the most recent airliner jet engine).
I loved your little humour insertions from time to time on this video. Whether intentional or not, you had me laughing sir.
Good explanation as always.
I used to work for Honeywell and to be honest, I haven't seen any project (PV or CV) with this kind of design ;)
Engineers don't make jokes. They engineer them. And then write about them. ^_^
You're ability to self-depricate sarcastically while noting engineering humor is amazing lol. Seriously, the fact that you can explain complicated systems so simply is a gift for us all, thank you. And more of that sarcastic humor, I love it.
Lubrication and cooling for the turbines biggest challenge
I know solutions to help keep the running temperature cool, but I won't say what they are, due to certain types of people on the internet.
gav why not put a dry ice or water sleeve around them..it'd be much like putting a bag of ice on your head when you have a fever
they're already connected to the engine cooling system. so there isnt a whole lot more cooling you can really do there unless you could get the exhaust temp down significantly before it enters the turbo. the outer shaft can have holes in it to allow oil feed and drain to the inner shaft. not a huge deal i'd imagine.
egt's are just numbers lol
"keeping that inner shaft cool and spinning freely would be one heck of a challenge."
Not just spinning freely but handling the innate vibration problems of an automotive setup for that longer shaft along with gyroscopic reactions. I can't see something like a foil bearing lasting long in such an environment even though it'd probably be the best mechanical solution.
You could counter the heat problems my moving to silicon carbide or other high temp+high strength ceramic materials but that's going to come with its own sets of problems - and costs.
In any case if you do move to silicon carbide rotors, the fact that it's twice as strong as steel for 1/3 the mass means that if used in a conventional turbine you'd eliminate a large part of the lag issue and be able to spool to much higher velocities without requiring hideous mechanical complexity.
"I'm just clueless and I don't know about it." Very funny.
Great video dude I’m a mechanic been one for 20 yrs love your videos brother
g2skinny thanks!
Great video. An idea for a future video would be to go through a taxonomy of forced induction system types including turbine (if used)/compressor style, and system configurations in use today with examples. It would be neat to see the range of commercially available systems today from supercharged Corvettes to sequential turbo diesels, quad turbo Veyron, and supercharged+turbocharged systems etc.
The two shaft model is similar to a standard jet aircraft turbofan engine like the CFM-56 engine on Boeing 737's. Those engines also have two shafts with the large front fan driven by a power turbine on the inner shaft with a second power turbine on the outer shaft that drives the compressor stages which feeds the burners of the jet engine. These jet engines use that big front fan along with multiple axial stages to reach very high pressure ratios in the range of 35:1.
The single shaft turbo with both axial and centrifugal compressors is the more likely of the two to be put in service. It can provide tangible additional boost pressure with only a short extension of the shaft and perhaps a front support bearing. It could be created as an add on to existing turbos by screwing into the front of the compressor wheel and adding a short extension to the intake scroll shell.
Building concentric shafts in automotive size turbos would be very difficult to create and maintain. This is because the longer inner shaft would have to be relatively thin to fit inside the centrifugal shaft. The larger hollow centrifugal shaft would have to be lubricated internally to ensure proper lubrication of the inner shaft. This makes the two concentric shafts very difficult and expensive to design, build and maintain. This is not a big deal in a multi-million dollar jet engine but a big obstacle in a production engine turbocharger.
i learned my HND in automotive engineering with half the information this guy shows. if only you were my lecturer back in the day then who knows what i would know now. your information is super clear and precise and the drawings are decent as well.
Locomotive turbos: gear driven until you reach a certain RPM, then exhaust driven after... it's a combination supercharger and turbocharger. That would be an interesting technology to adapt to automotive - twin charging in one compact package.
The only issue is fuel economy. If you are constantly in turbo, you're gonna burn a ton of fuel.
@@caleblarsen5490 oh, definitely. They typically only operate in low rpm high load states for a very short period of time - after that, it's either high rpm high load to get to track speed or idle/cruising once at track speed.
The reason for being gear driven is that the turbo was optimized for high engine rpm operation - at low engine rpms, there's not enough exhaust gas volume to spin the turbo to the necessary turbo rpms; in a locomotive with a large engine, true twin charging or sequential turbo systems would be far too complex and large to be useful - hence the single unit that does both.
I like having a VGT on my truck (Detroit Diesel) because I can use light throttle to spool the turbocharger before a hill without using as much fuel. I can see how this Honeywell/Garrett design would be useful.
Frank Whittle is angry at you not remembering his jet design with what you call a “radial” he called centrifugal compressor. I know I’m geeking out on you, but you do make a great videos on great subjects. Thumbs up, to you as always.
That's why I love this channel, dry and devoid of any humor. JK :)
And all talking about different engine induction systems and applications that this is NOT about:/
During WW II many, many aircraft used multi-stage multi-speed superchargers and turbochargers. Some, such as the P-47 used a turbocharger feeding a supercharger. Because there is nothing a turbocharger or supercharger likes more than being fed by another turbocharger or supercharger. The German Bf-109 used a supercharger with a very advanced speed control that smoothly adjusted boost according to altitude.
"very dry and void of any resemblance of humor." Wasn't that a joke tho
The "axial-radial" configuration is also known as "mixed flow."
I didn't know there was so many different types of turbos! Love the technology.
Only just realised these videos are taken in one take! So impressive
I mean like taken with no cuts
A better descriptor is “Centrifugal” Flow rather than “Radial” Flow. This is the same technology as a jet engine. Since we are talking Honeywell turbochargers, look at the cutaway of the Honeywell (née Garrett) TFE-731 Turbofan engine. It has multiple axial flow stages in its compressor section followed by a centrifugal flow compressor before compressed air is sent to the burner section and then on to the exhaust turbines that drive the compressor and bypass fan sections of the engine.
That Honewell turbo could be called twin spool with variable stators.
On another matter not unrelated, the 1st 'mans' jet engine was the J79. It was such a mechanically correct design that many are still in use today. It has variable stators and is of single spool design. There is a youtube video of a bloke with a cutaway j79 motor explaining the operation and gas flow. It is a short video and very informative.
I work at Honeywell and of the turbos that have had this design, the issue is with bore-through wheels. Mainly compressor wheels as our manufacturing process would cause minor imperfections within the bore which caused stress fractures at speed.
Have the test showed any improvements worth noting with these (before self destruction)?
Ksegg was and I think still is doing variable vanes but 3d printed turbos.. cool stuff.
Twin spool is the right name of it in aviation. This is my long time prediction they will soon use the design of hybrid compressor of the jet engine...
Allison 250
Very informative but now you have me looking for two-shaft turbochargers for my project. 🤔
same . . .whats your belt-less boost project?
You guys might get a kick out of some of the aircraft engines used in WW2, like the turbo compound Wright 3350, plus most others had either centrifugal superchargers, turbosuperchargers, or both, mostly to "normalize" the thin air at high altitude. But the TC 3350 had three turbos which had shafts that added the power right back to the crank for efficiency. The last dying throes of the large recips.
Reciprocating engines for planes are used to this day. They aren't dying, and especially were not back then.
@@exploranator I said "large" recips. Dead. Gone.
"I could probably do the entire channel on formula one from here on out if I really wanted to" is what you said in a video in 2012... please do more
Thanks for the information. As I would like to use a dual turbo setup (one per bank) on a 5.2L based 383 Stroker (500HP-600HP NA) in a Chevy S-10. Although ideally a dual sequential setup would be outstanding if theres enough room in the engine bay. Small turbo blown into the Large turbo continuously (1000HP+). Unless I'm missing something obvious that would prevent this from working correctly.
Thanks for the insight to this new turbo design, I've seen bits and pieces of it but thought it was all about the extra set of blades but it actually has a second shaft as well. Seems like a really good idea in theory, but also its just another thing that can go wrong in some cases lol.
I was just watching a video a couple days ago showing a compound turbo setup on a diesel and thought “why has nobody come up with multistage turbochargers, like turbojet/turbofan engines?” I think it could eliminate lots of weight and complexity from an engine bay...
This is exactly like a turbine engine.
Minus the combustion chamber, yeah. It's very similar to a turbofan, except the second stage with a higher compression ratio compressor is radial rather than axial, obviously. I think this video would have been even better if he had noted the similarities between this and a turbofan engine.
Additionally, you can make a turbojet engine out of a turbocharger, actually. The outlet of the compressor feeds a combustion chamber, and that feeds the inlet of the turbine. Can even make them with afterburners. Seeing one made with a turbo like this would be really freaking cool.
@@anthonyantoine9232 the engine is the combustion chamber. a complex one, but its just a gas generator as far as the turbo is concerned.
Reminds me of the input shaft on a dual clutch trans. A solid shaft riding inside another hollow shaft, both turning independently, but on the same axis.
We hooked you up dawg, we installed a turbo in your truck, we fitted not one, but two shafts in yaw turbo dawg.
This was the first step on the road to compound turbo design, gale banks had a similar thing for the vette years ago
I do enjoy your videos. I especially like how you supercharge your Honda S2000. A lot of what you say in your videos goes right over my head. I'm more of a Hands-On learner than a book learner. You reminds me of a lot of Kevin Cameron of Cycle World magazine he always would write engineering articles in Cycle World magazine. Now, he is getting older but still writing he has put out some CZcams videos. I would suggest giving some of his past articles I read if you can.
One reason we don't see two-shaft turbos in common automotive applications: it's apparently patented by Honeywell so no one else is able to use that design without paying for it (if they even license it). That said we also don't see sequential turbos done very often either, so their claim that sequential is more expensive probably holds up, else sequential turbos would be more commonly employed.
Ford/International 6.4 diesel has sequential turbos.
Very nice :)
CZcams turbine mechanic AgentJayZ would disapprove of your description of the variable state vanes, unless they are actually supposed to be inlet guide vanes. His videos on turbo machinery operation and theory are well done.
Does the low inertia of the first stage help reduce turbo-lag?
Apparently the Honeywell turbocharger uses 2 concentric shafts. Lubricating the outer shaft should be no problem since it could be lubricated in the same manner as with a conventional turbocharger. However, lubricating the inner shaft would be an extreme challenge. I suppose that the outer shaft could have holes in it through which the oil could flow to lubricate and cool bearings between it and the inner shaft and simply let that oil be lost. Perhaps they could get a special dispensation from the EPA to ignore the resulting blue smoke. The EPA right now seems amenable to reducing many pollution restrictions.
Very interesting. A small packaged sequential turbo setup.
What's the difference between twin scroll turbos and dual-volute turbos? I understand that fundamentally each type splits the exhaust flow to the turbo, but what do they differently and how does that affect boost response and overall flow?
I've been seeing some recent patent documents from Borg Warner about dual-volute turbos.
I'm pretty sure they're synonymous.
I've never heard the term "radial" compressor. In aviation, we call this a centrifugal compressor. The turbine section of a turbocharger typically has what is known as "radial inflow", where the exhaust gas impinges on the turbine at the outer edge and then flows toward the shaft and then out the exhaust.
That video is much, much better than your early efforts. Good work!
Turbos be like: baaaaahh
Supercharges be like: weeeeeeeee
superchargers are "tssssssssssssssssss"
"baaaahhh" is the engine
He's referring to a "roots" style & you're referring to a centrifugal
That sounds like a blow off valve now.
-TCs is like this high pitch whistling bird is stuck in the engine bay.
-Roots SCs sounds more like there's a banshee tied up in the trunk.
turbos be like ---------------BAHHHHHHHHHHHHHHHHHHH
super be like -weeeeeeeeeeeEEEEEEEEEEEE
get ur super to turbo right man
Turbos use free air superchargers mechanically have to bring in air . Supercharger are 4 x more expensive but they look cool and most can't be repaired.
Ford used a turbo similar to that design in the 2011-2014 ford powerstrokes. It proved to be somewhat problematic and they have since gone back to a more conventional vgt design. The turbo is a garret 851824.
deflecting the flow out to the highest torque radius of the radial is always going to increase the force. They're centripetal devices and the intent is to impart velocity to increase pressure so pushing the flow out and making it more laminar to the input will do a lot.
Awesome, I started to read SAE papers when I begun reading the Bob is the oil guy forums
One of the flaws I can see in this sort of set up is going to be the cost of complexity and service. I would be interested in seeing price comparison of a similar flowing set of sequential turbo chargers.
Twin and triple shaft (or spool, as it's termed) gas turbine engines were developed in the 80s.
Awesome upload as always. So I picked up the new 2019 VW Jetta with the 1.4l turbo and a MANUAL trans! Yup, VW is still making a base compact car with a manual option on the base S trim. It is actually pretty amazing so far but of course I still have about 800 miles to go on the break-in so I have not gone full send with her yet. This is the new 7th generation Jetta using the Audi MQB platform and it is nearly as large as a midsize car now. As an old dude I would say this is the perfect budget way for a youngster to get into a manual car that is still fun to drive while they get comfortable with the stick shift. Then they can trade up for BRZ or Mustang in a few years when ready for the rear wheel drive experience. Continued success for your channel and thank you for what you do. I use your uploads all the time to explain mechanical stuff to friends and family.
Pezz Pezzer congrats on the new ride!
That's pretty cool. I just spent a few minutes on VW"s site looking at how one can spec that model. Manual trans, and 16" or 17" aluminum wheels would be nice. 17" may be a bit too heavy for that lower HP/torque though.
You are right about that and extremely smooth riding but yet with that manual at least still fun to jam around in. I dig the looks better than the competitors in this segment and again manual FTW.
This old guy is happy. BTW if you were not joking about your age a few weeks ago I am a tad shocked you are older than me.
Pezz Pezzer Where I live (outside the US) you can get a manual with nearly every trim of every car VW makes
Such a cool idea to extend the compressor map of a regular turbo.
As you mentioned in the video, a lot less complex than a twin turbo set up.
I have a Nissan Navara (Frontera) 2.3TT diesel and there is an awful lot going on just driving down the road.
Yes it works, and makes a broad spread of torque from around 1200rpm up, but it's very complex.
Science and tech guys just can't ever seem to get enough of something that already works more than well enough as is without trying to turn it into something far more complicated than it has to be and by then,all the extra fancy cool new additional designs and components are no longer all that beneficial in the end when compared to the technology's original yet efficient form. The more additional parts and contraptions added would also reduce reliability as well by adding extra tight tolerances for having the shafts balanced along with extra bearings that can go bad. What the turbo industry should really be working on is how to actually make turbochargers last longer since they work in very harsh and high heat based conditions. For example,work on finding even more durable materials for components that could put an extended warrantee to where turbochargers could be guaranteed to remain in operational conditions for at least twice as long as what they currently are as a means to save the consumer more money without having to worry about dealing with so many rebuilds or replacements being so necessary.
Honeywell patent covers the Garrett original design which was an adaptation of the Garrett AirResearch Auxiliary Power Unit (APU) TSCP700 used in McDonnell Douglas DC-10 and MD-11 as well as Airbus A300B4. Yep, it's not new. But one of the critique of this design is that it is overly complex with its variable vanes. In aircraft use these vanes are powered hydraulically by fuel or servo air. In my experience, especially with the early ones, in which the vanes powered by servo air, I have to change the fuel control or its components as air leaks are difficult to trace. Other and later versions of APU especially single shaft design, are much more reliable.
Just found this super small turbo at the junk yard, I’m going to put it inmy Honda TRX400.
Did you do it???
Should do a video of the most efficient spinning turbos and which style turbo charges create the most power and maybe also adding which create the least amount of lag, adding if they were all about the same size or so. I’d like to see that in a video!!
Sort of like a more compact compound turbochargers setup. Instead of running multiple turbochargers, it's an all in one.
"Swirl"? No. Just optimizing the angle at which the incoming airflow meets the axial compressor intake blades to improve flow (reduce turbulence and drag at the inlet blades). Likewise on the exhaust side, optimizing the flow outward to extract more energy from the flow (not lose energy to turbulence).
I Saw The First Example Of The Axial And Radial Wheel Turbo And I'm Thinking There Is No Way That Would Work. The Lag Would Be Horrendous Because The Weight Of The Rotating Assembly. Then I Saw An Actual Two Shaft Turbo And Boom! MIND BLOWN Hahahaha
How to hold the oil in?
Something needs to hold the inner turbo shaft in place, so it does not move back and forth and it still needs to seal oil.
The outer shaft needs to be ekstra large to allow the inner shaft, leading to lower efficiency then a regular turbo.
The bearing part of the turbo is generally the smallest part of the turbo, if this part is made bigger to allow 2 shafts and a longer turbo shaft with ekstra fan, the packaging could be worse then 2 normal turboes.
I have never seen this kind of turbo used anywhere, so the patent could just be a shotgun patent, shooting at something and patent all the idears hit by the shot.
What happened to BorgeWarner's twin scroll butterfly controlled turbos from a few years ago?
A little more than halfway through the video I already learned that Honeywell also makes turbos. Here I thought they made HVAC thermostats, alarm system components, and other household stuff only.
Well, they do make jet engines...
I come from a more electronics background so I didn't realize they made anything like that. Really interesting though. Thank you for the info.
Definitely need more collaborations with Car Throttle. Jason explains something really complicated, Alex then decides if it drifts and/or can be fisted.
Having worked on F-15's, our jet engine compressor is axially designed. I don't see how your drawing in the upper right will get any compression out of the axial compressor without a stator behind it (with vanes tilted in the opposite direction). Every compressor stage in a jet engine has a fixed stator between each compressor stage alternating the vane angle and building pressure by changing flow direction (or perhaps I should say flow deflection). The radial compressor uses the housing to develop pressure, plus the flow direction changing 90 degrees causes pressure, so doesn't need to have one. Are you sure there isn't a stator in there?
The dual shaft has stators of a variable geometry variety, which jet engine compressors also employ on some stages. There are articulated arms which gang these together and tilt them in unison.
I realize that you are describing automotive turbo or superchargers and not jet engines, but the compressors of both serve the same function. People have successfully hacked radial automotive turbochargers into simple jet engines by hooking the compressor and turbine stages together through a jet combustion chamber, so I believe the engineering similarities are a sound comparison.
Dual shaft? I feel like I got the shaft. I would rather you said dual compressor. I still only see one shaft. Love your videos sort of. I think everyone knows how I mean that. Keep up the work.
The extra mass of the axial turbine will represent a performance compromise/cost that, perhaps Honeywell don’t want to openly discuss.
That compromise will manifest itself as lag and/or spool up delay.
The only way to properly compare what the true benefits and/or downsides of the design are, is to plot boost pressure against exhaust turbine pressure and/or crankshaft rotational speed and/or time.
The additional turbine is not a bad idea.
But Garrett know (whether or not they openly admit it in their literature) the 2 shaft (or dual compressor turbine) turbocharger concept - compared to any other turbocharger with the same exhaust/compressor turbine geometry - *trades off additional boost for a delay in compressor/turbine shaft acceleration times; which means more lag and/or spool up delays.
Essentially this is why most European car/engine manufacturers use a similar concept of another in-line (axial/other) pre-compressor, but power it with electrons, not exhaust gases.
That way the *above-mentioned trade odds are almost completely removed.
Good video.
The Porsche 718 GTS has a variable vane turbo. Thanks for the video.
This is very similar to modern jet and turbine engines. Most modern turbine engines use more than one shaft (called spools), with GE for instance using two spool engines and Rolls Royce preferring three spools. Also in many helicopter turboshaft engines and some turboprops a radial compressor stage is added to multiple axial stages in a very similar way to what is shown here. This is done when tight packaging is a prime concern (replacing several axial stages with a single radial results in a much shorter engine). As far as I know all engines that use that extra radial stage do it on a common shaft with the preceding axial stages.
I would guess that these turbochargers are not yet in use due to costs. Multiple spools turbomachinery are very expensive to design and manufacture. When Rolls Royce first developed their three spool engines they had underestimated the magnitude of the challenge they were facing, and the company nearly went bankrupt with the UK government having to bail them out.
Also, while axial compressors are far superior to radials (they are far more efficient, and can use multiple stages for much higher pressure ratios), their aerodynamics don't scale well for the small sizes of turbochargers, so making that work would probably demand very tight manufacturing tolerances, also adding to high costs.
Neat, never heard of these. Closest to them I was aware of are compound turbo setups where you use a big turbo feeding a little turbo. Exhaust flow goes from cylinder head to the little turbo then the waste gas and waste gate bypassed exhaust feed the big one. So that way the big turbo can increase the PR to the little turbo. You get a very responsive setup with insane low end torque and power to redline. Maybe you could do a video on compounds like this, because most people don't seem to know about it.
I wonder if this enables the centrif to operate shock free compared to a single stage radial. If so, this would maintain a somewhat simpler design of the impeller and low manufacturing cost while also increasing it's thermal efficiency across the speed range. My guess is that the inlet experiences very good uniform flow circumferentially which helps.
The name you're looking for here is called a twin spool, similar to something like a turbo prop engine :)
It's a shame though, this would be a great idea although incredibly expensive in the real world.
I assume you mean sequential turbos in the traditional sense as used in the Supra and others? Because the comparison that comes to my mind is the use of compound turbos in diesel engines where the exhaust from the first turbo drives the turbine of a second turbo, which turns a compressor that sends boost into the compressor of the first turbo.
This tech maybe can eleminate the need to compound turbo system, good explain.. suitable for diesel application
I assume you know, but if not, turbines (at least half) use axial/ radial compressors. Also use Ng (compressor) and separate Np (turbine, “power”) shafts. This is 60s tech
On a 2 spool axial flow compressor jet engine, its is understood that the compressor eats up 50% of the energy from burning fuel. Therefore, turbo-superchargers are not "free" power on piston engines.
in a jet engine it is more like 2/3 the power used to drive the compressor. In a piston it's not "free" power it is the option to burn more fuel and make power using "free" power that would otherwise be waste as heat and noise out the exhaust. piston engines and turbine engines have very little in common
Alxial compressors give smaller pressure ratios per stage. I would argue a compound turbo system would be more efficient , maybe heavier but simpler. Check out the design of jet engines.
"Any number above 1." Got it 👍🏼
This seems like a great idea for a 4 cylinder or even an inline 6cyl application. OEM turbos tend to be small. They are lag free but dont offer much high end power. Big turbos dont give you that lowend response. This dual shaft design looks to solve this without taking up the space that a sequential tt setup would. The axial compressor "preps" the radial one so it can get up to speed faster.....like accelerating from a rolling start vs standing still.
A turbo with two compressors on one shaft but has two compressor housing back to back inline for compound turbo applications would be something I would like to see devolved.
They have them on Ford trucks now, I believe.
Your white board drawings have come a long way. Always glad to see a video like this.
I'd like to see more on a mechanism for vanes in the turbo. I'm curious about failure modes of a vane breaking free after a few years and getting sucked into the turbo.
I feel like it’s not used because the benefits don’t out weigh the complexity and possible reliability issues of using it at the time
My understanding of guide vanes is that a spinning fan tends to spin air and the guide vanes redirect it back into the desired direction. It's basic jet engine science. More efficient might be to replace the vanes with a counter rotating fan blade. Theoretically double the air could be pushed at the same RPM that way. I always had a problem with jet engine stator vanes. Stator meaning stationary. Why would you want to carry stationary weight in something so dynamic. And why wouldn't you want to make it twice as hard to max out the bearings.
When said the articles were dry from humor just like your videos i lost it 😂😂😂
I can't wait to see how small the intercooler between the 2 compressor stages is, and how, at such a small size, it has any kind of efficiency or flow at all... It will have to be liquid to air though....
I think it’s pretty funny how you put out this video after your “how much faster is the S2000” video. It seems like the two different kind of vanes would improve the supercharger design on your S2000. The down low torque would be increased.
Reliablilty with two shafts/ sets of bearings is thier Achilles heel. Variable intake, with hybrid electric boost motor on same shaft is the turbo design of the future
It's interesting that there are no Nozzles ahead of the axial turbine buckets to help direct exhaust flow.
Closest to that is VGTs(Powerstroke).
Was going to say. They are using 2 centrifugal stages however.