Anti-lag systems

[mrluke]

But once again, adding complexity for the sake of overcoming a different complexity.

Getting rid of the MGU-H creates the need to recover what is lost, but if they go back to the equal level of complexity, what's the point? Quite a few anti lag setups are fairly simple to implement at this level.

I'm not opposed to either solution, but they have to decide what they are changing the regs for and what the end goal is. Variable geometry and twin scroll both have costs probably more than anti lag systems, but in the overall scheme of things none are all that much. WIth increased electrical energy available, there might not be a need for any of the above really.

Twin scroll is a no-brainer. There's not really any complexity, its just two feeds into the turbine housing. There's no moving parts to it.

For F1 though, packaging, scavenging optimization, two wastegates, etc would all come into the picture. More than anything a space issue, and though revs are down vs previous years I don't know if they would save money in the long run. Taken to extremes as F1 does, it would become the new MGU-H of finding those small percentages to satisfy the entire rev range.

As has been stated by others, F1 turned the MGU-H into something more complex, proving how little hard knowledge on it was out there. I think they would do the same with variable or twin scroll to some extent.

Anti lag takes little in terms of development. For that matter they would drive the turbo without harvesting from it, using the electrical energy.

As I've said, I'm not opposed to which direction they do, but with cost cutting measures in place it might suggest a less expensive development process. Twin scroll hurdles aren't hard to overcome in street builds, but seem to have a much lesser advantage at higher outputs compared to single scrolls, and at F1 revs they might lose top end performance for the sake of low end ICE performance when they already have electrical energy to help overcome that small windows of low rev boost problems.

Huh?

They all already have them and have done from 2014?

[Airshifter]

Twin scroll is a no-brainer. There's not really any complexity, its just two feeds into the turbine housing. There's no moving parts to it.

For F1 though, packaging, scavenging optimization, two wastegates, etc would all come into the picture. More than anything a space issue, and though revs are down vs previous years I don't know if they would save money in the long run. Taken to extremes as F1 does, it would become the new MGU-H of finding those small percentages to satisfy the entire rev range.

As has been stated by others, F1 turned the MGU-H into something more complex, proving how little hard knowledge on it was out there. I think they would do the same with variable or twin scroll to some extent.

Anti lag takes little in terms of development. For that matter they would drive the turbo without harvesting from it, using the electrical energy.

As I've said, I'm not opposed to which direction they do, but with cost cutting measures in place it might suggest a less expensive development process. Twin scroll hurdles aren't hard to overcome in street builds, but seem to have a much lesser advantage at higher outputs compared to single scrolls, and at F1 revs they might lose top end performance for the sake of low end ICE performance when they already have electrical energy to help overcome that small windows of low rev boost problems.

Huh?

They all already have them and have done from 2014?

https://encrypted-tbn0.gstatic.com/imag ... w&usqp=CAU

Can't be missed in that photo for sure. Even with egg on my face, it's amazing the lengths they went to so that package would allow the desired exhaust length. I'd love to see the ports themselves, as it's tightly wrapped stuff. I'd seen other photos that appeared the lumps had single inlets, possibly split in hindsight as I haven't seen many photos with the exhaust works intact.


But pushing my ignorance on the turbo design aside, that brings the thread topic more to the front again. Would teams want to employ some type of anti lag system with the MGU-H out of the picture, or given the choice would they want to simply drive the compressor side and not harvest, still using electrical energy?

Was the advantage of the MGU-H enough on the compressor side to warrant keeping it in that role, or would they just further refine the intake works and use anti lag, if in fact they feel either is warranted with the additional electrical energy they will be allowed to use?

[noname]

Huh?

They all already have them and have done from 2014?

https://encrypted-tbn0.gstatic.com/imag ... w&usqp=CAU

It is only fake rendering, Renault used single-inlet, mono-scroll, turbine.

Twin scroll turbines are good at part load, especially in low-revving engines (like cv diesels).
In F1 engine you can make use of exhaust gas pulsation by playing with manifolds.

[gruntguru]

More fake rendering?


http://www.electric-vehiclenews.com/201 ... turbo.html

[Blackout]

There are show cars, and there are show engines. That's a show engine with fake/never-raced turbo + plenum + exhaust.
The 2014 Renault turbine was single entry indeed

https://i.imgur.com/5Nq4BSn.jpg

[mrluke]

Here's Honda's 2015 effort


2016


Mercedes 2014


Ferrari 2015 - might be single scroll? Difficult to see anything at all.


Struggling to find photos of the renault engine in a car where you can see the turbine.

[noname]

Here's Honda's 2015 effort (...)

Ferrari and Honda used single-volute, twin-inlet setup.

Former evaluated twin-scroll option, but I do not know if it was implemented.

Honda used this approach at least till 2018.

[luke352]

You guys do realise just because a turbo may have two different intake points it doesn't make it twin scroll right?

Same for a turbo with a single inlet that doesn't mean it's single scroll. In fact most twin scroll turbos only have a single inlet which is internally separated.

The only one from those images above you could make any claim is twin scroll in the renault render but it's a render so the real thing could have been either.

[mrluke]

Here's Honda's 2015 effort (...)

Ferrari and Honda used single-volute, twin-inlet setup.

Former evaluated twin-scroll option, but I do not know if it was implemented.

Honda used this approach at least till 2018.

You clearly have good knowledge on this so thanks for sharing

Twin scroll is generally about separating the exhaust pulses right up to the turbine wheel. Wouldn't a twin inlet single volute achieve most of this anyway? In practice / implementation is there actually much difference between these two options? If you can get most of the benefits with better packaging / weight then I can see the logic for it?

[luke352]

Twin scroll run "separate" housings or chambers as well and direct the gases onto a different parts of the turbine blade in order to try and get a more broad power spread.

One chamber (typically the larger) targets the outer edge of the blade for higher turbine speed (top end power) and the other (typically smaller) chamber is directed towards the inner part of the blade to help accelerate the turbine for better transient or low end response.

The result is you can make a bigger turbo with better low end response in order to get more broad and responsive power but you won't make as much outright power as single scroll.

A single scroll with with two inlets but going into the same chamber won't achieve the same as a twin scroll. But if you have a MGU coupled to the turbo and a MGU-K then there is reason to use twin scroll since the purpose of the small chamber is being done by the MGU coupled to the turbo.

So they may have used twin scroll in earlier designs of the current regs when they were still trying to figure out optimal energy recovery and deployment but as they worked through those issues twin scroll would have become redundant and single scroll for more outright power would have been more preferable.

[Zynerji]

Twin scroll run "separate" housings or chambers as well and direct the gases onto a different parts of the turbine blade in order to try and get a more broad power spread.

One chamber (typically the larger) targets the outer edge of the blade for higher turbine speed (top end power) and the other (typically smaller) chamber is directed towards the inner part of the blade to help accelerate the turbine for better transient or low end response.

The result is you can make a bigger turbo with better low end response in order to get more broad and responsive power but you won't make as much outright power as single scroll.

A single scroll with with two inlets but going into the same chamber won't achieve the same as a twin scroll. But if you have a MGU coupled to the turbo and a MGU-K then there is reason to use twin scroll since the purpose of the small chamber is being done by the MGU coupled to the turbo.

So they may have used twin scroll in earlier designs of the current regs when they were still trying to figure out optimal energy recovery and deployment but as they worked through those issues twin scroll would have become redundant and single scroll for more outright power would have been more preferable.

I agree with everything youve said here.

I also believe that if a twin scroll can max out the fuel flow limit, that a single scroll will not make more power.

Now, in road-race cars with no MGUH, I think the twin scroll is the obvious choice.

[mrluke]

Twin scroll run "separate" housings or chambers as well and direct the gases onto a different parts of the turbine blade in order to try and get a more broad power spread.

One chamber (typically the larger) targets the outer edge of the blade for higher turbine speed (top end power) and the other (typically smaller) chamber is directed towards the inner part of the blade to help accelerate the turbine for better transient or low end response.

My understanding is that twin scrolls are generally the same size and aimed at basically the same part of the turbine

as below



I understand it works by separating exhaust pulses, the lines below is exhaust pressure from each exhaust pulse:



Then the twin scroll housing removes the interference between each pulse



Thereby improving spool.

The closest thing I can find to your description is this patent drawing from Koenigsegg labelled as "variable geometry twin-turbo"



Is this what you are referring to?

That aside, the twin entry single volute is pretty unusual. As the entry points are at opposite sides of the turbine housing I would assume that provides much of the pulse separation anyway?

The result is you can make a bigger turbo with better low end response in order to get more broad and responsive power but you won't make as much outright power as single scroll.

For nominally the "same size" housing, twin scroll tends to be a slightly smaller volume as the dividing wall comes out of the available volume. However given the same housing volume I cant see any reason why twin scroll would limit max power. Do you have an explanation or source for this?

A single scroll with with two inlets but going into the same chamber won't achieve the same as a twin scroll. But if you have a MGU coupled to the turbo and a MGU-K then there is reason to use twin scroll since the purpose of the small chamber is being done by the MGU coupled to the turbo.

So they may have used twin scroll in earlier designs of the current regs when they were still trying to figure out optimal energy recovery and deployment but as they worked through those issues twin scroll would have become redundant and single scroll for more outright power would have been more preferable.

I'm happy to be wrong but I doubt the teams would want to waste their available electrical deployment on spooling up a turbo anymore than they actually need to.

edit: technical drawings from https://www.autozine.org/technical_scho ... ion_2.html

[luke352]

[

My understanding is that twin scrolls are generally the same size and aimed at basically the same part of the turbine

as below

https://upload.wikimedia.org/wikipedia/ ... _turbo.JPG

I understand it works by separating exhaust pulses, the lines below is exhaust pressure from each exhaust pulse:

https://www.autozine.org/technical_scho ... chart2.jpg

Then the twin scroll housing removes the interference between each pulse

https://www.autozine.org/technical_scho ... chart4.jpg

To my eye in the cutaway above the angled chamber/volute is smaller than the upright positioned one.

But think about how the flow and pulses will interact with the blades even though aimed in general direction. The more upright one is going to flow more easily out across the blade and retain more energy as it flows across the blade. The one that is angled back in and aimed at the base of the blade will end up imparting more energy at the base of the blade and have lost lots of energy before it flows across the rest of the blade and out the exhaust.

Test this design also allows for them to utilise the pulses more whilst reducing not stopping the two airflows interfering with each other.

I am on my phone currently so don't have sources handy. But may be able to find some later.
I may be wrong but this is how the article I read described it when I went researching a while ago.

[saviour stivala]

Volute twin scroll flow (VTF) is good for low RPM. While volute open flow (VOF) is good for high RPM. From pictures of the formula one engines one can tell if both banks exhausts are entering the turbine housing at one point or at two different points around the circumference of the housing. But from pictures alone it cannot be ascertained if both pipes from each bank entering at one point are entering individually (twin entry) and neither if (twin flow/twin scroll/twin volute). When pictures shows entry at two different places around the circumference of the housing, it cannot be ascertained that the housing is (twin volute).

[luke352]

https://x-engineer.org/twin-scroll-turbo/

Otherwise the engineering explained guy does a video on it as do several other people.

But you can get two types. Both types still utilize both airflow and pulses. Ones with simply a divided scroll/volutes of same size but you still get energy impacting on different parts of the blade simply due to the angle the airflow/pulses impact the turbine.
The other style you also have volutes of different size as well, so one is smaller in order to maintain a higher velocity and is for low end response and the a larger volute for the top end.
You can also do stuff with valves and utilising a twin scroll and direct all flow into one volute and then as boost pressure/turbine speed increases the valve slowly opens up flow to the second volute,