Twin Scroll Turbine Housings explained

[@exploranator]

Excellent. The ONLY turbo channel I have found on KZbin that RECOGNIZES that it is the pulse MAXIMIZATION, not EVEN PULSE SEPARATION that causes a turbo to respond more quickly! What works wonderfully on a naturally aspirated engine, ie: evenly-separated exhaust pulses, to maximize scavenging, DOES NOT WORK ON THE TURBOCHARGER!!! What a turbocharger WANTS is the most pulsated flow it can get at low RPM to spin the turbo up more quickly. On the opposite end, 4-2-1 headers on four-cylinder engines combine exhaust pulses exactly the same distance from each other (if the F.O. is 1-3-2-4, they combine 1 and 2 in one half and 3 and 4 in the other) to help scavenging. What is surprising to me is that some turbo channels seem to think that that is the right way to manage pulsation on a turbo manifold also!!! That is also part of why turbo engines have such small exhaust tract volume before the turbine(s.) Pulsation maximization plus heat and velocity retention. The butterfly-valve single-volute-half is an interesting take on boost response enhancement. The Mitsubishi housing looks to be a fascinating approach, also. I wonder about putting a truly large butterfly between halves of a bifurcated manifold (axis of butterfly rotation parallel with flow path) that opens up at a set RPM or pressure to allow LESS pulsation at higher RPM where it is then just an obstacle to efficient exhaust flow. Again, this would be a very large butterfly for maximum efficiency. It does not need to be round, but can be a long ellipse with the long side also along the flow path, to allow pulsations to travel through both halves of the bifurcated exhaust stream freely, for the benefits of bifurcated and single-chamber volutes combined with a simple bit of technology. With a proper setup, the wastegate could be opened less than it presently is.

[@TurboDirectSA]

Thanks for the comments -

[@1atinlove]

Ohhh no! Professor i must have missed this class...sitting in now. Im not sure how i missed

[@TurboDirectSA]

LOL -

[@cetGT3]

Beautifully presented...made chuckle also at the Chinese paper weight turbo 😂😄😅

[@TurboDirectSA]

LOL - thats pretty much what they are, especially eh ball bearing models, they far away from a quality product.

[@TurboS-gh5wc]

Thank you for making these videos. This is why i went with twinscroll just better for the engine as it keeps exhaust flow from backing up.

[@TurboDirectSA]

Pleasure - glad you enjoyed it.

[@kylej489]

Excellent video mate, I didn’t know about those Mitsubishi housings, they look brilliant 👌🏻

[@TurboDirectSA]

Mitsubishi are a serious contender, and very under rated. They are winning ALOT more OEM business because of their technology and designs.

[@ps-ri2qk]

Very interesting and informative video, thank you. It was my understanding that one volute in a twin scroll (using my bmw b58) is designed smaller - creating higher pressure airflow at low rpm's while the second volute is larger for more air volume a t high rpm's, basically cutting turbo lag time at low rpm's. Ironically it's so responsive (I drive in "comfort" mode) that I haven't even paid specific attention to it. Pretty sure it's managed by the ECM, works amazingly well whatever they did.

[@TurboDirectSA]

Pleasure - glad you enjoy the content. I assume you referring to the A90 twin port head. Either way there is no transition valve or control mechanism to switch between volutes. The AR of the volute is spot on, and the engine CID is large enough to drive the efficient solid disc back turbine. and high flow compressor - this is an example of a perfectly matched turbocharger/engine combination.

[@MikeJones-on9vm]

Excellent informative video, I hear that the new AcuraTLX Type S is going to have a twin scroll turbo v6.

[@TurboDirectSA]

We dont get this car here so i have no info on it at all im afraid. :-(

[@chippyjohn1]

I thought of a merge valve for twin scroll when I was a first year apprentice. Mechanics said it was a silly idea. Several years later I see that Borg Warner has used the same design. It doesn't seem to be main stream though, not sure why.

[@TurboDirectSA]

They are used alot by Mitsubishi and BorgWarner in some Diesel applications. We have these in stock and move them often.

[@DenySmashinton]

Great vid. However the idea that a smaller AR will always reduce lag has been proven wrong several times on the dyno. I wish I could link the vid but I cant remember what it was. It was a 2JZ with a 30 sized turbo which most people would agree is on the small size for a 2J however changing the AR to subsequently larger housings massively improved spool times and obviously gave more top end. They then fitted a more appropriately sized 35 which was much better again for power however they only tried it with the 1.06. The reasoning was the 1.06 was so much better with the 30 they shouldn't bother with the smaller housings on the 35 which IMO was a mistake in the testing. I am absolutely amazed people in this profession do not understand that the AR is a ratio not size so therefore a 0.82 on a 35 is not smaller than a 1.06 0n a 30. I would have loved to see what a smaller AR done on the larger frame turbo. My opinion is if your turbo is on the small side them always go with the biggest AR. If your turbo is huge than the size of the turbine will give decent flow on is own so a smaller AR might be appropriate there.

[@TurboDirectSA]

I must disagree - smaller AR will ALWAYS improve response, BUT because of the backpressure the POWER OUTPUT will be reduced substantially depending on which side of extremities you lie. Remember the more back pressure the more you are affecting the ENGINES VE (volumetric efficiency) -- similar to blocking cylinders on the head. If you watch the BOOST GAUGE you WILL see faster boost build up - BUT as i have already mentioned, HORSEPOWER WILL NOT BE AS MUCH --- always separate HP and Boost response - they are NOT the same thing and DONT always go hand in hand.

[@antoniohinojos3808]

Awesome video mate.

[@TurboDirectSA]

Thank you buddy

[@thannh2fasst]

Thanks! Been waiting for this video 🤝

[@TurboDirectSA]

Pleasure

[@heberrodrigues3903]

Hope to see fast your design from that exhaust like mitsubishi 😉 Great vídeo Thanks 😉

[@TurboDirectSA]

Thanks for the compliment

[@BrokenSilvia]

Awesome video! Thank you

[@TurboDirectSA]

Pleasure - happy to hear you enjoyed it.

[@flyjum]

Would the two separate ARs on the Mitsubishi turbo housing have two radically different back pressures? I would imaging tuning that engine would be difficult as a result

[@TurboDirectSA]

Yes they do -- the volute dimensions are different, but if you saw the manifold and runner design it would make sense to you. There are less runners (in this specific engine) leading to the smaller volute and more leading to the larger volute. There is a bypass valve between them aswell which during tuning i can imagine must be fully open so that the engine breathes and the tuning can be concluded. Once this is done , i would assume that only then the boost "control" setup starts and the actuator is setup for what parameters are required before it is opened up and bypassed etc. I dont have too much info on this engine that uses this turbo, but thats about all i know on it.

[@MrChando1975]

Good explanation Thank you!

[@TurboDirectSA]

Pleasure - glad you enjoyed this.

[@davids1090]

Thanks a lot for this video, for the first time I finally understood, what exactly is, how it works, and what benefits can provide a twin scroll set up. I have an EFR7163 on my forged 1.8t 20v vag, make it about 500bhp, going on spool about 4000rpm. My setup is single scroll, both turbine housing, and cast manifold. Would like to ask, if move my setup to twin scroll, both manifold and turbine housing (can a turbine housing bought alone?) would I be able to anticipate my spool? Would go in spool let's say 500rpm sooner, without touching anything else? Would it be a noticeable difference in driving having same turbine just swapping setup? Thanks a lot in advance You are very clear and full of skills!

[@TurboDirectSA]

Glad you found some valuable information David. The best thing to do on this engine before going twin scroll is to change the crank for the 2.0litre crank. This alone will give you MUCH better spool on the 20V engine. It will also make more power aswell. Once you have done this, i doubt you will want/need to go twin scroll on the housing.

[@douglang4615]

Thank you for the video . Question. Is there a difference in design as far as the turbine wheel goes .. For a twin and single scroll? Are the inducer tips longer for more leverage with the twin scroll to help with spool up .. And if u fitted a twin scroll housing on what is meant to be a single scroll turbine . What would it do to response ? Thank you again For all you do. 😊 An

[@TurboDirectSA]

No Doug no difference in the design of the turbine inducer blade design at all. SOME turbos have a mixed flow turbine stage which relates to the angle of the incoming gas path and the design of the turbine blades - for reference google a picture of the IS38 turbine wheel blades, you'll understand what i mean when you see it. For the Scooby turbo designs, there is no mixed flow turbine design. Using twin scroll turbine housings with a normal turbine blade design will offer response improvement only because you have pulse seperation coming into the housing.

[@MrBillDaBear]

With the variable A/R housing of the Mitsubishi, wouldn’t the cylinders feeding the smaller volute experience greater back pressure?

[@TurboDirectSA]

Yes thats exactly what happens until boost comes up quickly, then the second volute opens via a butterfly valve if used, otherwise the manifold will have a bypass valve integrated (similar to the BorgWarner Bitubo design) to control the incoming flow.

[@MrBillDaBear]

@@TurboDirectSA excellent information as always, thank you!

[@farmer3242]

Hi. Im putting a efr9174 with twin scroll t4 on my 4 L barra engine, my idea was to get another stock log style psr manifold cut off the t3 flange and get a divided t4 flange welded onto it. The pulses obviously wont be completely divided but the front 3 and the rear 3 cylinders only gather together for a very short distance before hitting the turbo. How well or effective do you think it will be? Should i make a divider plate and weld it to inside of flange to divide the pulses better? Another question, i will have to run a wastegate feed off each volute just after the turbine inlet and merge them together into one pipe to go to wastegate. What do you think? Also does the efr9174 have a stainless steel turbine housing? Thanks heaps

[@TurboDirectSA]

Barra is more than capable to spool the 9180 especially with the GAMMA-TI turbine wheel. The risk of welding inside the manifold is not worth the results. The manifold will spool the turbo no problem because of the size of the barra. I would weld the inlet into the gate on the turbine housing itself, just above the inlet of the turbine housing, 3inches past the flange face. Use one gate and save massive space under the hood.

[@farmer3242]

@@TurboDirectSA awesome thanks

[@TurboDirectSA]

Pleasure - happy to help @@farmer3242

[@tommylyeah]

10:36 Ah, a "quick spool valve" (as I've heard them called). I'm quite interested in them; was gonna ask you about them.😅 Does it matter which volute you block off?

[@e34boat88]

ur comment is old but i would block the bigger volute at low boost and start opening the bigger one as boost rises

[@AlexMotoCy]

Something I think you didn't cover. What if you have an un equil exhaust set up, a normal manifold not tuned, and youbput a twin scroll turbo will you still se better response on spool ??

[@TurboDirectSA]

There is still a pulse separation, i believe there will still be benefit, but because the manifold length is hugely different (normal log type manifold with flange face on one end) there might only be gains seen in the higher RPM range when the energy pulse is high.

[@EscortRSTWRC]

Quick question😊 wouldn't it be more efficiant to have cyl 1 and 4 in one section, and 2 and 3 in the other, running a 4 cylinder engine with 1-3-4-2 firing order? Having the pulses reaching the turbinewheel 1-2-1-2...etc?

[@TurboDirectSA]

There are many vairants of the "tuned port" manifolds out there, opposing runners and side by side runners, different engines work better with either.... Subaru versus inline 4cyl will differ.

[@EscortRSTWRC]

@@TurboDirectSA i see😊 I would just believe that a solution with the first and the third firing cylinder sharing a volute, would be better in terms of pulse interference and when running cams that have more overlap than oem cams?

[@EscortRSTWRC]

@@TurboDirectSA Where could i find more info about these Mitsubishi housings with variable a/r? Looks very interesting😊

[@TurboDirectSA]

@@EscortRSTWRC Well it all depends on the runner length, and how much pulse seperation you want/need - this is only decided when physically tested. Not unless you can draw (accurately) the manifold and housing combination and do simulation in a CAD/CAM program of sorts. Like i say, different engines and combinations will better suit different setups.

[@TurboDirectSA]

@@EscortRSTWRC Industrial applications only at this stage.

[@gerryroetsYosi]

Hey Chris what Garrett turbos has twin scroll. And there compressor map. With big efficiency iland

[@TurboDirectSA]

Hey Gerry, yes plenty applications have twin scroll turbine housing options. What frame size, flow rate, vehicle application are you looking for?

[@812_huffinpaint]

What about using a dual inlet dual scroll flange and having a wastegate in one side that opens at a determined psi to help with boost response.? Im planning on trying this to spool my v8 a little quicker but information on this subject is scarce.

[@TurboDirectSA]

Not sure how the design looks, but closing off one side of the volute in a twin scroll setup always helps - been done many times for over 15 years already, but tricky to setup.

[@812_huffinpaint]

So it would be a single 2.5 from the header y-pipe about 4' long feeding into another Y, One side going to a 60mm wastegate with a 4or5 psi spring then reduced to 2" then into one side of turbo flange. The other side of the Y would be reduced to 2" then fed straight into the other side of turbo flange . I'm hoping this would make it spool a little quicker.

[@TurboDirectSA]

Cant picture that im afraid - simply build a adapter plate that bolt underneath the inlet flange on the turbine housing with a butterfly actuated by a low boost actuator which will block the one scroll until a certain pressure is reached, at which point the butterfly opens - keep it simple and affordable

[@MrGerharddebeer]

Nicely explained, question I have is how do you now size the housing correctly, for example GTX3582R T3 0.63ar if I now want better response and flow more up top how do I calculate the divided T3 or even T4 housing required

[@TurboDirectSA]

Thanks for the comments, i will setup for a video explaining this in due course. Its simple and quick, and based on p2c ratio, just like the compressor is. Stay tuned

[@chippyjohn1]

You are lucky. Garrett has turbine flow maps, look at them. Work out the flow of your engine without boost, you can use this to see where the turbo will spool on the rpm range, and then look at how much it flows when at desired boost and rpm and look at turbine flow map for given pressure ratio and you can choose what A/R suits your needs. None of the manufacturers explain how to choose an A/R, but it is very simple. It is a shame BW does not show turbine flow maps.

[@rifleman7313]

Good video, I just have not heard about a butterfly actuated twin scroll spacer before. I will need to learn more about this concept. Especially if I want to maximize the responsiveness of a S475 turbo and a smaller 5.3L LS engine as a daily driver. Where would I go to learn more about this design? As I'm not very well versed with turbochargers and even less so with twin scroll or divided turbocharger housing/manifolds. However when you mentioned the Mitsubishi variable AR twin scroll housing and how great the idea/concept is. I couldn't help but imagine this housing with a 25%/50% smaller than a regular S475 turbo valute on one side and a 25%/50% larger than a regular S475 turbo on the other. As this might be able for both a faster spool/response time and at the same time a higher boost capability. Am I anywhere close to being correct in my reasoning?

[@TurboDirectSA]

Thanks for the comment - this butterfly valve has been used for many years, the first time i saw this was in 2008-2010 already - simple but great idea to 'block off' one of the scrolls in the turbine housing, to spool the turbo faster through one smaller "AR" i am not sure if there is anywhere to go really - to learn about this.

[@3l340]

Здравствуйте, коллектор single-scroll под эту проставку установить?

[@general23cmp]

Does twin scroll provide any benefit on a twin turbo v8 setup? My four header pipes on each side merge into a collector and then would feed the twin scroll. Is that bad? Previously you suggested twin scroll for me, but I’m unsure how I’d be able to get the correct pair of exhaust tubes to each volute since they’re not all on the same side of the engine. Thanks.

[@TurboDirectSA]

There are two routes to go with any VEE type engine - or flat opposed engine with separate banks. Single turbo and then twin turbo. Single turbo is cheaper to upgrade, but you have the problem of positioning the turbo so that you have similar length manifold runners, which normally requires the turbo to be installed on one side of the engine, making the runners on that side much shorter than the opposite side. For this installation i would use a single entry turbine housing design, as you wont see any benefit from the separation of the pulses due to the different length runners. The twin turbo setup is more expensive but looks nicer if you are able to install visibly, and with symmetrical turbos - the runner lengths are easier to control, and then you would install Twin scroll turbine housings on both sides, separating the pulses to gain the most efficiency from the turbos.

[@general23cmp]

@@TurboDirectSA Yes, but for my twin turbo application, I cannot really pair “opposite” pulses into each scroll. If the firing order is 18436572, the cylinders you’d want to pair into each scroll are on the opposite sides of the engine. Hopefully my question makes sense. For example, cylinders 1 and 6 are firing opposite of each other, but are also on opposite sides of the engine. I guess I could pair 1+5, 3+7, 8+6, and 4+2 to separate pulses as much as possible, but it’s not ideal.

[@TurboDirectSA]

@@general23cmp 100% you would still couple 1 and 3, -- 5 and 7 together on the one VEE and then 2 and 4, -- 6 and 8 together on the other VEE - this makes a difference and is beneficial. We have experience with this - see here:- kzbin.info/www/bejne/aZ6ol36wqNpspdU

[@barbiegamaestan456]

My mitsubishi based turbo has a divided t4 flange but then merges to a single volute before it starts to curve around. What is the idea behind this design?

[@TurboDirectSA]

Do you have any more info on this or a link to see pictures of this setup?

[@barbiegamaestan456]

Hey mate, the turbo is a HKS GTIII-4R made by IHI. I tried linking the website I think the comment got removed but a google search will find it.

[@TurboDirectSA]

@@barbiegamaestan456 I know the turbo, but i need to see the installation.

[@mobeenvalodia3882]

Are you guys going to make a quick spool valve

[@TurboDirectSA]

Not at the moment no - with launch control and the exotic fuels being used, it pretty much negates the requirement some.

[@kingkage7km]

Video idea! Can you go over the difference of a 6262 turbo vs a 6266 vs a 6259 turbo (inducer/inducer)? And the benefits of each setup. I know the bigger turbine wheel can take higher flow but same compressor wheel.

[@TurboDirectSA]

We dont really have any PTE turbos on hand to compare. Apologies

[@kingkage7km]

@@TurboDirectSA doesn't have to be Pte, can be any company. Just want to see the advantages and disadvantages of using the same compressor wheel with a slightly different turbine wheel

[@TurboDirectSA]

@@kingkage7km I have done a video on this already - its the comparison between the G30-900 and the G35-900 same compressor but with a different turbine wheel - check it out.

[@kingkage7km]

@@TurboDirectSA thank you

[@TurboDirectSA]

@@kingkage7km Pleasure Sir

[@mohammed9692]

Hey I have a quick question I have the new g45-1500 and I have a problem ,if the turbine housing is twinscroll and my manifold is designed for v band but its not on a split firing order all the cylinder outlet will go into a single colector to the turbo is this an issue? ,I cut the v band and modified the flang to suit the turbo then iv try it on the dyno it made 100 hp less than the old gtx45 gen 1 and cause serios back pressure so is that a relevant or it won’t make any difference in hp or backpressure I hope you can fix my problem🙏🏻

[@TurboDirectSA]

Did you physically measure the backpressure? I can tell you from experience that the G-series turbos are not cut out to what they are advertised as - they do not make the printed catalogue power, and are lazy in comparison to the older Gen1 and Gen2 GTX models - i dont believe there will be a 100HP difference just from the collector/manifold design change at the same boost, same engine and same AR turbine housing. Very unlikely. What i would do is measure the EMAP on the existing G45, and then re-install the old turbo, and verify the power and measure the EMAP and my bet is that the G45 is the issue....

[@mohammed9692]

I would like to ask what is the max boost for an 1.01ar with a full exhaust 4 inch and how would I know the right housing for achieving the right boost without backpressure lot to learn from you🙏🏻

[@TurboDirectSA]

Thanks for the comment - ill need alot more info to provide any form of answer for you. What turbine? What Family AR? (T3, T4, T6 etc), what engine? What VE is the engine? there are just too many variables to provide you with answer without more info. The easiest way to to physically measure the EMAP, thats if you already have the turbo and housing in place with the build completed, but if you dont, then i need alot more info to guide you.

[@theerashangovender1041]

Hello So on a twin scroll turbo and manifold must you use twin wastegate?

[@TurboDirectSA]

Good question - and the answer isn't as simple as you might think. The single gate will work 100% BUT the position of the gate is key. We normally position the gate ontop of the turbine housing itself just past the inlet flange, along the spine. this is the best position for linear control, and ease of installation. However you can install two gates if you prefer to install them on the sides of the separated collector just before the inlet to the turbine housing.

[@theerashangovender1041]

​@TurboDirect S.A Good day So I installed a Borgwarner sx200sxe on my 1.8t 20v vw engine, the turbo is very laggy, will this housing help and work on the sx200sxe?

[@daledavies2334]

Why would you plumb 1 and 3 into one side of the twin scroll and 2 and 4 into the other side. On cross plane V8 engines there is 2 axjasent cylinders on one bank that fire 90° apart. The second of the two tends to push hot exhaust into the first cylinder causing a detonation issue. The 4 cylinder with consecutive cylinders pushing exhaust into the first in the firing order. Mazda addressed this when introducing their Skyactiv series engines with higher compression. 1 and 4 firing 360° apart are connected in one collector which prevents hot exhaust diluting the other cylinder. Turbo manifolds are short to get the hot exhaust into the turbo quickly, many using a regular cast manifold. To my thinking it would be best to plumb 1& 4 and 2&3 together into the scrolls. Now 1&3 and 2&4 together could provide a stronger pressure hit to spin the turbine up, but I worry about the possible hot exhaust gas dilution.

[@TurboDirectSA]

Dale you are 100% correct, each engine will have a different setup depending on its design from the factory. The big bang nike engine from Yamaha is also another tricky one when it comes to the manifold design.

[@simonetdi]

​@@TurboDirectSA what do you think would be better for a 2.0l diesel with a 35 that would rev 5500 rpm, 1&4 and 2&3 or 1&2 and 3&4?

[@TurboDirectSA]

@@simonetdi What do you mean by 'with a 35'??

[@simonetdi]

@@TurboDirectSA 70/60 turbine wheel

[@TurboDirectSA]

@@simonetdi The 35 does not have this size turbine wheel.

[@dougmarthaler3066]

Which Mitsubishi turbos have the dual sized volutes? Are they available aftermarket? Does any other turbo manufacturer use this design?

[@TurboDirectSA]

Sorry i cant tell you, there are a range of heavyduty machines that use these in the TD08 series, but this is not a performance product. Not that i know of, MHI is the only housing i have seen with this design to date.

[@aftastosk6016]

I have another question that may sound silly, but still it came up into my mind since I noticed that in all twin scroll diagrams, in a 4 cylinder engine with the usual 1-3-4-2 firing order, cylinders 1 and 4 feed the housing part that faces the exhaust, and 2 and 3 the one that faces the compressor. Does it make any difference which is connected with which or not?

[@TurboDirectSA]

It makes no difference which port is fed from which coupled cylinders, they are seperated entirely.

[@aftastosk6016]

@@TurboDirectSA Thanks!

[@TurboDirectSA]

@@aftastosk6016 Pleasure sir

[@redda991]

Hi mate you need to make a Landcruiser 1HD FTE twin scroll , i no you run them in South Africa . They'll sell like hot cakes in Australia.

[@TurboDirectSA]

We have them here yeah, but not as popular as the 4.5 V8 79 series -- this we make a Hybrid solution which outperforms your local Gturbo upgraded unit - We busy with a new complete turbocharger which will produce a true 400WHP setup with similar response to the stock turbocharger on the 4.5D -- shoot me an email [e-mail] and let me know more about the 1HD FTE turbo you guys want.

[@mohammed9692]

Do I need a twin wasegate for a twinscroll setup to get the best benefits or its fine with single wasegate? I hope you replay asap to modify my mainfold 🙏🏻

[@TurboDirectSA]

Shoot an email to chris on [e-mail] - i will notify him to reply to you.

[@DevineDigital]

Love the video, it looks like they designed the vw ea888 gen 3 engines with a twin scroll integrated manifold, but decided to stick with a single scroll turbo design. Am I looking at this correctly? I know you all have been doing a lot with VW applications in past videos.

[@TurboDirectSA]

The EA888 IS38 turbo is not a true twin scroll, the seperator is only 1 inch deep into the housing and then opens into a single scroll turbine housing.

[@kcdickinson9373]

​@@TurboDirectSA sorry about the old thread revival, but it's currently relevant to me. Being that the IS38 isn't truly a twin scroll, does a quick spool valve in that specific dynamic provide any benefit? I would hallucinate that the singular inlet would produce a higher velocity exhaust gas than wide open. Like blowing on a little fan with a straw vs with your lips alone. Currently I run a small Garrett twin scroll on my ea888.3, at least I believe the gt2260s is a twin scroll. Have you done any testing with a quick spool valve on the ea888.3? I'm looking at shifting to a Borg Warner s252 (or Garrett gt2871) is it easy to speculate on the likely advantages and disadvantages of a quick spool valve on the 2.0T going into a single volute Borg Warner VS. Garrett twin? I know you said that there's still a benefit going to a twin scroll even if you don't have a manifold for it and you still see a benefit if you have a tune port manifold and a single volute but what I'm looking for is the difference if you add a quick spool valve into that mix is there scenario where it does more harm than good and is there a scenario that is worth knowing about? Side note, I love that Mitsubishi turbine housing, I just kept thinking that's a twin turbo setup in one housing and picturing that with a digital quick spool valve is a fun thought. I guess the next level from that is a VGT, but I don't think I've really ever seen 4 cylinder street car with a VGT. And that's a whole new interesting thought I never had before right now. But of course the only VGTs my minimal experience has ever shown me are for diesels, and I have no knowledge about them but what a badass concept for a little GTI or golf r

[@TurboDirectSA]

@@kcdickinson9373 No worries at all - the EA888 is NOT a twin scroll turbine housing, the housing inlet has what seems like two port, BUT the divider is literally just over an inch long inside the housing inlet port. Then the volute reverts to a single scroll. This was done to match to the cylinder head shape, which is cast with two of the cylinders exiting out of one port, and the other two out the second port. a quick spool valve will never work on this type of housing, because there is no true divide between the ports/volutes - VGT is old already and installed on the Porsche 911 Turbo S 5 years ago - BorgWarner for the win once again with the first passenger gasoline driven engine with VNT installed.

[@kcdickinson9373]

@@TurboDirectSA the IS38 is not twin scroll, that makes sense, like you said. The exhaust side of the cylinder head is tuned port though, correct? Or are you saying the cylinder head doesn't actually have isolated matched pairs exiting together? I didn't inspect it that thoroughly and I wasn't looking for that specifically either. If it is a tuned port cylinder head (because the ea888 doesn't have an external manifold, it's just designed as part of the head) and the gt2260s being a twin scroll, that would make a quick spool valve functional, wouldn't it?

[@TurboDirectSA]

@@kcdickinson9373 Yes correct head is tuned port - part of the casting in the head itself. Cyl1 and 3 and then Cyl4 and 2 are paired together. A quick spool valve is a valve that is able to close off one of the ports entirely and then open it again when required, the GT2260S has a tiny little turbo that is a normal rotating assembly used in many other applications, nothing new, and in fact a cheap 'fix' to provide a higher flow rate to the IS38 stock unit. You would need to check inside the turbine housing of the GT2260S to confirm if the separation spreads throughout the entire volute or not - i doubt it does.

[@mkivst180]

Randomly came across your channel, very nice information and video. Thanks for the video. Quick question, when you mention about the adapter with valve, i think on the market currently they are called quick spool valve, i wonder if there exists a spool valve that work with twin scroll designed manifold ?

[@TurboDirectSA]

Thanks for the compliment - glad you enjoying the content. The Quick Spool valve does come in a twin scroll design - thats precisely what makes it beneficial to spool larger turbos up. Not sure who makes these, but we played with these in 2010 and they worked very well.

[@mkivst180]

@@TurboDirectSA sorry i should have been more clear, what a mean is a spool valve that will work with devided exhaust manifold + twin scroll turbo. Do Such valve exists?

[@TurboDirectSA]

@@mkivst180 Absolutely yes - this is the only application you would use a quick spool valve - in a twin scroll application. You want to block the one port of the turbine housing to allow all the gasses to enter into the one port only, which will spool the turbo up faster, once you are up to a prescribed pressure, the other port opens up with a butterfly in the valve.

[@mkivst180]

@@TurboDirectSA from normal understanding point of view, the normal type of spool valve on the market cannot be used for devided exhaust manifold. If the valve is in shut position, say in 4cyl engine, where are those two exhaust gas gonna go since valve is shut? So my question is a spool valve that will work for devided exhaust manifold If Such thing ever exists at all?

[@TurboDirectSA]

@@mkivst180 Im not sure what you referring to, we obviously talking about two different things - there is only one design of a quick spool valve that im aware of, as described in my video and in my previous comment.

[@mizanhaslie2302]

Hello there, currently i have a gtx3576r with a .63Ar open scroll but using a twin scroll manifold. If i were to go twin scroll turbine housing, should i the same size? Twinscroll .63? Or go slightly bigger? Twinscroll .82?

[@TurboDirectSA]

It all depends on what you are trying to achieve..... if yo looking for the best response, then stay with the AR63, if you looking for more HP up in the higher RPM range, then move to the larger AR housing, the lower backpressure will open up additional power in the higher engine RPM

[@mizanhaslie2302]

Because some say twinscroll AR is half of the open scroll.. say .63 open...then i should be using around .82 twin scroll.. im really going towards more respond...and will not be revving more than 7.5k rpm on a 4g63

[@TurboDirectSA]

@@mizanhaslie2302 Not true - thats why there is an AR on the housing - an AR63 is an AR63 no matter what shape it is. Stick with the AR63

[@mizanhaslie2302]

Thanks for the advise.. always been a fan of your informative channel.. keep it up mate..

[@TurboDirectSA]

@@mizanhaslie2302 Thank you Mizan - much appreciated.

[@oscarcareycasanova]

excellent information, you will have the link where to buy the Mitsubishi housing I need it for a holset hx35 twinscroll 

[@TurboDirectSA]

Thanks for the compliment! Careful it wont mount to the HX35 - it uses a Vband as opposed to a flange face.

[@valyuno1356]

Very informative video thank you. But I was wondering what would happen if you run a twin scroll housing on an open manifold? 🤔 In my particular case I'm interested in a s257sxe that only comes with twin scroll housing and I will be running a open cast manifold. I guess you don't have any benefits out of this, but are there some downsides, is it a bad idea?

[@TurboDirectSA]

There are benefits if your manifold splits to separate the pulses. Yes not all the way through the housing (as its not twin scroll) but it does help.

[@valyuno1356]

@@TurboDirectSA well it's a rev9 for a 7mgte so it's absolutely not the case haha 😅 But it still look like the best combination for what I want, so as long as it don't create problem I guess it's good Thank you very much for your response !

[@TurboDirectSA]

@@valyuno1356 Happy to help - Enjoy

[@emericaskater734z]

Have any input on about how much I'd actually benefit from going from a 1.00ar to 1.32ar power-wise? The car has a 2.2l 4g63 with a precision 6466 1.00ar. Currently, the car made 748whp/585wtq on a mustang dyno at 45psi, but the power is dropping off hard after 6800 rpms due to the turbo being out of steam. Debating if it is worth the switch, and how much it'll actually pick my powerband up on the top end. Thanks

[@exploranator]

Internet guy here with no accountability whatsoever: Do you care about anything other than top of the power curve? What is the overall pounds-per-minute flow rating of the turbocharger? Do you have your maps for your turbine and compressor available? Can the turbine even flow more pounds per minute, regardless of which housing you put on it? If and ONLY if your compressor is still within it efficiency islands, as in not off the map at the top end, or near overspeeding territory, then a turbine with a larger A/R of 1.32 will likely make more power than a 1.00 A/R, because it seems that the exhaust turbine is being choked off. However, you will most likely lose some power at lower RPM as the same turbine housing that allows exhaust to flow more freely can cost power at lower RPM. What is the pounds-per-minute of the Precision Turbo compressor? From Precision's site: PTE's GEN2 PT6466 CEA® Turbocharger features the following: � Exclusive GEN2 CEA® (Competition Engineered Aerodynamics) compressor wheel machined from a 2618-aluminum forging � Higher efficiency and faster transient response for maximum power and performance � 64mm inducer compressor wheel � Compressor cover options: � - "Ported S" compressor cover 4.0" inlet/2.5" outlet � Exclusive CEA® (Competition Engineered Aerodynamics) 66mm, 76 trim turbine wheel � Turbine housing options: � - T3 .63 or .82 A/R with 4 bolt (2.5") discharge � - T3 .63 A/R with 5 bolt discharge (with or without wastegate hole) � - T3 .63 or .82 A/R with 3" OD (outer diameter) V-Band discharge � - V-Band inlet .82 A/R with V-Band discharge � - T4 .58, .68, .81 or .96 A/R with 3 5/8" OD (outer diameter) V-Band discharge � - T4 Divided .84, 1.0, 1.15 or 1.32 A/R with 3 5/8" OD (outer diameter) V-Band discharge � - Buick .63 or .85 A/R � - K26 .82 A/R � * NOTE: Additional cost may apply for certain housings. � Available with an air-cooled, dual ceramic ball-bearing center housing rotating assembly (CHRA) What are your turbine and compressor sizes? Are you using a divided exhaust turbine housing? Does whoever installed this provide any information whatsoever?

[@barvajz1106]

hello, why i need 2 wastegates for twinscroll manifold? thanks

[@TurboDirectSA]

You only require two wastegates when you have a manifold design that does not merge the entire collector together as one - a good example is the flat 4 of flat6 engine configurations and V6 and V8 etc -

[@barvajz1106]

@@TurboDirectSA yes, i know, but why? r6 m54b30

[@TurboDirectSA]

@@barvajz1106 Because in order to control boost properly you need to be able to control the entire incoming energy feed to the turbine. You cannot expect to control the turbine speed by only regulating 50% of the incoming energy being directed to the turbine. This is why the internal swing valve is situated AFTER the incoming energy has merged past the collector.

[@barvajz1106]

@@TurboDirectSA thanks a lot, now i got it.

[@TurboDirectSA]

@@barvajz1106 Pleasure my friend - anytime.

[@shafieksalie3119]

Brilliant 👏 my f30 320d have a twin scroll turbo I can't see it 😄😄😄🤪

[@atmchiptuning7205]

Shafiek your 320D has a variable geometry turbo. Not twin scroll :)

[@shafieksalie3119]

@@atmchiptuning7205 ok but bmw say twon scroll

[@atmchiptuning7205]

@@shafieksalie3119 "Twin power turbo", because a twin scroll and a VGT turbo, are almost like having two turbos, sort of haha. But your turbo is not twin scroll.

[@raymondloubser4720]

Can i use a twin scroll turbo with a normal exhaust housing

[@TurboDirectSA]

@@raymondloubser4720 yes of course you can, just make sure your manifold gasket face is not a twin scroll gasket inside an open port housing it it will Burn and cause damage to the turbine wheel

[@saied695]

Hi you mentioned something that peaked my interest for a moment and I wonder if there is an error in my thinking. You mentioned the 2 volutes in a twin scroll setup, and then you showed a differential Ar. twin scroll turbine housing (mitsubishi). Is it that all twin scrolls are symmetrical in volume and pressure and only the mitsubishi differential Ar. one is asymmetrical? Or, do they all come asymmetrical but not to the difference in asymmetry as the mitsubishi housing shown? Looking forward to tour reply ☺️ thank you.

[@TurboDirectSA]

All the housings are normally and generally symmetrical - i showed the MHI housing to throw some interesting information into the market - the asymmetrical housings are not popular at all, but work exceptionally well, this is why i mentioned it.

[@saied695]

@@TurboDirectSA thank you much!! 😊😊 for the clarification. I always thought the twin scroll had 2 different size volutes. But that has cleared up Alot.

[@TurboDirectSA]

@@saied695 Pleasure buddy -

[@aftastosk6016]

@@TurboDirectSA actually I have ordered a twin scroll Td04HL just before you uploaded this video and I am awaiting delivery. I am assuming (based on the photos) that it is also an assymetrical a/r because the external pattern of the housing seems similar with the MHI assymetrical housings. However I have no idea IF and what's the a/r difference between the two and I wonder if there is any info inside the box. I assume that the 0.61 a/r is the bigger housing. I am very curious of how it would end up performing, I have a bit of fear that if it's the case with assymetrical housing, this may cause tuning problems.

[@TurboDirectSA]

@@aftastosk6016 Thanks for the comment, no its not asymmetrical im afraid, the turbine housing you will receive will be symmetrical, there ar not many housings made with asymmetrical setups/designs out there - as it requires additional boost control components.

[@muntee33]

What huh, wait... 9:10 is basically describing a 4 into 2 into 1 style system... Where #1&#3 primary open into a collector where the scavenging low pressure wave is largely wasted... It's basically a slightly less efficient sequential turbo set up, but both primaries/collectors/turbine housings feed in parrallal onto/into a larger single turbo, turbine wheel.

[@TurboDirectSA]

Pulse separation is the key to uninterrupted reverse pulse reverberation. scavenging on a turbocharged engine (OEM turbocharged engine) has camshaft profiles that lessen the scavenging effect - improving boost response.

[@seemaab]

Great video! Quick question, what is the difference between twinentry and twin scroll? They both have seperate volutes but does the twin scroll actually have a valve inside? Thanks from the UK!

[@TurboDirectSA]

I have never heard of twin air turbos, so i cannot comment - twin scroll turbine housings that are internally gated will have a swing valve (internal discharge gate) installed and integral to the housing. Free floating housings that are twin scroll will have no valve inside -

[@seemaab]

@@TurboDirectSA sorry I mean twin entry. Kinagwa do them

[@TurboDirectSA]

@@seemaab kinugawa are chinese knock offs -- i have seen some of their housings, and they tried to get Forced Performance to buy their products, and the level of quality (real poor quality - according to FP) was clear to see in a video they made of the housings that these guys tried to copy, but they couldnt even get the material correct to start with. Twin entry are simply a name used for twin scroll divided housings.

[@seemaab]

@@TurboDirectSA there Arashi sub brands got some rave reviews. So twin entry is divider housing without the valve

[@TurboDirectSA]

@@seemaab yes twin scroll as long as its free floating

[@Jesse-nd6bz]

Hey mate, super informative video and very interesting, I'm new to turbos and I'm about to single turbo swap my 1jz gte non vvti, but I am having a very hard time deciding weather to go twin scroll or single scroll, have watched a lot of videos and read a heap of online forums about twin scroll vs single scroll on a 6 cylinder engine but its very confusing as people have different opinions. I will be using a pulsar gtx3076 0.82A/R and a 6boost manifold but would you be able to recommend if I should go twin scroll or single? the turbo is on the smaller side and I'm looking to push around 400/450hp, I'm really undecided so any feedback would be greatly appreciated, thanks!

[@TurboDirectSA]

Thanks for the compliment - the project is not very high HP and if you will be using the car for street driving, and areas where you need low down response, go for a twin scroll manifold - it help no matter how you look at it. The only issue you will have is finding a turbine housing with a small enough AR in twin scroll format. The AR61 housing is Vband, and will spool quickly, the issue is that Garrett dont make a small AR twin scroll housing - so using say an AR1.01 twin scroll turbine housing will actually spool later than the Vband AR61 -- If there is a small twin scroll housing, use it. If not - stick to Vband - simple as that.

[@Jesse-nd6bz]

@@TurboDirectSA Thanks Mate! I really appreciate the response!

[@TurboDirectSA]

@@Jesse-nd6bz Anytime - happy to help.

[@danielferraro59]

quick question please. i have bought a holset twin scroll hx35 for my modified porsche 944 turbo, that normally uses a kkk26 single scroll t3 flange,...will this still be ok to use ? many thanks Daniel 😊

[@TurboDirectSA]

Hey Daniel, it depends on which holset HX35 turbo you using or combination thereof. There are literally hundreds of them. Holset are designed specifically for the diesel application sector and the combination/relationship match between the turbine and compressor ends are specific to the engine they designed to operate on. I am not a fan of the holset "make a plan" setups, which for the most part dont even have compressor maps to support. Let me know what the turbo or CHRA part# is, and ill dig up the specifications and advise from there.

[@danielferraro59]

thankyou very much! will take a look and get back to you in couple of hours . thanks for tour reply! Daniel 😊

[@danielferraro59]

hi again, here’s some details : assy 4036531 serial T1307346262 cust 504087676 model hx35 the casting numbers on the actual scroll housing are: 3504246 16 129 12 10 13 123 E18 hope you can figure something from these numbers? thanks so much for your time ! Daniel 😊

[@TurboDirectSA]

@@danielferraro59 The casting numbers dont refer to any part number of any of the components, nor the turbo (assembled complete unit) part#. Do you have a turbo part#? This would be found on the name plate situated most commonly on the compressor housing near the outlet.

[@danielferraro59]

these are all the number on the inlet and outlet externals . on the core there’s a serial number that reads :p03777051s131993165cttp customer no: 3777051 don’t know if the core would give you the external parts info or not or there generic to a single scroll holset also ect of the same size ?????

[@martinrodger9565]

Was the Mazda rx7 the original twin scroll spool valve?

[@TurboDirectSA]

That was a twin turbo with turbine transition valve, opens to re-direct the incoming pulse energy into the larger turbocharger after a certain boost pressure is reached.

[@martinrodger9565]

TurboDirect S.A Is than not the FD: was FC not single turbo with a spool valve on a divided housing single turbo?

[@martinrodger9565]

Looking it up. The series 4 13bt was a hybrid spool valve on a single scroll and the series 5 13bt was a fully divided single turbo with no valve. We used the Mazda series 4 valve on a divided housing T4 turbine on a Sierra cosworth (housing from a Bentley turbo) and it made a measurable difference.

[@TurboDirectSA]

@@martinrodger9565 Indeed it was - the twin used a transition valve -

[@TurboDirectSA]

@@martinrodger9565 It will make a massive difference, now go use a larger AR turbine housing and up the boost, youll see results that will astound you.

[@xoxo9623]

how the turbine blade for twin scroll looks like

[@kanowait-carrodus8001]

Hello, you mentioned that you working on your own asymmetrical style setup for a 6 cylinder (popular in your country) what engine? TIA.

[@TurboDirectSA]

Thanks for listening to the end - the housing idea we have been playing with is going to suit our new product line which we are trying to conclude before the end of the year .... more to come on this - but the popular 6bangers here are the 1JZ, 2JZ, RB26 and RB25 - i personally prefer the TB48

[@kanowait-carrodus8001]

@@TurboDirectSA NO worries, i do like your content, very informative stuff, I'm currently doing a 4.0lt ford barra build and very interested in a twin scroll and after seeing the asymmetrical style turbine housing it makes so much sense regarding spool lag.

[@TurboDirectSA]

@@kanowait-carrodus8001 Hey Kano - on the Barra you dont need anything like the assymetrical housing, the Barra spools up large turbos with ease. Its the smaller 2JZ and 1JZ engines that battle some.

[@kanowait-carrodus8001]

@@TurboDirectSA can I please get your email address, I think I wanna work with you guys regarding my turbo setup in the near future, thank you kindly.

[@TurboDirectSA]

@@kanowait-carrodus8001 [e-mail]

[@upnorthyooper1196]

Wouldn't that mitsubishi turbo have more back pressure on 2 of the cylinders?

[@TurboDirectSA]

No you would build the manifold to split the pulses, and entrance into the tongue area is joined into a single entry to the inducer blades

[@mohammed9692]

And do proper twinscroll set up needs twin wasegate or it fine with single wasegate

[@aliamini1735]

You went wrong on the runner merging. 1-4 are toghether and 32 are togherher

[@TurboDirectSA]

There are many ways to arrange the piping, depending on the housing inlet, collector vs wastegate routing etc - i mentioned one of many.

[@carminescotto3775]

Hi can I ask you a question?

[@BilerTV]

Great video!!! The TwinPower Turbo system on the BMW B57 3 liter diesel engines, is this like the Mitsubishi turbo You show in the end if this video? New sub from here 👍👌😊

[@TurboDirectSA]

The twin power is slightly different in the design, it does not have two different size volutes in its turbine housing.

[@BilerTV]

Thanx alot @@TurboDirectSA 👍

[@TurboDirectSA]

@@BilerTV Pleasure sir

[@trumanhw]

awesome. Thank. you. (engineering explained sucks in comparison).

[@muntee33]

Why not just place an independently controlled/fed fuel injector and ignition system in the turbine housing and bleed off o2 from the compressor housing/wheel to be ignited in the 'valute' to spool the turbo up to the boost threshold from much lower in the rpm range? (Effectively increasing the displacement of the engine, with the increased displacement having an exponential increase in the volumetric efficiency of the engine. ( Turning a 2.5L engine into a 3L engine that has the ability to flow the same volume of gas (output) as a 4L engine at

[@Drunken_Hamster]

I need to stop you around the 8-minute mark to correct some timing physics here. If the goal is to have the pulses as separated and far apart as possible, you don't want cylinders that fire closely after each other to be going down the same collector and then volute. So disregard the firing ORDER of an inline 4 for a second, and think about the firing INTERVAL of the piston pairs. Any two pistons in the engine that are opposite in TDC vs BDC will effectively fire 180 degrees apart from each other. 1 and 3 will fire 180 degrees apart, as will 1 and 2. However the opposite is also true; any two pistons in the engine that are EQUAL in TDC or BDC will effectively fire *360 degrees* apart(so 2 and 3 are a pair, 1 and 4 are a pair), giving even more spacing between events and minimizing interruption or interference off pulses. So on an inline four, what you ideally want is the center two cylinders to one volute/scroll, and the outer two cylinders on the other volute/scroll. On an inline 6 it's even simpler than that since an inline 6 is two mirrored inline 3s stuck end to end. Each half of an inline 6 (front half and back half) will have respective firing intervals 240 degrees apart within themselves, giving less potential interference than your 1+3, then 2+4 example(not to mention smoother, more even flow since yours would be 180 degrees apart, then 540 degrees of silence), but slightly more than my 1+4 and 2+3 pair example on an inline 4. The industry COULD potentially optimize inline 6 turbos with 3 scrolls, which would work best with a 1+6, 2+5, and 3+4 pairing regardless of firing _order,_ but as you said, even a 3rd scroll is likely more hassle than it's worth to manufacture when twin scrolls work fine as is.

[@TurboDirectSA]

The only way to shorten or lengthen the INTERVALS is to use a MILLER cycle engine - and the performance of the engine will suffer enormously - separation is key, intervals are irrelevant and uncontrollable. R&D is the key here, depending on turbo size, AR choice and CR of the engine, choosing to separate 2 and 4 or 2 and 3 will yield different results - the application would need to be matched to the choice accordingly.

[@Drunken_Hamster]

​@@TurboDirectSA The interval is the amount of time in crankshaft degrees between firing pulses. Every layout of engine has different firing intervals regardless of firing order. And to keep it simple, on a flatplane inline 4, the firing interval is 180-180-180-180 between all 4 cylinders. So whether the firing order is 1-3-4-2 or something else, it doesn't make a difference. 1 and 3 will have the same interval as 1 and 2. The same goes for 4 and 3 vs 4 and 2. "But no, 1 and 3 on a 1-3-4-2 are 180-degrees apart, but 1 and 2 are 720 degrees apart" I hear you say. And technically, you are correct. But as far as the engine's flow is concerned it doesn't matter because it is a continuous repeating CYCLE. 1-3-4-2-1-3-4-2 That was two revolutions. See how once the cycle is complete it goes from 2 to 1? Notice how they're just as close together as 1 and 3 at the start of the cycle? That is effectively and factually a 180-degree separation. A turbocharger WILL NOT see a difference from having 1 and 3 plumbed to it compared to 1 and 2, ASSUMING the pipes are all equal lengths, still. However what a turbo WILL see a difference on is whether you have two 180-degree pairs or two 360-degree pairs plumbed to it, IE my 1-4//2-3 example. That IS fundamentally different from the other two pairings since the two outer pairs of cylinders are on the same movement, but opposite strokes. In fact, this 360-degree pairing leads to almost zero interference between cylinder pairs, which is why parallel twins with such a crankshaft can operate with ONE carb and siamese exhaust ports with no ill effects. And that "lack of interference" or exhaust pulse stacking is exactly why 4-2-1 aka "tri-Y" headers for N/A 4-cylinders are not only made, but extremely beneficial to torque below the curve in a street engine.

[@TurboDirectSA]

@@Drunken_Hamster firing/timing of the ignition event yes, intervals in terms of degrees of crank rotation for a typical 4 cylinder engine 1,3,4,2 - there is no different at all in this. Nope its not 180degree separation, its 90 degree separation - 360 divided by 4 equals 90. With a 6 cylinder engine you will have 60 degree separation between cylinders in terms of crank rotation - 360 degrees divided by 6 cylinders equals 60..... Nope - once again pulse separation is determined by the manifold design, if you are separating cylinders 2 and 3 (which are 180degrees apart in terms of ignition event) or if you are separating cylinders 1 and 3 (which are 90degrees apart in terms of ignition event) there is a massive difference in the intervals. HOWEVER if yo keep going you will see similar intervals as they catch up with cylinders 2 and 4..... Over-complicating things makes for confusion, separate the pulses, and use a Twin scroll turbine housing where necessary/applicable, and you wont go wrong.

[@Drunken_Hamster]

@@TurboDirectSA It's 720/4, not 360. A full volumetric cycle in an Otto-cycle engine is 4 strokes, each consisting of 180 degrees of rotation. 180*4 is 720. Yes, any separation is probably better than none, but having an optimized design is also important. Just saying, you don't want to be giving people false information for their builds with your diagrams. Every single inline-4 twin-scroll manifold on the market is 1-4/2-3 paired for maximum separation within each scroll, and an even separation between scrolls.

[@TurboDirectSA]

@@Drunken_Hamster Otto cycle engine requires 720degrees to complete an entire combustion cycle - ALL cylinders going through each phase of the 4 strokes. This is NOT what we are talking about when referring to intervals - which occur every 90degrees. Optimised design depends on many things as mentioned in my previous comment. Research reverse pulse reverberation.

[@CalculatedRiskAK]

The correct setup for a twin scroll manifold on a 4 cylinder is to pair 1+4 and 2+3, as their combustion events happen 360 degrees apart, not 180 degrees apart. Pairing off the cylinders the way they are on the diagram will be no different than a single scroll manifold with the pulses interfering.

[@TurboDirectSA]

Incorrect - we have tested a traditional log type manifold, branch with collector, branch without collector, and pulse seperated manifold setups with 1+3 and 2+4 aswell as 1+2 and 3+4 and finally 1+4 and 2+3 ALL of these seperated setups provide benefits over the log type and traditional manifold design without collector. Which is best - that depends on the application and where you want to make your power. Changing the length and diameter of the runners mid way also made big differences in both performance but also sound .... we have tried almost ny design you can think of, before we opened our mouth on a public platform.